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Write exact xlog position of timeline switch in the timeline history file.

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This allows us to do some more rigorous sanity checking for various
incorrect point-in-time recovery scenarios, and provides more information
for debugging purposes. It will also come handy in the upcoming patch to
allow timeline switches to be replicated by streaming replication.
This commit is contained in:
Heikki Linnakangas
2012-12-04 15:28:58 +02:00
parent a84c30dda5
commit 32f4de0adf
3 changed files with 248 additions and 91 deletions
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144
src/backend/access/transam/timeline.c
View File

@@ -12,10 +12,10 @@
*
* Each line in the file represents a timeline switch:
*
* <parentTLI> <xlogfname> <reason>
* <parentTLI> <switchpoint> <reason>
*
* parentTLI ID of the parent timeline
* xlogfname filename of the WAL segment where the switch happened
* switchpoint XLogRecPtr of the WAL position where the switch happened
* reason human-readable explanation of why the timeline was changed
*
* The fields are separated by tabs. Lines beginning with # are comments, and
@@ -56,10 +56,18 @@ readTimeLineHistory(TimeLineID targetTLI)
char histfname[MAXFNAMELEN];
char fline[MAXPGPATH];
FILE *fd;
TimeLineHistoryEntry *entry;
TimeLineID lasttli = 0;
XLogRecPtr prevend;
/* Timeline 1 does not have a history file, so no need to check */
if (targetTLI == 1)
return list_make1_int((int) targetTLI);
{
entry = (TimeLineHistoryEntry *) palloc(sizeof(TimeLineHistoryEntry));
entry->tli = targetTLI;
entry->begin = entry->end = InvalidXLogRecPtr;
return list_make1(entry);
}
if (InArchiveRecovery)
{
@@ -77,7 +85,10 @@ readTimeLineHistory(TimeLineID targetTLI)
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", path)));
/* Not there, so assume no parents */
return list_make1_int((int) targetTLI);
entry = (TimeLineHistoryEntry *) palloc(sizeof(TimeLineHistoryEntry));
entry->tli = targetTLI;
entry->begin = entry->end = InvalidXLogRecPtr;
return list_make1(entry);
}
result = NIL;
@@ -85,12 +96,15 @@ readTimeLineHistory(TimeLineID targetTLI)
/*
* Parse the file...
*/
prevend = InvalidXLogRecPtr;
while (fgets(fline, sizeof(fline), fd) != NULL)
{
/* skip leading whitespace and check for # comment */
char *ptr;
char *endptr;
TimeLineID tli;
uint32 switchpoint_hi;
uint32 switchpoint_lo;
int nfields;
for (ptr = fline; *ptr; ptr++)
{
@@ -100,38 +114,56 @@ readTimeLineHistory(TimeLineID targetTLI)
if (*ptr == '\0' || *ptr == '#')
continue;
/* expect a numeric timeline ID as first field of line */
tli = (TimeLineID) strtoul(ptr, &endptr, 0);
if (endptr == ptr)
nfields = sscanf(fline, "%u\t%X/%X", &tli, &switchpoint_hi, &switchpoint_lo);
if (nfields < 1)
{
/* expect a numeric timeline ID as first field of line */
ereport(FATAL,
(errmsg("syntax error in history file: %s", fline),
errhint("Expected a numeric timeline ID.")));
}
if (nfields != 3)
ereport(FATAL,
(errmsg("syntax error in history file: %s", fline),
errhint("Expected an XLOG switchpoint location.")));
if (result &&
tli <= (TimeLineID) linitial_int(result))
if (result && tli <= lasttli)
ereport(FATAL,
(errmsg("invalid data in history file: %s", fline),
errhint("Timeline IDs must be in increasing sequence.")));
lasttli = tli;
entry = (TimeLineHistoryEntry *) palloc(sizeof(TimeLineHistoryEntry));
entry->tli = tli;
entry->begin = prevend;
entry->end = ((uint64) (switchpoint_hi)) << 32 | (uint64) switchpoint_lo;
prevend = entry->end;
/* Build list with newest item first */
result = lcons_int((int) tli, result);
result = lcons(entry, result);
/* we ignore the remainder of each line */
}
FreeFile(fd);
if (result &&
targetTLI <= (TimeLineID) linitial_int(result))
if (result && targetTLI <= lasttli)
ereport(FATAL,
(errmsg("invalid data in history file \"%s\"", path),
errhint("Timeline IDs must be less than child timeline's ID.")));
result = lcons_int((int) targetTLI, result);
/*
* Create one more entry for the "tip" of the timeline, which has no
* entry in the history file.
