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The header block of TwoPhaseGetDummyBackendId mentioned incorrectly TwoPhaseGetDummyProc. Reported-by: Oleksii Kliukin Discussion: https://postgr.es/m/D8336E40-BBE1-4954-98BB-7830D3F5CB36@hintbits.com
2496 lines
71 KiB
C
2496 lines
71 KiB
C
/*-------------------------------------------------------------------------
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*
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* twophase.c
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* Two-phase commit support functions.
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*
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* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/backend/access/transam/twophase.c
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*
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* NOTES
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* Each global transaction is associated with a global transaction
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* identifier (GID). The client assigns a GID to a postgres
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* transaction with the PREPARE TRANSACTION command.
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*
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* We keep all active global transactions in a shared memory array.
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* When the PREPARE TRANSACTION command is issued, the GID is
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* reserved for the transaction in the array. This is done before
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* a WAL entry is made, because the reservation checks for duplicate
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* GIDs and aborts the transaction if there already is a global
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* transaction in prepared state with the same GID.
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*
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* A global transaction (gxact) also has dummy PGXACT and PGPROC; this is
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* what keeps the XID considered running by TransactionIdIsInProgress.
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* It is also convenient as a PGPROC to hook the gxact's locks to.
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*
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* Information to recover prepared transactions in case of crash is
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* now stored in WAL for the common case. In some cases there will be
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* an extended period between preparing a GXACT and commit/abort, in
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* which case we need to separately record prepared transaction data
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* in permanent storage. This includes locking information, pending
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* notifications etc. All that state information is written to the
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* per-transaction state file in the pg_twophase directory.
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* All prepared transactions will be written prior to shutdown.
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*
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* Life track of state data is following:
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*
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* * On PREPARE TRANSACTION backend writes state data only to the WAL and
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* stores pointer to the start of the WAL record in
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* gxact->prepare_start_lsn.
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* * If COMMIT occurs before checkpoint then backend reads data from WAL
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* using prepare_start_lsn.
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* * On checkpoint state data copied to files in pg_twophase directory and
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* fsynced
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* * If COMMIT happens after checkpoint then backend reads state data from
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* files
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*
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* During replay and replication, TwoPhaseState also holds information
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* about active prepared transactions that haven't been moved to disk yet.
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*
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* Replay of twophase records happens by the following rules:
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*
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* * At the beginning of recovery, pg_twophase is scanned once, filling
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* TwoPhaseState with entries marked with gxact->inredo and
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* gxact->ondisk. Two-phase file data older than the XID horizon of
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* the redo position are discarded.
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* * On PREPARE redo, the transaction is added to TwoPhaseState->prepXacts.
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* gxact->inredo is set to true for such entries.
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* * On Checkpoint we iterate through TwoPhaseState->prepXacts entries
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* that have gxact->inredo set and are behind the redo_horizon. We
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* save them to disk and then switch gxact->ondisk to true.
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* * On COMMIT/ABORT we delete the entry from TwoPhaseState->prepXacts.
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* If gxact->ondisk is true, the corresponding entry from the disk
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* is additionally deleted.
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* * RecoverPreparedTransactions(), StandbyRecoverPreparedTransactions()
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* and PrescanPreparedTransactions() have been modified to go through
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* gxact->inredo entries that have not made it to disk.
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <time.h>
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#include <unistd.h>
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#include "access/commit_ts.h"
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#include "access/htup_details.h"
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#include "access/subtrans.h"
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#include "access/transam.h"
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#include "access/twophase.h"
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#include "access/twophase_rmgr.h"
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#include "access/xact.h"
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#include "access/xlog.h"
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#include "access/xloginsert.h"
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#include "access/xlogutils.h"
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#include "access/xlogreader.h"
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#include "catalog/pg_type.h"
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#include "catalog/storage.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "pg_trace.h"
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#include "pgstat.h"
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#include "replication/origin.h"
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#include "replication/syncrep.h"
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#include "replication/walsender.h"
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#include "storage/fd.h"
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#include "storage/ipc.h"
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#include "storage/predicate.h"
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#include "storage/proc.h"
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#include "storage/procarray.h"
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#include "storage/sinvaladt.h"
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#include "storage/smgr.h"
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#include "utils/builtins.h"
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#include "utils/memutils.h"
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#include "utils/timestamp.h"
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/*
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* Directory where Two-phase commit files reside within PGDATA
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*/
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#define TWOPHASE_DIR "pg_twophase"
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/* GUC variable, can't be changed after startup */
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int max_prepared_xacts = 0;
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/*
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* This struct describes one global transaction that is in prepared state
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* or attempting to become prepared.
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*
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* The lifecycle of a global transaction is:
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*
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* 1. After checking that the requested GID is not in use, set up an entry in
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* the TwoPhaseState->prepXacts array with the correct GID and valid = false,
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* and mark it as locked by my backend.
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*
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* 2. After successfully completing prepare, set valid = true and enter the
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* referenced PGPROC into the global ProcArray.
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*
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* 3. To begin COMMIT PREPARED or ROLLBACK PREPARED, check that the entry is
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* valid and not locked, then mark the entry as locked by storing my current
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* backend ID into locking_backend. This prevents concurrent attempts to
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* commit or rollback the same prepared xact.
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*
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* 4. On completion of COMMIT PREPARED or ROLLBACK PREPARED, remove the entry
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* from the ProcArray and the TwoPhaseState->prepXacts array and return it to
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* the freelist.
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*
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* Note that if the preparing transaction fails between steps 1 and 2, the
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* entry must be removed so that the GID and the GlobalTransaction struct
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* can be reused. See AtAbort_Twophase().
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*
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* typedef struct GlobalTransactionData *GlobalTransaction appears in
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* twophase.h
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*/
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typedef struct GlobalTransactionData
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{
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GlobalTransaction next; /* list link for free list */
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int pgprocno; /* ID of associated dummy PGPROC */
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BackendId dummyBackendId; /* similar to backend id for backends */
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TimestampTz prepared_at; /* time of preparation */
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/*
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* Note that we need to keep track of two LSNs for each GXACT. We keep
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* track of the start LSN because this is the address we must use to read
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* state data back from WAL when committing a prepared GXACT. We keep
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* track of the end LSN because that is the LSN we need to wait for prior
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* to commit.
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*/
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XLogRecPtr prepare_start_lsn; /* XLOG offset of prepare record start */
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XLogRecPtr prepare_end_lsn; /* XLOG offset of prepare record end */
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TransactionId xid; /* The GXACT id */
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Oid owner; /* ID of user that executed the xact */
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BackendId locking_backend; /* backend currently working on the xact */
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bool valid; /* true if PGPROC entry is in proc array */
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bool ondisk; /* true if prepare state file is on disk */
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bool inredo; /* true if entry was added via xlog_redo */
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char gid[GIDSIZE]; /* The GID assigned to the prepared xact */
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} GlobalTransactionData;
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/*
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* Two Phase Commit shared state. Access to this struct is protected
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* by TwoPhaseStateLock.
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*/
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typedef struct TwoPhaseStateData
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{
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/* Head of linked list of free GlobalTransactionData structs */
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GlobalTransaction freeGXacts;
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/* Number of valid prepXacts entries. */
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int numPrepXacts;
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/* There are max_prepared_xacts items in this array */
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GlobalTransaction prepXacts[FLEXIBLE_ARRAY_MEMBER];
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} TwoPhaseStateData;
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static TwoPhaseStateData *TwoPhaseState;
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/*
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* Global transaction entry currently locked by us, if any. Note that any
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* access to the entry pointed to by this variable must be protected by
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* TwoPhaseStateLock, though obviously the pointer itself doesn't need to be
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* (since it's just local memory).
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*/
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static GlobalTransaction MyLockedGxact = NULL;
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static bool twophaseExitRegistered = false;
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static void RecordTransactionCommitPrepared(TransactionId xid,
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int nchildren,
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TransactionId *children,
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int nrels,
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RelFileNode *rels,
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int ninvalmsgs,
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SharedInvalidationMessage *invalmsgs,
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bool initfileinval,
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const char *gid);
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static void RecordTransactionAbortPrepared(TransactionId xid,
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int nchildren,
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TransactionId *children,
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int nrels,
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RelFileNode *rels,
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const char *gid);
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static void ProcessRecords(char *bufptr, TransactionId xid,
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const TwoPhaseCallback callbacks[]);
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static void RemoveGXact(GlobalTransaction gxact);
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static void XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len);
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static char *ProcessTwoPhaseBuffer(TransactionId xid,
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XLogRecPtr prepare_start_lsn,
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bool fromdisk, bool setParent, bool setNextXid);
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static void MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid,
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const char *gid, TimestampTz prepared_at, Oid owner,
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Oid databaseid);
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static void RemoveTwoPhaseFile(TransactionId xid, bool giveWarning);
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static void RecreateTwoPhaseFile(TransactionId xid, void *content, int len);
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/*
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* Initialization of shared memory
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*/
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Size
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TwoPhaseShmemSize(void)
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{
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Size size;
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/* Need the fixed struct, the array of pointers, and the GTD structs */
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size = offsetof(TwoPhaseStateData, prepXacts);
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size = add_size(size, mul_size(max_prepared_xacts,
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sizeof(GlobalTransaction)));
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size = MAXALIGN(size);
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size = add_size(size, mul_size(max_prepared_xacts,
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sizeof(GlobalTransactionData)));
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return size;
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}
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void
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TwoPhaseShmemInit(void)
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{
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bool found;
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TwoPhaseState = ShmemInitStruct("Prepared Transaction Table",
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TwoPhaseShmemSize(),
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&found);
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if (!IsUnderPostmaster)
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{
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GlobalTransaction gxacts;
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int i;
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Assert(!found);
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TwoPhaseState->freeGXacts = NULL;
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TwoPhaseState->numPrepXacts = 0;
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/*
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* Initialize the linked list of free GlobalTransactionData structs
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*/
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gxacts = (GlobalTransaction)
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((char *) TwoPhaseState +
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MAXALIGN(offsetof(TwoPhaseStateData, prepXacts) +
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sizeof(GlobalTransaction) * max_prepared_xacts));
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for (i = 0; i < max_prepared_xacts; i++)
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{
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/* insert into linked list */
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gxacts[i].next = TwoPhaseState->freeGXacts;
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TwoPhaseState->freeGXacts = &gxacts[i];
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/* associate it with a PGPROC assigned by InitProcGlobal */
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gxacts[i].pgprocno = PreparedXactProcs[i].pgprocno;
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/*
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* Assign a unique ID for each dummy proc, so that the range of
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* dummy backend IDs immediately follows the range of normal
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* backend IDs. We don't dare to assign a real backend ID to dummy
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* procs, because prepared transactions don't take part in cache
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* invalidation like a real backend ID would imply, but having a
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* unique ID for them is nevertheless handy. This arrangement
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* allows you to allocate an array of size (MaxBackends +
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* max_prepared_xacts + 1), and have a slot for every backend and
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* prepared transaction. Currently multixact.c uses that
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* technique.
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*/
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gxacts[i].dummyBackendId = MaxBackends + 1 + i;
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}
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}
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else
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Assert(found);
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}
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/*
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* Exit hook to unlock the global transaction entry we're working on.
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*/
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static void
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AtProcExit_Twophase(int code, Datum arg)
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{
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/* same logic as abort */
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AtAbort_Twophase();
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}
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/*
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* Abort hook to unlock the global transaction entry we're working on.
