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postgres/src/backend/storage/ipc/sinvaladt.c

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/*-------------------------------------------------------------------------
*
* sinvaladt.c
* POSTGRES shared cache invalidation segment definitions.
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.23 1999/07/17 20:17:44 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include <signal.h>
#include <unistd.h>
#include "postgres.h"
#include "storage/backendid.h"
#include "storage/lmgr.h"
#include "utils/trace.h"
/* ----------------
* global variable notes
*
* SharedInvalidationSemaphore
*
* shmInvalBuffer
* the shared buffer segment, set by SISegmentAttach()
*
* MyBackendId
* might be removed later, used only for
* debugging in debug routines (end of file)
*
* SIDbId
* identification of buffer (disappears)
*
* SIRelId \
* SIDummyOid \ identification of buffer
* SIXidData /
* SIXid /
*
* XXX This file really needs to be cleaned up. We switched to using
* spinlocks to protect critical sections (as opposed to using fake
* relations and going through the lock manager) and some of the old
* cruft was 'ifdef'ed out, while other parts (now unused) are still
* compiled into the system. -mer 5/24/92
* ----------------
*/
#ifdef HAS_TEST_AND_SET
int SharedInvalidationLockId;
#else
IpcSemaphoreId SharedInvalidationSemaphore;
#endif
SISeg *shmInvalBuffer;
extern BackendId MyBackendId;
static void CleanupInvalidationState(int status, SISeg *segInOutP);
static BackendId SIAssignBackendId(SISeg *segInOutP, BackendTag backendTag);
static int SIGetNumEntries(SISeg *segP);
/************************************************************************/
/* SISetActiveProcess(segP, backendId) set the backend status active */
/* should be called only by the postmaster when creating a backend */
/************************************************************************/
/* XXX I suspect that the segP parameter is extraneous. -hirohama */
static void
SISetActiveProcess(SISeg *segInOutP, BackendId backendId)
{
/* mark all messages as read */
/* Assert(segP->procState[backendId - 1].tag == MyBackendTag); */
segInOutP->procState[backendId - 1].resetState = false;
segInOutP->procState[backendId - 1].limit = SIGetNumEntries(segInOutP);
}
/****************************************************************************/
/* SIBackendInit() initializes a backend to operate on the buffer */
/****************************************************************************/
int
SIBackendInit(SISeg *segInOutP)
{
LockRelId LtCreateRelId();
TransactionId LMITransactionIdCopy();
Assert(MyBackendTag > 0);
MyBackendId = SIAssignBackendId(segInOutP, MyBackendTag);
if (MyBackendId == InvalidBackendTag)
return 0;
#ifdef INVALIDDEBUG
elog(DEBUG, "SIBackendInit: backend tag %d; backend id %d.",
MyBackendTag, MyBackendId);
#endif /* INVALIDDEBUG */
SISetActiveProcess(segInOutP, MyBackendId);
on_shmem_exit(CleanupInvalidationState, (caddr_t) segInOutP);
return 1;
}
/* ----------------
* SIAssignBackendId
* ----------------
*/
static BackendId
SIAssignBackendId(SISeg *segInOutP, BackendTag backendTag)
{
Index index;
ProcState *stateP = NULL;
for (index = 0; index < segInOutP->maxBackends; index++)
{
if (segInOutP->procState[index].tag == InvalidBackendTag ||
segInOutP->procState[index].tag == backendTag)
{
stateP = &segInOutP->procState[index];
break;
}
if (!PointerIsValid(stateP) ||
(segInOutP->procState[index].resetState &&
(!stateP->resetState ||
stateP->tag < backendTag)) ||
(!stateP->resetState &&
(segInOutP->procState[index].limit <
stateP->limit ||
stateP->tag < backendTag)))
stateP = &segInOutP->procState[index];
}
/* verify that all "procState" entries checked for matching tags */
for (index++; index < segInOutP->maxBackends; index++)
{
if (segInOutP->procState[index].tag == backendTag)
elog(FATAL, "SIAssignBackendId: tag %d found twice", backendTag);
}
Assert(stateP);
if (stateP->tag != InvalidBackendTag)
{
if (stateP->tag == backendTag)
elog(NOTICE, "SIAssignBackendId: reusing tag %d", backendTag);
else
{
elog(NOTICE, "SIAssignBackendId: discarding tag %d", stateP->tag);
return InvalidBackendTag;
}
}
stateP->tag = backendTag;
return 1 + stateP - &segInOutP->procState[0];
}
/************************************************************************/
/* The following function should be called only by the postmaster !! */
/************************************************************************/
/************************************************************************/
/* SISetDeadProcess(segP, backendId) set the backend status DEAD */
/* should be called only by the postmaster when a backend died */
/************************************************************************/
static void
SISetDeadProcess(SISeg *segP, int backendId)
{
/* XXX call me.... */
segP->procState[backendId - 1].resetState = false;
segP->procState[backendId - 1].limit = -1;
segP->procState[backendId - 1].tag = InvalidBackendTag;
}
/*
* CleanupInvalidationState
* Note:
* This is a temporary hack. ExitBackend should call this instead
* of exit (via on_shmem_exit).
