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postgres/src/backend/access/transam/xact.c
Bruce Momjian 5d950e3b0c Stamp copyrights for year 2011.
2011-01-01 13:18:15 -05:00

4808 lines
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/*-------------------------------------------------------------------------
*
* xact.c
* top level transaction system support routines
*
* See src/backend/access/transam/README for more information.
*
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/access/transam/xact.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <time.h>
#include <unistd.h>
#include "access/multixact.h"
#include "access/subtrans.h"
#include "access/transam.h"
#include "access/twophase.h"
#include "access/xact.h"
#include "access/xlogutils.h"
#include "catalog/catalog.h"
#include "catalog/namespace.h"
#include "catalog/storage.h"
#include "commands/async.h"
#include "commands/tablecmds.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "libpq/be-fsstubs.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "replication/walsender.h"
#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "storage/lmgr.h"
#include "storage/procarray.h"
#include "storage/sinvaladt.h"
#include "storage/smgr.h"
#include "storage/standby.h"
#include "utils/combocid.h"
#include "utils/guc.h"
#include "utils/inval.h"
#include "utils/memutils.h"
#include "utils/relcache.h"
#include "utils/relmapper.h"
#include "utils/snapmgr.h"
#include "pg_trace.h"
/*
* User-tweakable parameters
*/
int DefaultXactIsoLevel = XACT_READ_COMMITTED;
int XactIsoLevel;
bool DefaultXactReadOnly = false;
bool XactReadOnly;
bool XactSyncCommit = true;
int CommitDelay = 0; /* precommit delay in microseconds */
int CommitSiblings = 5; /* # concurrent xacts needed to sleep */
/*
* MyXactAccessedTempRel is set when a temporary relation is accessed.
* We don't allow PREPARE TRANSACTION in that case. (This is global
* so that it can be set from heapam.c.)
*/
bool MyXactAccessedTempRel = false;
/*
* transaction states - transaction state from server perspective
*/
typedef enum TransState
{
TRANS_DEFAULT, /* idle */
TRANS_START, /* transaction starting */
TRANS_INPROGRESS, /* inside a valid transaction */
TRANS_COMMIT, /* commit in progress */
TRANS_ABORT, /* abort in progress */
TRANS_PREPARE /* prepare in progress */
} TransState;
/*
* transaction block states - transaction state of client queries
*
* Note: the subtransaction states are used only for non-topmost
* transactions; the others appear only in the topmost transaction.
*/
typedef enum TBlockState
{
/* not-in-transaction-block states */
TBLOCK_DEFAULT, /* idle */
TBLOCK_STARTED, /* running single-query transaction */
/* transaction block states */
TBLOCK_BEGIN, /* starting transaction block */
TBLOCK_INPROGRESS, /* live transaction */
TBLOCK_END, /* COMMIT received */
TBLOCK_ABORT, /* failed xact, awaiting ROLLBACK */
TBLOCK_ABORT_END, /* failed xact, ROLLBACK received */
TBLOCK_ABORT_PENDING, /* live xact, ROLLBACK received */
TBLOCK_PREPARE, /* live xact, PREPARE received */
/* subtransaction states */
TBLOCK_SUBBEGIN, /* starting a subtransaction */
TBLOCK_SUBINPROGRESS, /* live subtransaction */
TBLOCK_SUBEND, /* RELEASE received */
TBLOCK_SUBABORT, /* failed subxact, awaiting ROLLBACK */
TBLOCK_SUBABORT_END, /* failed subxact, ROLLBACK received */
TBLOCK_SUBABORT_PENDING, /* live subxact, ROLLBACK received */
TBLOCK_SUBRESTART, /* live subxact, ROLLBACK TO received */
TBLOCK_SUBABORT_RESTART /* failed subxact, ROLLBACK TO received */
} TBlockState;
/*
* transaction state structure
*/
typedef struct TransactionStateData
{
TransactionId transactionId; /* my XID, or Invalid if none */
SubTransactionId subTransactionId; /* my subxact ID */
char *name; /* savepoint name, if any */
int savepointLevel; /* savepoint level */
TransState state; /* low-level state */
TBlockState blockState; /* high-level state */
int nestingLevel; /* transaction nesting depth */
int gucNestLevel; /* GUC context nesting depth */
MemoryContext curTransactionContext; /* my xact-lifetime context */
ResourceOwner curTransactionOwner; /* my query resources */
TransactionId *childXids; /* subcommitted child XIDs, in XID order */
int nChildXids; /* # of subcommitted child XIDs */
int maxChildXids; /* allocated size of childXids[] */
Oid prevUser; /* previous CurrentUserId setting */
int prevSecContext; /* previous SecurityRestrictionContext */
bool prevXactReadOnly; /* entry-time xact r/o state */
bool startedInRecovery; /* did we start in recovery? */
struct TransactionStateData *parent; /* back link to parent */
} TransactionStateData;
typedef TransactionStateData *TransactionState;
/*
* CurrentTransactionState always points to the current transaction state
* block. It will point to TopTransactionStateData when not in a
* transaction at all, or when in a top-level transaction.
*/
static TransactionStateData TopTransactionStateData = {
0, /* transaction id */
0, /* subtransaction id */
NULL, /* savepoint name */
0, /* savepoint level */
TRANS_DEFAULT, /* transaction state */
TBLOCK_DEFAULT, /* transaction block state from the client
* perspective */
0, /* transaction nesting depth */
0, /* GUC context nesting depth */
NULL, /* cur transaction context */
NULL, /* cur transaction resource owner */
NULL, /* subcommitted child Xids */
0, /* # of subcommitted child Xids */
0, /* allocated size of childXids[] */
InvalidOid, /* previous CurrentUserId setting */
0, /* previous SecurityRestrictionContext */
false, /* entry-time xact r/o state */
false, /* startedInRecovery */
NULL /* link to parent state block */
};
/*
* unreportedXids holds XIDs of all subtransactions that have not yet been
* reported in a XLOG_XACT_ASSIGNMENT record.
*/
static int nUnreportedXids;
static TransactionId unreportedXids[PGPROC_MAX_CACHED_SUBXIDS];
static TransactionState CurrentTransactionState = &TopTransactionStateData;
/*
* The subtransaction ID and command ID assignment counters are global
* to a whole transaction, so we do not keep them in the state stack.
*/
static SubTransactionId currentSubTransactionId;
static CommandId currentCommandId;
static bool currentCommandIdUsed;
/*
* xactStartTimestamp is the value of transaction_timestamp().
* stmtStartTimestamp is the value of statement_timestamp().
* xactStopTimestamp is the time at which we log a commit or abort WAL record.
* These do not change as we enter and exit subtransactions, so we don't
* keep them inside the TransactionState stack.
*/
static TimestampTz xactStartTimestamp;
static TimestampTz stmtStartTimestamp;
static TimestampTz xactStopTimestamp;
/*
* GID to be used for preparing the current transaction. This is also
* global to a whole transaction, so we don't keep it in the state stack.
*/
static char *prepareGID;
/*
* Some commands want to force synchronous commit.
*/
static bool forceSyncCommit = false;
/*
* Private context for transaction-abort work --- we reserve space for this
* at startup to ensure that AbortTransaction and AbortSubTransaction can work
* when we've run out of memory.
*/
static MemoryContext TransactionAbortContext = NULL;
/*
* List of add-on start- and end-of-xact callbacks
*/
typedef struct XactCallbackItem
{
struct XactCallbackItem *next;
XactCallback callback;
void *arg;
} XactCallbackItem;
static XactCallbackItem *Xact_callbacks = NULL;
/*
* List of add-on start- and end-of-subxact callbacks
*/
typedef struct SubXactCallbackItem
{
struct SubXactCallbackItem *next;
SubXactCallback callback;
void *arg;
} SubXactCallbackItem;
static SubXactCallbackItem *SubXact_callbacks = NULL;
/* local function prototypes */
static void AssignTransactionId(TransactionState s);
static void AbortTransaction(void);
static void AtAbort_Memory(void);
static void AtCleanup_Memory(void);
static void AtAbort_ResourceOwner(void);
static void AtCCI_LocalCache(void);
static void AtCommit_Memory(void);
static void AtStart_Cache(void);
static void AtStart_Memory(void);
static void AtStart_ResourceOwner(void);
static void CallXactCallbacks(XactEvent event);
static void CallSubXactCallbacks(SubXactEvent event,
SubTransactionId mySubid,
SubTransactionId parentSubid);
static void CleanupTransaction(void);
static void CommitTransaction(void);
static TransactionId RecordTransactionAbort(bool isSubXact);
static void StartTransaction(void);
static void StartSubTransaction(void);
static void CommitSubTransaction(void);
static void AbortSubTransaction(void);
static void CleanupSubTransaction(void);
static void PushTransaction(void);
static void PopTransaction(void);
static void AtSubAbort_Memory(void);
static void AtSubCleanup_Memory(void);
static void AtSubAbort_ResourceOwner(void);
static void AtSubCommit_Memory(void);
static void AtSubStart_Memory(void);
static void AtSubStart_ResourceOwner(void);
static void ShowTransactionState(const char *str);
static void ShowTransactionStateRec(TransactionState state);
static const char *BlockStateAsString(TBlockState blockState);
static const char *TransStateAsString(TransState state);
/* ----------------------------------------------------------------
* transaction state accessors
* ----------------------------------------------------------------
*/
/*
* IsTransactionState
*
* This returns true if we are inside a valid transaction; that is,
* it is safe to initiate database access, take heavyweight locks, etc.
*/
bool
IsTransactionState(void)
{
TransactionState s = CurrentTransactionState;
/*
* TRANS_DEFAULT and TRANS_ABORT are obviously unsafe states. However, we
* also reject the startup/shutdown states TRANS_START, TRANS_COMMIT,
* TRANS_PREPARE since it might be too soon or too late within those
* transition states to do anything interesting. Hence, the only "valid"
* state is TRANS_INPROGRESS.
*/
return (s->state == TRANS_INPROGRESS);
}
/*
* IsAbortedTransactionBlockState
*
* This returns true if we are within an aborted transaction block.
*/
bool
IsAbortedTransactionBlockState(void)
{
TransactionState s = CurrentTransactionState;
if (s->blockState == TBLOCK_ABORT ||
s->blockState == TBLOCK_SUBABORT)
return true;
return false;
}
/*
* GetTopTransactionId
*
* This will return the XID of the main transaction, assigning one if
* it's not yet set. Be careful to call this only inside a valid xact.
*/
TransactionId
GetTopTransactionId(void)
{
if (!TransactionIdIsValid(TopTransactionStateData.transactionId))
AssignTransactionId(&TopTransactionStateData);
return TopTransactionStateData.transactionId;
}
/*
* GetTopTransactionIdIfAny
*
* This will return the XID of the main transaction, if one is assigned.
* It will return InvalidTransactionId if we are not currently inside a
* transaction, or inside a transaction that hasn't yet been assigned an XID.
*/
TransactionId
GetTopTransactionIdIfAny(void)
{
return TopTransactionStateData.transactionId;
}
/*
* GetCurrentTransactionId
*
* This will return the XID of the current transaction (main or sub
* transaction), assigning one if it's not yet set. Be careful to call this
* only inside a valid xact.
*/
TransactionId
GetCurrentTransactionId(void)
{
TransactionState s = CurrentTransactionState;
if (!TransactionIdIsValid(s->transactionId))
AssignTransactionId(s);
return s->transactionId;
}
/*
* GetCurrentTransactionIdIfAny
*
* This will return the XID of the current sub xact, if one is assigned.
* It will return InvalidTransactionId if we are not currently inside a
* transaction, or inside a transaction that hasn't been assigned an XID yet.
*/
TransactionId
GetCurrentTransactionIdIfAny(void)
{
return CurrentTransactionState->transactionId;
}
/*
* AssignTransactionId
*
* Assigns a new permanent XID to the given TransactionState.
* We do not assign XIDs to transactions until/unless this is called.
* Also, any parent TransactionStates that don't yet have XIDs are assigned
* one; this maintains the invariant that a child transaction has an XID
* following its parent's.
*/
static void
AssignTransactionId(TransactionState s)
{
bool isSubXact = (s->parent != NULL);
ResourceOwner currentOwner;
/* Assert that caller didn't screw up */
Assert(!TransactionIdIsValid(s->transactionId));
Assert(s->state == TRANS_INPROGRESS);
/*
* Ensure parent(s) have XIDs, so that a child always has an XID later
* than its parent. Musn't recurse here, or we might get a stack overflow
* if we're at the bottom of a huge stack of subtransactions none of which
* have XIDs yet.
*/
if (isSubXact && !TransactionIdIsValid(s->parent->transactionId))
{
TransactionState p = s->parent;
TransactionState *parents;
size_t parentOffset = 0;
parents = palloc(sizeof(TransactionState) * s->nestingLevel);
while (p != NULL && !TransactionIdIsValid(p->transactionId))
{
parents[parentOffset++] = p;
p = p->parent;
}
/*
* This is technically a recursive call, but the recursion will
* never be more than one layer deep.
*/
while (parentOffset != 0)
AssignTransactionId(parents[--parentOffset]);
pfree(parents);
}
/*
* Generate a new Xid and record it in PG_PROC and pg_subtrans.
*
* NB: we must make the subtrans entry BEFORE the Xid appears anywhere in
* shared storage other than PG_PROC; because if there's no room for it in
* PG_PROC, the subtrans entry is needed to ensure that other backends see
* the Xid as "running". See GetNewTransactionId.
*/
s->transactionId = GetNewTransactionId(isSubXact);
if (isSubXact)
SubTransSetParent(s->transactionId, s->parent->transactionId, false);
/*
* Acquire lock on the transaction XID. (We assume this cannot block.) We
* have to ensure that the lock is assigned to the transaction's own
* ResourceOwner.
*/
currentOwner = CurrentResourceOwner;
PG_TRY();
{
CurrentResourceOwner = s->curTransactionOwner;
XactLockTableInsert(s->transactionId);
}
PG_CATCH();
{
/* Ensure CurrentResourceOwner is restored on error */
CurrentResourceOwner = currentOwner;
PG_RE_THROW();
}
PG_END_TRY();
CurrentResourceOwner = currentOwner;
/*
* Every PGPROC_MAX_CACHED_SUBXIDS assigned transaction ids within each
* top-level transaction we issue a WAL record for the assignment. We
* include the top-level xid and all the subxids that have not yet been
* reported using XLOG_XACT_ASSIGNMENT records.
*
* This is required to limit the amount of shared memory required in a hot
* standby server to keep track of in-progress XIDs. See notes for
* RecordKnownAssignedTransactionIds().
*
* We don't keep track of the immediate parent of each subxid, only the
* top-level transaction that each subxact belongs to. This is correct in
* recovery only because aborted subtransactions are separately WAL
* logged.
*/
if (isSubXact && XLogStandbyInfoActive())
{
unreportedXids[nUnreportedXids] = s->transactionId;
nUnreportedXids++;
/*
* ensure this test matches similar one in
* RecoverPreparedTransactions()
*/
if (nUnreportedXids >= PGPROC_MAX_CACHED_SUBXIDS)
{
XLogRecData rdata[2];
xl_xact_assignment xlrec;
/*
* xtop is always set by now because we recurse up transaction
* stack to the highest unassigned xid and then come back down
*/
xlrec.xtop = GetTopTransactionId();
Assert(TransactionIdIsValid(xlrec.xtop));
xlrec.nsubxacts = nUnreportedXids;
rdata[0].data = (char *) &xlrec;
rdata[0].len = MinSizeOfXactAssignment;
rdata[0].buffer = InvalidBuffer;
rdata[0].next = &rdata[1];
rdata[1].data = (char *) unreportedXids;
rdata[1].len = PGPROC_MAX_CACHED_SUBXIDS * sizeof(TransactionId);
rdata[1].buffer = InvalidBuffer;
rdata[1].next = NULL;
(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ASSIGNMENT, rdata);
nUnreportedXids = 0;
}
}
}
/*
* GetCurrentSubTransactionId
*/
SubTransactionId
GetCurrentSubTransactionId(void)
{
TransactionState s = CurrentTransactionState;
return s->subTransactionId;
}
/*
* GetCurrentCommandId
*
* "used" must be TRUE if the caller intends to use the command ID to mark
* inserted/updated/deleted tuples. FALSE means the ID is being fetched
* for read-only purposes (ie, as a snapshot validity cutoff). See
* CommandCounterIncrement() for discussion.