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*/
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void
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AtAbort_Twophase(void)
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{
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if (MyLockedGxact == NULL)
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return;
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/*
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* What to do with the locked global transaction entry? If we were in the
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* process of preparing the transaction, but haven't written the WAL
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* record and state file yet, the transaction must not be considered as
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* prepared. Likewise, if we are in the process of finishing an
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* already-prepared transaction, and fail after having already written the
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* 2nd phase commit or rollback record to the WAL, the transaction should
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* not be considered as prepared anymore. In those cases, just remove the
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* entry from shared memory.
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*
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* Otherwise, the entry must be left in place so that the transaction can
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* be finished later, so just unlock it.
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*
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* If we abort during prepare, after having written the WAL record, we
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* might not have transferred all locks and other state to the prepared
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* transaction yet. Likewise, if we abort during commit or rollback,
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* after having written the WAL record, we might not have released all the
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* resources held by the transaction yet. In those cases, the in-memory
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* state can be wrong, but it's too late to back out.
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*/
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LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
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if (!MyLockedGxact->valid)
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RemoveGXact(MyLockedGxact);
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else
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MyLockedGxact->locking_backend = InvalidBackendId;
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LWLockRelease(TwoPhaseStateLock);
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MyLockedGxact = NULL;
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}
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/*
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* This is called after we have finished transferring state to the prepared
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* PGXACT entry.
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*/
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void
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PostPrepare_Twophase(void)
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{
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LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
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MyLockedGxact->locking_backend = InvalidBackendId;
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LWLockRelease(TwoPhaseStateLock);
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MyLockedGxact = NULL;
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}
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/*
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* MarkAsPreparing
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* Reserve the GID for the given transaction.
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*/
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GlobalTransaction
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MarkAsPreparing(TransactionId xid, const char *gid,
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TimestampTz prepared_at, Oid owner, Oid databaseid)
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{
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GlobalTransaction gxact;
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int i;
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if (strlen(gid) >= GIDSIZE)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("transaction identifier \"%s\" is too long",
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gid)));
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/* fail immediately if feature is disabled */
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if (max_prepared_xacts == 0)
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ereport(ERROR,
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(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
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errmsg("prepared transactions are disabled"),
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errhint("Set max_prepared_transactions to a nonzero value.")));
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/* on first call, register the exit hook */
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if (!twophaseExitRegistered)
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{
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before_shmem_exit(AtProcExit_Twophase, 0);
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twophaseExitRegistered = true;
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}
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LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
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/* Check for conflicting GID */
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for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
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{
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gxact = TwoPhaseState->prepXacts[i];
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if (strcmp(gxact->gid, gid) == 0)
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{
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ereport(ERROR,
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(errcode(ERRCODE_DUPLICATE_OBJECT),
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errmsg("transaction identifier \"%s\" is already in use",
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gid)));
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}
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}
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/* Get a free gxact from the freelist */
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if (TwoPhaseState->freeGXacts == NULL)
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ereport(ERROR,
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(errcode(ERRCODE_OUT_OF_MEMORY),
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errmsg("maximum number of prepared transactions reached"),
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errhint("Increase max_prepared_transactions (currently %d).",
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max_prepared_xacts)));
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gxact = TwoPhaseState->freeGXacts;
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TwoPhaseState->freeGXacts = gxact->next;
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MarkAsPreparingGuts(gxact, xid, gid, prepared_at, owner, databaseid);
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gxact->ondisk = false;
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/* And insert it into the active array */
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Assert(TwoPhaseState->numPrepXacts < max_prepared_xacts);
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TwoPhaseState->prepXacts[TwoPhaseState->numPrepXacts++] = gxact;
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LWLockRelease(TwoPhaseStateLock);
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return gxact;
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}
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/*
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* MarkAsPreparingGuts
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*
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* This uses a gxact struct and puts it into the active array.
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* NOTE: this is also used when reloading a gxact after a crash; so avoid
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* assuming that we can use very much backend context.
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*
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* Note: This function should be called with appropriate locks held.
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*/
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static void
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MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
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TimestampTz prepared_at, Oid owner, Oid databaseid)
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{
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PGPROC *proc;
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PGXACT *pgxact;
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int i;
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Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
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Assert(gxact != NULL);
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proc = &ProcGlobal->allProcs[gxact->pgprocno];
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pgxact = &ProcGlobal->allPgXact[gxact->pgprocno];
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/* Initialize the PGPROC entry */
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MemSet(proc, 0, sizeof(PGPROC));
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proc->pgprocno = gxact->pgprocno;
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SHMQueueElemInit(&(proc->links));
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proc->waitStatus = STATUS_OK;
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/* We set up the gxact's VXID as InvalidBackendId/XID */
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proc->lxid = (LocalTransactionId) xid;
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pgxact->xid = xid;
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pgxact->xmin = InvalidTransactionId;
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pgxact->delayChkpt = false;
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pgxact->vacuumFlags = 0;
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proc->pid = 0;
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proc->backendId = InvalidBackendId;
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proc->databaseId = databaseid;
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proc->roleId = owner;
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proc->tempNamespaceId = InvalidOid;
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proc->isBackgroundWorker = false;
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proc->lwWaiting = false;
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proc->lwWaitMode = 0;
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proc->waitLock = NULL;
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proc->waitProcLock = NULL;
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for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
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SHMQueueInit(&(proc->myProcLocks[i]));
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/* subxid data must be filled later by GXactLoadSubxactData */
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pgxact->overflowed = false;
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pgxact->nxids = 0;
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gxact->prepared_at = prepared_at;
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gxact->xid = xid;
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gxact->owner = owner;
|
|
gxact->locking_backend = MyBackendId;
|
|
gxact->valid = false;
|
|
gxact->inredo = false;
|
|
strcpy(gxact->gid, gid);
|
|
|
|
/*
|
|
* Remember that we have this GlobalTransaction entry locked for us. If we
|
|
* abort after this, we must release it.
|
|
*/
|
|
MyLockedGxact = gxact;
|
|
}
|
|
|
|
/*
|
|
* GXactLoadSubxactData
|
|
*
|
|
* If the transaction being persisted had any subtransactions, this must
|
|
* be called before MarkAsPrepared() to load information into the dummy
|
|
* PGPROC.
|
|
*/
|
|
static void
|
|
GXactLoadSubxactData(GlobalTransaction gxact, int nsubxacts,
|
|
TransactionId *children)
|
|
{
|
|
PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
|
|
PGXACT *pgxact = &ProcGlobal->allPgXact[gxact->pgprocno];
|
|
|
|
/* We need no extra lock since the GXACT isn't valid yet */
|
|
if (nsubxacts > PGPROC_MAX_CACHED_SUBXIDS)
|
|
{
|
|
pgxact->overflowed = true;
|
|
nsubxacts = PGPROC_MAX_CACHED_SUBXIDS;
|
|
}
|
|
if (nsubxacts > 0)
|
|
{
|
|
memcpy(proc->subxids.xids, children,
|
|
nsubxacts * sizeof(TransactionId));
|
|
pgxact->nxids = nsubxacts;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* MarkAsPrepared
|
|
* Mark the GXACT as fully valid, and enter it into the global ProcArray.
|
|
*
|
|
* lock_held indicates whether caller already holds TwoPhaseStateLock.
|
|
*/
|
|
static void
|
|
MarkAsPrepared(GlobalTransaction gxact, bool lock_held)
|
|
{
|
|
/* Lock here may be overkill, but I'm not convinced of that ... */
|
|
if (!lock_held)
|
|
LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
|
|
Assert(!gxact->valid);
|
|
gxact->valid = true;
|
|
if (!lock_held)
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
/*
|
|
* Put it into the global ProcArray so TransactionIdIsInProgress considers
|
|
* the XID as still running.
|
|
*/
|
|
ProcArrayAdd(&ProcGlobal->allProcs[gxact->pgprocno]);
|
|
}
|
|
|
|
/*
|
|
* LockGXact
|
|
* Locate the prepared transaction and mark it busy for COMMIT or PREPARE.
|
|
*/
|
|
static GlobalTransaction
|
|
LockGXact(const char *gid, Oid user)
|
|
{
|
|
int i;
|
|
|
|
/* on first call, register the exit hook */
|
|
if (!twophaseExitRegistered)
|
|
{
|
|
before_shmem_exit(AtProcExit_Twophase, 0);
|
|
twophaseExitRegistered = true;
|
|
}
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
|
|
|
|
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
|
|
{
|
|
GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
|
|
PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
|
|
|
|
/* Ignore not-yet-valid GIDs */
|
|
if (!gxact->valid)
|
|
continue;
|
|
if (strcmp(gxact->gid, gid) != 0)
|
|
continue;
|
|
|
|
/* Found it, but has someone else got it locked? */
|
|
if (gxact->locking_backend != InvalidBackendId)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
|
|
errmsg("prepared transaction with identifier \"%s\" is busy",
|
|
gid)));
|
|
|
|
if (user != gxact->owner && !superuser_arg(user))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
|
|
errmsg("permission denied to finish prepared transaction"),
|
|
errhint("Must be superuser or the user that prepared the transaction.")));
|
|
|
|
/*
|
|
* Note: it probably would be possible to allow committing from
|
|
* another database; but at the moment NOTIFY is known not to work and
|
|
* there may be some other issues as well. Hence disallow until
|
|
* someone gets motivated to make it work.
|
|
*/
|
|
if (MyDatabaseId != proc->databaseId)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("prepared transaction belongs to another database"),
|
|
errhint("Connect to the database where the transaction was prepared to finish it.")));
|
|
|
|
/* OK for me to lock it */
|
|
gxact->locking_backend = MyBackendId;
|
|
MyLockedGxact = gxact;
|
|
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
return gxact;
|
|
}
|
|
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_UNDEFINED_OBJECT),
|
|
errmsg("prepared transaction with identifier \"%s\" does not exist",
|
|
gid)));
|
|
|
|
/* NOTREACHED */
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* RemoveGXact
|
|
* Remove the prepared transaction from the shared memory array.
|
|
*
|
|
* NB: caller should have already removed it from ProcArray
|
|
*/
|
|
static void
|
|
RemoveGXact(GlobalTransaction gxact)
|
|
{
|
|
int i;
|
|
|
|
Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
|
|
|
|
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
|
|
{
|
|
if (gxact == TwoPhaseState->prepXacts[i])
|
|
{
|
|
/* remove from the active array */
|
|
TwoPhaseState->numPrepXacts--;
|
|
TwoPhaseState->prepXacts[i] = TwoPhaseState->prepXacts[TwoPhaseState->numPrepXacts];
|
|
|
|
/* and put it back in the freelist */
|
|
gxact->next = TwoPhaseState->freeGXacts;
|
|
TwoPhaseState->freeGXacts = gxact;
|
|
|
|
return;
|
|
}
|
|
}
|
|
|
|
elog(ERROR, "failed to find %p in GlobalTransaction array", gxact);
|
|
}
|
|
|
|
/*
|
|
* Returns an array of all prepared transactions for the user-level
|
|
* function pg_prepared_xact.
|
|
*
|
|
* The returned array and all its elements are copies of internal data
|
|
* structures, to minimize the time we need to hold the TwoPhaseStateLock.
|
|
*
|
|
* WARNING -- we return even those transactions that are not fully prepared
|
|
* yet. The caller should filter them out if he doesn't want them.
|
|
*
|
|
* The returned array is palloc'd.