*/
static void
CleanupInvalidationState(int status, /* XXX */
SISeg *segInOutP) /* XXX style */
{
Assert(PointerIsValid(segInOutP));
SISetDeadProcess(segInOutP, MyBackendId);
}
/************************************************************************/
/* SIComputeSize() - compute size and offsets for SI segment */
/************************************************************************/
static void
SIComputeSize(SISegOffsets *oP, int maxBackends)
{
int A,
B,
a,
b,
totalSize;
A = 0;
/* sizeof(SISeg) includes the first ProcState entry */
a = sizeof(SISeg) + sizeof(ProcState) * (maxBackends - 1);
a = MAXALIGN(a); /* offset to first data entry */
b = sizeof(SISegEntry) * MAXNUMMESSAGES;
B = A + a + b;
B = MAXALIGN(B);
totalSize = B - A;
oP->startSegment = A;
oP->offsetToFirstEntry = a; /* relative to A */
oP->offsetToEndOfSegment = totalSize; /* relative to A */
}
/************************************************************************/
/* SISetStartEntrySection(segP, offset) - sets the offset */
/************************************************************************/
static void
SISetStartEntrySection(SISeg *segP, Offset offset)
{
segP->startEntrySection = offset;
}
/************************************************************************/
/* SIGetStartEntrySection(segP) - returnss the offset */
/************************************************************************/
static Offset
SIGetStartEntrySection(SISeg *segP)
{
return segP->startEntrySection;
}
/************************************************************************/
/* SISetEndEntrySection(segP, offset) - sets the offset */
/************************************************************************/
static void
SISetEndEntrySection(SISeg *segP, Offset offset)
{
segP->endEntrySection = offset;
}
/************************************************************************/
/* SISetEndEntryChain(segP, offset) - sets the offset */
/************************************************************************/
static void
SISetEndEntryChain(SISeg *segP, Offset offset)
{
segP->endEntryChain = offset;
}
/************************************************************************/
/* SIGetEndEntryChain(segP) - returnss the offset */
/************************************************************************/
static Offset
SIGetEndEntryChain(SISeg *segP)
{
return segP->endEntryChain;
}
/************************************************************************/
/* SISetStartEntryChain(segP, offset) - sets the offset */
/************************************************************************/
static void
SISetStartEntryChain(SISeg *segP, Offset offset)
{
segP->startEntryChain = offset;
}
/************************************************************************/
/* SIGetStartEntryChain(segP) - returns the offset */
/************************************************************************/
static Offset
SIGetStartEntryChain(SISeg *segP)
{
return segP->startEntryChain;
}
/************************************************************************/
/* SISetNumEntries(segP, num) sets the current nuber of entries */
/************************************************************************/
static bool
SISetNumEntries(SISeg *segP, int num)
{
if (num <= MAXNUMMESSAGES)
{
segP->numEntries = num;
return true;
}
else
{
return false; /* table full */
}
}
/************************************************************************/
/* SIGetNumEntries(segP) - returns the current nuber of entries */
/************************************************************************/
static int
SIGetNumEntries(SISeg *segP)
{
return segP->numEntries;
}
/************************************************************************/
/* SISetMaxNumEntries(segP, num) sets the maximal number of entries */
/************************************************************************/
static bool
SISetMaxNumEntries(SISeg *segP, int num)
{
if (num <= MAXNUMMESSAGES)
{
segP->maxNumEntries = num;
return true;
}
else
{
return false; /* wrong number */
}
}
/************************************************************************/
/* SIGetProcStateLimit(segP, i) returns the limit of read messages */
/************************************************************************/
#define SIGetProcStateLimit(segP,i) \
((segP)->procState[i].limit)
/************************************************************************/
