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Commiteddbf39

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committed
Extend yesterday's patch so that the bgwriter is also told to forget
pending fsyncs during DROP DATABASE. Obviously necessary in hindsight :-(
1 parent530b10c commiteddbf39

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4 files changed

+124
-55
lines changed

4 files changed

+124
-55
lines changed

‎src/backend/commands/dbcommands.c

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
*
1414
*
1515
* IDENTIFICATION
16-
* $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.189 2007/01/16 13:28:56 alvherre Exp $
16+
* $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.190 2007/01/17 16:25:01 tgl Exp $
1717
*
1818
*-------------------------------------------------------------------------
1919
*/
@@ -40,6 +40,7 @@
4040
#include"postmaster/bgwriter.h"
4141
#include"storage/freespace.h"
4242
#include"storage/procarray.h"
43+
#include"storage/smgr.h"
4344
#include"utils/acl.h"
4445
#include"utils/builtins.h"
4546
#include"utils/flatfiles.h"
@@ -643,6 +644,12 @@ dropdb(const char *dbname, bool missing_ok)
643644
*/
644645
FreeSpaceMapForgetDatabase(db_id);
645646

647+
/*
648+
* Tell bgwriter to forget any pending fsync requests for files in the
649+
* database; else it'll fail at next checkpoint.
650+
*/
651+
ForgetDatabaseFsyncRequests(db_id);
652+
646653
/*
647654
* On Windows, force a checkpoint so that the bgwriter doesn't hold any
648655
* open files, which would cause rmdir() to fail.

‎src/backend/postmaster/bgwriter.c

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,7 @@
3737
*
3838
*
3939
* IDENTIFICATION
40-
* $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.35 2007/01/1700:17:20 tgl Exp $
40+
* $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.36 2007/01/1716:25:01 tgl Exp $
4141
*
4242
*-------------------------------------------------------------------------
4343
*/
@@ -103,7 +103,7 @@
103103
typedefstruct
104104
{
105105
RelFileNodernode;
106-
BlockNumbersegno;/*InvalidBlockNumber means "revoke" */
106+
BlockNumbersegno;/*see md.c for special values */
107107
/* might add a real request-type field later; not needed yet */
108108
}BgWriterRequest;
109109

@@ -695,16 +695,16 @@ RequestCheckpoint(bool waitforit, bool warnontime)
695695
* ForwardFsyncRequest
696696
*Forward a file-fsync request from a backend to the bgwriter
697697
*
698-
* segno specifies which segment (not block!) of the relation needs to be
699-
* fsync'd. If segno == InvalidBlockNumber, the meaning is to revoke any
700-
* pending fsync requests for the entire relation (this message is sent
701-
* when the relation is about to be deleted).
702-
*
703698
* Whenever a backend is compelled to write directly to a relation
704699
* (which should be seldom, if the bgwriter is getting its job done),
705700
* the backend calls this routine to pass over knowledge that the relation
706701
* is dirty and must be fsync'd before next checkpoint.
707702
*
703+
* segno specifies which segment (not block!) of the relation needs to be
704+
* fsync'd. (Since the valid range is much less than BlockNumber, we can
705+
* use high values for special flags; that's all internal to md.c, which
706+
* see for details.)
707+
*
708708
* If we are unable to pass over the request (at present, this can happen
709709
* if the shared memory queue is full), we return false. That forces
710710
* the backend to do its own fsync. We hope that will be even more seldom.

‎src/backend/storage/smgr/md.c

Lines changed: 106 additions & 46 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/storage/smgr/md.c,v 1.126 2007/01/1700:17:21 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/storage/smgr/md.c,v 1.127 2007/01/1716:25:01 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -31,6 +31,10 @@
3131
/* interval for calling AbsorbFsyncRequests in mdsync */
3232
#defineFSYNCS_PER_ABSORB10
3333

34+
/* special values for the segno arg to RememberFsyncRequest */
35+
#defineFORGET_RELATION_FSYNC(InvalidBlockNumber)
36+
#defineFORGET_DATABASE_FSYNC(InvalidBlockNumber-1)
37+
3438
/*
3539
* On Windows, we have to interpret EACCES as possibly meaning the same as
3640
* ENOENT, because if a file is unlinked-but-not-yet-gone on that platform,
@@ -258,30 +262,7 @@ mdunlink(RelFileNode rnode, bool isRedo)
258262
* We have to clean out any pending fsync requests for the doomed relation,
259263
* else the next mdsync() will fail.
260264
*/
261-
if (pendingOpsTable)
262-
{
263-
/* standalone backend or startup process: fsync state is local */
264-
RememberFsyncRequest(rnode,InvalidBlockNumber);
265-
}
266-
elseif (IsUnderPostmaster)
267-
{
268-
/*
269-
* Notify the bgwriter about it. If we fail to queue the revoke
270-
* message, we have to sleep and try again ... ugly, but hopefully
271-
* won't happen often.
272-
*
273-
* XXX should we CHECK_FOR_INTERRUPTS in this loop? Escaping with
274-
* an error would leave the no-longer-used file still present on
275-
* disk, which would be bad, so I'm inclined to assume that the
276-
* bgwriter will always empty the queue soon.
277-
*/
278-
while (!ForwardFsyncRequest(rnode,InvalidBlockNumber))
279-
pg_usleep(10000L);/* 10 msec seems a good number */
280-
/*
281-
* Note we don't wait for the bgwriter to actually absorb the
282-
* revoke message; see mdsync() for the implications.
283-
*/
284-
}
265+
ForgetRelationFsyncRequests(rnode);
285266