|
|
*/
|
|
static int
|
|
GetPreparedTransactionList(GlobalTransaction *gxacts)
|
|
{
|
|
GlobalTransaction array;
|
|
int num;
|
|
int i;
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
|
|
|
|
if (TwoPhaseState->numPrepXacts == 0)
|
|
{
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
*gxacts = NULL;
|
|
return 0;
|
|
}
|
|
|
|
num = TwoPhaseState->numPrepXacts;
|
|
array = (GlobalTransaction) palloc(sizeof(GlobalTransactionData) * num);
|
|
*gxacts = array;
|
|
for (i = 0; i < num; i++)
|
|
memcpy(array + i, TwoPhaseState->prepXacts[i],
|
|
sizeof(GlobalTransactionData));
|
|
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
return num;
|
|
}
|
|
|
|
|
|
/* Working status for pg_prepared_xact */
|
|
typedef struct
|
|
{
|
|
GlobalTransaction array;
|
|
int ngxacts;
|
|
int currIdx;
|
|
} Working_State;
|
|
|
|
/*
|
|
* pg_prepared_xact
|
|
* Produce a view with one row per prepared transaction.
|
|
*
|
|
* This function is here so we don't have to export the
|
|
* GlobalTransactionData struct definition.
|
|
*/
|
|
Datum
|
|
pg_prepared_xact(PG_FUNCTION_ARGS)
|
|
{
|
|
FuncCallContext *funcctx;
|
|
Working_State *status;
|
|
|
|
if (SRF_IS_FIRSTCALL())
|
|
{
|
|
TupleDesc tupdesc;
|
|
MemoryContext oldcontext;
|
|
|
|
/* create a function context for cross-call persistence */
|
|
funcctx = SRF_FIRSTCALL_INIT();
|
|
|
|
/*
|
|
* Switch to memory context appropriate for multiple function calls
|
|
*/
|
|
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
|
|
|
|
/* build tupdesc for result tuples */
|
|
/* this had better match pg_prepared_xacts view in system_views.sql */
|
|
tupdesc = CreateTemplateTupleDesc(5);
|
|
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "transaction",
|
|
XIDOID, -1, 0);
|
|
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "gid",
|
|
TEXTOID, -1, 0);
|
|
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "prepared",
|
|
TIMESTAMPTZOID, -1, 0);
|
|
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "ownerid",
|
|
OIDOID, -1, 0);
|
|
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "dbid",
|
|
OIDOID, -1, 0);
|
|
|
|
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
|
|
|
|
/*
|
|
* Collect all the 2PC status information that we will format and send
|
|
* out as a result set.
|
|
*/
|
|
status = (Working_State *) palloc(sizeof(Working_State));
|
|
funcctx->user_fctx = (void *) status;
|
|
|
|
status->ngxacts = GetPreparedTransactionList(&status->array);
|
|
status->currIdx = 0;
|
|
|
|
MemoryContextSwitchTo(oldcontext);
|
|
}
|
|
|
|
funcctx = SRF_PERCALL_SETUP();
|
|
status = (Working_State *) funcctx->user_fctx;
|
|
|
|
while (status->array != NULL && status->currIdx < status->ngxacts)
|
|
{
|
|
GlobalTransaction gxact = &status->array[status->currIdx++];
|
|
PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
|
|
PGXACT *pgxact = &ProcGlobal->allPgXact[gxact->pgprocno];
|
|
Datum values[5];
|
|
bool nulls[5];
|
|
HeapTuple tuple;
|
|
Datum result;
|
|
|
|
if (!gxact->valid)
|
|
continue;
|
|
|
|
/*
|
|
* Form tuple with appropriate data.
|
|
*/
|
|
MemSet(values, 0, sizeof(values));
|
|
MemSet(nulls, 0, sizeof(nulls));
|
|
|
|
values[0] = TransactionIdGetDatum(pgxact->xid);
|
|
values[1] = CStringGetTextDatum(gxact->gid);
|
|
values[2] = TimestampTzGetDatum(gxact->prepared_at);
|
|
values[3] = ObjectIdGetDatum(gxact->owner);
|
|
values[4] = ObjectIdGetDatum(proc->databaseId);
|
|
|
|
tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
|
|
result = HeapTupleGetDatum(tuple);
|
|
SRF_RETURN_NEXT(funcctx, result);
|
|
}
|
|
|
|
SRF_RETURN_DONE(funcctx);
|
|
}
|
|
|
|
/*
|
|
* TwoPhaseGetGXact
|
|
* Get the GlobalTransaction struct for a prepared transaction
|
|
* specified by XID
|
|
*/
|
|
static GlobalTransaction
|
|
TwoPhaseGetGXact(TransactionId xid)
|
|
{
|
|
GlobalTransaction result = NULL;
|
|
int i;
|
|
|
|
static TransactionId cached_xid = InvalidTransactionId;
|
|
static GlobalTransaction cached_gxact = NULL;
|
|
|
|
/*
|
|
* During a recovery, COMMIT PREPARED, or ABORT PREPARED, we'll be called
|
|
* repeatedly for the same XID. We can save work with a simple cache.
|
|
*/
|
|
if (xid == cached_xid)
|
|
return cached_gxact;
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
|
|
|
|
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
|
|
{
|
|
GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
|
|
PGXACT *pgxact = &ProcGlobal->allPgXact[gxact->pgprocno];
|
|
|
|
if (pgxact->xid == xid)
|
|
{
|
|
result = gxact;
|
|
break;
|
|
}
|
|
}
|
|
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
if (result == NULL) /* should not happen */
|
|
elog(ERROR, "failed to find GlobalTransaction for xid %u", xid);
|
|
|
|
cached_xid = xid;
|
|
cached_gxact = result;
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* TwoPhaseGetDummyBackendId
|
|
* Get the dummy backend ID for prepared transaction specified by XID
|
|
*
|
|
* Dummy backend IDs are similar to real backend IDs of real backends.
|
|
* They start at MaxBackends + 1, and are unique across all currently active
|
|
* real backends and prepared transactions.
|
|
*/
|
|
BackendId
|
|
TwoPhaseGetDummyBackendId(TransactionId xid)
|
|
{
|
|
GlobalTransaction gxact = TwoPhaseGetGXact(xid);
|
|
|
|
return gxact->dummyBackendId;
|
|
}
|
|
|
|
/*
|
|
* TwoPhaseGetDummyProc
|
|
* Get the PGPROC that represents a prepared transaction specified by XID
|
|
*/
|
|
PGPROC *
|
|
TwoPhaseGetDummyProc(TransactionId xid)
|
|
{
|
|
GlobalTransaction gxact = TwoPhaseGetGXact(xid);
|
|
|
|
return &ProcGlobal->allProcs[gxact->pgprocno];
|
|
}
|
|
|
|
/************************************************************************/
|
|
/* State file support */
|
|
/************************************************************************/
|
|
|
|
#define TwoPhaseFilePath(path, xid) \
|
|
snprintf(path, MAXPGPATH, TWOPHASE_DIR "/%08X", xid)
|
|
|
|
/*
|
|
* 2PC state file format:
|
|
*
|
|
* 1. TwoPhaseFileHeader
|
|
* 2. TransactionId[] (subtransactions)
|
|
* 3. RelFileNode[] (files to be deleted at commit)
|
|
* 4. RelFileNode[] (files to be deleted at abort)
|
|
* 5. SharedInvalidationMessage[] (inval messages to be sent at commit)
|
|
* 6. TwoPhaseRecordOnDisk
|
|
* 7. ...
|
|
* 8. TwoPhaseRecordOnDisk (end sentinel, rmid == TWOPHASE_RM_END_ID)
|
|
* 9. checksum (CRC-32C)
|
|
*
|
|
* Each segment except the final checksum is MAXALIGN'd.
|
|
*/
|
|
|
|
/*
|
|
* Header for a 2PC state file
|
|
*/
|
|
#define TWOPHASE_MAGIC 0x57F94534 /* format identifier */
|
|
|
|
typedef struct TwoPhaseFileHeader
|
|
{
|
|
uint32 magic; /* format identifier */
|
|
uint32 total_len; /* actual file length */
|
|
TransactionId xid; /* original transaction XID */
|
|
Oid database; /* OID of database it was in */
|
|
TimestampTz prepared_at; /* time of preparation */
|
|
Oid owner; /* user running the transaction */
|
|
int32 nsubxacts; /* number of following subxact XIDs */
|
|
int32 ncommitrels; /* number of delete-on-commit rels */
|
|
int32 nabortrels; /* number of delete-on-abort rels */
|
|
int32 ninvalmsgs; /* number of cache invalidation messages */
|
|
bool initfileinval; /* does relcache init file need invalidation? */
|
|
uint16 gidlen; /* length of the GID - GID follows the header */
|
|
XLogRecPtr origin_lsn; /* lsn of this record at origin node */
|
|
TimestampTz origin_timestamp; /* time of prepare at origin node */
|
|
} TwoPhaseFileHeader;
|
|
|
|
/*
|
|
* Header for each record in a state file
|
|
*
|
|
* NOTE: len counts only the rmgr data, not the TwoPhaseRecordOnDisk header.
|
|
* The rmgr data will be stored starting on a MAXALIGN boundary.
|
|
*/
|
|
typedef struct TwoPhaseRecordOnDisk
|
|
{
|
|
uint32 len; /* length of rmgr data */
|
|
TwoPhaseRmgrId rmid; /* resource manager for this record */
|
|
uint16 info; /* flag bits for use by rmgr */
|
|
} TwoPhaseRecordOnDisk;
|
|
|
|
/*
|
|
* During prepare, the state file is assembled in memory before writing it
|
|
* to WAL and the actual state file. We use a chain of StateFileChunk blocks
|
|
* for that.
|
|
*/
|
|
typedef struct StateFileChunk
|
|
{
|
|
char *data;
|
|
uint32 len;
|
|
struct StateFileChunk *next;
|
|
} StateFileChunk;
|
|
|
|
static struct xllist
|
|
{
|
|
StateFileChunk *head; /* first data block in the chain */
|
|
StateFileChunk *tail; /* last block in chain */
|
|
uint32 num_chunks;
|
|
uint32 bytes_free; /* free bytes left in tail block */
|
|
uint32 total_len; /* total data bytes in chain */
|
|
} records;
|
|
|
|
|
|
/*
|
|
* Append a block of data to records data structure.
|
|
*
|
|
* NB: each block is padded to a MAXALIGN multiple. This must be
|
|
* accounted for when the file is later read!
|
|
*
|
|
* The data is copied, so the caller is free to modify it afterwards.
|
|
*/
|
|
static void
|
|
save_state_data(const void *data, uint32 len)
|
|
{
|
|
uint32 padlen = MAXALIGN(len);
|
|
|
|
if (padlen > records.bytes_free)
|
|
{
|
|
records.tail->next = palloc0(sizeof(StateFileChunk));
|
|
records.tail = records.tail->next;
|
|
records.tail->len = 0;
|
|
records.tail->next = NULL;
|
|
records.num_chunks++;
|
|
|
|
records.bytes_free = Max(padlen, 512);
|
|
records.tail->data = palloc(records.bytes_free);
|
|
}
|
|
|
|
memcpy(((char *) records.tail->data) + records.tail->len, data, len);
|
|
records.tail->len += padlen;
|
|
records.bytes_free -= padlen;
|
|
records.total_len += padlen;
|
|
}
|
|
|
|
/*
|
|
* Start preparing a state file.
|
|
*
|
|
* Initializes data structure and inserts the 2PC file header record.