/* SIIncNumEntries(segP, num) increments the current nuber of entries */
/************************************************************************/
static bool
SIIncNumEntries(SISeg *segP, int num)
{
/*
* Try to prevent table overflow. When the table is 70% full send a
* SIGUSR2 to the postmaster which will send it back to all the
* backends. This will be handled by Async_NotifyHandler() with a
* StartTransactionCommand() which will flush unread SI entries for
* each backend. dz - 27 Jan 1998
*/
if (segP->numEntries == (MAXNUMMESSAGES * 70 / 100))
{
TPRINTF(TRACE_VERBOSE,
"SIIncNumEntries: table is 70%% full, signaling postmaster");
kill(getppid(), SIGUSR2);
}
if ((segP->numEntries + num) <= MAXNUMMESSAGES)
{
segP->numEntries = segP->numEntries + num;
return true;
}
else
{
return false; /* table full */
}
}
/************************************************************************/
/* SIDecNumEntries(segP, num) decrements the current nuber of entries */
/************************************************************************/
static bool
SIDecNumEntries(SISeg *segP, int num)
{
if ((segP->numEntries - num) >= 0)
{
segP->numEntries = segP->numEntries - num;
return true;
}
else
{
return false; /* not enough entries in table */
}
}
/************************************************************************/
/* SISetStartFreeSpace(segP, offset) - sets the offset */
/************************************************************************/
static void
SISetStartFreeSpace(SISeg *segP, Offset offset)
{
segP->startFreeSpace = offset;
}
/************************************************************************/
/* SIGetStartFreeSpace(segP) - returns the offset */
/************************************************************************/
static Offset
SIGetStartFreeSpace(SISeg *segP)
{
return segP->startFreeSpace;
}
/************************************************************************/
/* SIGetFirstDataEntry(segP) returns first data entry */
/************************************************************************/
static SISegEntry *
SIGetFirstDataEntry(SISeg *segP)
{
SISegEntry *eP;
Offset startChain;
startChain = SIGetStartEntryChain(segP);
if (startChain == InvalidOffset)
return NULL;
eP = (SISegEntry *) ((Pointer) segP +
SIGetStartEntrySection(segP) +
startChain);
return eP;
}
/************************************************************************/
/* SIGetLastDataEntry(segP) returns last data entry in the chain */
/************************************************************************/
static SISegEntry *
SIGetLastDataEntry(SISeg *segP)
{
SISegEntry *eP;
Offset endChain;
endChain = SIGetEndEntryChain(segP);
if (endChain == InvalidOffset)
return NULL;
eP = (SISegEntry *) ((Pointer) segP +
SIGetStartEntrySection(segP) +
endChain);
return eP;
}
/************************************************************************/
/* SIGetNextDataEntry(segP, offset) returns next data entry */
/************************************************************************/
static SISegEntry *
SIGetNextDataEntry(SISeg *segP, Offset offset)
{
SISegEntry *eP;
if (offset == InvalidOffset)
return NULL;
eP = (SISegEntry *) ((Pointer) segP +
SIGetStartEntrySection(segP) +
offset);
return eP;
}
/************************************************************************/
/* SIGetNthDataEntry(segP, n) returns the n-th data entry in chain */
/************************************************************************/
static SISegEntry *
SIGetNthDataEntry(SISeg *segP,
int n) /* must range from 1 to MaxMessages */
{
SISegEntry *eP;
int i;
if (n <= 0)
return NULL;
eP = SIGetFirstDataEntry(segP);
for (i = 1; i < n; i++)
{
/* skip one and get the next */
eP = SIGetNextDataEntry(segP, eP->next);
}
return eP;
}
/************************************************************************/
/* SIEntryOffset(segP, entryP) returns the offset for an pointer */
/************************************************************************/
static Offset
SIEntryOffset(SISeg *segP, SISegEntry *entryP)
{
/* relative to B !! */
return ((Offset) ((Pointer) entryP -
(Pointer) segP -
SIGetStartEntrySection(segP)));
}
/************************************************************************/
/* SISetDataEntry(segP, data) - sets a message in the segemnt */