*/
CommandId
GetCurrentCommandId(bool used)
{
/* this is global to a transaction, not subtransaction-local */
if (used)
currentCommandIdUsed = true;
return currentCommandId;
}
/*
* GetCurrentTransactionStartTimestamp
*/
TimestampTz
GetCurrentTransactionStartTimestamp(void)
{
return xactStartTimestamp;
}
/*
* GetCurrentStatementStartTimestamp
*/
TimestampTz
GetCurrentStatementStartTimestamp(void)
{
return stmtStartTimestamp;
}
/*
* GetCurrentTransactionStopTimestamp
*
* We return current time if the transaction stop time hasn't been set
* (which can happen if we decide we don't need to log an XLOG record).
*/
TimestampTz
GetCurrentTransactionStopTimestamp(void)
{
if (xactStopTimestamp != 0)
return xactStopTimestamp;
return GetCurrentTimestamp();
}
/*
* SetCurrentStatementStartTimestamp
*/
void
SetCurrentStatementStartTimestamp(void)
{
stmtStartTimestamp = GetCurrentTimestamp();
}
/*
* SetCurrentTransactionStopTimestamp
*/
static inline void
SetCurrentTransactionStopTimestamp(void)
{
xactStopTimestamp = GetCurrentTimestamp();
}
/*
* GetCurrentTransactionNestLevel
*
* Note: this will return zero when not inside any transaction, one when
* inside a top-level transaction, etc.
*/
int
GetCurrentTransactionNestLevel(void)
{
TransactionState s = CurrentTransactionState;
return s->nestingLevel;
}
/*
* TransactionIdIsCurrentTransactionId
*/
bool
TransactionIdIsCurrentTransactionId(TransactionId xid)
{
TransactionState s;
/*
* We always say that BootstrapTransactionId is "not my transaction ID"
* even when it is (ie, during bootstrap). Along with the fact that
* transam.c always treats BootstrapTransactionId as already committed,
* this causes the tqual.c routines to see all tuples as committed, which
* is what we need during bootstrap. (Bootstrap mode only inserts tuples,
* it never updates or deletes them, so all tuples can be presumed good
* immediately.)
*
* Likewise, InvalidTransactionId and FrozenTransactionId are certainly
* not my transaction ID, so we can just return "false" immediately for
* any non-normal XID.
*/
if (!TransactionIdIsNormal(xid))
return false;
/*
* We will return true for the Xid of the current subtransaction, any of
* its subcommitted children, any of its parents, or any of their
* previously subcommitted children. However, a transaction being aborted
* is no longer "current", even though it may still have an entry on the
* state stack.
*/
for (s = CurrentTransactionState; s != NULL; s = s->parent)
{
int low,
high;
if (s->state == TRANS_ABORT)
continue;
if (!TransactionIdIsValid(s->transactionId))
continue; /* it can't have any child XIDs either */
if (TransactionIdEquals(xid, s->transactionId))
return true;
/* As the childXids array is ordered, we can use binary search */
low = 0;
high = s->nChildXids - 1;
while (low <= high)
{
int middle;
TransactionId probe;
middle = low + (high - low) / 2;
probe = s->childXids[middle];
if (TransactionIdEquals(probe, xid))
return true;
else if (TransactionIdPrecedes(probe, xid))
low = middle + 1;
else
high = middle - 1;
}
}
return false;
}
/*
* TransactionStartedDuringRecovery
*
* Returns true if the current transaction started while recovery was still
* in progress. Recovery might have ended since so RecoveryInProgress() might
* return false already.
*/
bool
TransactionStartedDuringRecovery(void)
{
return CurrentTransactionState->startedInRecovery;
}
/*
* CommandCounterIncrement
*/
void
CommandCounterIncrement(void)
{
/*
* If the current value of the command counter hasn't been "used" to mark
* tuples, we need not increment it, since there's no need to distinguish
* a read-only command from others. This helps postpone command counter
* overflow, and keeps no-op CommandCounterIncrement operations cheap.
*/
if (currentCommandIdUsed)
{
currentCommandId += 1;
if (currentCommandId == FirstCommandId) /* check for overflow */
{
currentCommandId -= 1;
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("cannot have more than 2^32-1 commands in a transaction")));
}
currentCommandIdUsed = false;
/* Propagate new command ID into static snapshots */
SnapshotSetCommandId(currentCommandId);
/*
* Make any catalog changes done by the just-completed command visible
* in the local syscache. We obviously don't need to do this after a
* read-only command. (But see hacks in inval.c to make real sure we
* don't think a command that queued inval messages was read-only.)
*/
AtCCI_LocalCache();
}
}
/*
* ForceSyncCommit
*
* Interface routine to allow commands to force a synchronous commit of the
* current top-level transaction
*/
void
ForceSyncCommit(void)
{
forceSyncCommit = true;
}
/* ----------------------------------------------------------------
* StartTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtStart_Cache
*/
static void
AtStart_Cache(void)
{
AcceptInvalidationMessages();
}
/*
* AtStart_Memory
*/
static void
AtStart_Memory(void)
{
TransactionState s = CurrentTransactionState;
/*
* If this is the first time through, create a private context for
* AbortTransaction to work in. By reserving some space now, we can
* insulate AbortTransaction from out-of-memory scenarios. Like
* ErrorContext, we set it up with slow growth rate and a nonzero minimum
* size, so that space will be reserved immediately.
*/
if (TransactionAbortContext == NULL)
TransactionAbortContext =
AllocSetContextCreate(TopMemoryContext,
"TransactionAbortContext",
32 * 1024,
32 * 1024,
32 * 1024);
/*
* We shouldn't have a transaction context already.
*/
Assert(TopTransactionContext == NULL);
/*
* Create a toplevel context for the transaction.
*/
TopTransactionContext =
AllocSetContextCreate(TopMemoryContext,
"TopTransactionContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/*
* In a top-level transaction, CurTransactionContext is the same as
* TopTransactionContext.
*/
CurTransactionContext = TopTransactionContext;
s->curTransactionContext = CurTransactionContext;
/* Make the CurTransactionContext active. */
MemoryContextSwitchTo(CurTransactionContext);
}
/*
* AtStart_ResourceOwner
*/
static void
AtStart_ResourceOwner(void)
{
TransactionState s = CurrentTransactionState;
/*
* We shouldn't have a transaction resource owner already.
*/
Assert(TopTransactionResourceOwner == NULL);
/*
* Create a toplevel resource owner for the transaction.
*/
s->curTransactionOwner = ResourceOwnerCreate(NULL, "TopTransaction");
TopTransactionResourceOwner = s->curTransactionOwner;
CurTransactionResourceOwner = s->curTransactionOwner;
CurrentResourceOwner = s->curTransactionOwner;
}
/* ----------------------------------------------------------------
* StartSubTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtSubStart_Memory
*/
static void
AtSubStart_Memory(void)
{
TransactionState s = CurrentTransactionState;
Assert(CurTransactionContext != NULL);
/*
* Create a CurTransactionContext, which will be used to hold data that
* survives subtransaction commit but disappears on subtransaction abort.
* We make it a child of the immediate parent's CurTransactionContext.
*/
CurTransactionContext = AllocSetContextCreate(CurTransactionContext,
"CurTransactionContext",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
s->curTransactionContext = CurTransactionContext;
/* Make the CurTransactionContext active. */
MemoryContextSwitchTo(CurTransactionContext);
}
/*
* AtSubStart_ResourceOwner
*/
static void
AtSubStart_ResourceOwner(void)
{
TransactionState s = CurrentTransactionState;
Assert(s->parent != NULL);
/*
* Create a resource owner for the subtransaction. We make it a child of
* the immediate parent's resource owner.
*/
s->curTransactionOwner =
ResourceOwnerCreate(s->parent->curTransactionOwner,
"SubTransaction");
CurTransactionResourceOwner = s->curTransactionOwner;
CurrentResourceOwner = s->curTransactionOwner;
}
/* ----------------------------------------------------------------
* CommitTransaction stuff
* ----------------------------------------------------------------
*/
/*
* RecordTransactionCommit
*
* Returns latest XID among xact and its children, or InvalidTransactionId
* if the xact has no XID. (We compute that here just because it's easier.)
*/
static TransactionId
RecordTransactionCommit(void)
{
TransactionId xid = GetTopTransactionIdIfAny();
bool markXidCommitted = TransactionIdIsValid(xid);
TransactionId latestXid = InvalidTransactionId;
int nrels;
RelFileNode *rels;
int nchildren;
TransactionId *children;
int nmsgs = 0;
SharedInvalidationMessage *invalMessages = NULL;
bool RelcacheInitFileInval = false;
bool wrote_xlog;
/* Get data needed for commit record */
nrels = smgrGetPendingDeletes(true, &rels);
nchildren = xactGetCommittedChildren(&children);
if (XLogStandbyInfoActive())
nmsgs = xactGetCommittedInvalidationMessages(&invalMessages,
&RelcacheInitFileInval);
wrote_xlog = (XactLastRecEnd.xrecoff != 0);
/*
* If we haven't been assigned an XID yet, we neither can, nor do we want
* to write a COMMIT record.
*/
if (!markXidCommitted)
{
/*
* We expect that every smgrscheduleunlink is followed by a catalog
* update, and hence XID assignment, so we shouldn't get here with any
* pending deletes. Use a real test not just an Assert to check this,
* since it's a bit fragile.
*/
if (nrels != 0)
elog(ERROR, "cannot commit a transaction that deleted files but has no xid");
/* Can't have child XIDs either; AssignTransactionId enforces this */
Assert(nchildren == 0);
/*
* If we didn't create XLOG entries, we're done here; otherwise we
* should flush those entries the same as a commit record. (An
* example of a possible record that wouldn't cause an XID to be
* assigned is a sequence advance record due to nextval() --- we want
* to flush that to disk before reporting commit.)
*/
if (!wrote_xlog)
goto cleanup;
}
else
{
/*
* Begin commit critical section and insert the commit XLOG record.
*/
XLogRecData rdata[4];
int lastrdata = 0;
xl_xact_commit xlrec;
/* Tell bufmgr and smgr to prepare for commit */
BufmgrCommit();
/*
* Set flags required for recovery processing of commits.
*/
xlrec.xinfo = 0;
if (RelcacheInitFileInval)
xlrec.xinfo |= XACT_COMPLETION_UPDATE_RELCACHE_FILE;
if (forceSyncCommit)
xlrec.xinfo |= XACT_COMPLETION_FORCE_SYNC_COMMIT;
xlrec.dbId = MyDatabaseId;
xlrec.tsId = MyDatabaseTableSpace;
/*
* Mark ourselves as within our "commit critical section". This
* forces any concurrent checkpoint to wait until we've updated
* pg_clog. Without this, it is possible for the checkpoint to set
* REDO after the XLOG record but fail to flush the pg_clog update to
* disk, leading to loss of the transaction commit if the system
* crashes a little later.
*
* Note: we could, but don't bother to, set this flag in
* RecordTransactionAbort. That's because loss of a transaction abort
* is noncritical; the presumption would be that it aborted, anyway.
*
* It's safe to change the inCommit flag of our own backend without
* holding the ProcArrayLock, since we're the only one modifying it.
* This makes checkpoint's determination of which xacts are inCommit a
* bit fuzzy, but it doesn't matter.
*/
START_CRIT_SECTION();
MyProc->inCommit = true;
SetCurrentTransactionStopTimestamp();
xlrec.xact_time = xactStopTimestamp;
xlrec.nrels = nrels;
xlrec.nsubxacts = nchildren;
xlrec.nmsgs = nmsgs;
rdata[0].data = (char *) (&xlrec);
rdata[0].len = MinSizeOfXactCommit;
rdata[0].buffer = InvalidBuffer;
/* dump rels to delete */
if (nrels > 0)
{
rdata[0].next = &(rdata[1]);
rdata[1].data = (char *) rels;
rdata[1].len = nrels * sizeof(RelFileNode);
rdata[1].buffer = InvalidBuffer;
lastrdata = 1;
}
/* dump committed child Xids */
if (nchildren > 0)
{
rdata[lastrdata].next = &(rdata[2]);
rdata[2].data = (char *) children;
rdata[2].len = nchildren * sizeof(TransactionId);
rdata[2].buffer = InvalidBuffer;
lastrdata = 2;
}
/* dump shared cache invalidation messages */
if (nmsgs > 0)
{
rdata[lastrdata].next = &(rdata[3]);
rdata[3].data = (char *) invalMessages;
rdata[3].len = nmsgs * sizeof(SharedInvalidationMessage);
rdata[3].buffer = InvalidBuffer;
lastrdata = 3;
}
rdata[lastrdata].next = NULL;
(void) XLogInsert(RM_XACT_ID, XLOG_XACT_COMMIT, rdata);
}
/*
* Check if we want to commit asynchronously. We can allow the XLOG flush
* to happen asynchronously if synchronous_commit=off, or if the current
* transaction has not performed any WAL-logged operation. The latter case
* can arise if the current transaction wrote only to temporary tables.
* In case of a crash, the loss of such a transaction will be irrelevant
* since temp tables will be lost anyway. (Given the foregoing, you might
* think that it would be unnecessary to emit the XLOG record at all in
* this case, but we don't currently try to do that. It would certainly
* cause problems at least in Hot Standby mode, where the KnownAssignedXids
* machinery requires tracking every XID assignment. It might be OK to
* skip it only when wal_level < hot_standby, but for now we don't.)
*
* However, if we're doing cleanup of any non-temp rels or committing any
* command that wanted to force sync commit, then we must flush XLOG
* immediately. (We must not allow asynchronous commit if there are any
* non-temp tables to be deleted, because we might delete the files before
* the COMMIT record is flushed to disk. We do allow asynchronous commit
* if all to-be-deleted tables are temporary though, since they are lost
* anyway if we crash.)
*/
if ((wrote_xlog && XactSyncCommit) || forceSyncCommit || nrels > 0)
{
/*
* Synchronous commit case:
*
* Sleep before flush! So we can flush more than one commit records
* per single fsync. (The idea is some other backend may do the
* XLogFlush while we're sleeping. This needs work still, because on
* most Unixen, the minimum select() delay is 10msec or more, which is
* way too long.)
*
* We do not sleep if enableFsync is not turned on, nor if there are
* fewer than CommitSiblings other backends with active transactions.
*/
if (CommitDelay > 0 && enableFsync &&
MinimumActiveBackends(CommitSiblings))
pg_usleep(CommitDelay);
XLogFlush(XactLastRecEnd);
/*
* Wake up all walsenders to send WAL up to the COMMIT record
* immediately if replication is enabled
*/
if (max_wal_senders > 0)
WalSndWakeup();
/*
* Now we may update the CLOG, if we wrote a COMMIT record above
*/
if (markXidCommitted)
TransactionIdCommitTree(xid, nchildren, children);
}
else
{
/*
* Asynchronous commit case:
*
* This enables possible committed transaction loss in the case of a
* postmaster crash because WAL buffers are left unwritten. Ideally we
* could issue the WAL write without the fsync, but some
* wal_sync_methods do not allow separate write/fsync.