|
|
*/
|
|
void
|
|
StartPrepare(GlobalTransaction gxact)
|
|
{
|
|
PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
|
|
PGXACT *pgxact = &ProcGlobal->allPgXact[gxact->pgprocno];
|
|
TransactionId xid = pgxact->xid;
|
|
TwoPhaseFileHeader hdr;
|
|
TransactionId *children;
|
|
RelFileNode *commitrels;
|
|
RelFileNode *abortrels;
|
|
SharedInvalidationMessage *invalmsgs;
|
|
|
|
/* Initialize linked list */
|
|
records.head = palloc0(sizeof(StateFileChunk));
|
|
records.head->len = 0;
|
|
records.head->next = NULL;
|
|
|
|
records.bytes_free = Max(sizeof(TwoPhaseFileHeader), 512);
|
|
records.head->data = palloc(records.bytes_free);
|
|
|
|
records.tail = records.head;
|
|
records.num_chunks = 1;
|
|
|
|
records.total_len = 0;
|
|
|
|
/* Create header */
|
|
hdr.magic = TWOPHASE_MAGIC;
|
|
hdr.total_len = 0; /* EndPrepare will fill this in */
|
|
hdr.xid = xid;
|
|
hdr.database = proc->databaseId;
|
|
hdr.prepared_at = gxact->prepared_at;
|
|
hdr.owner = gxact->owner;
|
|
hdr.nsubxacts = xactGetCommittedChildren(&children);
|
|
hdr.ncommitrels = smgrGetPendingDeletes(true, &commitrels);
|
|
hdr.nabortrels = smgrGetPendingDeletes(false, &abortrels);
|
|
hdr.ninvalmsgs = xactGetCommittedInvalidationMessages(&invalmsgs,
|
|
&hdr.initfileinval);
|
|
hdr.gidlen = strlen(gxact->gid) + 1; /* Include '\0' */
|
|
|
|
save_state_data(&hdr, sizeof(TwoPhaseFileHeader));
|
|
save_state_data(gxact->gid, hdr.gidlen);
|
|
|
|
/*
|
|
* Add the additional info about subxacts, deletable files and cache
|
|
* invalidation messages.
|
|
*/
|
|
if (hdr.nsubxacts > 0)
|
|
{
|
|
save_state_data(children, hdr.nsubxacts * sizeof(TransactionId));
|
|
/* While we have the child-xact data, stuff it in the gxact too */
|
|
GXactLoadSubxactData(gxact, hdr.nsubxacts, children);
|
|
}
|
|
if (hdr.ncommitrels > 0)
|
|
{
|
|
save_state_data(commitrels, hdr.ncommitrels * sizeof(RelFileNode));
|
|
pfree(commitrels);
|
|
}
|
|
if (hdr.nabortrels > 0)
|
|
{
|
|
save_state_data(abortrels, hdr.nabortrels * sizeof(RelFileNode));
|
|
pfree(abortrels);
|
|
}
|
|
if (hdr.ninvalmsgs > 0)
|
|
{
|
|
save_state_data(invalmsgs,
|
|
hdr.ninvalmsgs * sizeof(SharedInvalidationMessage));
|
|
pfree(invalmsgs);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Finish preparing state data and writing it to WAL.
|
|
*/
|
|
void
|
|
EndPrepare(GlobalTransaction gxact)
|
|
{
|
|
TwoPhaseFileHeader *hdr;
|
|
StateFileChunk *record;
|
|
bool replorigin;
|
|
|
|
/* Add the end sentinel to the list of 2PC records */
|
|
RegisterTwoPhaseRecord(TWOPHASE_RM_END_ID, 0,
|
|
NULL, 0);
|
|
|
|
/* Go back and fill in total_len in the file header record */
|
|
hdr = (TwoPhaseFileHeader *) records.head->data;
|
|
Assert(hdr->magic == TWOPHASE_MAGIC);
|
|
hdr->total_len = records.total_len + sizeof(pg_crc32c);
|
|
|
|
replorigin = (replorigin_session_origin != InvalidRepOriginId &&
|
|
replorigin_session_origin != DoNotReplicateId);
|
|
|
|
if (replorigin)
|
|
{
|
|
Assert(replorigin_session_origin_lsn != InvalidXLogRecPtr);
|
|
hdr->origin_lsn = replorigin_session_origin_lsn;
|
|
hdr->origin_timestamp = replorigin_session_origin_timestamp;
|
|
}
|
|
else
|
|
{
|
|
hdr->origin_lsn = InvalidXLogRecPtr;
|
|
hdr->origin_timestamp = 0;
|
|
}
|
|
|
|
/*
|
|
* If the data size exceeds MaxAllocSize, we won't be able to read it in
|
|
* ReadTwoPhaseFile. Check for that now, rather than fail in the case
|
|
* where we write data to file and then re-read at commit time.
|
|
*/
|
|
if (hdr->total_len > MaxAllocSize)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
|
|
errmsg("two-phase state file maximum length exceeded")));
|
|
|
|
/*
|
|
* Now writing 2PC state data to WAL. We let the WAL's CRC protection
|
|
* cover us, so no need to calculate a separate CRC.
|
|
*
|
|
* We have to set delayChkpt here, too; otherwise a checkpoint starting
|
|
* immediately after the WAL record is inserted could complete without
|
|
* fsync'ing our state file. (This is essentially the same kind of race
|
|
* condition as the COMMIT-to-clog-write case that RecordTransactionCommit
|
|
* uses delayChkpt for; see notes there.)
|
|
*
|
|
* We save the PREPARE record's location in the gxact for later use by
|
|
* CheckPointTwoPhase.
|
|
*/
|
|
XLogEnsureRecordSpace(0, records.num_chunks);
|
|
|
|
START_CRIT_SECTION();
|
|
|
|
MyPgXact->delayChkpt = true;
|
|
|
|
XLogBeginInsert();
|
|
for (record = records.head; record != NULL; record = record->next)
|
|
XLogRegisterData(record->data, record->len);
|
|
|
|
XLogSetRecordFlags(XLOG_INCLUDE_ORIGIN);
|
|
|
|
gxact->prepare_end_lsn = XLogInsert(RM_XACT_ID, XLOG_XACT_PREPARE);
|
|
|
|
if (replorigin)
|
|
{
|
|
/* Move LSNs forward for this replication origin */
|
|
replorigin_session_advance(replorigin_session_origin_lsn,
|
|
gxact->prepare_end_lsn);
|
|
}
|
|
|
|
XLogFlush(gxact->prepare_end_lsn);
|
|
|
|
/* If we crash now, we have prepared: WAL replay will fix things */
|
|
|
|
/* Store record's start location to read that later on Commit */
|
|
gxact->prepare_start_lsn = ProcLastRecPtr;
|
|
|
|
/*
|
|
* Mark the prepared transaction as valid. As soon as xact.c marks
|
|
* MyPgXact as not running our XID (which it will do immediately after
|
|
* this function returns), others can commit/rollback the xact.
|
|
*
|
|
* NB: a side effect of this is to make a dummy ProcArray entry for the
|
|
* prepared XID. This must happen before we clear the XID from MyPgXact,
|
|
* else there is a window where the XID is not running according to
|
|
* TransactionIdIsInProgress, and onlookers would be entitled to assume
|
|
* the xact crashed. Instead we have a window where the same XID appears
|
|
* twice in ProcArray, which is OK.
|
|
*/
|
|
MarkAsPrepared(gxact, false);
|
|
|
|
/*
|
|
* Now we can mark ourselves as out of the commit critical section: a
|
|
* checkpoint starting after this will certainly see the gxact as a
|
|
* candidate for fsyncing.
|
|
*/
|
|
MyPgXact->delayChkpt = false;
|
|
|
|
/*
|
|
* Remember that we have this GlobalTransaction entry locked for us. If
|
|
* we crash after this point, it's too late to abort, but we must unlock
|
|
* it so that the prepared transaction can be committed or rolled back.
|
|
*/
|
|
MyLockedGxact = gxact;
|
|
|
|
END_CRIT_SECTION();
|
|
|
|
/*
|
|
* Wait for synchronous replication, if required.
|
|
*
|
|
* Note that at this stage we have marked the prepare, but still show as
|
|
* running in the procarray (twice!) and continue to hold locks.
|
|
*/
|
|
SyncRepWaitForLSN(gxact->prepare_end_lsn, false);
|
|
|
|
records.tail = records.head = NULL;
|
|
records.num_chunks = 0;
|
|
}
|
|
|
|
/*
|
|
* Register a 2PC record to be written to state file.
|
|
*/
|
|
void
|
|
RegisterTwoPhaseRecord(TwoPhaseRmgrId rmid, uint16 info,
|
|
const void *data, uint32 len)
|
|
{
|
|
TwoPhaseRecordOnDisk record;
|
|
|
|
record.rmid = rmid;
|
|
record.info = info;
|
|
record.len = len;
|
|
save_state_data(&record, sizeof(TwoPhaseRecordOnDisk));
|
|
if (len > 0)
|
|
save_state_data(data, len);
|
|
}
|
|
|
|
|
|
/*
|
|
* Read and validate the state file for xid.
|
|
*
|
|
* If it looks OK (has a valid magic number and CRC), return the palloc'd
|
|
* contents of the file, issuing an error when finding corrupted data. If
|
|
* missing_ok is true, which indicates that missing files can be safely
|
|
* ignored, then return NULL. This state can be reached when doing recovery.
|
|
*/
|
|
static char *
|
|
ReadTwoPhaseFile(TransactionId xid, bool missing_ok)
|
|
{
|
|
char path[MAXPGPATH];
|
|
char *buf;
|
|
TwoPhaseFileHeader *hdr;
|
|
int fd;
|
|
struct stat stat;
|
|
uint32 crc_offset;
|
|
pg_crc32c calc_crc,
|
|
file_crc;
|
|
int r;
|
|
|
|
TwoPhaseFilePath(path, xid);
|
|
|
|
fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
|
|
if (fd < 0)
|
|
{
|
|
if (missing_ok && errno == ENOENT)
|
|
return NULL;
|
|
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not open file \"%s\": %m", path)));
|
|
}
|
|
|
|
/*
|
|
* Check file length. We can determine a lower bound pretty easily. We
|
|
* set an upper bound to avoid palloc() failure on a corrupt file, though
|
|
* we can't guarantee that we won't get an out of memory error anyway,
|
|
* even on a valid file.
|
|
*/
|
|
if (fstat(fd, &stat))
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not stat file \"%s\": %m", path)));
|
|
|
|
if (stat.st_size < (MAXALIGN(sizeof(TwoPhaseFileHeader)) +
|
|
MAXALIGN(sizeof(TwoPhaseRecordOnDisk)) +
|
|
sizeof(pg_crc32c)) ||
|
|
stat.st_size > MaxAllocSize)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DATA_CORRUPTED),
|
|
errmsg_plural("incorrect size of file \"%s\": %zu byte",
|
|
"incorrect size of file \"%s\": %zu bytes",
|
|
(Size) stat.st_size, path,
|
|
(Size) stat.st_size)));
|
|
|
|
crc_offset = stat.st_size - sizeof(pg_crc32c);
|
|
if (crc_offset != MAXALIGN(crc_offset))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DATA_CORRUPTED),
|
|
errmsg("incorrect alignment of CRC offset for file \"%s\"",
|
|
path)));
|
|
|
|
/*
|
|
* OK, slurp in the file.
