database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-15 19:21:59 +03:00
Code Activity

Update xact.c comments for clarity.

Browse Source
This commit is contained in:
Bruce Momjian
2002-11-13 03:12:05 +00:00
parent 34529aeb64
commit 63e9734542
2 changed files with 102 additions and 114 deletions
Download Patch File Download Diff File Expand all files Collapse all files

59
src/backend/access/transam/xact.c
View File

@ -8,13 +8,13 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.137 2002/11/11 22:19:20 tgl Exp $ * $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.138 2002/11/13 03:12:05 momjian Exp $
* *
* NOTES * NOTES
* Transaction aborts can now occur two ways: * Transaction aborts can now occur two ways:
* *
* 1) system dies from some internal cause (Assert, etc..) * 1) system dies from some internal cause (syntax error, etc..)
* 2) user types abort * 2) user types ABORT
* *
* These two cases used to be treated identically, but now * These two cases used to be treated identically, but now
* we need to distinguish them. Why? consider the following * we need to distinguish them. Why? consider the following
@ -30,8 +30,8 @@
* In case 1, we want to abort the transaction and return to the * In case 1, we want to abort the transaction and return to the
* default state. In case 2, there may be more commands coming * default state. In case 2, there may be more commands coming
* our way which are part of the same transaction block and we have * our way which are part of the same transaction block and we have
* to ignore these commands until we see an END transaction. * to ignore these commands until we see a COMMIT transaction or
* (or an ABORT! --djm) * ROLLBACK.
* *
* Internal aborts are now handled by AbortTransactionBlock(), just as * Internal aborts are now handled by AbortTransactionBlock(), just as
* they always have been, and user aborts are now handled by * they always have been, and user aborts are now handled by
@ -52,14 +52,6 @@
* TransactionCommandContext until this point. * TransactionCommandContext until this point.
* *
* NOTES * NOTES
* This file is an attempt at a redesign of the upper layer
* of the V1 transaction system which was too poorly thought
* out to describe. This new system hopes to be both simpler
* in design, simpler to extend and needs to contain added
* functionality to solve problems beyond the scope of the V1
* system. (In particuler, communication of transaction
* information between parallel backends has to be supported)
*
* The essential aspects of the transaction system are: * The essential aspects of the transaction system are:
* *
* o transaction id generation * o transaction id generation
@ -69,7 +61,7 @@
* o lock cleanup * o lock cleanup
* *
* Hence, the functional division of the transaction code is * Hence, the functional division of the transaction code is
* based on what of the above things need to be done during * based on which of the above things need to be done during
* a start/commit/abort transaction. For instance, the * a start/commit/abort transaction. For instance, the
* routine AtCommit_Memory() takes care of all the memory * routine AtCommit_Memory() takes care of all the memory
* cleanup stuff done at commit time. * cleanup stuff done at commit time.
@ -99,17 +91,17 @@
* CommitTransactionBlock * CommitTransactionBlock
* AbortTransactionBlock * AbortTransactionBlock
* *
* These are invoked only in responce to a user "BEGIN", "END", * These are invoked only in responce to a user "BEGIN WORK", "COMMIT",
* or "ABORT" command. The tricky part about these functions * or "ROLLBACK" command. The tricky part about these functions
* is that they are called within the postgres main loop, in between * is that they are called within the postgres main loop, in between
* the StartTransactionCommand() and CommitTransactionCommand(). * the StartTransactionCommand() and CommitTransactionCommand().
* *
* For example, consider the following sequence of user commands: * For example, consider the following sequence of user commands:
* *
* 1) begin * 1) begin
* 2) retrieve (foo.all) * 2) select * from foo
* 3) append foo (bar = baz) * 3) insert into foo (bar = baz)
* 4) end * 4) commit
* *
* in the main processing loop, this results in the following * in the main processing loop, this results in the following
* transaction sequence: * transaction sequence:
@ -120,15 +112,15 @@
* \ CommitTransactionCommand(); * \ CommitTransactionCommand();
* *
* / StartTransactionCommand(); * / StartTransactionCommand();
* 2) < ProcessQuery(); << retrieve (foo.all) * 2) < ProcessQuery(); << select * from foo
* \ CommitTransactionCommand(); * \ CommitTransactionCommand();
* *
* / StartTransactionCommand(); * / StartTransactionCommand();