*
* Report the latest async commit LSN, so that the WAL writer knows to
* flush this commit.
*/
XLogSetAsyncXactLSN(XactLastRecEnd);
/*
* We must not immediately update the CLOG, since we didn't flush the
* XLOG. Instead, we store the LSN up to which the XLOG must be
* flushed before the CLOG may be updated.
*/
if (markXidCommitted)
TransactionIdAsyncCommitTree(xid, nchildren, children, XactLastRecEnd);
}
/*
* If we entered a commit critical section, leave it now, and let
* checkpoints proceed.
*/
if (markXidCommitted)
{
MyProc->inCommit = false;
END_CRIT_SECTION();
}
/* Compute latestXid while we have the child XIDs handy */
latestXid = TransactionIdLatest(xid, nchildren, children);
/* Reset XactLastRecEnd until the next transaction writes something */
XactLastRecEnd.xrecoff = 0;
cleanup:
/* Clean up local data */
if (rels)
pfree(rels);
return latestXid;
}
/*
* AtCCI_LocalCache
*/
static void
AtCCI_LocalCache(void)
{
/*
* Make any pending relation map changes visible. We must do this before
* processing local sinval messages, so that the map changes will get
* reflected into the relcache when relcache invals are processed.
*/
AtCCI_RelationMap();
/*
* Make catalog changes visible to me for the next command.
*/
CommandEndInvalidationMessages();
}
/*
* AtCommit_Memory
*/
static void
AtCommit_Memory(void)
{
/*
* Now that we're "out" of a transaction, have the system allocate things
* in the top memory context instead of per-transaction contexts.
*/
MemoryContextSwitchTo(TopMemoryContext);
/*
* Release all transaction-local memory.
*/
Assert(TopTransactionContext != NULL);
MemoryContextDelete(TopTransactionContext);
TopTransactionContext = NULL;
CurTransactionContext = NULL;
CurrentTransactionState->curTransactionContext = NULL;
}
/* ----------------------------------------------------------------
* CommitSubTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtSubCommit_Memory
*/
static void
AtSubCommit_Memory(void)
{
TransactionState s = CurrentTransactionState;
Assert(s->parent != NULL);
/* Return to parent transaction level's memory context. */
CurTransactionContext = s->parent->curTransactionContext;
MemoryContextSwitchTo(CurTransactionContext);
/*
* Ordinarily we cannot throw away the child's CurTransactionContext,
* since the data it contains will be needed at upper commit. However, if
* there isn't actually anything in it, we can throw it away. This avoids
* a small memory leak in the common case of "trivial" subxacts.
*/
if (MemoryContextIsEmpty(s->curTransactionContext))
{
MemoryContextDelete(s->curTransactionContext);
s->curTransactionContext = NULL;
}
}
/*
* AtSubCommit_childXids
*
* Pass my own XID and my child XIDs up to my parent as committed children.
*/
static void
AtSubCommit_childXids(void)
{
TransactionState s = CurrentTransactionState;
int new_nChildXids;
Assert(s->parent != NULL);
/*
* The parent childXids array will need to hold my XID and all my
* childXids, in addition to the XIDs already there.
*/
new_nChildXids = s->parent->nChildXids + s->nChildXids + 1;
/* Allocate or enlarge the parent array if necessary */
if (s->parent->maxChildXids < new_nChildXids)
{
int new_maxChildXids;
TransactionId *new_childXids;
/*
* Make it 2x what's needed right now, to avoid having to enlarge it
* repeatedly. But we can't go above MaxAllocSize. (The latter limit
* is what ensures that we don't need to worry about integer overflow
* here or in the calculation of new_nChildXids.)
*/
new_maxChildXids = Min(new_nChildXids * 2,
(int) (MaxAllocSize / sizeof(TransactionId)));
if (new_maxChildXids < new_nChildXids)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("maximum number of committed subtransactions (%d) exceeded",
(int) (MaxAllocSize / sizeof(TransactionId)))));
/*
* We keep the child-XID arrays in TopTransactionContext; this avoids
* setting up child-transaction contexts for what might be just a few
* bytes of grandchild XIDs.
*/
if (s->parent->childXids == NULL)
new_childXids =
MemoryContextAlloc(TopTransactionContext,
new_maxChildXids * sizeof(TransactionId));
else
new_childXids = repalloc(s->parent->childXids,
new_maxChildXids * sizeof(TransactionId));
s->parent->childXids = new_childXids;
s->parent->maxChildXids = new_maxChildXids;
}
/*
* Copy all my XIDs to parent's array.
*
* Note: We rely on the fact that the XID of a child always follows that
* of its parent. By copying the XID of this subtransaction before the
* XIDs of its children, we ensure that the array stays ordered. Likewise,
* all XIDs already in the array belong to subtransactions started and
* subcommitted before us, so their XIDs must precede ours.
*/
s->parent->childXids[s->parent->nChildXids] = s->transactionId;
if (s->nChildXids > 0)
memcpy(&s->parent->childXids[s->parent->nChildXids + 1],
s->childXids,
s->nChildXids * sizeof(TransactionId));
s->parent->nChildXids = new_nChildXids;
/* Release child's array to avoid leakage */
if (s->childXids != NULL)
pfree(s->childXids);
/* We must reset these to avoid double-free if fail later in commit */
s->childXids = NULL;
s->nChildXids = 0;
s->maxChildXids = 0;
}
/* ----------------------------------------------------------------
* AbortTransaction stuff
* ----------------------------------------------------------------
*/
/*
* RecordTransactionAbort
*
* Returns latest XID among xact and its children, or InvalidTransactionId
* if the xact has no XID. (We compute that here just because it's easier.)
*/
static TransactionId
RecordTransactionAbort(bool isSubXact)
{
TransactionId xid = GetCurrentTransactionIdIfAny();
TransactionId latestXid;
int nrels;
RelFileNode *rels;
int nchildren;
TransactionId *children;
XLogRecData rdata[3];
int lastrdata = 0;
xl_xact_abort xlrec;
/*
* If we haven't been assigned an XID, nobody will care whether we aborted
* or not. Hence, we're done in that case. It does not matter if we have
* rels to delete (note that this routine is not responsible for actually
* deleting 'em). We cannot have any child XIDs, either.
*/
if (!TransactionIdIsValid(xid))
{
/* Reset XactLastRecEnd until the next transaction writes something */
if (!isSubXact)
XactLastRecEnd.xrecoff = 0;
return InvalidTransactionId;
}
/*
* We have a valid XID, so we should write an ABORT record for it.
*
* We do not flush XLOG to disk here, since the default assumption after a
* crash would be that we aborted, anyway. For the same reason, we don't
* need to worry about interlocking against checkpoint start.
*/
/*
* Check that we haven't aborted halfway through RecordTransactionCommit.
*/
if (TransactionIdDidCommit(xid))
elog(PANIC, "cannot abort transaction %u, it was already committed",
xid);
/* Fetch the data we need for the abort record */
nrels = smgrGetPendingDeletes(false, &rels);
nchildren = xactGetCommittedChildren(&children);
/* XXX do we really need a critical section here? */
START_CRIT_SECTION();
/* Write the ABORT record */
if (isSubXact)
xlrec.xact_time = GetCurrentTimestamp();
else
{
SetCurrentTransactionStopTimestamp();
xlrec.xact_time = xactStopTimestamp;
}
xlrec.nrels = nrels;
xlrec.nsubxacts = nchildren;
rdata[0].data = (char *) (&xlrec);
rdata[0].len = MinSizeOfXactAbort;
rdata[0].buffer = InvalidBuffer;
/* dump rels to delete */
if (nrels > 0)
{
rdata[0].next = &(rdata[1]);
rdata[1].data = (char *) rels;
rdata[1].len = nrels * sizeof(RelFileNode);
rdata[1].buffer = InvalidBuffer;
lastrdata = 1;
}
/* dump committed child Xids */
if (nchildren > 0)
{
rdata[lastrdata].next = &(rdata[2]);
rdata[2].data = (char *) children;
rdata[2].len = nchildren * sizeof(TransactionId);
rdata[2].buffer = InvalidBuffer;
lastrdata = 2;
}
rdata[lastrdata].next = NULL;
(void) XLogInsert(RM_XACT_ID, XLOG_XACT_ABORT, rdata);
/*
* Report the latest async abort LSN, so that the WAL writer knows to
* flush this abort. There's nothing to be gained by delaying this, since
* WALWriter may as well do this when it can. This is important with
* streaming replication because if we don't flush WAL regularly we will
* find that large aborts leave us with a long backlog for when commits
* occur after the abort, increasing our window of data loss should
* problems occur at that point.
*/
if (!isSubXact)
XLogSetAsyncXactLSN(XactLastRecEnd);
/*
* Mark the transaction aborted in clog. This is not absolutely necessary
* but we may as well do it while we are here; also, in the subxact case
* it is helpful because XactLockTableWait makes use of it to avoid
* waiting for already-aborted subtransactions. It is OK to do it without
* having flushed the ABORT record to disk, because in event of a crash
* we'd be assumed to have aborted anyway.
*/
TransactionIdAbortTree(xid, nchildren, children);
END_CRIT_SECTION();
/* Compute latestXid while we have the child XIDs handy */
latestXid = TransactionIdLatest(xid, nchildren, children);
/*
* If we're aborting a subtransaction, we can immediately remove failed
* XIDs from PGPROC's cache of running child XIDs. We do that here for
* subxacts, because we already have the child XID array at hand. For
* main xacts, the equivalent happens just after this function returns.
*/
if (isSubXact)
XidCacheRemoveRunningXids(xid, nchildren, children, latestXid);
/* Reset XactLastRecEnd until the next transaction writes something */
if (!isSubXact)
XactLastRecEnd.xrecoff = 0;
/* And clean up local data */
if (rels)
pfree(rels);
return latestXid;
}
/*
* AtAbort_Memory
*/
static void
AtAbort_Memory(void)
{
/*
* Switch into TransactionAbortContext, which should have some free space
* even if nothing else does. We'll work in this context until we've
* finished cleaning up.
*
* It is barely possible to get here when we've not been able to create
* TransactionAbortContext yet; if so use TopMemoryContext.
*/
if (TransactionAbortContext != NULL)
MemoryContextSwitchTo(TransactionAbortContext);
else
MemoryContextSwitchTo(TopMemoryContext);
}
/*
* AtSubAbort_Memory
*/
static void
AtSubAbort_Memory(void)
{
Assert(TransactionAbortContext != NULL);
MemoryContextSwitchTo(TransactionAbortContext);
}
/*
* AtAbort_ResourceOwner
*/
static void
AtAbort_ResourceOwner(void)
{
/*
* Make sure we have a valid ResourceOwner, if possible (else it will be
* NULL, which is OK)
*/
CurrentResourceOwner = TopTransactionResourceOwner;
}
/*
* AtSubAbort_ResourceOwner
*/
static void
AtSubAbort_ResourceOwner(void)
{
TransactionState s = CurrentTransactionState;
/* Make sure we have a valid ResourceOwner */
CurrentResourceOwner = s->curTransactionOwner;
}
/*
* AtSubAbort_childXids
*/
static void
AtSubAbort_childXids(void)
{
TransactionState s = CurrentTransactionState;
/*
* We keep the child-XID arrays in TopTransactionContext (see
* AtSubCommit_childXids). This means we'd better free the array
* explicitly at abort to avoid leakage.
*/
if (s->childXids != NULL)
pfree(s->childXids);
s->childXids = NULL;
s->nChildXids = 0;
s->maxChildXids = 0;
/*
* We could prune the unreportedXids array here. But we don't bother. That
* would potentially reduce number of XLOG_XACT_ASSIGNMENT records but it
* would likely introduce more CPU time into the more common paths, so we
* choose not to do that.
*/
}
/* ----------------------------------------------------------------
* CleanupTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtCleanup_Memory
*/
static void
AtCleanup_Memory(void)
{
Assert(CurrentTransactionState->parent == NULL);
/*
* Now that we're "out" of a transaction, have the system allocate things
* in the top memory context instead of per-transaction contexts.
*/
MemoryContextSwitchTo(TopMemoryContext);
/*
* Clear the special abort context for next time.
*/
if (TransactionAbortContext != NULL)
MemoryContextResetAndDeleteChildren(TransactionAbortContext);
/*
* Release all transaction-local memory.
*/
if (TopTransactionContext != NULL)
MemoryContextDelete(TopTransactionContext);
TopTransactionContext = NULL;
CurTransactionContext = NULL;
CurrentTransactionState->curTransactionContext = NULL;
}
/* ----------------------------------------------------------------
* CleanupSubTransaction stuff
* ----------------------------------------------------------------
*/
/*
* AtSubCleanup_Memory
*/
static void
AtSubCleanup_Memory(void)
{
TransactionState s = CurrentTransactionState;
Assert(s->parent != NULL);
/* Make sure we're not in an about-to-be-deleted context */
MemoryContextSwitchTo(s->parent->curTransactionContext);
CurTransactionContext = s->parent->curTransactionContext;
/*
* Clear the special abort context for next time.
*/
if (TransactionAbortContext != NULL)
MemoryContextResetAndDeleteChildren(TransactionAbortContext);
/*
* Delete the subxact local memory contexts. Its CurTransactionContext can
* go too (note this also kills CurTransactionContexts from any children
* of the subxact).
*/
if (s->curTransactionContext)
MemoryContextDelete(s->curTransactionContext);
s->curTransactionContext = NULL;
}
/* ----------------------------------------------------------------
* interface routines
* ----------------------------------------------------------------
*/
/*
* StartTransaction
*/
static void
StartTransaction(void)
{
TransactionState s;
VirtualTransactionId vxid;
/*
* Let's just make sure the state stack is empty
*/
s = &TopTransactionStateData;
CurrentTransactionState = s;
/*
* check the current transaction state
*/
if (s->state != TRANS_DEFAULT)
elog(WARNING, "StartTransaction while in %s state",
TransStateAsString(s->state));
/*
* set the current transaction state information appropriately during
* start processing
*/
s->state = TRANS_START;
s->transactionId = InvalidTransactionId; /* until assigned */
/*
* Make sure we've reset xact state variables
*
* If recovery is still in progress, mark this transaction as read-only.
* We have lower level defences in XLogInsert and elsewhere to stop us
* from modifying data during recovery, but this gives the normal
* indication to the user that the transaction is read-only.
*/
if (RecoveryInProgress())
{
s->startedInRecovery = true;
XactReadOnly = true;
}
else
{
s->startedInRecovery = false;
XactReadOnly = DefaultXactReadOnly;
}
XactIsoLevel = DefaultXactIsoLevel;
forceSyncCommit = false;
MyXactAccessedTempRel = false;
/*
* reinitialize within-transaction counters
*/
s->subTransactionId = TopSubTransactionId;
currentSubTransactionId = TopSubTransactionId;
currentCommandId = FirstCommandId;
currentCommandIdUsed = false;
/*
* initialize reported xid accounting
*/
nUnreportedXids = 0;
/*
* must initialize resource-management stuff first
*/
AtStart_Memory();
AtStart_ResourceOwner();
/*
* Assign a new LocalTransactionId, and combine it with the backendId to
* form a virtual transaction id.