|
|
*/
|
|
buf = (char *) palloc(stat.st_size);
|
|
|
|
pgstat_report_wait_start(WAIT_EVENT_TWOPHASE_FILE_READ);
|
|
r = read(fd, buf, stat.st_size);
|
|
if (r != stat.st_size)
|
|
{
|
|
if (r < 0)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not read file \"%s\": %m", path)));
|
|
else
|
|
ereport(ERROR,
|
|
(errmsg("could not read file \"%s\": read %d of %zu",
|
|
path, r, (Size) stat.st_size)));
|
|
}
|
|
|
|
pgstat_report_wait_end();
|
|
CloseTransientFile(fd);
|
|
|
|
hdr = (TwoPhaseFileHeader *) buf;
|
|
if (hdr->magic != TWOPHASE_MAGIC)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DATA_CORRUPTED),
|
|
errmsg("invalid magic number stored in file \"%s\"",
|
|
path)));
|
|
|
|
if (hdr->total_len != stat.st_size)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DATA_CORRUPTED),
|
|
errmsg("invalid size stored in file \"%s\"",
|
|
path)));
|
|
|
|
INIT_CRC32C(calc_crc);
|
|
COMP_CRC32C(calc_crc, buf, crc_offset);
|
|
FIN_CRC32C(calc_crc);
|
|
|
|
file_crc = *((pg_crc32c *) (buf + crc_offset));
|
|
|
|
if (!EQ_CRC32C(calc_crc, file_crc))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DATA_CORRUPTED),
|
|
errmsg("calculated CRC checksum does not match value stored in file \"%s\"",
|
|
path)));
|
|
|
|
return buf;
|
|
}
|
|
|
|
/*
|
|
* ParsePrepareRecord
|
|
*/
|
|
void
|
|
ParsePrepareRecord(uint8 info, char *xlrec, xl_xact_parsed_prepare *parsed)
|
|
{
|
|
TwoPhaseFileHeader *hdr;
|
|
char *bufptr;
|
|
|
|
hdr = (TwoPhaseFileHeader *) xlrec;
|
|
bufptr = xlrec + MAXALIGN(sizeof(TwoPhaseFileHeader));
|
|
|
|
parsed->origin_lsn = hdr->origin_lsn;
|
|
parsed->origin_timestamp = hdr->origin_timestamp;
|
|
parsed->twophase_xid = hdr->xid;
|
|
parsed->dbId = hdr->database;
|
|
parsed->nsubxacts = hdr->nsubxacts;
|
|
parsed->nrels = hdr->ncommitrels;
|
|
parsed->nabortrels = hdr->nabortrels;
|
|
parsed->nmsgs = hdr->ninvalmsgs;
|
|
|
|
strncpy(parsed->twophase_gid, bufptr, hdr->gidlen);
|
|
bufptr += MAXALIGN(hdr->gidlen);
|
|
|
|
parsed->subxacts = (TransactionId *) bufptr;
|
|
bufptr += MAXALIGN(hdr->nsubxacts * sizeof(TransactionId));
|
|
|
|
parsed->xnodes = (RelFileNode *) bufptr;
|
|
bufptr += MAXALIGN(hdr->ncommitrels * sizeof(RelFileNode));
|
|
|
|
parsed->abortnodes = (RelFileNode *) bufptr;
|
|
bufptr += MAXALIGN(hdr->nabortrels * sizeof(RelFileNode));
|
|
|
|
parsed->msgs = (SharedInvalidationMessage *) bufptr;
|
|
bufptr += MAXALIGN(hdr->ninvalmsgs * sizeof(SharedInvalidationMessage));
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
* Reads 2PC data from xlog. During checkpoint this data will be moved to
|
|
* twophase files and ReadTwoPhaseFile should be used instead.
|
|
*
|
|
* Note clearly that this function can access WAL during normal operation,
|
|
* similarly to the way WALSender or Logical Decoding would do.
|
|
*
|
|
*/
|
|
static void
|
|
XlogReadTwoPhaseData(XLogRecPtr lsn, char **buf, int *len)
|
|
{
|
|
XLogRecord *record;
|
|
XLogReaderState *xlogreader;
|
|
char *errormsg;
|
|
|
|
xlogreader = XLogReaderAllocate(wal_segment_size, &read_local_xlog_page,
|
|
NULL);
|
|
if (!xlogreader)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OUT_OF_MEMORY),
|
|
errmsg("out of memory"),
|
|
errdetail("Failed while allocating a WAL reading processor.")));
|
|
|
|
record = XLogReadRecord(xlogreader, lsn, &errormsg);
|
|
if (record == NULL)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not read two-phase state from WAL at %X/%X",
|
|
(uint32) (lsn >> 32),
|
|
(uint32) lsn)));
|
|
|
|
if (XLogRecGetRmid(xlogreader) != RM_XACT_ID ||
|
|
(XLogRecGetInfo(xlogreader) & XLOG_XACT_OPMASK) != XLOG_XACT_PREPARE)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("expected two-phase state data is not present in WAL at %X/%X",
|
|
(uint32) (lsn >> 32),
|
|
(uint32) lsn)));
|
|
|
|
if (len != NULL)
|
|
*len = XLogRecGetDataLen(xlogreader);
|
|
|
|
*buf = palloc(sizeof(char) * XLogRecGetDataLen(xlogreader));
|
|
memcpy(*buf, XLogRecGetData(xlogreader), sizeof(char) * XLogRecGetDataLen(xlogreader));
|
|
|
|
XLogReaderFree(xlogreader);
|
|
}
|
|
|
|
|
|
/*
|
|
* Confirms an xid is prepared, during recovery
|
|
*/
|
|
bool
|
|
StandbyTransactionIdIsPrepared(TransactionId xid)
|
|
{
|
|
char *buf;
|
|
TwoPhaseFileHeader *hdr;
|
|
bool result;
|
|
|
|
Assert(TransactionIdIsValid(xid));
|
|
|
|
if (max_prepared_xacts <= 0)
|
|
return false; /* nothing to do */
|
|
|
|
/* Read and validate file */
|
|
buf = ReadTwoPhaseFile(xid, true);
|
|
if (buf == NULL)
|
|
return false;
|
|
|
|
/* Check header also */
|
|
hdr = (TwoPhaseFileHeader *) buf;
|
|
result = TransactionIdEquals(hdr->xid, xid);
|
|
pfree(buf);
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* FinishPreparedTransaction: execute COMMIT PREPARED or ROLLBACK PREPARED
|
|
*/
|
|
void
|
|
FinishPreparedTransaction(const char *gid, bool isCommit)
|
|
{
|
|
GlobalTransaction gxact;
|
|
PGPROC *proc;
|
|
PGXACT *pgxact;
|
|
TransactionId xid;
|
|
char *buf;
|
|
char *bufptr;
|
|
TwoPhaseFileHeader *hdr;
|
|
TransactionId latestXid;
|
|
TransactionId *children;
|
|
RelFileNode *commitrels;
|
|
RelFileNode *abortrels;
|
|
RelFileNode *delrels;
|
|
int ndelrels;
|
|
SharedInvalidationMessage *invalmsgs;
|
|
|
|
/*
|
|
* Validate the GID, and lock the GXACT to ensure that two backends do not
|
|
* try to commit the same GID at once.
|
|
*/
|
|
gxact = LockGXact(gid, GetUserId());
|
|
proc = &ProcGlobal->allProcs[gxact->pgprocno];
|
|
pgxact = &ProcGlobal->allPgXact[gxact->pgprocno];
|
|
xid = pgxact->xid;
|
|
|
|
/*
|
|
* Read and validate 2PC state data. State data will typically be stored
|
|
* in WAL files if the LSN is after the last checkpoint record, or moved
|
|
* to disk if for some reason they have lived for a long time.
|
|
*/
|
|
if (gxact->ondisk)
|
|
buf = ReadTwoPhaseFile(xid, false);
|
|
else
|
|
XlogReadTwoPhaseData(gxact->prepare_start_lsn, &buf, NULL);
|
|
|
|
|
|
/*
|
|
* Disassemble the header area
|
|
*/
|
|
hdr = (TwoPhaseFileHeader *) buf;
|
|
Assert(TransactionIdEquals(hdr->xid, xid));
|
|
bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
|
|
bufptr += MAXALIGN(hdr->gidlen);
|
|
children = (TransactionId *) bufptr;
|
|
bufptr += MAXALIGN(hdr->nsubxacts * sizeof(TransactionId));
|
|
commitrels = (RelFileNode *) bufptr;
|
|
bufptr += MAXALIGN(hdr->ncommitrels * sizeof(RelFileNode));
|
|
abortrels = (RelFileNode *) bufptr;
|
|
bufptr += MAXALIGN(hdr->nabortrels * sizeof(RelFileNode));
|
|
invalmsgs = (SharedInvalidationMessage *) bufptr;
|
|
bufptr += MAXALIGN(hdr->ninvalmsgs * sizeof(SharedInvalidationMessage));
|
|
|
|
/* compute latestXid among all children */
|
|
latestXid = TransactionIdLatest(xid, hdr->nsubxacts, children);
|
|
|
|
/* Prevent cancel/die interrupt while cleaning up */
|
|
HOLD_INTERRUPTS();
|
|
|
|
/*
|
|
* The order of operations here is critical: make the XLOG entry for
|
|
* commit or abort, then mark the transaction committed or aborted in
|
|
* pg_xact, then remove its PGPROC from the global ProcArray (which means
|
|
* TransactionIdIsInProgress will stop saying the prepared xact is in
|
|
* progress), then run the post-commit or post-abort callbacks. The
|
|
* callbacks will release the locks the transaction held.
|
|
*/
|
|
if (isCommit)
|
|
RecordTransactionCommitPrepared(xid,
|
|
hdr->nsubxacts, children,
|
|
hdr->ncommitrels, commitrels,
|
|
hdr->ninvalmsgs, invalmsgs,
|
|
hdr->initfileinval, gid);
|
|
else
|
|
RecordTransactionAbortPrepared(xid,
|
|
hdr->nsubxacts, children,
|
|
hdr->nabortrels, abortrels,
|
|
gid);
|
|
|
|
ProcArrayRemove(proc, latestXid);
|
|
|
|
/*
|
|
* In case we fail while running the callbacks, mark the gxact invalid so
|
|
* no one else will try to commit/rollback, and so it will be recycled if
|
|
* we fail after this point. It is still locked by our backend so it
|
|
* won't go away yet.
|
|
*
|
|
* (We assume it's safe to do this without taking TwoPhaseStateLock.)
|
|
*/
|
|
gxact->valid = false;
|
|
|
|
/*
|
|
* We have to remove any files that were supposed to be dropped. For
|
|
* consistency with the regular xact.c code paths, must do this before
|
|
* releasing locks, so do it before running the callbacks.
|
|
*
|
|
* NB: this code knows that we couldn't be dropping any temp rels ...
|
|
*/
|
|
if (isCommit)
|
|
{
|
|
delrels = commitrels;
|
|
ndelrels = hdr->ncommitrels;
|
|
}
|
|
else
|
|
{
|
|
delrels = abortrels;
|
|
ndelrels = hdr->nabortrels;
|
|
}
|
|
|
|
/* Make sure files supposed to be dropped are dropped */
|
|
DropRelationFiles(delrels, ndelrels, false);
|
|
|
|
/*
|
|
* Handle cache invalidation messages.