/************************************************************************/
bool
SISetDataEntry(SISeg *segP, SharedInvalidData *data)
{
Offset offsetToNewData;
SISegEntry *eP,
*lastP;
if (!SIIncNumEntries(segP, 1))
return false; /* no space */
/* get a free entry */
offsetToNewData = SIGetStartFreeSpace(segP);
eP = SIGetNextDataEntry(segP, offsetToNewData); /* it's a free one */
SISetStartFreeSpace(segP, eP->next);
/* fill it up */
eP->entryData = *data;
eP->isfree = false;
eP->next = InvalidOffset;
/* handle insertion point at the end of the chain !! */
lastP = SIGetLastDataEntry(segP);
if (lastP == NULL)
{
/* there is no chain, insert the first entry */
SISetStartEntryChain(segP, SIEntryOffset(segP, eP));
}
else
{
/* there is a last entry in the chain */
lastP->next = SIEntryOffset(segP, eP);
}
SISetEndEntryChain(segP, SIEntryOffset(segP, eP));
return true;
}
/************************************************************************/
/* SIDecProcLimit(segP, num) decrements all process limits */
/************************************************************************/
static void
SIDecProcLimit(SISeg *segP, int num)
{
int i;
for (i = 0; i < segP->maxBackends; i++)
{
/* decrement only, if there is a limit > 0 */
if (segP->procState[i].limit > 0)
{
segP->procState[i].limit = segP->procState[i].limit - num;
if (segP->procState[i].limit < 0)
{
/* limit was not high enough, reset to zero */
/* negative means it's a dead backend */
segP->procState[i].limit = 0;
}
}
}
}
/************************************************************************/
/* SIDelDataEntry(segP) - free the FIRST entry */
/************************************************************************/
bool
SIDelDataEntry(SISeg *segP)
{
SISegEntry *e1P;
if (!SIDecNumEntries(segP, 1))
{
/* no entries in buffer */
return false;
}
e1P = SIGetFirstDataEntry(segP);
SISetStartEntryChain(segP, e1P->next);
if (SIGetStartEntryChain(segP) == InvalidOffset)
{
/* it was the last entry */
SISetEndEntryChain(segP, InvalidOffset);
}
/* free the entry */
e1P->isfree = true;
e1P->next = SIGetStartFreeSpace(segP);
SISetStartFreeSpace(segP, SIEntryOffset(segP, e1P));
SIDecProcLimit(segP, 1);
return true;
}
/************************************************************************/
/* SISetProcStateInvalid(segP) checks and marks a backends state as */
/* invalid */
/************************************************************************/
void
SISetProcStateInvalid(SISeg *segP)
{
int i;
for (i = 0; i < segP->maxBackends; i++)
{
if (segP->procState[i].limit == 0)
{
/* backend i didn't read any message */
segP->procState[i].resetState = true;
/*
* XXX signal backend that it has to reset its internal cache
* ?
*/
}
}
}
/************************************************************************/
/* SIReadEntryData(segP, backendId, function) */
/* - marks messages to be read by id */
/* and executes function */
/************************************************************************/
void
SIReadEntryData(SISeg *segP,
int backendId,
void (*invalFunction) (),
void (*resetFunction) ())
{
int i = 0;
SISegEntry *data;
Assert(segP->procState[backendId - 1].tag == MyBackendTag);
if (!segP->procState[backendId - 1].resetState)
{
/* invalidate data, but only those, you have not seen yet !! */
/* therefore skip read messages */
data = SIGetNthDataEntry(segP,
SIGetProcStateLimit(segP, backendId - 1) + 1);
while (data != NULL)
{
i++;
segP->procState[backendId - 1].limit++; /* one more message read */
invalFunction(data->entryData.cacheId,
data->entryData.hashIndex,
&data->entryData.pointerData);
data = SIGetNextDataEntry(segP, data->next);
}
/* SIDelExpiredDataEntries(segP); */
}
else
{
/* backend must not read messages, its own state has to be reset */
elog(NOTICE, "SIReadEntryData: cache state reset");
resetFunction(); /* XXXX call it here, parameters? */
/* new valid state--mark all messages "read" */
segP->procState[backendId - 1].resetState = false;
segP->procState[backendId - 1].limit = SIGetNumEntries(segP);
}
/* check whether we can remove dead messages */
if (i > MAXNUMMESSAGES)
elog(FATAL, "SIReadEntryData: Invalid segment state");
}
/************************************************************************/
/* SIDelExpiredDataEntries (segP) - removes irrelevant messages */
/************************************************************************/
void