*/
vxid.backendId = MyBackendId;
vxid.localTransactionId = GetNextLocalTransactionId();
/*
* Lock the virtual transaction id before we announce it in the proc array
*/
VirtualXactLockTableInsert(vxid);
/*
* Advertise it in the proc array. We assume assignment of
* LocalTransactionID is atomic, and the backendId should be set already.
*/
Assert(MyProc->backendId == vxid.backendId);
MyProc->lxid = vxid.localTransactionId;
TRACE_POSTGRESQL_TRANSACTION_START(vxid.localTransactionId);
/*
* set transaction_timestamp() (a/k/a now()). We want this to be the same
* as the first command's statement_timestamp(), so don't do a fresh
* GetCurrentTimestamp() call (which'd be expensive anyway). Also, mark
* xactStopTimestamp as unset.
*/
xactStartTimestamp = stmtStartTimestamp;
xactStopTimestamp = 0;
pgstat_report_xact_timestamp(xactStartTimestamp);
/*
* initialize current transaction state fields
*
* note: prevXactReadOnly is not used at the outermost level
*/
s->nestingLevel = 1;
s->gucNestLevel = 1;
s->childXids = NULL;
s->nChildXids = 0;
s->maxChildXids = 0;
GetUserIdAndSecContext(&s->prevUser, &s->prevSecContext);
/* SecurityRestrictionContext should never be set outside a transaction */
Assert(s->prevSecContext == 0);
/*
* initialize other subsystems for new transaction
*/
AtStart_GUC();
AtStart_Inval();
AtStart_Cache();
AfterTriggerBeginXact();
/*
* done with start processing, set current transaction state to "in
* progress"
*/
s->state = TRANS_INPROGRESS;
ShowTransactionState("StartTransaction");
}
/*
* CommitTransaction
*
* NB: if you change this routine, better look at PrepareTransaction too!
*/
static void
CommitTransaction(void)
{
TransactionState s = CurrentTransactionState;
TransactionId latestXid;
ShowTransactionState("CommitTransaction");
/*
* check the current transaction state
*/
if (s->state != TRANS_INPROGRESS)
elog(WARNING, "CommitTransaction while in %s state",
TransStateAsString(s->state));
Assert(s->parent == NULL);
/*
* Do pre-commit processing (most of this stuff requires database access,
* and in fact could still cause an error...)
*
* It is possible for CommitHoldablePortals to invoke functions that queue
* deferred triggers, and it's also possible that triggers create holdable
* cursors. So we have to loop until there's nothing left to do.
*/
for (;;)
{
/*
* Fire all currently pending deferred triggers.
*/
AfterTriggerFireDeferred();
/*
* Convert any open holdable cursors into static portals. If there
* weren't any, we are done ... otherwise loop back to check if they
* queued deferred triggers. Lather, rinse, repeat.
*/
if (!CommitHoldablePortals())
break;
}
/* Now we can shut down the deferred-trigger manager */
AfterTriggerEndXact(true);
/* Close any open regular cursors */
AtCommit_Portals();
/*
* Let ON COMMIT management do its thing (must happen after closing
* cursors, to avoid dangling-reference problems)
*/
PreCommit_on_commit_actions();
/* close large objects before lower-level cleanup */
AtEOXact_LargeObject(true);
/*
* Insert notifications sent by NOTIFY commands into the queue. This
* should be late in the pre-commit sequence to minimize time spent
* holding the notify-insertion lock.
*/
PreCommit_Notify();
/* Prevent cancel/die interrupt while cleaning up */
HOLD_INTERRUPTS();
/* Commit updates to the relation map --- do this as late as possible */
AtEOXact_RelationMap(true);
/*
* set the current transaction state information appropriately during
* commit processing
*/
s->state = TRANS_COMMIT;
/*
* Here is where we really truly commit.
*/
latestXid = RecordTransactionCommit();
TRACE_POSTGRESQL_TRANSACTION_COMMIT(MyProc->lxid);
/*
* Let others know about no transaction in progress by me. Note that this
* must be done _before_ releasing locks we hold and _after_
* RecordTransactionCommit.
*/
ProcArrayEndTransaction(MyProc, latestXid);
/*
* This is all post-commit cleanup. Note that if an error is raised here,
* it's too late to abort the transaction. This should be just
* noncritical resource releasing.
*
* The ordering of operations is not entirely random. The idea is:
* release resources visible to other backends (eg, files, buffer pins);
* then release locks; then release backend-local resources. We want to
* release locks at the point where any backend waiting for us will see
* our transaction as being fully cleaned up.
*
* Resources that can be associated with individual queries are handled by
* the ResourceOwner mechanism. The other calls here are for backend-wide
* state.
*/
CallXactCallbacks(XACT_EVENT_COMMIT);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
true, true);
/* Check we've released all buffer pins */
AtEOXact_Buffers(true);
/* Clean up the relation cache */
AtEOXact_RelationCache(true);
/* Clean up the snapshot manager */
AtEarlyCommit_Snapshot();
/*
* Make catalog changes visible to all backends. This has to happen after
* relcache references are dropped (see comments for
* AtEOXact_RelationCache), but before locks are released (if anyone is
* waiting for lock on a relation we've modified, we want them to know
* about the catalog change before they start using the relation).
*/
AtEOXact_Inval(true);
/*
* Likewise, dropping of files deleted during the transaction is best done
* after releasing relcache and buffer pins. (This is not strictly
* necessary during commit, since such pins should have been released
* already, but this ordering is definitely critical during abort.)
*/
smgrDoPendingDeletes(true);
AtEOXact_MultiXact();
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_LOCKS,
true, true);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
true, true);
/* Check we've released all catcache entries */
AtEOXact_CatCache(true);
AtCommit_Notify();
AtEOXact_GUC(true, 1);
AtEOXact_SPI(true);
AtEOXact_on_commit_actions(true);
AtEOXact_Namespace(true);
/* smgrcommit already done */
AtEOXact_Files();
AtEOXact_ComboCid();
AtEOXact_HashTables(true);
AtEOXact_PgStat(true);
AtEOXact_Snapshot(true);
pgstat_report_xact_timestamp(0);
CurrentResourceOwner = NULL;
ResourceOwnerDelete(TopTransactionResourceOwner);
s->curTransactionOwner = NULL;
CurTransactionResourceOwner = NULL;
TopTransactionResourceOwner = NULL;
AtCommit_Memory();
s->transactionId = InvalidTransactionId;
s->subTransactionId = InvalidSubTransactionId;
s->nestingLevel = 0;
s->gucNestLevel = 0;
s->childXids = NULL;
s->nChildXids = 0;
s->maxChildXids = 0;
/*
* done with commit processing, set current transaction state back to
* default
*/
s->state = TRANS_DEFAULT;
RESUME_INTERRUPTS();
}
/*
* PrepareTransaction
*
* NB: if you change this routine, better look at CommitTransaction too!
*/
static void
PrepareTransaction(void)
{
TransactionState s = CurrentTransactionState;
TransactionId xid = GetCurrentTransactionId();
GlobalTransaction gxact;
TimestampTz prepared_at;
ShowTransactionState("PrepareTransaction");
/*
* check the current transaction state
*/
if (s->state != TRANS_INPROGRESS)
elog(WARNING, "PrepareTransaction while in %s state",
TransStateAsString(s->state));
Assert(s->parent == NULL);
/*
* Do pre-commit processing (most of this stuff requires database access,
* and in fact could still cause an error...)
*
* It is possible for PrepareHoldablePortals to invoke functions that
* queue deferred triggers, and it's also possible that triggers create
* holdable cursors. So we have to loop until there's nothing left to do.
*/
for (;;)
{
/*
* Fire all currently pending deferred triggers.
*/
AfterTriggerFireDeferred();
/*
* Convert any open holdable cursors into static portals. If there
* weren't any, we are done ... otherwise loop back to check if they
* queued deferred triggers. Lather, rinse, repeat.
*/
if (!PrepareHoldablePortals())
break;
}
/* Now we can shut down the deferred-trigger manager */
AfterTriggerEndXact(true);
/* Close any open regular cursors */
AtCommit_Portals();
/*
* Let ON COMMIT management do its thing (must happen after closing
* cursors, to avoid dangling-reference problems)
*/
PreCommit_on_commit_actions();
/* close large objects before lower-level cleanup */
AtEOXact_LargeObject(true);
/* NOTIFY will be handled below */
/*
* Don't allow PREPARE TRANSACTION if we've accessed a temporary table in
* this transaction. Having the prepared xact hold locks on another
* backend's temp table seems a bad idea --- for instance it would prevent
* the backend from exiting. There are other problems too, such as how to
* clean up the source backend's local buffers and ON COMMIT state if the
* prepared xact includes a DROP of a temp table.
*
* We must check this after executing any ON COMMIT actions, because they
* might still access a temp relation.
*
* XXX In principle this could be relaxed to allow some useful special
* cases, such as a temp table created and dropped all within the
* transaction. That seems to require much more bookkeeping though.
*/
if (MyXactAccessedTempRel)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot PREPARE a transaction that has operated on temporary tables")));
/* Prevent cancel/die interrupt while cleaning up */
HOLD_INTERRUPTS();
/*
* set the current transaction state information appropriately during
* prepare processing
*/
s->state = TRANS_PREPARE;
prepared_at = GetCurrentTimestamp();
/* Tell bufmgr and smgr to prepare for commit */
BufmgrCommit();
/*
* Reserve the GID for this transaction. This could fail if the requested
* GID is invalid or already in use.
*/
gxact = MarkAsPreparing(xid, prepareGID, prepared_at,
GetUserId(), MyDatabaseId);
prepareGID = NULL;
/*
* Collect data for the 2PC state file. Note that in general, no actual
* state change should happen in the called modules during this step,
* since it's still possible to fail before commit, and in that case we
* want transaction abort to be able to clean up. (In particular, the
* AtPrepare routines may error out if they find cases they cannot
* handle.) State cleanup should happen in the PostPrepare routines
* below. However, some modules can go ahead and clear state here because
* they wouldn't do anything with it during abort anyway.
*
* Note: because the 2PC state file records will be replayed in the same
* order they are made, the order of these calls has to match the order in
* which we want things to happen during COMMIT PREPARED or ROLLBACK
* PREPARED; in particular, pay attention to whether things should happen
* before or after releasing the transaction's locks.
*/
StartPrepare(gxact);
AtPrepare_Notify();
AtPrepare_Locks();
AtPrepare_PgStat();
AtPrepare_MultiXact();
AtPrepare_RelationMap();
/*
* Here is where we really truly prepare.
*
* We have to record transaction prepares even if we didn't make any
* updates, because the transaction manager might get confused if we lose
* a global transaction.
*/
EndPrepare(gxact);
/*
* Now we clean up backend-internal state and release internal resources.
*/
/* Reset XactLastRecEnd until the next transaction writes something */
XactLastRecEnd.xrecoff = 0;
/*
* Let others know about no transaction in progress by me. This has to be
* done *after* the prepared transaction has been marked valid, else
* someone may think it is unlocked and recyclable.
*/
ProcArrayClearTransaction(MyProc);
/*
* This is all post-transaction cleanup. Note that if an error is raised
* here, it's too late to abort the transaction. This should be just
* noncritical resource releasing. See notes in CommitTransaction.
*/
CallXactCallbacks(XACT_EVENT_PREPARE);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
true, true);
/* Check we've released all buffer pins */
AtEOXact_Buffers(true);
/* Clean up the relation cache */
AtEOXact_RelationCache(true);
/* Clean up the snapshot manager */
AtEarlyCommit_Snapshot();
/* notify doesn't need a postprepare call */
PostPrepare_PgStat();
PostPrepare_Inval();
PostPrepare_smgr();
PostPrepare_MultiXact(xid);
PostPrepare_Locks(xid);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_LOCKS,
true, true);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
true, true);
/* Check we've released all catcache entries */
AtEOXact_CatCache(true);
/* PREPARE acts the same as COMMIT as far as GUC is concerned */
AtEOXact_GUC(true, 1);
AtEOXact_SPI(true);
AtEOXact_on_commit_actions(true);
AtEOXact_Namespace(true);
/* smgrcommit already done */
AtEOXact_Files();
AtEOXact_ComboCid();
AtEOXact_HashTables(true);
/* don't call AtEOXact_PgStat here */
AtEOXact_Snapshot(true);
CurrentResourceOwner = NULL;
ResourceOwnerDelete(TopTransactionResourceOwner);
s->curTransactionOwner = NULL;
CurTransactionResourceOwner = NULL;
TopTransactionResourceOwner = NULL;
AtCommit_Memory();
s->transactionId = InvalidTransactionId;
s->subTransactionId = InvalidSubTransactionId;
s->nestingLevel = 0;
s->gucNestLevel = 0;
s->childXids = NULL;
s->nChildXids = 0;
s->maxChildXids = 0;
/*
* done with 1st phase commit processing, set current transaction state
* back to default
*/
s->state = TRANS_DEFAULT;
RESUME_INTERRUPTS();
}
/*
* AbortTransaction
*/
static void
AbortTransaction(void)
{
TransactionState s = CurrentTransactionState;
TransactionId latestXid;
/* Prevent cancel/die interrupt while cleaning up */
HOLD_INTERRUPTS();
/* Make sure we have a valid memory context and resource owner */
AtAbort_Memory();
AtAbort_ResourceOwner();
/*
* Release any LW locks we might be holding as quickly as possible.
* (Regular locks, however, must be held till we finish aborting.)
* Releasing LW locks is critical since we might try to grab them again
* while cleaning up!
*/
LWLockReleaseAll();
/* Clean up buffer I/O and buffer context locks, too */
AbortBufferIO();
UnlockBuffers();
/*
* Also clean up any open wait for lock, since the lock manager will choke
* if we try to wait for another lock before doing this.
*/
LockWaitCancel();
/*
* check the current transaction state
*/
if (s->state != TRANS_INPROGRESS && s->state != TRANS_PREPARE)
elog(WARNING, "AbortTransaction while in %s state",
TransStateAsString(s->state));
Assert(s->parent == NULL);
/*
* set the current transaction state information appropriately during the
* abort processing
*/
s->state = TRANS_ABORT;
/*
* Reset user ID which might have been changed transiently. We need this
* to clean up in case control escaped out of a SECURITY DEFINER function
* or other local change of CurrentUserId; therefore, the prior value of
* SecurityRestrictionContext also needs to be restored.
*
* (Note: it is not necessary to restore session authorization or role
* settings here because those can only be changed via GUC, and GUC will
* take care of rolling them back if need be.)
*/
SetUserIdAndSecContext(s->prevUser, s->prevSecContext);
/*
* do abort processing
*/
AfterTriggerEndXact(false); /* 'false' means it's abort */
AtAbort_Portals();
AtEOXact_LargeObject(false);
AtAbort_Notify();
AtEOXact_RelationMap(false);
/*
* Advertise the fact that we aborted in pg_clog (assuming that we got as
* far as assigning an XID to advertise).
*/
latestXid = RecordTransactionAbort(false);
TRACE_POSTGRESQL_TRANSACTION_ABORT(MyProc->lxid);
/*
* Let others know about no transaction in progress by me. Note that this
* must be done _before_ releasing locks we hold and _after_
* RecordTransactionAbort.
*/
ProcArrayEndTransaction(MyProc, latestXid);
/*
* Post-abort cleanup. See notes in CommitTransaction() concerning
* ordering. We can skip all of it if the transaction failed before
* creating a resource owner.