|
|
*
|
|
* Relcache init file invalidation requires processing both before and
|
|
* after we send the SI messages. See AtEOXact_Inval()
|
|
*/
|
|
if (hdr->initfileinval)
|
|
RelationCacheInitFilePreInvalidate();
|
|
SendSharedInvalidMessages(invalmsgs, hdr->ninvalmsgs);
|
|
if (hdr->initfileinval)
|
|
RelationCacheInitFilePostInvalidate();
|
|
|
|
/* And now do the callbacks */
|
|
if (isCommit)
|
|
ProcessRecords(bufptr, xid, twophase_postcommit_callbacks);
|
|
else
|
|
ProcessRecords(bufptr, xid, twophase_postabort_callbacks);
|
|
|
|
PredicateLockTwoPhaseFinish(xid, isCommit);
|
|
|
|
/* Count the prepared xact as committed or aborted */
|
|
AtEOXact_PgStat(isCommit);
|
|
|
|
/*
|
|
* And now we can clean up any files we may have left.
|
|
*/
|
|
if (gxact->ondisk)
|
|
RemoveTwoPhaseFile(xid, true);
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
|
|
RemoveGXact(gxact);
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
MyLockedGxact = NULL;
|
|
|
|
RESUME_INTERRUPTS();
|
|
|
|
pfree(buf);
|
|
}
|
|
|
|
/*
|
|
* Scan 2PC state data in memory and call the indicated callbacks for each 2PC record.
|
|
*/
|
|
static void
|
|
ProcessRecords(char *bufptr, TransactionId xid,
|
|
const TwoPhaseCallback callbacks[])
|
|
{
|
|
for (;;)
|
|
{
|
|
TwoPhaseRecordOnDisk *record = (TwoPhaseRecordOnDisk *) bufptr;
|
|
|
|
Assert(record->rmid <= TWOPHASE_RM_MAX_ID);
|
|
if (record->rmid == TWOPHASE_RM_END_ID)
|
|
break;
|
|
|
|
bufptr += MAXALIGN(sizeof(TwoPhaseRecordOnDisk));
|
|
|
|
if (callbacks[record->rmid] != NULL)
|
|
callbacks[record->rmid] (xid, record->info,
|
|
(void *) bufptr, record->len);
|
|
|
|
bufptr += MAXALIGN(record->len);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Remove the 2PC file for the specified XID.
|
|
*
|
|
* If giveWarning is false, do not complain about file-not-present;
|
|
* this is an expected case during WAL replay.
|
|
*/
|
|
static void
|
|
RemoveTwoPhaseFile(TransactionId xid, bool giveWarning)
|
|
{
|
|
char path[MAXPGPATH];
|
|
|
|
TwoPhaseFilePath(path, xid);
|
|
if (unlink(path))
|
|
if (errno != ENOENT || giveWarning)
|
|
ereport(WARNING,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not remove file \"%s\": %m", path)));
|
|
}
|
|
|
|
/*
|
|
* Recreates a state file. This is used in WAL replay and during
|
|
* checkpoint creation.
|
|
*
|
|
* Note: content and len don't include CRC.
|
|
*/
|
|
static void
|
|
RecreateTwoPhaseFile(TransactionId xid, void *content, int len)
|
|
{
|
|
char path[MAXPGPATH];
|
|
pg_crc32c statefile_crc;
|
|
int fd;
|
|
|
|
/* Recompute CRC */
|
|
INIT_CRC32C(statefile_crc);
|
|
COMP_CRC32C(statefile_crc, content, len);
|
|
FIN_CRC32C(statefile_crc);
|
|
|
|
TwoPhaseFilePath(path, xid);
|
|
|
|
fd = OpenTransientFile(path,
|
|
O_CREAT | O_TRUNC | O_WRONLY | PG_BINARY);
|
|
if (fd < 0)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not recreate file \"%s\": %m", path)));
|
|
|
|
/* Write content and CRC */
|
|
errno = 0;
|
|
pgstat_report_wait_start(WAIT_EVENT_TWOPHASE_FILE_WRITE);
|
|
if (write(fd, content, len) != len)
|
|
{
|
|
int save_errno = errno;
|
|
|
|
pgstat_report_wait_end();
|
|
CloseTransientFile(fd);
|
|
|
|
/* if write didn't set errno, assume problem is no disk space */
|
|
errno = save_errno ? save_errno : ENOSPC;
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not write file \"%s\": %m", path)));
|
|
}
|
|
if (write(fd, &statefile_crc, sizeof(pg_crc32c)) != sizeof(pg_crc32c))
|
|
{
|
|
int save_errno = errno;
|
|
|
|
pgstat_report_wait_end();
|
|
CloseTransientFile(fd);
|
|
|
|
/* if write didn't set errno, assume problem is no disk space */
|
|
errno = save_errno ? save_errno : ENOSPC;
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not write file \"%s\": %m", path)));
|
|
}
|
|
pgstat_report_wait_end();
|
|
|
|
/*
|
|
* We must fsync the file because the end-of-replay checkpoint will not do
|
|
* so, there being no GXACT in shared memory yet to tell it to.
|
|
*/
|
|
pgstat_report_wait_start(WAIT_EVENT_TWOPHASE_FILE_SYNC);
|
|
if (pg_fsync(fd) != 0)
|
|
{
|
|
int save_errno = errno;
|
|
|
|
CloseTransientFile(fd);
|
|
errno = save_errno;
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not fsync file \"%s\": %m", path)));
|
|
}
|
|
pgstat_report_wait_end();
|
|
|
|
if (CloseTransientFile(fd) != 0)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not close file \"%s\": %m", path)));
|
|
}
|
|
|
|
/*
|
|
* CheckPointTwoPhase -- handle 2PC component of checkpointing.
|
|
*
|
|
* We must fsync the state file of any GXACT that is valid or has been
|
|
* generated during redo and has a PREPARE LSN <= the checkpoint's redo
|
|
* horizon. (If the gxact isn't valid yet, has not been generated in
|
|
* redo, or has a later LSN, this checkpoint is not responsible for
|
|
* fsyncing it.)
|
|
*
|
|
* This is deliberately run as late as possible in the checkpoint sequence,
|
|
* because GXACTs ordinarily have short lifespans, and so it is quite
|
|
* possible that GXACTs that were valid at checkpoint start will no longer
|
|
* exist if we wait a little bit. With typical checkpoint settings this
|
|
* will be about 3 minutes for an online checkpoint, so as a result we
|
|
* expect that there will be no GXACTs that need to be copied to disk.
|
|
*
|
|
* If a GXACT remains valid across multiple checkpoints, it will already
|
|
* be on disk so we don't bother to repeat that write.
|
|
*/
|
|
void
|
|
CheckPointTwoPhase(XLogRecPtr redo_horizon)
|
|
{
|
|
int i;
|
|
int serialized_xacts = 0;
|
|
|
|
if (max_prepared_xacts <= 0)
|
|
return; /* nothing to do */
|
|
|
|
TRACE_POSTGRESQL_TWOPHASE_CHECKPOINT_START();
|
|
|
|
/*
|
|
* We are expecting there to be zero GXACTs that need to be copied to
|
|
* disk, so we perform all I/O while holding TwoPhaseStateLock for
|
|
* simplicity. This prevents any new xacts from preparing while this
|
|
* occurs, which shouldn't be a problem since the presence of long-lived
|
|
* prepared xacts indicates the transaction manager isn't active.
|
|
*
|
|
* It's also possible to move I/O out of the lock, but on every error we
|
|
* should check whether somebody committed our transaction in different
|
|
* backend. Let's leave this optimization for future, if somebody will
|
|
* spot that this place cause bottleneck.
|
|
*
|
|
* Note that it isn't possible for there to be a GXACT with a
|
|
* prepare_end_lsn set prior to the last checkpoint yet is marked invalid,
|
|
* because of the efforts with delayChkpt.
|
|
*/
|
|
LWLockAcquire(TwoPhaseStateLock, LW_SHARED);
|
|
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
|
|
{
|
|
/*
|
|
* Note that we are using gxact not pgxact so this works in recovery
|
|
* also
|
|
*/
|
|
GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
|
|
|
|
if ((gxact->valid || gxact->inredo) &&
|
|
!gxact->ondisk &&
|
|
gxact->prepare_end_lsn <= redo_horizon)
|
|
{
|
|
char *buf;
|
|
int len;
|
|
|
|
XlogReadTwoPhaseData(gxact->prepare_start_lsn, &buf, &len);
|
|
RecreateTwoPhaseFile(gxact->xid, buf, len);
|
|
gxact->ondisk = true;
|
|
gxact->prepare_start_lsn = InvalidXLogRecPtr;
|
|
gxact->prepare_end_lsn = InvalidXLogRecPtr;
|
|
pfree(buf);
|
|
serialized_xacts++;
|
|
}
|
|
}
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
/*
|
|
* Flush unconditionally the parent directory to make any information
|
|
* durable on disk. Two-phase files could have been removed and those
|
|
* removals need to be made persistent as well as any files newly created
|
|
* previously since the last checkpoint.
|
|
*/
|
|
fsync_fname(TWOPHASE_DIR, true);
|
|
|
|
TRACE_POSTGRESQL_TWOPHASE_CHECKPOINT_DONE();
|
|
|
|
if (log_checkpoints && serialized_xacts > 0)
|
|
ereport(LOG,
|
|
(errmsg_plural("%u two-phase state file was written "
|
|
"for a long-running prepared transaction",
|
|
"%u two-phase state files were written "
|
|
"for long-running prepared transactions",
|
|
serialized_xacts,
|
|
serialized_xacts)));
|
|
}
|
|
|
|
/*
|
|
* restoreTwoPhaseData
|
|
*
|
|
* Scan pg_twophase and fill TwoPhaseState depending on the on-disk data.
|
|
* This is called once at the beginning of recovery, saving any extra
|
|
* lookups in the future. Two-phase files that are newer than the
|
|
* minimum XID horizon are discarded on the way.
|
|
*/
|
|
void
|
|
restoreTwoPhaseData(void)
|
|
{
|
|
DIR *cldir;
|
|
struct dirent *clde;
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
|
|
cldir = AllocateDir(TWOPHASE_DIR);
|
|
while ((clde = ReadDir(cldir, TWOPHASE_DIR)) != NULL)
|
|
{
|
|
if (strlen(clde->d_name) == 8 &&
|
|
strspn(clde->d_name, "0123456789ABCDEF") == 8)
|
|
{
|
|
TransactionId xid;
|
|
char *buf;
|
|
|
|
xid = (TransactionId) strtoul(clde->d_name, NULL, 16);
|
|
|
|
buf = ProcessTwoPhaseBuffer(xid, InvalidXLogRecPtr,
|
|
true, false, false);
|
|
if (buf == NULL)
|
|
continue;
|
|
|
|
PrepareRedoAdd(buf, InvalidXLogRecPtr,
|
|
InvalidXLogRecPtr, InvalidRepOriginId);
|
|
}
|
|
}
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
FreeDir(cldir);
|
|
}
|
|
|
|
/*
|
|
* PrescanPreparedTransactions
|
|
*
|
|
* Scan the shared memory entries of TwoPhaseState and determine the range
|
|
* of valid XIDs present. This is run during database startup, after we
|
|
* have completed reading WAL. ShmemVariableCache->nextXid has been set to
|
|
* one more than the highest XID for which evidence exists in WAL.
|
|
*
|
|
* We throw away any prepared xacts with main XID beyond nextXid --- if any
|
|
* are present, it suggests that the DBA has done a PITR recovery to an
|
|
* earlier point in time without cleaning out pg_twophase. We dare not
|
|
* try to recover such prepared xacts since they likely depend on database
|
|
* state that doesn't exist now.