* 3) < ProcessQuery(); << append foo (bar = baz) * 3) < ProcessQuery(); << insert into foo (bar = baz)
* \ CommitTransactionCommand(); * \ CommitTransactionCommand();
* *
* / StartTransactionCommand(); * / StartTransactionCommand();
* 4) / ProcessUtility(); << end * 4) / ProcessUtility(); << commit
* \ CommitTransactionBlock(); * \ CommitTransactionBlock();
* \ CommitTransactionCommand(); * \ CommitTransactionCommand();
* *
@ -139,19 +131,14 @@
* outside these calls they need to do normal start/commit * outside these calls they need to do normal start/commit
* processing. * processing.
* *
* Furthermore, suppose the "retrieve (foo.all)" caused an abort * Furthermore, suppose the "select * from foo" caused an abort
* condition. We would then want to abort the transaction and * condition. We would then want to abort the transaction and
* ignore all subsequent commands up to the "end". * ignore all subsequent commands up to the "commit".
* -cim 3/23/90 * -cim 3/23/90
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
/*
* Large object clean up added in CommitTransaction() to prevent buffer leaks.
* [PA, 7/17/98]
* [PA] is Pascal Andr<64> <andre@via.ecp.fr>
*/
#include "postgres.h" #include "postgres.h"
#include <unistd.h> #include <unistd.h>
@ -201,9 +188,8 @@ static void CommitTransaction(void);
static void RecordTransactionAbort(void); static void RecordTransactionAbort(void);
static void StartTransaction(void); static void StartTransaction(void);
/* ---------------- /*
* global variables holding the current transaction state. * global variables holding the current transaction state.
* ----------------
*/ */
static TransactionStateData CurrentTransactionStateData = { static TransactionStateData CurrentTransactionStateData = {
0, /* transaction id */ 0, /* transaction id */
@ -211,7 +197,7 @@ static TransactionStateData CurrentTransactionStateData = {
0, /* scan command id */ 0, /* scan command id */
0x0, /* start time */ 0x0, /* start time */
TRANS_DEFAULT, /* transaction state */ TRANS_DEFAULT, /* transaction state */
TBLOCK_DEFAULT /* transaction block state */ TBLOCK_DEFAULT /* transaction block state of client queries */
}; };
TransactionState CurrentTransactionState = &CurrentTransactionStateData; TransactionState CurrentTransactionState = &CurrentTransactionStateData;
@ -853,7 +839,6 @@ AtCleanup_Memory(void)
/* -------------------------------- /* --------------------------------
* StartTransaction * StartTransaction
*
* -------------------------------- * --------------------------------
*/ */
static void static void
@ -930,7 +915,6 @@ CurrentXactInProgress(void)
/* -------------------------------- /* --------------------------------
* CommitTransaction * CommitTransaction
*
* -------------------------------- * --------------------------------
*/ */
static void static void
@ -1051,7 +1035,6 @@ CommitTransaction(void)
/* -------------------------------- /* --------------------------------
* AbortTransaction * AbortTransaction
*
* -------------------------------- * --------------------------------
*/ */
static void static void
@ -1158,7 +1141,6 @@ AbortTransaction(void)
/* -------------------------------- /* --------------------------------
* CleanupTransaction * CleanupTransaction
*
* -------------------------------- * --------------------------------
*/ */
static void static void
@ -1730,6 +1712,11 @@ IsTransactionBlock(void)
return false; return false;
} }
/*
* XLOG support routines
*/
void void
xact_redo(XLogRecPtr lsn, XLogRecord *record) xact_redo(XLogRecPtr lsn, XLogRecord *record)
{ {

15
src/include/access/xact.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* $Id: xact.h,v 1.46 2002/10/21 22:06:20 tgl Exp $ * $Id: xact.h,v 1.47 2002/11/13 03:12:05 momjian Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -46,9 +46,11 @@ typedef struct TransactionStateData
typedef TransactionStateData *TransactionState; typedef TransactionStateData *TransactionState;
/* ---------------- /*
* transaction states * transaction states - transaction state from server perspective
* ---------------- *
* Syntax error could cause transaction to abort, but client code thinks
* it is still in a transaction, so we have to wait for COMMIT/ROLLBACK.
*/ */
#define TRANS_DEFAULT 0 #define TRANS_DEFAULT 0
#define TRANS_START 1 #define TRANS_START 1
@ -56,9 +58,8 @@ typedef TransactionStateData *TransactionState;
#define TRANS_COMMIT 3 #define TRANS_COMMIT 3
#define TRANS_ABORT 4 #define TRANS_ABORT 4
/* ---------------- /*
* transaction block states * transaction block states - transaction state of client queries
* ----------------
*/ */
#define TBLOCK_DEFAULT 0 #define TBLOCK_DEFAULT 0
#define TBLOCK_BEGIN 1 #define TBLOCK_BEGIN 1