*/
if (TopTransactionResourceOwner != NULL)
{
CallXactCallbacks(XACT_EVENT_ABORT);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
false, true);
AtEOXact_Buffers(false);
AtEOXact_RelationCache(false);
AtEOXact_Inval(false);
smgrDoPendingDeletes(false);
AtEOXact_MultiXact();
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_LOCKS,
false, true);
ResourceOwnerRelease(TopTransactionResourceOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
false, true);
AtEOXact_CatCache(false);
AtEOXact_GUC(false, 1);
AtEOXact_SPI(false);
AtEOXact_on_commit_actions(false);
AtEOXact_Namespace(false);
AtEOXact_Files();
AtEOXact_ComboCid();
AtEOXact_HashTables(false);
AtEOXact_PgStat(false);
AtEOXact_Snapshot(false);
pgstat_report_xact_timestamp(0);
}
/*
* State remains TRANS_ABORT until CleanupTransaction().
*/
RESUME_INTERRUPTS();
}
/*
* CleanupTransaction
*/
static void
CleanupTransaction(void)
{
TransactionState s = CurrentTransactionState;
/*
* State should still be TRANS_ABORT from AbortTransaction().
*/
if (s->state != TRANS_ABORT)
elog(FATAL, "CleanupTransaction: unexpected state %s",
TransStateAsString(s->state));
/*
* do abort cleanup processing
*/
AtCleanup_Portals(); /* now safe to release portal memory */
CurrentResourceOwner = NULL; /* and resource owner */
if (TopTransactionResourceOwner)
ResourceOwnerDelete(TopTransactionResourceOwner);
s->curTransactionOwner = NULL;
CurTransactionResourceOwner = NULL;
TopTransactionResourceOwner = NULL;
AtCleanup_Memory(); /* and transaction memory */
s->transactionId = InvalidTransactionId;
s->subTransactionId = InvalidSubTransactionId;
s->nestingLevel = 0;
s->gucNestLevel = 0;
s->childXids = NULL;
s->nChildXids = 0;
s->maxChildXids = 0;
/*
* done with abort processing, set current transaction state back to
* default
*/
s->state = TRANS_DEFAULT;
}
/*
* StartTransactionCommand
*/
void
StartTransactionCommand(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* if we aren't in a transaction block, we just do our usual start
* transaction.
*/
case TBLOCK_DEFAULT:
StartTransaction();
s->blockState = TBLOCK_STARTED;
break;
/*
* We are somewhere in a transaction block or subtransaction and
* about to start a new command. For now we do nothing, but
* someday we may do command-local resource initialization. (Note
* that any needed CommandCounterIncrement was done by the
* previous CommitTransactionCommand.)
*/
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
break;
/*
* Here we are in a failed transaction block (one of the commands
* caused an abort) so we do nothing but remain in the abort
* state. Eventually we will get a ROLLBACK command which will
* get us out of this state. (It is up to other code to ensure
* that no commands other than ROLLBACK will be processed in these
* states.)
*/
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
break;
/* These cases are invalid. */
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
case TBLOCK_PREPARE:
elog(ERROR, "StartTransactionCommand: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
/*
* We must switch to CurTransactionContext before returning. This is
* already done if we called StartTransaction, otherwise not.
*/
Assert(CurTransactionContext != NULL);
MemoryContextSwitchTo(CurTransactionContext);
}
/*
* CommitTransactionCommand
*/
void
CommitTransactionCommand(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* This shouldn't happen, because it means the previous
* StartTransactionCommand didn't set the STARTED state
* appropriately.
*/
case TBLOCK_DEFAULT:
elog(FATAL, "CommitTransactionCommand: unexpected state %s",
BlockStateAsString(s->blockState));
break;
/*
* If we aren't in a transaction block, just do our usual
* transaction commit, and return to the idle state.
*/
case TBLOCK_STARTED:
CommitTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We are completing a "BEGIN TRANSACTION" command, so we change
* to the "transaction block in progress" state and return. (We
* assume the BEGIN did nothing to the database, so we need no
* CommandCounterIncrement.)
*/
case TBLOCK_BEGIN:
s->blockState = TBLOCK_INPROGRESS;
break;
/*
* This is the case when we have finished executing a command
* someplace within a transaction block. We increment the command
* counter and return.
*/
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
CommandCounterIncrement();
break;
/*
* We are completing a "COMMIT" command. Do it and return to the
* idle state.
*/
case TBLOCK_END:
CommitTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* Here we are in the middle of a transaction block but one of the
* commands caused an abort so we do nothing but remain in the
* abort state. Eventually we will get a ROLLBACK comand.
*/
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
break;
/*
* Here we were in an aborted transaction block and we just got
* the ROLLBACK command from the user, so clean up the
* already-aborted transaction and return to the idle state.
*/
case TBLOCK_ABORT_END:
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* Here we were in a perfectly good transaction block but the user
* told us to ROLLBACK anyway. We have to abort the transaction
* and then clean up.
*/
case TBLOCK_ABORT_PENDING:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We are completing a "PREPARE TRANSACTION" command. Do it and
* return to the idle state.
*/
case TBLOCK_PREPARE:
PrepareTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We were just issued a SAVEPOINT inside a transaction block.
* Start a subtransaction. (DefineSavepoint already did
* PushTransaction, so as to have someplace to put the SUBBEGIN
* state.)
*/
case TBLOCK_SUBBEGIN:
StartSubTransaction();
s->blockState = TBLOCK_SUBINPROGRESS;
break;
/*
* We were issued a COMMIT or RELEASE command, so we end the
* current subtransaction and return to the parent transaction.
* The parent might be ended too, so repeat till we are all the
* way out or find an INPROGRESS transaction.
*/
case TBLOCK_SUBEND:
do
{
CommitSubTransaction();
s = CurrentTransactionState; /* changed by pop */
} while (s->blockState == TBLOCK_SUBEND);
/* If we had a COMMIT command, finish off the main xact too */
if (s->blockState == TBLOCK_END)
{
Assert(s->parent == NULL);
CommitTransaction();
s->blockState = TBLOCK_DEFAULT;
}
else if (s->blockState == TBLOCK_PREPARE)
{
Assert(s->parent == NULL);
PrepareTransaction();
s->blockState = TBLOCK_DEFAULT;
}
else
{
Assert(s->blockState == TBLOCK_INPROGRESS ||
s->blockState == TBLOCK_SUBINPROGRESS);
}
break;
/*
* The current already-failed subtransaction is ending due to a
* ROLLBACK or ROLLBACK TO command, so pop it and recursively
* examine the parent (which could be in any of several states).
*/
case TBLOCK_SUBABORT_END:
CleanupSubTransaction();
CommitTransactionCommand();
break;
/*
* As above, but it's not dead yet, so abort first.
*/
case TBLOCK_SUBABORT_PENDING:
AbortSubTransaction();
CleanupSubTransaction();
CommitTransactionCommand();
break;
/*
* The current subtransaction is the target of a ROLLBACK TO
* command. Abort and pop it, then start a new subtransaction
* with the same name.
*/
case TBLOCK_SUBRESTART:
{
char *name;
int savepointLevel;
/* save name and keep Cleanup from freeing it */
name = s->name;
s->name = NULL;
savepointLevel = s->savepointLevel;
AbortSubTransaction();
CleanupSubTransaction();
DefineSavepoint(NULL);
s = CurrentTransactionState; /* changed by push */
s->name = name;
s->savepointLevel = savepointLevel;
/* This is the same as TBLOCK_SUBBEGIN case */
AssertState(s->blockState == TBLOCK_SUBBEGIN);
StartSubTransaction();
s->blockState = TBLOCK_SUBINPROGRESS;
}
break;
/*
* Same as above, but the subtransaction had already failed, so we
* don't need AbortSubTransaction.
*/
case TBLOCK_SUBABORT_RESTART:
{
char *name;
int savepointLevel;
/* save name and keep Cleanup from freeing it */
name = s->name;
s->name = NULL;
savepointLevel = s->savepointLevel;
CleanupSubTransaction();
DefineSavepoint(NULL);
s = CurrentTransactionState; /* changed by push */
s->name = name;
s->savepointLevel = savepointLevel;
/* This is the same as TBLOCK_SUBBEGIN case */
AssertState(s->blockState == TBLOCK_SUBBEGIN);
StartSubTransaction();
s->blockState = TBLOCK_SUBINPROGRESS;
}
break;
}
}
/*
* AbortCurrentTransaction
*/
void
AbortCurrentTransaction(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
case TBLOCK_DEFAULT:
if (s->state == TRANS_DEFAULT)
{
/* we are idle, so nothing to do */
}
else
{
/*
* We can get here after an error during transaction start
* (state will be TRANS_START). Need to clean up the
* incompletely started transaction. First, adjust the
* low-level state to suppress warning message from
* AbortTransaction.
*/
if (s->state == TRANS_START)
s->state = TRANS_INPROGRESS;
AbortTransaction();
CleanupTransaction();
}
break;
/*
* if we aren't in a transaction block, we just do the basic abort
* & cleanup transaction.
*/
case TBLOCK_STARTED:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* If we are in TBLOCK_BEGIN it means something screwed up right
* after reading "BEGIN TRANSACTION". We assume that the user
* will interpret the error as meaning the BEGIN failed to get him
* into a transaction block, so we should abort and return to idle
* state.
*/
case TBLOCK_BEGIN:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We are somewhere in a transaction block and we've gotten a
* failure, so we abort the transaction and set up the persistent
* ABORT state. We will stay in ABORT until we get a ROLLBACK.
*/
case TBLOCK_INPROGRESS:
AbortTransaction();
s->blockState = TBLOCK_ABORT;
/* CleanupTransaction happens when we exit TBLOCK_ABORT_END */
break;
/*
* Here, we failed while trying to COMMIT. Clean up the
* transaction and return to idle state (we do not want to stay in
* the transaction).
*/
case TBLOCK_END:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* Here, we are already in an aborted transaction state and are
* waiting for a ROLLBACK, but for some reason we failed again! So
* we just remain in the abort state.
*/
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
break;
/*
* We are in a failed transaction and we got the ROLLBACK command.
* We have already aborted, we just need to cleanup and go to idle
* state.
*/
case TBLOCK_ABORT_END:
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We are in a live transaction and we got a ROLLBACK command.
* Abort, cleanup, go to idle state.
*/
case TBLOCK_ABORT_PENDING:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* Here, we failed while trying to PREPARE. Clean up the
* transaction and return to idle state (we do not want to stay in
* the transaction).
*/
case TBLOCK_PREPARE:
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* We got an error inside a subtransaction. Abort just the
* subtransaction, and go to the persistent SUBABORT state until
* we get ROLLBACK.
*/
case TBLOCK_SUBINPROGRESS:
AbortSubTransaction();
s->blockState = TBLOCK_SUBABORT;
break;
/*
* If we failed while trying to create a subtransaction, clean up
* the broken subtransaction and abort the parent. The same
* applies if we get a failure while ending a subtransaction.
*/
case TBLOCK_SUBBEGIN:
case TBLOCK_SUBEND:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
AbortSubTransaction();
CleanupSubTransaction();
AbortCurrentTransaction();
break;
/*
* Same as above, except the Abort() was already done.
*/
case TBLOCK_SUBABORT_END:
case TBLOCK_SUBABORT_RESTART:
CleanupSubTransaction();
AbortCurrentTransaction();
break;
}
}
/*
* PreventTransactionChain
*
* This routine is to be called by statements that must not run inside
* a transaction block, typically because they have non-rollback-able
* side effects or do internal commits.
*
* If we have already started a transaction block, issue an error; also issue
* an error if we appear to be running inside a user-defined function (which
* could issue more commands and possibly cause a failure after the statement
* completes). Subtransactions are verboten too.
*
* isTopLevel: passed down from ProcessUtility to determine whether we are
* inside a function or multi-query querystring. (We will always fail if
* this is false, but it's convenient to centralize the check here instead of
* making callers do it.)
* stmtType: statement type name, for error messages.
*/
void
PreventTransactionChain(bool isTopLevel, const char *stmtType)
{
/*
* xact block already started?
*/
if (IsTransactionBlock())
ereport(ERROR,
(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
/* translator: %s represents an SQL statement name */
errmsg("%s cannot run inside a transaction block",
stmtType)));
/*
* subtransaction?
*/
if (IsSubTransaction())
ereport(ERROR,
(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
/* translator: %s represents an SQL statement name */
errmsg("%s cannot run inside a subtransaction",
stmtType)));
/*
* inside a function call?
*/
if (!isTopLevel)
ereport(ERROR,
(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
/* translator: %s represents an SQL statement name */
errmsg("%s cannot be executed from a function or multi-command string",
stmtType)));
/* If we got past IsTransactionBlock test, should be in default state */
if (CurrentTransactionState->blockState != TBLOCK_DEFAULT &&
CurrentTransactionState->blockState != TBLOCK_STARTED)
elog(FATAL, "cannot prevent transaction chain");
/* all okay */
}
/*
* RequireTransactionChain
*
* This routine is to be called by statements that must run inside
* a transaction block, because they have no effects that persist past
* transaction end (and so calling them outside a transaction block
* is presumably an error). DECLARE CURSOR is an example.
*
* If we appear to be running inside a user-defined function, we do not
* issue an error, since the function could issue more commands that make
* use of the current statement's results. Likewise subtransactions.
* Thus this is an inverse for PreventTransactionChain.
*
* isTopLevel: passed down from ProcessUtility to determine whether we are
* inside a function.
* stmtType: statement type name, for error messages.
*/
void
RequireTransactionChain(bool isTopLevel, const char *stmtType)
{
/*
* xact block already started?
*/
if (IsTransactionBlock())
return;
/*
* subtransaction?
*/
if (IsSubTransaction())
return;
/*
* inside a function call?
*/
if (!isTopLevel)
return;
ereport(ERROR,
(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
/* translator: %s represents an SQL statement name */
errmsg("%s can only be used in transaction blocks",
stmtType)));
}
/*
* IsInTransactionChain
*
* This routine is for statements that need to behave differently inside
* a transaction block than when running as single commands. ANALYZE is
* currently the only example.
*
* isTopLevel: passed down from ProcessUtility to determine whether we are
* inside a function.
*/
bool
IsInTransactionChain(bool isTopLevel)
{
/*
* Return true on same conditions that would make PreventTransactionChain
* error out
*/
if (IsTransactionBlock())
return true;
if (IsSubTransaction())
return true;
if (!isTopLevel)
return true;
if (CurrentTransactionState->blockState != TBLOCK_DEFAULT &&
CurrentTransactionState->blockState != TBLOCK_STARTED)
return true;
return false;
}
/*
* Register or deregister callback functions for start- and end-of-xact
* operations.
*
* These functions are intended for use by dynamically loaded modules.
* For built-in modules we generally just hardwire the appropriate calls
* (mainly because it's easier to control the order that way, where needed).
*
* At transaction end, the callback occurs post-commit or post-abort, so the
* callback functions can only do noncritical cleanup.
*/
void
RegisterXactCallback(XactCallback callback, void *arg)
{
XactCallbackItem *item;
item = (XactCallbackItem *)
MemoryContextAlloc(TopMemoryContext, sizeof(XactCallbackItem));
item->callback = callback;
item->arg = arg;
item->next = Xact_callbacks;
Xact_callbacks = item;
}
void
UnregisterXactCallback(XactCallback callback, void *arg)
{
XactCallbackItem *item;
XactCallbackItem *prev;
prev = NULL;
for (item = Xact_callbacks; item; prev = item, item = item->next)
{
if (item->callback == callback && item->arg == arg)
{
if (prev)
prev->next = item->next;
else
Xact_callbacks = item->next;
pfree(item);
break;
}
}
}
static void
CallXactCallbacks(XactEvent event)
{
XactCallbackItem *item;
for (item = Xact_callbacks; item; item = item->next)
(*item->callback) (event, item->arg);
}
/*
* Register or deregister callback functions for start- and end-of-subxact
* operations.