SIDelExpiredDataEntries(SISeg *segP)
{
int min,
i,
h;
min = 9999999;
for (i = 0; i < segP->maxBackends; i++)
{
h = SIGetProcStateLimit(segP, i);
if (h >= 0)
{ /* backend active */
if (h < min)
min = h;
}
}
if (min != 9999999)
{
/* we can remove min messages */
for (i = 1; i <= min; i++)
{
/* this adjusts also the state limits! */
if (!SIDelDataEntry(segP))
elog(FATAL, "SIDelExpiredDataEntries: Invalid segment state");
}
}
}
/************************************************************************/
/* SISegInit(segP) - initializes the segment */
/************************************************************************/
static void
SISegInit(SISeg *segP, SISegOffsets *oP, int maxBackends)
{
int i;
SISegEntry *eP;
/* set semaphore ids in the segment */
/* XXX */
SISetStartEntrySection(segP, oP->offsetToFirstEntry);
SISetEndEntrySection(segP, oP->offsetToEndOfSegment);
SISetStartFreeSpace(segP, 0);
SISetStartEntryChain(segP, InvalidOffset);
SISetEndEntryChain(segP, InvalidOffset);
SISetNumEntries(segP, 0);
SISetMaxNumEntries(segP, MAXNUMMESSAGES);
segP->maxBackends = maxBackends;
for (i = 0; i < segP->maxBackends; i++)
{
segP->procState[i].limit = -1; /* no backend active !! */
segP->procState[i].resetState = false;
segP->procState[i].tag = InvalidBackendTag;
}
/* construct a chain of free entries */
for (i = 1; i < MAXNUMMESSAGES; i++)
{
eP = (SISegEntry *) ((Pointer) segP +
SIGetStartEntrySection(segP) +
(i - 1) * sizeof(SISegEntry));
eP->isfree = true;
eP->next = i * sizeof(SISegEntry); /* relative to B */
}
/* handle the last free entry separate */
eP = (SISegEntry *) ((Pointer) segP +
SIGetStartEntrySection(segP) +
(MAXNUMMESSAGES - 1) * sizeof(SISegEntry));
eP->isfree = true;
eP->next = InvalidOffset; /* it's the end of the chain !! */
}
/************************************************************************/
/* SISegmentKill(key) - kill any segment */
/************************************************************************/
static void
SISegmentKill(int key) /* the corresponding key for the segment */
{
IpcMemoryKill(key);
}
/************************************************************************/
/* SISegmentGet(key, size) - get a shared segment of size <size> */
/* returns a segment id */
/************************************************************************/
static IpcMemoryId
SISegmentGet(int key, /* the corresponding key for the segment */
int size, /* size of segment in bytes */
bool create)
{
IpcMemoryId shmid;
if (create)
shmid = IpcMemoryCreate(key, size, IPCProtection);
else
shmid = IpcMemoryIdGet(key, size);
return shmid;
}
/************************************************************************/
/* SISegmentAttach(shmid) - attach a shared segment with id shmid */
/************************************************************************/
static void
SISegmentAttach(IpcMemoryId shmid)
{
shmInvalBuffer = (struct SISeg *) IpcMemoryAttach(shmid);
if (shmInvalBuffer == IpcMemAttachFailed)
{
/* XXX use validity function */
elog(NOTICE, "SISegmentAttach: Could not attach segment");
elog(FATAL, "SISegmentAttach: %m");
}
}
/************************************************************************/
/* SISegmentInit() initialize SI segment */
/* */
/* NB: maxBackends param is only valid when killExistingSegment is true */
/************************************************************************/
int
SISegmentInit(bool killExistingSegment, IPCKey key, int maxBackends)
{
SISegOffsets offsets;
IpcMemoryId shmId;
bool create;
if (killExistingSegment)
{
/* Kill existing segment */
/* set semaphore */
SISegmentKill(key);
/* Get a shared segment */
SIComputeSize(&offsets, maxBackends);
create = true;
shmId = SISegmentGet(key, offsets.offsetToEndOfSegment, create);
if (shmId < 0)
{
perror("SISegmentGet: failed");
return -1; /* an error */
}
/* Attach the shared cache invalidation segment */
/* sets the global variable shmInvalBuffer */
SISegmentAttach(shmId);
/* Init shared memory table */
SISegInit(shmInvalBuffer, &offsets, maxBackends);
}
else
{
/* use an existing segment */
create = false;
shmId = SISegmentGet(key, 0, create);
if (shmId < 0)
{
perror("SISegmentGet: getting an existent segment failed");
return -1; /* an error */
}
/* Attach the shared cache invalidation segment */
SISegmentAttach(shmId);
}
return 1;
}
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