|
|
*
|
|
* However, we will advance nextXid beyond any subxact XIDs belonging to
|
|
* valid prepared xacts. We need to do this since subxact commit doesn't
|
|
* write a WAL entry, and so there might be no evidence in WAL of those
|
|
* subxact XIDs.
|
|
*
|
|
* On corrupted two-phase files, fail immediately. Keeping around broken
|
|
* entries and let replay continue causes harm on the system, and a new
|
|
* backup should be rolled in.
|
|
*
|
|
* Our other responsibility is to determine and return the oldest valid XID
|
|
* among the prepared xacts (if none, return ShmemVariableCache->nextXid).
|
|
* This is needed to synchronize pg_subtrans startup properly.
|
|
*
|
|
* If xids_p and nxids_p are not NULL, pointer to a palloc'd array of all
|
|
* top-level xids is stored in *xids_p. The number of entries in the array
|
|
* is returned in *nxids_p.
|
|
*/
|
|
TransactionId
|
|
PrescanPreparedTransactions(TransactionId **xids_p, int *nxids_p)
|
|
{
|
|
TransactionId origNextXid = ShmemVariableCache->nextXid;
|
|
TransactionId result = origNextXid;
|
|
TransactionId *xids = NULL;
|
|
int nxids = 0;
|
|
int allocsize = 0;
|
|
int i;
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
|
|
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
|
|
{
|
|
TransactionId xid;
|
|
char *buf;
|
|
GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
|
|
|
|
Assert(gxact->inredo);
|
|
|
|
xid = gxact->xid;
|
|
|
|
buf = ProcessTwoPhaseBuffer(xid,
|
|
gxact->prepare_start_lsn,
|
|
gxact->ondisk, false, true);
|
|
|
|
if (buf == NULL)
|
|
continue;
|
|
|
|
/*
|
|
* OK, we think this file is valid. Incorporate xid into the
|
|
* running-minimum result.
|
|
*/
|
|
if (TransactionIdPrecedes(xid, result))
|
|
result = xid;
|
|
|
|
if (xids_p)
|
|
{
|
|
if (nxids == allocsize)
|
|
{
|
|
if (nxids == 0)
|
|
{
|
|
allocsize = 10;
|
|
xids = palloc(allocsize * sizeof(TransactionId));
|
|
}
|
|
else
|
|
{
|
|
allocsize = allocsize * 2;
|
|
xids = repalloc(xids, allocsize * sizeof(TransactionId));
|
|
}
|
|
}
|
|
xids[nxids++] = xid;
|
|
}
|
|
|
|
pfree(buf);
|
|
}
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
if (xids_p)
|
|
{
|
|
*xids_p = xids;
|
|
*nxids_p = nxids;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* StandbyRecoverPreparedTransactions
|
|
*
|
|
* Scan the shared memory entries of TwoPhaseState and setup all the required
|
|
* information to allow standby queries to treat prepared transactions as still
|
|
* active.
|
|
*
|
|
* This is never called at the end of recovery - we use
|
|
* RecoverPreparedTransactions() at that point.
|
|
*
|
|
* The lack of calls to SubTransSetParent() calls here is by design;
|
|
* those calls are made by RecoverPreparedTransactions() at the end of recovery
|
|
* for those xacts that need this.
|
|
*/
|
|
void
|
|
StandbyRecoverPreparedTransactions(void)
|
|
{
|
|
int i;
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
|
|
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
|
|
{
|
|
TransactionId xid;
|
|
char *buf;
|
|
GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
|
|
|
|
Assert(gxact->inredo);
|
|
|
|
xid = gxact->xid;
|
|
|
|
buf = ProcessTwoPhaseBuffer(xid,
|
|
gxact->prepare_start_lsn,
|
|
gxact->ondisk, false, false);
|
|
if (buf != NULL)
|
|
pfree(buf);
|
|
}
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
}
|
|
|
|
/*
|
|
* RecoverPreparedTransactions
|
|
*
|
|
* Scan the shared memory entries of TwoPhaseState and reload the state for
|
|
* each prepared transaction (reacquire locks, etc).
|
|
*
|
|
* This is run at the end of recovery, but before we allow backends to write
|
|
* WAL.
|
|
*
|
|
* At the end of recovery the way we take snapshots will change. We now need
|
|
* to mark all running transactions with their full SubTransSetParent() info
|
|
* to allow normal snapshots to work correctly if snapshots overflow.
|
|
* We do this here because by definition prepared transactions are the only
|
|
* type of write transaction still running, so this is necessary and
|
|
* complete.
|
|
*/
|
|
void
|
|
RecoverPreparedTransactions(void)
|
|
{
|
|
int i;
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
|
|
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
|
|
{
|
|
TransactionId xid;
|
|
char *buf;
|
|
GlobalTransaction gxact = TwoPhaseState->prepXacts[i];
|
|
char *bufptr;
|
|
TwoPhaseFileHeader *hdr;
|
|
TransactionId *subxids;
|
|
const char *gid;
|
|
|
|
xid = gxact->xid;
|
|
|
|
/*
|
|
* Reconstruct subtrans state for the transaction --- needed because
|
|
* pg_subtrans is not preserved over a restart. Note that we are
|
|
* linking all the subtransactions directly to the top-level XID;
|
|
* there may originally have been a more complex hierarchy, but
|
|
* there's no need to restore that exactly. It's possible that
|
|
* SubTransSetParent has been set before, if the prepared transaction
|
|
* generated xid assignment records.
|
|
*/
|
|
buf = ProcessTwoPhaseBuffer(xid,
|
|
gxact->prepare_start_lsn,
|
|
gxact->ondisk, true, false);
|
|
if (buf == NULL)
|
|
continue;
|
|
|
|
ereport(LOG,
|
|
(errmsg("recovering prepared transaction %u from shared memory", xid)));
|
|
|
|
hdr = (TwoPhaseFileHeader *) buf;
|
|
Assert(TransactionIdEquals(hdr->xid, xid));
|
|
bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
|
|
gid = (const char *) bufptr;
|
|
bufptr += MAXALIGN(hdr->gidlen);
|
|
subxids = (TransactionId *) bufptr;
|
|
bufptr += MAXALIGN(hdr->nsubxacts * sizeof(TransactionId));
|
|
bufptr += MAXALIGN(hdr->ncommitrels * sizeof(RelFileNode));
|
|
bufptr += MAXALIGN(hdr->nabortrels * sizeof(RelFileNode));
|
|
bufptr += MAXALIGN(hdr->ninvalmsgs * sizeof(SharedInvalidationMessage));
|
|
|
|
/*
|
|
* Recreate its GXACT and dummy PGPROC. But, check whether it was
|
|
* added in redo and already has a shmem entry for it.
|
|
*/
|
|
MarkAsPreparingGuts(gxact, xid, gid,
|
|
hdr->prepared_at,
|
|
hdr->owner, hdr->database);
|
|
|
|
/* recovered, so reset the flag for entries generated by redo */
|
|
gxact->inredo = false;
|
|
|
|
GXactLoadSubxactData(gxact, hdr->nsubxacts, subxids);
|
|
MarkAsPrepared(gxact, true);
|
|
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
|
|
/*
|
|
* Recover other state (notably locks) using resource managers.
|
|
*/
|
|
ProcessRecords(bufptr, xid, twophase_recover_callbacks);
|
|
|
|
/*
|
|
* Release locks held by the standby process after we process each
|
|
* prepared transaction. As a result, we don't need too many
|
|
* additional locks at any one time.
|
|
*/
|
|
if (InHotStandby)
|
|
StandbyReleaseLockTree(xid, hdr->nsubxacts, subxids);
|
|
|
|
/*
|
|
* We're done with recovering this transaction. Clear MyLockedGxact,
|
|
* like we do in PrepareTransaction() during normal operation.
|
|
*/
|
|
PostPrepare_Twophase();
|
|
|
|
pfree(buf);
|
|
|
|
LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
|
|
}
|
|
|
|
LWLockRelease(TwoPhaseStateLock);
|
|
}
|
|
|
|
/*
|
|
* ProcessTwoPhaseBuffer
|
|
*
|
|
* Given a transaction id, read it either from disk or read it directly
|
|
* via shmem xlog record pointer using the provided "prepare_start_lsn".
|
|
*
|
|
* If setParent is true, set up subtransaction parent linkages.
|
|
*
|
|
* If setNextXid is true, set ShmemVariableCache->nextXid to the newest
|
|
* value scanned.
|
|
*/
|
|
static char *
|
|
ProcessTwoPhaseBuffer(TransactionId xid,
|
|
XLogRecPtr prepare_start_lsn,
|
|
bool fromdisk,
|
|
bool setParent, bool setNextXid)
|
|
{
|
|
TransactionId origNextXid = ShmemVariableCache->nextXid;
|
|
TransactionId *subxids;
|
|
char *buf;
|
|
TwoPhaseFileHeader *hdr;
|
|
int i;
|
|
|
|
Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
|
|
|
|
if (!fromdisk)
|
|
Assert(prepare_start_lsn != InvalidXLogRecPtr);
|
|
|
|
/* Already processed? */
|
|
if (TransactionIdDidCommit(xid) || TransactionIdDidAbort(xid))
|
|
{
|
|
if (fromdisk)
|
|
{
|
|
ereport(WARNING,
|
|
(errmsg("removing stale two-phase state file for transaction %u",
|
|
xid)));
|
|
RemoveTwoPhaseFile(xid, true);
|
|
}
|
|
else
|
|
{
|
|
ereport(WARNING,
|
|
(errmsg("removing stale two-phase state from memory for transaction %u",
|
|
xid)));
|
|
PrepareRedoRemove(xid, true);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/* Reject XID if too new */
|
|
if (TransactionIdFollowsOrEquals(xid, origNextXid))
|
|
{
|
|
if (fromdisk)
|
|
{
|
|
ereport(WARNING,
|
|
(errmsg("removing future two-phase state file for transaction %u",
|
|
xid)));
|
|
RemoveTwoPhaseFile(xid, true);
|
|
}
|
|
else
|
|
{
|
|
ereport(WARNING,
|
|
(errmsg("removing future two-phase state from memory for transaction %u",
|
|
xid)));
|
|
PrepareRedoRemove(xid, true);
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
if (fromdisk)
|
|
{
|
|
/* Read and validate file */
|
|
buf = ReadTwoPhaseFile(xid, false);
|
|
}
|
|
else
|
|
{
|
|
/* Read xlog data */
|
|
XlogReadTwoPhaseData(prepare_start_lsn, &buf, NULL);
|
|
}
|
|
|
|
/* Deconstruct header */
|
|
hdr = (TwoPhaseFileHeader *) buf;
|
|
if (!TransactionIdEquals(hdr->xid, xid))
|
|
{
|
|
if (fromdisk)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DATA_CORRUPTED),
|
|
errmsg("corrupted two-phase state file for transaction \"%u\"",
|
|
xid)));
|
|
else
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DATA_CORRUPTED),
|
|
errmsg("corrupted two-phase state in memory for transaction \"%u\"",
|
|
xid)));
|
|
}
|
|
|
|
/*
|
|
* Examine subtransaction XIDs ... they should all follow main XID, and
|
|
* they may force us to advance nextXid.