*
* Pretty much same as above, but for subtransaction events.
*
* At subtransaction end, the callback occurs post-subcommit or post-subabort,
* so the callback functions can only do noncritical cleanup. At
* subtransaction start, the callback is called when the subtransaction has
* finished initializing.
*/
void
RegisterSubXactCallback(SubXactCallback callback, void *arg)
{
SubXactCallbackItem *item;
item = (SubXactCallbackItem *)
MemoryContextAlloc(TopMemoryContext, sizeof(SubXactCallbackItem));
item->callback = callback;
item->arg = arg;
item->next = SubXact_callbacks;
SubXact_callbacks = item;
}
void
UnregisterSubXactCallback(SubXactCallback callback, void *arg)
{
SubXactCallbackItem *item;
SubXactCallbackItem *prev;
prev = NULL;
for (item = SubXact_callbacks; item; prev = item, item = item->next)
{
if (item->callback == callback && item->arg == arg)
{
if (prev)
prev->next = item->next;
else
SubXact_callbacks = item->next;
pfree(item);
break;
}
}
}
static void
CallSubXactCallbacks(SubXactEvent event,
SubTransactionId mySubid,
SubTransactionId parentSubid)
{
SubXactCallbackItem *item;
for (item = SubXact_callbacks; item; item = item->next)
(*item->callback) (event, mySubid, parentSubid, item->arg);
}
/* ----------------------------------------------------------------
* transaction block support
* ----------------------------------------------------------------
*/
/*
* BeginTransactionBlock
* This executes a BEGIN command.
*/
void
BeginTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* We are not inside a transaction block, so allow one to begin.
*/
case TBLOCK_STARTED:
s->blockState = TBLOCK_BEGIN;
break;
/*
* Already a transaction block in progress.
*/
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
ereport(WARNING,
(errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
errmsg("there is already a transaction in progress")));
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
case TBLOCK_PREPARE:
elog(FATAL, "BeginTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
}
/*
* PrepareTransactionBlock
* This executes a PREPARE command.
*
* Since PREPARE may actually do a ROLLBACK, the result indicates what
* happened: TRUE for PREPARE, FALSE for ROLLBACK.
*
* Note that we don't actually do anything here except change blockState.
* The real work will be done in the upcoming PrepareTransaction().
* We do it this way because it's not convenient to change memory context,
* resource owner, etc while executing inside a Portal.
*/
bool
PrepareTransactionBlock(char *gid)
{
TransactionState s;
bool result;
/* Set up to commit the current transaction */
result = EndTransactionBlock();
/* If successful, change outer tblock state to PREPARE */
if (result)
{
s = CurrentTransactionState;
while (s->parent != NULL)
s = s->parent;
if (s->blockState == TBLOCK_END)
{
/* Save GID where PrepareTransaction can find it again */
prepareGID = MemoryContextStrdup(TopTransactionContext, gid);
s->blockState = TBLOCK_PREPARE;
}
else
{
/*
* ignore case where we are not in a transaction;
* EndTransactionBlock already issued a warning.
*/
Assert(s->blockState == TBLOCK_STARTED);
/* Don't send back a PREPARE result tag... */
result = false;
}
}
return result;
}
/*
* EndTransactionBlock
* This executes a COMMIT command.
*
* Since COMMIT may actually do a ROLLBACK, the result indicates what
* happened: TRUE for COMMIT, FALSE for ROLLBACK.
*
* Note that we don't actually do anything here except change blockState.
* The real work will be done in the upcoming CommitTransactionCommand().
* We do it this way because it's not convenient to change memory context,
* resource owner, etc while executing inside a Portal.
*/
bool
EndTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
bool result = false;
switch (s->blockState)
{
/*
* We are in a transaction block, so tell CommitTransactionCommand
* to COMMIT.
*/
case TBLOCK_INPROGRESS:
s->blockState = TBLOCK_END;
result = true;
break;
/*
* We are in a failed transaction block. Tell
* CommitTransactionCommand it's time to exit the block.
*/
case TBLOCK_ABORT:
s->blockState = TBLOCK_ABORT_END;
break;
/*
* We are in a live subtransaction block. Set up to subcommit all
* open subtransactions and then commit the main transaction.
*/
case TBLOCK_SUBINPROGRESS:
while (s->parent != NULL)
{
if (s->blockState == TBLOCK_SUBINPROGRESS)
s->blockState = TBLOCK_SUBEND;
else
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
s = s->parent;
}
if (s->blockState == TBLOCK_INPROGRESS)
s->blockState = TBLOCK_END;
else
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
result = true;
break;
/*
* Here we are inside an aborted subtransaction. Treat the COMMIT
* as ROLLBACK: set up to abort everything and exit the main
* transaction.
*/
case TBLOCK_SUBABORT:
while (s->parent != NULL)
{
if (s->blockState == TBLOCK_SUBINPROGRESS)
s->blockState = TBLOCK_SUBABORT_PENDING;
else if (s->blockState == TBLOCK_SUBABORT)
s->blockState = TBLOCK_SUBABORT_END;
else
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
s = s->parent;
}
if (s->blockState == TBLOCK_INPROGRESS)
s->blockState = TBLOCK_ABORT_PENDING;
else if (s->blockState == TBLOCK_ABORT)
s->blockState = TBLOCK_ABORT_END;
else
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
/*
* The user issued COMMIT when not inside a transaction. Issue a
* WARNING, staying in TBLOCK_STARTED state. The upcoming call to
* CommitTransactionCommand() will then close the transaction and
* put us back into the default state.
*/
case TBLOCK_STARTED:
ereport(WARNING,
(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
errmsg("there is no transaction in progress")));
result = true;
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
case TBLOCK_PREPARE:
elog(FATAL, "EndTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
return result;
}
/*
* UserAbortTransactionBlock
* This executes a ROLLBACK command.
*
* As above, we don't actually do anything here except change blockState.
*/
void
UserAbortTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/*
* We are inside a transaction block and we got a ROLLBACK command
* from the user, so tell CommitTransactionCommand to abort and
* exit the transaction block.
*/
case TBLOCK_INPROGRESS:
s->blockState = TBLOCK_ABORT_PENDING;
break;
/*
* We are inside a failed transaction block and we got a ROLLBACK
* command from the user. Abort processing is already done, so
* CommitTransactionCommand just has to cleanup and go back to
* idle state.
*/
case TBLOCK_ABORT:
s->blockState = TBLOCK_ABORT_END;
break;
/*
* We are inside a subtransaction. Mark everything up to top
* level as exitable.
*/
case TBLOCK_SUBINPROGRESS:
case TBLOCK_SUBABORT:
while (s->parent != NULL)
{
if (s->blockState == TBLOCK_SUBINPROGRESS)
s->blockState = TBLOCK_SUBABORT_PENDING;
else if (s->blockState == TBLOCK_SUBABORT)
s->blockState = TBLOCK_SUBABORT_END;
else
elog(FATAL, "UserAbortTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
s = s->parent;
}
if (s->blockState == TBLOCK_INPROGRESS)
s->blockState = TBLOCK_ABORT_PENDING;
else if (s->blockState == TBLOCK_ABORT)
s->blockState = TBLOCK_ABORT_END;
else
elog(FATAL, "UserAbortTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
/*
* The user issued ABORT when not inside a transaction. Issue a
* WARNING and go to abort state. The upcoming call to
* CommitTransactionCommand() will then put us back into the
* default state.
*/
case TBLOCK_STARTED:
ereport(NOTICE,
(errcode(ERRCODE_NO_ACTIVE_SQL_TRANSACTION),
errmsg("there is no transaction in progress")));
s->blockState = TBLOCK_ABORT_PENDING;
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
case TBLOCK_PREPARE:
elog(FATAL, "UserAbortTransactionBlock: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
}
/*
* DefineSavepoint
* This executes a SAVEPOINT command.
*/
void
DefineSavepoint(char *name)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
/* Normal subtransaction start */
PushTransaction();
s = CurrentTransactionState; /* changed by push */
/*
* Savepoint names, like the TransactionState block itself, live
* in TopTransactionContext.
*/
if (name)
s->name = MemoryContextStrdup(TopTransactionContext, name);
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
case TBLOCK_PREPARE:
elog(FATAL, "DefineSavepoint: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
}
/*
* ReleaseSavepoint
* This executes a RELEASE command.
*
* As above, we don't actually do anything here except change blockState.
*/
void
ReleaseSavepoint(List *options)
{
TransactionState s = CurrentTransactionState;
TransactionState target,
xact;
ListCell *cell;
char *name = NULL;
switch (s->blockState)
{
/*
* We can't rollback to a savepoint if there is no savepoint
* defined.
*/
case TBLOCK_INPROGRESS:
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
break;
/*
* We are in a non-aborted subtransaction. This is the only valid
* case.
*/
case TBLOCK_SUBINPROGRESS:
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
case TBLOCK_PREPARE:
elog(FATAL, "ReleaseSavepoint: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
foreach(cell, options)
{
DefElem *elem = lfirst(cell);
if (strcmp(elem->defname, "savepoint_name") == 0)
name = strVal(elem->arg);
}
Assert(PointerIsValid(name));
for (target = s; PointerIsValid(target); target = target->parent)
{
if (PointerIsValid(target->name) && strcmp(target->name, name) == 0)
break;
}
if (!PointerIsValid(target))
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
/* disallow crossing savepoint level boundaries */
if (target->savepointLevel != s->savepointLevel)
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
/*
* Mark "commit pending" all subtransactions up to the target
* subtransaction. The actual commits will happen when control gets to
* CommitTransactionCommand.
*/
xact = CurrentTransactionState;
for (;;)
{
Assert(xact->blockState == TBLOCK_SUBINPROGRESS);
xact->blockState = TBLOCK_SUBEND;
if (xact == target)
break;
xact = xact->parent;
Assert(PointerIsValid(xact));
}
}
/*
* RollbackToSavepoint
* This executes a ROLLBACK TO <savepoint> command.
*
* As above, we don't actually do anything here except change blockState.
*/
void
RollbackToSavepoint(List *options)
{
TransactionState s = CurrentTransactionState;
TransactionState target,
xact;
ListCell *cell;
char *name = NULL;
switch (s->blockState)
{
/*
* We can't rollback to a savepoint if there is no savepoint
* defined.
*/
case TBLOCK_INPROGRESS:
case TBLOCK_ABORT:
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
break;
/*
* There is at least one savepoint, so proceed.
*/
case TBLOCK_SUBINPROGRESS:
case TBLOCK_SUBABORT:
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
case TBLOCK_PREPARE:
elog(FATAL, "RollbackToSavepoint: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
foreach(cell, options)
{
DefElem *elem = lfirst(cell);
if (strcmp(elem->defname, "savepoint_name") == 0)
name = strVal(elem->arg);
}
Assert(PointerIsValid(name));
for (target = s; PointerIsValid(target); target = target->parent)
{
if (PointerIsValid(target->name) && strcmp(target->name, name) == 0)
break;
}
if (!PointerIsValid(target))
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
/* disallow crossing savepoint level boundaries */
if (target->savepointLevel != s->savepointLevel)
ereport(ERROR,
(errcode(ERRCODE_S_E_INVALID_SPECIFICATION),
errmsg("no such savepoint")));
/*
* Mark "abort pending" all subtransactions up to the target
* subtransaction. The actual aborts will happen when control gets to
* CommitTransactionCommand.
*/
xact = CurrentTransactionState;
for (;;)
{
if (xact == target)
break;
if (xact->blockState == TBLOCK_SUBINPROGRESS)
xact->blockState = TBLOCK_SUBABORT_PENDING;
else if (xact->blockState == TBLOCK_SUBABORT)
xact->blockState = TBLOCK_SUBABORT_END;
else
elog(FATAL, "RollbackToSavepoint: unexpected state %s",
BlockStateAsString(xact->blockState));
xact = xact->parent;
Assert(PointerIsValid(xact));
}
/* And mark the target as "restart pending" */
if (xact->blockState == TBLOCK_SUBINPROGRESS)
xact->blockState = TBLOCK_SUBRESTART;
else if (xact->blockState == TBLOCK_SUBABORT)
xact->blockState = TBLOCK_SUBABORT_RESTART;
else
elog(FATAL, "RollbackToSavepoint: unexpected state %s",
BlockStateAsString(xact->blockState));
}
/*
* BeginInternalSubTransaction
* This is the same as DefineSavepoint except it allows TBLOCK_STARTED,
* TBLOCK_END, and TBLOCK_PREPARE states, and therefore it can safely be
* used in functions that might be called when not inside a BEGIN block
* or when running deferred triggers at COMMIT/PREPARE time. Also, it
* automatically does CommitTransactionCommand/StartTransactionCommand
* instead of expecting the caller to do it.
*/
void
BeginInternalSubTransaction(char *name)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
case TBLOCK_STARTED:
case TBLOCK_INPROGRESS:
case TBLOCK_END:
case TBLOCK_PREPARE:
case TBLOCK_SUBINPROGRESS:
/* Normal subtransaction start */
PushTransaction();
s = CurrentTransactionState; /* changed by push */
/*
* Savepoint names, like the TransactionState block itself, live
* in TopTransactionContext.
*/
if (name)
s->name = MemoryContextStrdup(TopTransactionContext, name);
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_SUBEND:
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
elog(FATAL, "BeginInternalSubTransaction: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
CommitTransactionCommand();
StartTransactionCommand();
}
/*
* ReleaseCurrentSubTransaction
*
* RELEASE (ie, commit) the innermost subtransaction, regardless of its
* savepoint name (if any).
* NB: do NOT use CommitTransactionCommand/StartTransactionCommand with this.
*/
void
ReleaseCurrentSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
if (s->blockState != TBLOCK_SUBINPROGRESS)
elog(ERROR, "ReleaseCurrentSubTransaction: unexpected state %s",
BlockStateAsString(s->blockState));
Assert(s->state == TRANS_INPROGRESS);
MemoryContextSwitchTo(CurTransactionContext);
CommitSubTransaction();
s = CurrentTransactionState; /* changed by pop */
Assert(s->state == TRANS_INPROGRESS);
}
/*
* RollbackAndReleaseCurrentSubTransaction
*
* ROLLBACK and RELEASE (ie, abort) the innermost subtransaction, regardless
* of its savepoint name (if any).
* NB: do NOT use CommitTransactionCommand/StartTransactionCommand with this.
*/
void
RollbackAndReleaseCurrentSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
/* Must be in a subtransaction */
case TBLOCK_SUBINPROGRESS:
case TBLOCK_SUBABORT:
break;
/* These cases are invalid. */
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_INPROGRESS:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_ABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
case TBLOCK_PREPARE:
elog(FATAL, "RollbackAndReleaseCurrentSubTransaction: unexpected state %s",
BlockStateAsString(s->blockState));
break;
}
/*
* Abort the current subtransaction, if needed.
*/
if (s->blockState == TBLOCK_SUBINPROGRESS)
AbortSubTransaction();
/* And clean it up, too */
CleanupSubTransaction();
s = CurrentTransactionState; /* changed by pop */
AssertState(s->blockState == TBLOCK_SUBINPROGRESS ||
s->blockState == TBLOCK_INPROGRESS ||
s->blockState == TBLOCK_STARTED);
}
/*
* AbortOutOfAnyTransaction
*
* This routine is provided for error recovery purposes. It aborts any
* active transaction or transaction block, leaving the system in a known
* idle state.
