diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/access/transam/xlog.c | 9 | ||||
| -rw-r--r-- | src/backend/replication/walsender.c | 24 | ||||
| -rw-r--r-- | src/include/access/xlog.h | 4 |
3 files changed, 20 insertions, 17 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 5787b3d164c..ab474c35b0d 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.424 2010/06/14 06:04:21 heikki Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.425 2010/06/17 16:41:25 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -6803,17 +6803,18 @@ GetInsertRecPtr(void) } /* - * GetWriteRecPtr -- Returns the current write position. + * GetFlushRecPtr -- Returns the current flush position, ie, the last WAL + * position known to be fsync'd to disk. */ XLogRecPtr -GetWriteRecPtr(void) +GetFlushRecPtr(void) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; XLogRecPtr recptr; SpinLockAcquire(&xlogctl->info_lck); - recptr = xlogctl->LogwrtResult.Write; + recptr = xlogctl->LogwrtResult.Flush; SpinLockRelease(&xlogctl->info_lck); return recptr; diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c index 7422f76251c..298737c89c2 100644 --- a/src/backend/replication/walsender.c +++ b/src/backend/replication/walsender.c @@ -3,8 +3,9 @@ * walsender.c * * The WAL sender process (walsender) is new as of Postgres 9.0. It takes - * charge of XLOG streaming sender in the primary server. At first, it is - * started by the postmaster when the walreceiver in the standby server + * care of sending XLOG from the primary server to a single recipient. + * (Note that there can be more than one walsender process concurrently.) + * It is started by the postmaster when the walreceiver of a standby server * connects to the primary server and requests XLOG streaming replication. * It attempts to keep reading XLOG records from the disk and sending them * to the standby server, as long as the connection is alive (i.e., like @@ -23,13 +24,11 @@ * This instruct walsender to send any outstanding WAL, including the * shutdown checkpoint record, and then exit. * - * Note that there can be more than one walsender process concurrently. * * Portions Copyright (c) 2010-2010, PostgreSQL Global Development Group * - * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/replication/walsender.c,v 1.26 2010/06/03 23:00:14 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/replication/walsender.c,v 1.27 2010/06/17 16:41:25 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -641,7 +640,7 @@ XLogRead(char *buf, XLogRecPtr recptr, Size nbytes) } /* - * Read up to MAX_SEND_SIZE bytes of WAL that's been written to disk, + * Read up to MAX_SEND_SIZE bytes of WAL that's been flushed to disk, * but not yet sent to the client, and send it. * * msgbuf is a work area in which the output message is constructed. It's @@ -663,11 +662,14 @@ XLogSend(char *msgbuf, bool *caughtup) WalDataMessageHeader msghdr; /* - * Attempt to send all data that's already been written out from WAL - * buffers (note it might not yet be fsync'd to disk). We cannot go - * further than that given the current implementation of XLogRead(). + * Attempt to send all data that's already been written out and fsync'd + * to disk. We cannot go further than what's been written out given the + * current implementation of XLogRead(). And in any case it's unsafe to + * send WAL that is not securely down to disk on the master: if the master + * subsequently crashes and restarts, slaves must not have applied any WAL + * that gets lost on the master. */ - SendRqstPtr = GetWriteRecPtr(); + SendRqstPtr = GetFlushRecPtr(); /* Quick exit if nothing to do */ if (XLByteLE(SendRqstPtr, sentPtr)) @@ -679,7 +681,7 @@ XLogSend(char *msgbuf, bool *caughtup) /* * Figure out how much to send in one message. If there's no more than * MAX_SEND_SIZE bytes to send, send everything. Otherwise send - * MAX_SEND_SIZE bytes, but round to logfile or page boundary. + * MAX_SEND_SIZE bytes, but round back to logfile or page boundary. * * The rounding is not only for performance reasons. Walreceiver * relies on the fact that we never split a WAL record across two diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 1a8f455dba6..cbadd7f91fb 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -6,7 +6,7 @@ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.112 2010/06/10 07:49:23 heikki Exp $ + * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.113 2010/06/17 16:41:25 tgl Exp $ */ #ifndef XLOG_H #define XLOG_H @@ -294,7 +294,7 @@ extern bool CreateRestartPoint(int flags); extern void XLogPutNextOid(Oid nextOid); extern XLogRecPtr GetRedoRecPtr(void); extern XLogRecPtr GetInsertRecPtr(void); -extern XLogRecPtr GetWriteRecPtr(void); +extern XLogRecPtr GetFlushRecPtr(void); extern void GetNextXidAndEpoch(TransactionId *xid, uint32 *epoch); extern TimeLineID GetRecoveryTargetTLI(void); |