|
|
*/
|
|
subxids = (TransactionId *) (buf +
|
|
MAXALIGN(sizeof(TwoPhaseFileHeader)) +
|
|
MAXALIGN(hdr->gidlen));
|
|
for (i = 0; i < hdr->nsubxacts; i++)
|
|
{
|
|
TransactionId subxid = subxids[i];
|
|
|
|
Assert(TransactionIdFollows(subxid, xid));
|
|
|
|
/* update nextXid if needed */
|
|
if (setNextXid &&
|
|
TransactionIdFollowsOrEquals(subxid,
|
|
ShmemVariableCache->nextXid))
|
|
{
|
|
/*
|
|
* We don't expect anyone else to modify nextXid, hence we don't
|
|
* need to hold a lock while examining it. We still acquire the
|
|
* lock to modify it, though, so we recheck.
|
|
*/
|
|
LWLockAcquire(XidGenLock, LW_EXCLUSIVE);
|
|
if (TransactionIdFollowsOrEquals(subxid,
|
|
ShmemVariableCache->nextXid))
|
|
{
|
|
ShmemVariableCache->nextXid = subxid;
|
|
TransactionIdAdvance(ShmemVariableCache->nextXid);
|
|
}
|
|
LWLockRelease(XidGenLock);
|
|
}
|
|
|
|
if (setParent)
|
|
SubTransSetParent(subxid, xid);
|
|
}
|
|
|
|
return buf;
|
|
}
|
|
|
|
|
|
/*
|
|
* RecordTransactionCommitPrepared
|
|
*
|
|
* This is basically the same as RecordTransactionCommit (q.v. if you change
|
|
* this function): in particular, we must set the delayChkpt flag to avoid a
|
|
* race condition.
|
|
*
|
|
* We know the transaction made at least one XLOG entry (its PREPARE),
|
|
* so it is never possible to optimize out the commit record.
|
|
*/
|
|
static void
|
|
RecordTransactionCommitPrepared(TransactionId xid,
|
|
int nchildren,
|
|
TransactionId *children,
|
|
int nrels,
|
|
RelFileNode *rels,
|
|
int ninvalmsgs,
|
|
SharedInvalidationMessage *invalmsgs,
|
|
bool initfileinval,
|
|
const char *gid)
|
|
{
|
|
XLogRecPtr recptr;
|
|
TimestampTz committs = GetCurrentTimestamp();
|
|
bool replorigin;
|
|
|
|
/*
|
|
* Are we using the replication origins feature? Or, in other words, are
|
|
* we replaying remote actions?
|
|
*/
|
|
replorigin = (replorigin_session_origin != InvalidRepOriginId &&
|
|
replorigin_session_origin != DoNotReplicateId);
|
|
|
|
START_CRIT_SECTION();
|
|
|
|
/* See notes in RecordTransactionCommit */
|
|
MyPgXact->delayChkpt = true;
|
|
|
|
/*
|
|
* Emit the XLOG commit record. Note that we mark 2PC commits as
|
|
* potentially having AccessExclusiveLocks since we don't know whether or
|
|
* not they do.
|
|
*/
|
|
recptr = XactLogCommitRecord(committs,
|
|
nchildren, children, nrels, rels,
|
|
ninvalmsgs, invalmsgs,
|
|
initfileinval, false,
|
|
MyXactFlags | XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK,
|
|
xid, gid);
|
|
|
|
|
|
if (replorigin)
|
|
/* Move LSNs forward for this replication origin */
|
|
replorigin_session_advance(replorigin_session_origin_lsn,
|
|
XactLastRecEnd);
|
|
|
|
/*
|
|
* Record commit timestamp. The value comes from plain commit timestamp
|
|
* if replorigin is not enabled, or replorigin already set a value for us
|
|
* in replorigin_session_origin_timestamp otherwise.
|
|
*
|
|
* We don't need to WAL-log anything here, as the commit record written
|
|
* above already contains the data.
|
|
*/
|
|
if (!replorigin || replorigin_session_origin_timestamp == 0)
|
|
replorigin_session_origin_timestamp = committs;
|
|
|
|
TransactionTreeSetCommitTsData(xid, nchildren, children,
|
|
replorigin_session_origin_timestamp,
|
|
replorigin_session_origin, false);
|
|
|
|
/*
|
|
* We don't currently try to sleep before flush here ... nor is there any
|
|
* support for async commit of a prepared xact (the very idea is probably
|
|
* a contradiction)
|
|
*/
|
|
|
|
/* Flush XLOG to disk */
|
|
XLogFlush(recptr);
|
|
|
|
/* Mark the transaction committed in pg_xact */
|
|
TransactionIdCommitTree(xid, nchildren, children);
|
|
|
|
/* Checkpoint can proceed now */
|
|
MyPgXact->delayChkpt = false;
|
|
|
|
END_CRIT_SECTION();
|
|
|
|
/*
|
|
* Wait for synchronous replication, if required.
|
|
*
|
|
* Note that at this stage we have marked clog, but still show as running
|
|
* in the procarray and continue to hold locks.
|
|
*/
|
|
SyncRepWaitForLSN(recptr, true);
|
|
}
|
|
|
|
/*
|
|
* RecordTransactionAbortPrepared
|
|
*
|
|
* This is basically the same as RecordTransactionAbort.
|
|
*
|
|
* We know the transaction made at least one XLOG entry (its PREPARE),
|
|
* so it is never possible to optimize out the abort record.
|
|
*/
|
|
static void
|
|
RecordTransactionAbortPrepared(TransactionId xid,
|
|
int nchildren,
|
|
TransactionId *children,
|
|
int nrels,
|
|
RelFileNode *rels,
|
|
const char *gid)
|
|
{
|
|
XLogRecPtr recptr;
|
|
|
|
/*
|
|
* Catch the scenario where we aborted partway through
|
|
* RecordTransactionCommitPrepared ...
|
|
*/
|
|
if (TransactionIdDidCommit(xid))
|
|
elog(PANIC, "cannot abort transaction %u, it was already committed",
|
|
xid);
|
|
|
|
START_CRIT_SECTION();
|
|
|
|
/*
|
|
* Emit the XLOG commit record. Note that we mark 2PC aborts as
|
|
* potentially having AccessExclusiveLocks since we don't know whether or
|
|
* not they do.
|
|
*/
|
|
recptr = XactLogAbortRecord(GetCurrentTimestamp(),
|
|
nchildren, children,
|
|
nrels, rels,
|
|
MyXactFlags | XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK,
|
|
xid, gid);
|
|
|
|
/* Always flush, since we're about to remove the 2PC state file */
|
|
XLogFlush(recptr);
|
|
|
|
/*
|
|
* Mark the transaction aborted in clog. This is not absolutely necessary
|
|
* but we may as well do it while we are here.
|
|
*/
|
|
TransactionIdAbortTree(xid, nchildren, children);
|
|
|
|
END_CRIT_SECTION();
|
|
|
|
/*
|
|
* Wait for synchronous replication, if required.
|
|
*
|
|
* Note that at this stage we have marked clog, but still show as running
|
|
* in the procarray and continue to hold locks.
|
|
*/
|
|
SyncRepWaitForLSN(recptr, false);
|
|
}
|
|
|
|
/*
|
|
* PrepareRedoAdd
|
|
*
|
|
* Store pointers to the start/end of the WAL record along with the xid in
|
|
* a gxact entry in shared memory TwoPhaseState structure. If caller
|
|
* specifies InvalidXLogRecPtr as WAL location to fetch the two-phase
|
|
* data, the entry is marked as located on disk.
|
|
*/
|
|
void
|
|
PrepareRedoAdd(char *buf, XLogRecPtr start_lsn,
|
|
XLogRecPtr end_lsn, RepOriginId origin_id)
|
|
{
|
|
TwoPhaseFileHeader *hdr = (TwoPhaseFileHeader *) buf;
|
|
char *bufptr;
|
|
const char *gid;
|
|
GlobalTransaction gxact;
|
|
|
|
Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
|
|
Assert(RecoveryInProgress());
|
|
|
|
bufptr = buf + MAXALIGN(sizeof(TwoPhaseFileHeader));
|
|
gid = (const char *) bufptr;
|
|
|
|
/*
|
|
* Reserve the GID for the given transaction in the redo code path.
|
|
*
|
|
* This creates a gxact struct and puts it into the active array.
|
|
*
|
|
* In redo, this struct is mainly used to track PREPARE/COMMIT entries in
|
|
* shared memory. Hence, we only fill up the bare minimum contents here.
|
|
* The gxact also gets marked with gxact->inredo set to true to indicate
|
|
* that it got added in the redo phase
|
|
*/
|
|
|
|
/* Get a free gxact from the freelist */
|
|
if (TwoPhaseState->freeGXacts == NULL)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OUT_OF_MEMORY),
|
|
errmsg("maximum number of prepared transactions reached"),
|
|
errhint("Increase max_prepared_transactions (currently %d).",
|
|
max_prepared_xacts)));
|
|
gxact = TwoPhaseState->freeGXacts;
|
|
TwoPhaseState->freeGXacts = gxact->next;
|
|
|
|
gxact->prepared_at = hdr->prepared_at;
|
|
gxact->prepare_start_lsn = start_lsn;
|
|
gxact->prepare_end_lsn = end_lsn;
|
|
gxact->xid = hdr->xid;
|
|
gxact->owner = hdr->owner;
|
|
gxact->locking_backend = InvalidBackendId;
|
|
gxact->valid = false;
|
|
gxact->ondisk = XLogRecPtrIsInvalid(start_lsn);
|
|
gxact->inredo = true; /* yes, added in redo */
|
|
strcpy(gxact->gid, gid);
|
|
|
|
/* And insert it into the active array */
|
|
Assert(TwoPhaseState->numPrepXacts < max_prepared_xacts);
|
|
TwoPhaseState->prepXacts[TwoPhaseState->numPrepXacts++] = gxact;
|
|
|
|
if (origin_id != InvalidRepOriginId)
|
|
{
|
|
/* recover apply progress */
|
|
replorigin_advance(origin_id, hdr->origin_lsn, end_lsn,
|
|
false /* backward */ , false /* WAL */ );
|
|
}
|
|
|
|
elog(DEBUG2, "added 2PC data in shared memory for transaction %u", gxact->xid);
|
|
}
|
|
|
|
/*
|
|
* PrepareRedoRemove
|
|
*
|
|
* Remove the corresponding gxact entry from TwoPhaseState. Also remove
|
|
* the 2PC file if a prepared transaction was saved via an earlier checkpoint.
|
|
*
|
|
* Caller must hold TwoPhaseStateLock in exclusive mode, because TwoPhaseState
|
|
* is updated.
|
|
*/
|
|
void
|
|
PrepareRedoRemove(TransactionId xid, bool giveWarning)
|
|
{
|
|
GlobalTransaction gxact = NULL;
|
|
int i;
|
|
bool found = false;
|
|
|
|
Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE));
|
|
Assert(RecoveryInProgress());
|
|
|
|
for (i = 0; i < TwoPhaseState->numPrepXacts; i++)
|
|
{
|
|
gxact = TwoPhaseState->prepXacts[i];
|
|
|
|
if (gxact->xid == xid)
|
|
{
|
|
Assert(gxact->inredo);
|
|
found = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Just leave if there is nothing, this is expected during WAL replay.
|
|
*/
|
|
if (!found)
|
|
return;
|
|
|
|
/*
|
|
* And now we can clean up any files we may have left.
|
|
*/
|
|
elog(DEBUG2, "removing 2PC data for transaction %u", xid);
|
|
if (gxact->ondisk)
|
|
RemoveTwoPhaseFile(xid, giveWarning);
|
|
RemoveGXact(gxact);
|
|
|
|
return;
|
|
}
|