*/
void
AbortOutOfAnyTransaction(void)
{
TransactionState s = CurrentTransactionState;
/*
* Get out of any transaction or nested transaction
*/
do
{
switch (s->blockState)
{
case TBLOCK_DEFAULT:
/* Not in a transaction, do nothing */
break;
case TBLOCK_STARTED:
case TBLOCK_BEGIN:
case TBLOCK_INPROGRESS:
case TBLOCK_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_PREPARE:
/* In a transaction, so clean up */
AbortTransaction();
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
case TBLOCK_ABORT:
case TBLOCK_ABORT_END:
/* AbortTransaction already done, still need Cleanup */
CleanupTransaction();
s->blockState = TBLOCK_DEFAULT;
break;
/*
* In a subtransaction, so clean it up and abort parent too
*/
case TBLOCK_SUBBEGIN:
case TBLOCK_SUBINPROGRESS:
case TBLOCK_SUBEND:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
AbortSubTransaction();
CleanupSubTransaction();
s = CurrentTransactionState; /* changed by pop */
break;
case TBLOCK_SUBABORT:
case TBLOCK_SUBABORT_END:
case TBLOCK_SUBABORT_RESTART:
/* As above, but AbortSubTransaction already done */
CleanupSubTransaction();
s = CurrentTransactionState; /* changed by pop */
break;
}
} while (s->blockState != TBLOCK_DEFAULT);
/* Should be out of all subxacts now */
Assert(s->parent == NULL);
}
/*
* IsTransactionBlock --- are we within a transaction block?
*/
bool
IsTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
if (s->blockState == TBLOCK_DEFAULT || s->blockState == TBLOCK_STARTED)
return false;
return true;
}
/*
* IsTransactionOrTransactionBlock --- are we within either a transaction
* or a transaction block? (The backend is only really "idle" when this
* returns false.)
*
* This should match up with IsTransactionBlock and IsTransactionState.
*/
bool
IsTransactionOrTransactionBlock(void)
{
TransactionState s = CurrentTransactionState;
if (s->blockState == TBLOCK_DEFAULT)
return false;
return true;
}
/*
* TransactionBlockStatusCode - return status code to send in ReadyForQuery
*/
char
TransactionBlockStatusCode(void)
{
TransactionState s = CurrentTransactionState;
switch (s->blockState)
{
case TBLOCK_DEFAULT:
case TBLOCK_STARTED:
return 'I'; /* idle --- not in transaction */
case TBLOCK_BEGIN:
case TBLOCK_SUBBEGIN:
case TBLOCK_INPROGRESS:
case TBLOCK_SUBINPROGRESS:
case TBLOCK_END:
case TBLOCK_SUBEND:
case TBLOCK_PREPARE:
return 'T'; /* in transaction */
case TBLOCK_ABORT:
case TBLOCK_SUBABORT:
case TBLOCK_ABORT_END:
case TBLOCK_SUBABORT_END:
case TBLOCK_ABORT_PENDING:
case TBLOCK_SUBABORT_PENDING:
case TBLOCK_SUBRESTART:
case TBLOCK_SUBABORT_RESTART:
return 'E'; /* in failed transaction */
}
/* should never get here */
elog(FATAL, "invalid transaction block state: %s",
BlockStateAsString(s->blockState));
return 0; /* keep compiler quiet */
}
/*
* IsSubTransaction
*/
bool
IsSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
if (s->nestingLevel >= 2)
return true;
return false;
}
/*
* StartSubTransaction
*
* If you're wondering why this is separate from PushTransaction: it's because
* we can't conveniently do this stuff right inside DefineSavepoint. The
* SAVEPOINT utility command will be executed inside a Portal, and if we
* muck with CurrentMemoryContext or CurrentResourceOwner then exit from
* the Portal will undo those settings. So we make DefineSavepoint just
* push a dummy transaction block, and when control returns to the main
* idle loop, CommitTransactionCommand will be called, and we'll come here
* to finish starting the subtransaction.
*/
static void
StartSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
if (s->state != TRANS_DEFAULT)
elog(WARNING, "StartSubTransaction while in %s state",
TransStateAsString(s->state));
s->state = TRANS_START;
/*
* Initialize subsystems for new subtransaction
*
* must initialize resource-management stuff first
*/
AtSubStart_Memory();
AtSubStart_ResourceOwner();
AtSubStart_Inval();
AtSubStart_Notify();
AfterTriggerBeginSubXact();
s->state = TRANS_INPROGRESS;
/*
* Call start-of-subxact callbacks
*/
CallSubXactCallbacks(SUBXACT_EVENT_START_SUB, s->subTransactionId,
s->parent->subTransactionId);
ShowTransactionState("StartSubTransaction");
}
/*
* CommitSubTransaction
*
* The caller has to make sure to always reassign CurrentTransactionState
* if it has a local pointer to it after calling this function.
*/
static void
CommitSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
ShowTransactionState("CommitSubTransaction");
if (s->state != TRANS_INPROGRESS)
elog(WARNING, "CommitSubTransaction while in %s state",
TransStateAsString(s->state));
/* Pre-commit processing goes here -- nothing to do at the moment */
s->state = TRANS_COMMIT;
/* Must CCI to ensure commands of subtransaction are seen as done */
CommandCounterIncrement();
/*
* Prior to 8.4 we marked subcommit in clog at this point. We now only
* perform that step, if required, as part of the atomic update of the
* whole transaction tree at top level commit or abort.
*/
/* Post-commit cleanup */
if (TransactionIdIsValid(s->transactionId))
AtSubCommit_childXids();
AfterTriggerEndSubXact(true);
AtSubCommit_Portals(s->subTransactionId,
s->parent->subTransactionId,
s->parent->curTransactionOwner);
AtEOSubXact_LargeObject(true, s->subTransactionId,
s->parent->subTransactionId);
AtSubCommit_Notify();
CallSubXactCallbacks(SUBXACT_EVENT_COMMIT_SUB, s->subTransactionId,
s->parent->subTransactionId);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
true, false);
AtEOSubXact_RelationCache(true, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Inval(true);
AtSubCommit_smgr();
/*
* The only lock we actually release here is the subtransaction XID lock.
* The rest just get transferred to the parent resource owner.
*/
CurrentResourceOwner = s->curTransactionOwner;
if (TransactionIdIsValid(s->transactionId))
XactLockTableDelete(s->transactionId);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_LOCKS,
true, false);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
true, false);
AtEOXact_GUC(true, s->gucNestLevel);
AtEOSubXact_SPI(true, s->subTransactionId);
AtEOSubXact_on_commit_actions(true, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Namespace(true, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Files(true, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_HashTables(true, s->nestingLevel);
AtEOSubXact_PgStat(true, s->nestingLevel);
AtSubCommit_Snapshot(s->nestingLevel);
/*
* We need to restore the upper transaction's read-only state, in case the
* upper is read-write while the child is read-only; GUC will incorrectly
* think it should leave the child state in place.
*/
XactReadOnly = s->prevXactReadOnly;
CurrentResourceOwner = s->parent->curTransactionOwner;
CurTransactionResourceOwner = s->parent->curTransactionOwner;
ResourceOwnerDelete(s->curTransactionOwner);
s->curTransactionOwner = NULL;
AtSubCommit_Memory();
s->state = TRANS_DEFAULT;
PopTransaction();
}
/*
* AbortSubTransaction
*/
static void
AbortSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
/* Prevent cancel/die interrupt while cleaning up */
HOLD_INTERRUPTS();
/* Make sure we have a valid memory context and resource owner */
AtSubAbort_Memory();
AtSubAbort_ResourceOwner();
/*
* Release any LW locks we might be holding as quickly as possible.
* (Regular locks, however, must be held till we finish aborting.)
* Releasing LW locks is critical since we might try to grab them again
* while cleaning up!
*
* FIXME This may be incorrect --- Are there some locks we should keep?
* Buffer locks, for example? I don't think so but I'm not sure.
*/
LWLockReleaseAll();
AbortBufferIO();
UnlockBuffers();
LockWaitCancel();
/*
* check the current transaction state
*/
ShowTransactionState("AbortSubTransaction");
if (s->state != TRANS_INPROGRESS)
elog(WARNING, "AbortSubTransaction while in %s state",
TransStateAsString(s->state));
s->state = TRANS_ABORT;
/*
* Reset user ID which might have been changed transiently. (See notes in
* AbortTransaction.)
*/
SetUserIdAndSecContext(s->prevUser, s->prevSecContext);
/*
* We can skip all this stuff if the subxact failed before creating a
* ResourceOwner...
*/
if (s->curTransactionOwner)
{
AfterTriggerEndSubXact(false);
AtSubAbort_Portals(s->subTransactionId,
s->parent->subTransactionId,
s->parent->curTransactionOwner);
AtEOSubXact_LargeObject(false, s->subTransactionId,
s->parent->subTransactionId);
AtSubAbort_Notify();
/* Advertise the fact that we aborted in pg_clog. */
(void) RecordTransactionAbort(true);
/* Post-abort cleanup */
if (TransactionIdIsValid(s->transactionId))
AtSubAbort_childXids();
CallSubXactCallbacks(SUBXACT_EVENT_ABORT_SUB, s->subTransactionId,
s->parent->subTransactionId);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_BEFORE_LOCKS,
false, false);
AtEOSubXact_RelationCache(false, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Inval(false);
AtSubAbort_smgr();
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_LOCKS,
false, false);
ResourceOwnerRelease(s->curTransactionOwner,
RESOURCE_RELEASE_AFTER_LOCKS,
false, false);
AtEOXact_GUC(false, s->gucNestLevel);
AtEOSubXact_SPI(false, s->subTransactionId);
AtEOSubXact_on_commit_actions(false, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Namespace(false, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_Files(false, s->subTransactionId,
s->parent->subTransactionId);
AtEOSubXact_HashTables(false, s->nestingLevel);
AtEOSubXact_PgStat(false, s->nestingLevel);
AtSubAbort_Snapshot(s->nestingLevel);
}
/*
* Restore the upper transaction's read-only state, too. This should be
* redundant with GUC's cleanup but we may as well do it for consistency
* with the commit case.
*/
XactReadOnly = s->prevXactReadOnly;
RESUME_INTERRUPTS();
}
/*
* CleanupSubTransaction
*
* The caller has to make sure to always reassign CurrentTransactionState
* if it has a local pointer to it after calling this function.
*/
static void
CleanupSubTransaction(void)
{
TransactionState s = CurrentTransactionState;
ShowTransactionState("CleanupSubTransaction");
if (s->state != TRANS_ABORT)
elog(WARNING, "CleanupSubTransaction while in %s state",
TransStateAsString(s->state));
AtSubCleanup_Portals(s->subTransactionId);
CurrentResourceOwner = s->parent->curTransactionOwner;
CurTransactionResourceOwner = s->parent->curTransactionOwner;
if (s->curTransactionOwner)
ResourceOwnerDelete(s->curTransactionOwner);
s->curTransactionOwner = NULL;
AtSubCleanup_Memory();
s->state = TRANS_DEFAULT;
PopTransaction();
}
/*
* PushTransaction
* Create transaction state stack entry for a subtransaction
*
* The caller has to make sure to always reassign CurrentTransactionState
* if it has a local pointer to it after calling this function.
*/
static void
PushTransaction(void)
{
TransactionState p = CurrentTransactionState;
TransactionState s;
/*
* We keep subtransaction state nodes in TopTransactionContext.
*/
s = (TransactionState)
MemoryContextAllocZero(TopTransactionContext,
sizeof(TransactionStateData));
/*
* Assign a subtransaction ID, watching out for counter wraparound.
*/
currentSubTransactionId += 1;
if (currentSubTransactionId == InvalidSubTransactionId)
{
currentSubTransactionId -= 1;
pfree(s);
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("cannot have more than 2^32-1 subtransactions in a transaction")));
}
/*
* We can now stack a minimally valid subtransaction without fear of
* failure.
*/
s->transactionId = InvalidTransactionId; /* until assigned */
s->subTransactionId = currentSubTransactionId;
s->parent = p;
s->nestingLevel = p->nestingLevel + 1;
s->gucNestLevel = NewGUCNestLevel();
s->savepointLevel = p->savepointLevel;
s->state = TRANS_DEFAULT;
s->blockState = TBLOCK_SUBBEGIN;
GetUserIdAndSecContext(&s->prevUser, &s->prevSecContext);
s->prevXactReadOnly = XactReadOnly;
CurrentTransactionState = s;
/*
* AbortSubTransaction and CleanupSubTransaction have to be able to cope
* with the subtransaction from here on out; in particular they should not
* assume that it necessarily has a transaction context, resource owner,
* or XID.
*/
}
/*
* PopTransaction
* Pop back to parent transaction state
*
* The caller has to make sure to always reassign CurrentTransactionState
* if it has a local pointer to it after calling this function.
*/
static void
PopTransaction(void)
{
TransactionState s = CurrentTransactionState;
if (s->state != TRANS_DEFAULT)
elog(WARNING, "PopTransaction while in %s state",
TransStateAsString(s->state));
if (s->parent == NULL)
elog(FATAL, "PopTransaction with no parent");
CurrentTransactionState = s->parent;
/* Let's just make sure CurTransactionContext is good */
CurTransactionContext = s->parent->curTransactionContext;
MemoryContextSwitchTo(CurTransactionContext);
/* Ditto for ResourceOwner links */
CurTransactionResourceOwner = s->parent->curTransactionOwner;
CurrentResourceOwner = s->parent->curTransactionOwner;
/* Free the old child structure */
if (s->name)
pfree(s->name);
pfree(s);
}
/*
* ShowTransactionState
* Debug support
*/
static void
ShowTransactionState(const char *str)
{
/* skip work if message will definitely not be printed */
if (log_min_messages <= DEBUG3 || client_min_messages <= DEBUG3)
{
elog(DEBUG3, "%s", str);
ShowTransactionStateRec(CurrentTransactionState);
}
}
/*
* ShowTransactionStateRec
* Recursive subroutine for ShowTransactionState
*/
static void
ShowTransactionStateRec(TransactionState s)
{
StringInfoData buf;
initStringInfo(&buf);
if (s->nChildXids > 0)
{
int i;
appendStringInfo(&buf, "%u", s->childXids[0]);
for (i = 1; i < s->nChildXids; i++)
appendStringInfo(&buf, " %u", s->childXids[i]);
}
if (s->parent)
ShowTransactionStateRec(s->parent);
/* use ereport to suppress computation if msg will not be printed */
ereport(DEBUG3,
(errmsg_internal("name: %s; blockState: %13s; state: %7s, xid/subid/cid: %u/%u/%u%s, nestlvl: %d, children: %s",
PointerIsValid(s->name) ? s->name : "unnamed",
BlockStateAsString(s->blockState),
TransStateAsString(s->state),
(unsigned int) s->transactionId,
(unsigned int) s->subTransactionId,
(unsigned int) currentCommandId,
currentCommandIdUsed ? " (used)" : "",
s->nestingLevel, buf.data)));
pfree(buf.data);
}
/*
* BlockStateAsString
* Debug support
*/
static const char *
BlockStateAsString(TBlockState blockState)
{
switch (blockState)
{
case TBLOCK_DEFAULT:
return "DEFAULT";
case TBLOCK_STARTED:
return "STARTED";
case TBLOCK_BEGIN:
return "BEGIN";
case TBLOCK_INPROGRESS:
return "INPROGRESS";
case TBLOCK_END:
return "END";
case TBLOCK_ABORT:
return "ABORT";
case TBLOCK_ABORT_END:
return "ABORT END";
case TBLOCK_ABORT_PENDING:
return "ABORT PEND";
case TBLOCK_PREPARE:
return "PREPARE";
case TBLOCK_SUBBEGIN:
return "SUB BEGIN";
case TBLOCK_SUBINPROGRESS:
return "SUB INPROGRS";
case TBLOCK_SUBEND:
return "SUB END";
case TBLOCK_SUBABORT:
return "SUB ABORT";
case TBLOCK_SUBABORT_END:
return "SUB ABORT END";
case TBLOCK_SUBABORT_PENDING:
return "SUB ABRT PEND";
case TBLOCK_SUBRESTART:
return "SUB RESTART";
case TBLOCK_SUBABORT_RESTART:
return "SUB AB RESTRT";
}
return "UNRECOGNIZED";
}
/*
* TransStateAsString
* Debug support
*/
static const char *
TransStateAsString(TransState state)
{
switch (state)
{
case TRANS_DEFAULT:
return "DEFAULT";
case TRANS_START:
return "START";
case TRANS_INPROGRESS:
return "INPROGR";
case TRANS_COMMIT:
return "COMMIT";
case TRANS_ABORT:
return "ABORT";
case TRANS_PREPARE:
return "PREPARE";
}
return "UNRECOGNIZED";
}
/*
* xactGetCommittedChildren
*
* Gets the list of committed children of the current transaction. The return
* value is the number of child transactions. *ptr is set to point to an
* array of TransactionIds. The array is allocated in TopTransactionContext;
* the caller should *not* pfree() it (this is a change from pre-8.4 code!).
