Update the location of last removed WAL segment in shared memory only

after actually removing one, so that if we can't remove segments because
WAL archiving is lagging behind, we don't unnecessarily forbid streaming
the old not-yet-archived segments that are still perfectly valid. Per
suggestion from Fujii Masao.

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index c5b7f7a98ceaf4c0411ce0dcd00b30159eb15e5b..379c6f11750b26ea4feff7f777d333668b302ca9 100644 (file)
--- 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 1.392 2010/04/12 09:52:29 heikki Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.393 2010/04/12 10:40:42 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -546,6 +546,7 @@ static void ExecuteRecoveryCommand(char *command, char *commandName,
                       bool failOnerror);
 static void PreallocXlogFiles(XLogRecPtr endptr);
 static void RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr);
+static void UpdateLastRemovedPtr(char *filename);
 static void ValidateXLOGDirectoryStructure(void);
 static void CleanupBackupHistory(void);
 static void UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force);
@@ -3168,6 +3169,31 @@ XLogGetLastRemoved(uint32 *log, uint32 *seg)
    SpinLockRelease(&xlogctl->info_lck);
 }
 
+/*
+ * Update the last removed log/seg pointer in shared memory, to reflect
+ * that the given XLOG file has been removed.
+ */
+static void
+UpdateLastRemovedPtr(char *filename)
+{
+   /* use volatile pointer to prevent code rearrangement */
+   volatile XLogCtlData *xlogctl = XLogCtl;
+   uint32      tli,
+               log,
+               seg;
+
+   XLogFromFileName(filename, &tli, &log, &seg);
+
+   SpinLockAcquire(&xlogctl->info_lck);
+   if (log > xlogctl->lastRemovedLog ||
+       (log == xlogctl->lastRemovedLog && seg > xlogctl->lastRemovedSeg))
+   {
+       xlogctl->lastRemovedLog = log;
+       xlogctl->lastRemovedSeg = seg;
+   }
+   SpinLockRelease(&xlogctl->info_lck);
+}
+
 /*
  * Recycle or remove all log files older or equal to passed log/seg#
  *
@@ -3189,20 +3215,8 @@ RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr)
    char        newpath[MAXPGPATH];
 #endif
    struct stat statbuf;
-   /* use volatile pointer to prevent code rearrangement */
-   volatile XLogCtlData *xlogctl = XLogCtl;
 
-   /* Update the last removed location in shared memory first */
-   SpinLockAcquire(&xlogctl->info_lck);
-   if (log > xlogctl->lastRemovedLog ||
-       (log == xlogctl->lastRemovedLog && seg > xlogctl->lastRemovedSeg))
-   {
-       xlogctl->lastRemovedLog = log;
-       xlogctl->lastRemovedSeg = seg;
-   }
-   SpinLockRelease(&xlogctl->info_lck);
-
-   elog(DEBUG1, "removing WAL segments older than %X/%X", log, seg);
+   elog(DEBUG2, "removing WAL segments older than %X/%X", log, seg);
 
    /*
     * Initialize info about where to try to recycle to.  We allow recycling
@@ -3252,6 +3266,9 @@ RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr)
            {
                snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlde->d_name);
 
+               /* Update the last removed location in shared memory first */
+               UpdateLastRemovedPtr(xlde->d_name);
+
                /*
                 * Before deleting the file, see if it can be recycled as a
                 * future log segment. Only recycle normal files, pg_standby

diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
index c93e3848e87368429e5dbb24f9aaea18168f2a5f..fa21f0a916a3348bcb4cf702601cdeed02b33f9d 100644 (file)
--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -11,7 +11,7 @@
  * 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_internal.h,v 1.31 2010/03/28 09:27:02 sriggs Exp $
+ * $PostgreSQL: pgsql/src/include/access/xlog_internal.h,v 1.32 2010/04/12 10:40:43 heikki Exp $
  */
 #ifndef XLOG_INTERNAL_H
 #define XLOG_INTERNAL_H
@@ -216,6 +216,9 @@ typedef XLogLongPageHeaderData *XLogLongPageHeader;
 #define XLogFileName(fname, tli, log, seg) \
    snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli, log, seg)
 
+#define XLogFromFileName(fname, tli, log, seg) \
+   sscanf(fname, "%08X%08X%08X", tli, log, seg)
+
 #define XLogFilePath(path, tli, log, seg)  \
    snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X", tli, log, seg)