*/
entry = (TimeLineHistoryEntry *) palloc(sizeof(TimeLineHistoryEntry));
entry->tli = targetTLI;
entry->begin = prevend;
entry->end = InvalidXLogRecPtr;
ereport(DEBUG3,
(errmsg_internal("history of timeline %u is %s",
targetTLI, nodeToString(result))));
result = lcons(entry, result);
return result;
}
@@ -214,7 +246,7 @@ findNewestTimeLine(TimeLineID startTLI)
*
* newTLI: ID of the new timeline
* parentTLI: ID of its immediate parent
* endTLI et al: ID of the last used WAL file, for annotation purposes
* switchpoint: XLOG position where the system switched to the new timeline
* reason: human-readable explanation of why the timeline was switched
*
* Currently this is only used at the end recovery, and so there are no locking
@@ -223,12 +255,11 @@ findNewestTimeLine(TimeLineID startTLI)
*/
void
writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
TimeLineID endTLI, XLogSegNo endLogSegNo, char *reason)
XLogRecPtr switchpoint, char *reason)
{
char path[MAXPGPATH];
char tmppath[MAXPGPATH];
char histfname[MAXFNAMELEN];
char xlogfname[MAXFNAMELEN];
char buffer[BLCKSZ];
int srcfd;
int fd;
@@ -313,13 +344,11 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
* If we did have a parent file, insert an extra newline just in case the
* parent file failed to end with one.
*/
XLogFileName(xlogfname, endTLI, endLogSegNo);
snprintf(buffer, sizeof(buffer),
"%s%u\t%s\t%s\n",
"%s%u\t%X/%X\t%s\n",
(srcfd < 0) ? "" : "\n",
parentTLI,
xlogfname,
(uint32) (switchpoint >> 32), (uint32) (switchpoint),
reason);
nbytes = strlen(buffer);
@@ -380,3 +409,70 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
TLHistoryFileName(histfname, newTLI);
XLogArchiveNotify(histfname);
}
/*
* Returns true if 'expectedTLEs' contains a timeline with id 'tli'
*/
bool
tliInHistory(TimeLineID tli, List *expectedTLEs)
{
ListCell *cell;
foreach(cell, expectedTLEs)
{
if (((TimeLineHistoryEntry *) lfirst(cell))->tli == tli)
return true;
}
return false;
}
/*
* Returns the ID of the timeline in use at a particular point in time, in
* the given timeline history.
*/
TimeLineID
tliOfPointInHistory(XLogRecPtr ptr, List *history)
{
ListCell *cell;
foreach(cell, history)
{
TimeLineHistoryEntry *tle = (TimeLineHistoryEntry *) lfirst(cell);
if ((XLogRecPtrIsInvalid(tle->begin) || XLByteLE(tle->begin, ptr)) &&
(XLogRecPtrIsInvalid(tle->end) || XLByteLT(ptr, tle->end)))
{
/* found it */
return tle->tli;
}
}
/* shouldn't happen. */
elog(ERROR, "timeline history was not contiguous");
return 0; /* keep compiler quiet */
}
/*
* Returns the point in history where we branched off the given timeline.
* Returns InvalidXLogRecPtr if the timeline is current (= we have not
* branched off from it), and throws an error if the timeline is not part of
* this server's history.
*/
XLogRecPtr
tliSwitchPoint(TimeLineID tli, List *history)
{
ListCell *cell;
foreach (cell, history)
{
TimeLineHistoryEntry *tle = (TimeLineHistoryEntry *) lfirst(cell);
if (tle->tli == tli)
return tle->end;
}
ereport(ERROR,
(errmsg("requested timeline %u is not in this server's history",
tli)));
return InvalidXLogRecPtr; /* keep compiler quiet */
}