* If there are no subxacts, *ptr is set to NULL.
*/
int
xactGetCommittedChildren(TransactionId **ptr)
{
TransactionState s = CurrentTransactionState;
if (s->nChildXids == 0)
*ptr = NULL;
else
*ptr = s->childXids;
return s->nChildXids;
}
/*
* XLOG support routines
*/
/*
* Before 9.0 this was a fairly short function, but now it performs many
* actions for which the order of execution is critical.
*/
static void
xact_redo_commit(xl_xact_commit *xlrec, TransactionId xid, XLogRecPtr lsn)
{
TransactionId *sub_xids;
SharedInvalidationMessage *inval_msgs;
TransactionId max_xid;
int i;
/* subxid array follows relfilenodes */
sub_xids = (TransactionId *) &(xlrec->xnodes[xlrec->nrels]);
/* invalidation messages array follows subxids */
inval_msgs = (SharedInvalidationMessage *) &(sub_xids[xlrec->nsubxacts]);
max_xid = TransactionIdLatest(xid, xlrec->nsubxacts, sub_xids);
/*
* Make sure nextXid is beyond any XID mentioned in the record.
*
* We don't expect anyone else to modify nextXid, hence we don't need to
* hold a lock while checking this. We still acquire the lock to modify
* it, though.
*/
if (TransactionIdFollowsOrEquals(max_xid,
ShmemVariableCache->nextXid))
{
LWLockAcquire(XidGenLock, LW_EXCLUSIVE);
ShmemVariableCache->nextXid = max_xid;
TransactionIdAdvance(ShmemVariableCache->nextXid);
LWLockRelease(XidGenLock);
}
if (standbyState == STANDBY_DISABLED)
{
/*
* Mark the transaction committed in pg_clog.
*/
TransactionIdCommitTree(xid, xlrec->nsubxacts, sub_xids);
}
else
{
/*
* If a transaction completion record arrives that has as-yet
* unobserved subtransactions then this will not have been fully
* handled by the call to RecordKnownAssignedTransactionIds() in the
* main recovery loop in xlog.c. So we need to do bookkeeping again to
* cover that case. This is confusing and it is easy to think this
* call is irrelevant, which has happened three times in development
* already. Leave it in.
*/
RecordKnownAssignedTransactionIds(max_xid);
/*
* Mark the transaction committed in pg_clog. We use async commit
* protocol during recovery to provide information on database
* consistency for when users try to set hint bits. It is important
* that we do not set hint bits until the minRecoveryPoint is past
* this commit record. This ensures that if we crash we don't see hint
* bits set on changes made by transactions that haven't yet
* recovered. It's unlikely but it's good to be safe.
*/
TransactionIdAsyncCommitTree(xid, xlrec->nsubxacts, sub_xids, lsn);
/*
* We must mark clog before we update the ProcArray.
*/
ExpireTreeKnownAssignedTransactionIds(xid, xlrec->nsubxacts, sub_xids, max_xid);
/*
* Send any cache invalidations attached to the commit. We must
* maintain the same order of invalidation then release locks as
* occurs in CommitTransaction().
*/
ProcessCommittedInvalidationMessages(inval_msgs, xlrec->nmsgs,
XactCompletionRelcacheInitFileInval(xlrec),
xlrec->dbId, xlrec->tsId);
/*
* Release locks, if any. We do this for both two phase and normal one
* phase transactions. In effect we are ignoring the prepare phase and
* just going straight to lock release.
*/
StandbyReleaseLockTree(xid, xlrec->nsubxacts, sub_xids);
}
/* Make sure files supposed to be dropped are dropped */
for (i = 0; i < xlrec->nrels; i++)
{
SMgrRelation srel = smgropen(xlrec->xnodes[i], InvalidBackendId);
ForkNumber fork;
for (fork = 0; fork <= MAX_FORKNUM; fork++)
{
if (smgrexists(srel, fork))
{
XLogDropRelation(xlrec->xnodes[i], fork);
smgrdounlink(srel, fork, true);
}
}
smgrclose(srel);
}
/*
* We issue an XLogFlush() for the same reason we emit ForceSyncCommit()
* in normal operation. For example, in DROP DATABASE, we delete all the
* files belonging to the database, and then commit the transaction. If we
* crash after all the files have been deleted but before the commit, you
* have an entry in pg_database without any files. To minimize the window
* for that, we use ForceSyncCommit() to rush the commit record to disk as
* quick as possible. We have the same window during recovery, and forcing
* an XLogFlush() (which updates minRecoveryPoint during recovery) helps
* to reduce that problem window, for any user that requested
* ForceSyncCommit().
*/
if (XactCompletionForceSyncCommit(xlrec))
XLogFlush(lsn);
}
/*
* Be careful with the order of execution, as with xact_redo_commit().
* The two functions are similar but differ in key places.
*
* Note also that an abort can be for a subtransaction and its children,
* not just for a top level abort. That means we have to consider
* topxid != xid, whereas in commit we would find topxid == xid always
* because subtransaction commit is never WAL logged.
*/
static void
xact_redo_abort(xl_xact_abort *xlrec, TransactionId xid)
{
TransactionId *sub_xids;
TransactionId max_xid;
int i;
sub_xids = (TransactionId *) &(xlrec->xnodes[xlrec->nrels]);
max_xid = TransactionIdLatest(xid, xlrec->nsubxacts, sub_xids);
/*
* Make sure nextXid is beyond any XID mentioned in the record.
*
* We don't expect anyone else to modify nextXid, hence we don't need to
* hold a lock while checking this. We still acquire the lock to modify
* it, though.
*/
if (TransactionIdFollowsOrEquals(max_xid,
ShmemVariableCache->nextXid))
{
LWLockAcquire(XidGenLock, LW_EXCLUSIVE);
ShmemVariableCache->nextXid = max_xid;
TransactionIdAdvance(ShmemVariableCache->nextXid);
LWLockRelease(XidGenLock);
}
if (standbyState == STANDBY_DISABLED)
{
/* Mark the transaction aborted in pg_clog, no need for async stuff */
TransactionIdAbortTree(xid, xlrec->nsubxacts, sub_xids);
}
else
{
/*
* If a transaction completion record arrives that has as-yet
* unobserved subtransactions then this will not have been fully
* handled by the call to RecordKnownAssignedTransactionIds() in the
* main recovery loop in xlog.c. So we need to do bookkeeping again to
* cover that case. This is confusing and it is easy to think this
* call is irrelevant, which has happened three times in development
* already. Leave it in.
*/
RecordKnownAssignedTransactionIds(max_xid);
/* Mark the transaction aborted in pg_clog, no need for async stuff */
TransactionIdAbortTree(xid, xlrec->nsubxacts, sub_xids);
/*
* We must update the ProcArray after we have marked clog.
*/
ExpireTreeKnownAssignedTransactionIds(xid, xlrec->nsubxacts, sub_xids, max_xid);
/*
* There are no flat files that need updating, nor invalidation
* messages to send or undo.
*/
/*
* Release locks, if any. There are no invalidations to send.
*/
StandbyReleaseLockTree(xid, xlrec->nsubxacts, sub_xids);
}
/* Make sure files supposed to be dropped are dropped */
for (i = 0; i < xlrec->nrels; i++)
{
SMgrRelation srel = smgropen(xlrec->xnodes[i], InvalidBackendId);
ForkNumber fork;
for (fork = 0; fork <= MAX_FORKNUM; fork++)
{
if (smgrexists(srel, fork))
{
XLogDropRelation(xlrec->xnodes[i], fork);
smgrdounlink(srel, fork, true);
}
}
smgrclose(srel);
}
}
void
xact_redo(XLogRecPtr lsn, XLogRecord *record)
{
uint8 info = record->xl_info & ~XLR_INFO_MASK;
/* Backup blocks are not used in xact records */
Assert(!(record->xl_info & XLR_BKP_BLOCK_MASK));
if (info == XLOG_XACT_COMMIT)
{
xl_xact_commit *xlrec = (xl_xact_commit *) XLogRecGetData(record);
xact_redo_commit(xlrec, record->xl_xid, lsn);
}
else if (info == XLOG_XACT_ABORT)
{
xl_xact_abort *xlrec = (xl_xact_abort *) XLogRecGetData(record);
xact_redo_abort(xlrec, record->xl_xid);
}
else if (info == XLOG_XACT_PREPARE)
{
/* the record contents are exactly the 2PC file */
RecreateTwoPhaseFile(record->xl_xid,
XLogRecGetData(record), record->xl_len);
}
else if (info == XLOG_XACT_COMMIT_PREPARED)
{
xl_xact_commit_prepared *xlrec = (xl_xact_commit_prepared *) XLogRecGetData(record);
xact_redo_commit(&xlrec->crec, xlrec->xid, lsn);
RemoveTwoPhaseFile(xlrec->xid, false);
}
else if (info == XLOG_XACT_ABORT_PREPARED)
{
xl_xact_abort_prepared *xlrec = (xl_xact_abort_prepared *) XLogRecGetData(record);
xact_redo_abort(&xlrec->arec, xlrec->xid);
RemoveTwoPhaseFile(xlrec->xid, false);
}
else if (info == XLOG_XACT_ASSIGNMENT)
{
xl_xact_assignment *xlrec = (xl_xact_assignment *) XLogRecGetData(record);
if (standbyState >= STANDBY_INITIALIZED)
ProcArrayApplyXidAssignment(xlrec->xtop,
xlrec->nsubxacts, xlrec->xsub);
}
else
elog(PANIC, "xact_redo: unknown op code %u", info);
}
static void
xact_desc_commit(StringInfo buf, xl_xact_commit *xlrec)
{
int i;
TransactionId *xacts;
xacts = (TransactionId *) &xlrec->xnodes[xlrec->nrels];
appendStringInfoString(buf, timestamptz_to_str(xlrec->xact_time));
if (xlrec->nrels > 0)
{
appendStringInfo(buf, "; rels:");
for (i = 0; i < xlrec->nrels; i++)
{
char *path = relpathperm(xlrec->xnodes[i], MAIN_FORKNUM);
appendStringInfo(buf, " %s", path);
pfree(path);
}
}
if (xlrec->nsubxacts > 0)
{
appendStringInfo(buf, "; subxacts:");
for (i = 0; i < xlrec->nsubxacts; i++)
appendStringInfo(buf, " %u", xacts[i]);
}
if (xlrec->nmsgs > 0)
{
SharedInvalidationMessage *msgs;
msgs = (SharedInvalidationMessage *) &xacts[xlrec->nsubxacts];
if (XactCompletionRelcacheInitFileInval(xlrec))
appendStringInfo(buf, "; relcache init file inval dbid %u tsid %u",
xlrec->dbId, xlrec->tsId);
appendStringInfo(buf, "; inval msgs:");
for (i = 0; i < xlrec->nmsgs; i++)
{
SharedInvalidationMessage *msg = &msgs[i];
if (msg->id >= 0)
appendStringInfo(buf, " catcache %d", msg->id);
else if (msg->id == SHAREDINVALCATALOG_ID)
appendStringInfo(buf, " catalog %u", msg->cat.catId);
else if (msg->id == SHAREDINVALRELCACHE_ID)
appendStringInfo(buf, " relcache %u", msg->rc.relId);
/* remaining cases not expected, but print something anyway */
else if (msg->id == SHAREDINVALSMGR_ID)
appendStringInfo(buf, " smgr");
else if (msg->id == SHAREDINVALRELMAP_ID)
appendStringInfo(buf, " relmap");
else
appendStringInfo(buf, " unknown id %d", msg->id);
}
}
}
static void
xact_desc_abort(StringInfo buf, xl_xact_abort *xlrec)
{
int i;
appendStringInfoString(buf, timestamptz_to_str(xlrec->xact_time));
if (xlrec->nrels > 0)
{
appendStringInfo(buf, "; rels:");
for (i = 0; i < xlrec->nrels; i++)
{
char *path = relpathperm(xlrec->xnodes[i], MAIN_FORKNUM);
appendStringInfo(buf, " %s", path);
pfree(path);
}
}
if (xlrec->nsubxacts > 0)
{
TransactionId *xacts = (TransactionId *)
&xlrec->xnodes[xlrec->nrels];
appendStringInfo(buf, "; subxacts:");
for (i = 0; i < xlrec->nsubxacts; i++)
appendStringInfo(buf, " %u", xacts[i]);
}
}
static void
xact_desc_assignment(StringInfo buf, xl_xact_assignment *xlrec)
{
int i;
appendStringInfo(buf, "subxacts:");
for (i = 0; i < xlrec->nsubxacts; i++)
appendStringInfo(buf, " %u", xlrec->xsub[i]);
}
void
xact_desc(StringInfo buf, uint8 xl_info, char *rec)
{
uint8 info = xl_info & ~XLR_INFO_MASK;
if (info == XLOG_XACT_COMMIT)
{
xl_xact_commit *xlrec = (xl_xact_commit *) rec;
appendStringInfo(buf, "commit: ");
xact_desc_commit(buf, xlrec);
}
else if (info == XLOG_XACT_ABORT)
{
xl_xact_abort *xlrec = (xl_xact_abort *) rec;
appendStringInfo(buf, "abort: ");
xact_desc_abort(buf, xlrec);
}
else if (info == XLOG_XACT_PREPARE)
{
appendStringInfo(buf, "prepare");
}
else if (info == XLOG_XACT_COMMIT_PREPARED)
{
xl_xact_commit_prepared *xlrec = (xl_xact_commit_prepared *) rec;
appendStringInfo(buf, "commit prepared %u: ", xlrec->xid);
xact_desc_commit(buf, &xlrec->crec);
}
else if (info == XLOG_XACT_ABORT_PREPARED)
{
xl_xact_abort_prepared *xlrec = (xl_xact_abort_prepared *) rec;
appendStringInfo(buf, "abort prepared %u: ", xlrec->xid);
xact_desc_abort(buf, &xlrec->arec);
}
else if (info == XLOG_XACT_ASSIGNMENT)
{
xl_xact_assignment *xlrec = (xl_xact_assignment *) rec;
/*
* Note that we ignore the WAL record's xid, since we're more
* interested in the top-level xid that issued the record and which
* xids are being reported here.
*/
appendStringInfo(buf, "xid assignment xtop %u: ", xlrec->xtop);
xact_desc_assignment(buf, xlrec);
}
else
appendStringInfo(buf, "UNKNOWN");
}
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