286267
path=relpath(rnode);
287268

@@ -894,7 +875,8 @@ mdsync(void)
894875
* what we will do is retry the whole process after absorbing fsync
895876
* request messages again. Since mdunlink() queues a "revoke" message
896877
* before actually unlinking, the fsync request is guaranteed to be gone
897-
* the second time if it really was this case.
878+
* the second time if it really was this case. DROP DATABASE likewise
879+
* has to tell us to forget fsync requests before it starts deletions.
898880
*/
899881
do {
900882
HASH_SEQ_STATUShstat;
@@ -1043,17 +1025,58 @@ register_dirty_segment(SMgrRelation reln, MdfdVec *seg)
10431025
* We stuff the fsync request into the local hash table for execution
10441026
* during the bgwriter's next checkpoint.
10451027
*
1046-
* segno == InvalidBlockNumber is a "revoke" request: remove any pending
1047-
* fsync requests for the whole relation.
1028+
* The range of possible segment numbers is way less than the range of
1029+
* BlockNumber, so we can reserve high values of segno for special purposes.
1030+
* We define two: FORGET_RELATION_FSYNC means to drop pending fsyncs for
1031+
* a relation, and FORGET_DATABASE_FSYNC means to drop pending fsyncs for
1032+
* a whole database. (These are a tad slow because the hash table has to be
1033+
* searched linearly, but it doesn't seem worth rethinking the table structure
1034+
* for them.)
10481035
*/
10491036
void
10501037
RememberFsyncRequest(RelFileNodernode,BlockNumbersegno)
10511038
{
10521039
Assert(pendingOpsTable);
10531040

1054-
if (segno!=InvalidBlockNumber)
1041+
if (segno==FORGET_RELATION_FSYNC)
1042+
{
1043+
/* Remove any pending requests for the entire relation */
1044+
HASH_SEQ_STATUShstat;
1045+
PendingOperationEntry*entry;
1046+
1047+
hash_seq_init(&hstat,pendingOpsTable);
1048+
while ((entry= (PendingOperationEntry*)hash_seq_search(&hstat))!=NULL)
1049+
{
1050+
if (RelFileNodeEquals(entry->tag.rnode,rnode))
1051+
{
1052+
/* Okay, delete this entry */
1053+
if (hash_search(pendingOpsTable,&entry->tag,
1054+
HASH_REMOVE,NULL)==NULL)
1055+
elog(ERROR,"pendingOpsTable corrupted");
1056+
}
1057+
}
1058+
}
1059+
elseif (segno==FORGET_DATABASE_FSYNC)
1060+
{
1061+
/* Remove any pending requests for the entire database */
1062+
HASH_SEQ_STATUShstat;
1063+
PendingOperationEntry*entry;
1064+
1065+
hash_seq_init(&hstat,pendingOpsTable);
1066+
while ((entry= (PendingOperationEntry*)hash_seq_search(&hstat))!=NULL)
1067+
{
1068+
if (entry->tag.rnode.dbNode==rnode.dbNode)
1069+
{
1070+
/* Okay, delete this entry */
1071+
if (hash_search(pendingOpsTable,&entry->tag,
1072+
HASH_REMOVE,NULL)==NULL)
1073+
elog(ERROR,"pendingOpsTable corrupted");
1074+
}
1075+
}
1076+
}
1077+
else
10551078
{
1056-
/*Enter a request to fsync this segment */
1079+
/*Normal case: enter a request to fsync this segment */
10571080
PendingOperationTagkey;
10581081
PendingOperationEntry*entry;
10591082
boolfound;
@@ -1070,29 +1093,66 @@ RememberFsyncRequest(RelFileNode rnode, BlockNumber segno)
10701093
if (!found)/* new entry, so initialize it */
10711094
entry->failures=0;
10721095
}
1073-
else
1096+
}
1097+
1098+
/*
1099+
* ForgetRelationFsyncRequests -- ensure any fsyncs for a rel are forgotten
1100+
*/
1101+
void
1102+
ForgetRelationFsyncRequests(RelFileNodernode)
1103+
{
1104+
if (pendingOpsTable)
1105+
{
1106+
/* standalone backend or startup process: fsync state is local */
1107+
RememberFsyncRequest(rnode,FORGET_RELATION_FSYNC);
1108+
}
1109+
elseif (IsUnderPostmaster)
10741110
{
10751111
/*
1076-
* Remove any pending requests for the entire relation. (This is a
1077-
* tad slow but it doesn't seem worth rethinking the table structure.)
1112+
* Notify the bgwriter about it. If we fail to queue the revoke
1113+
* message, we have to sleep and try again ... ugly, but hopefully
1114+
* won't happen often.
1115+
*
1116+
* XXX should we CHECK_FOR_INTERRUPTS in this loop? Escaping with
1117+
* an error would leave the no-longer-used file still present on
1118+
* disk, which would be bad, so I'm inclined to assume that the
1119+
* bgwriter will always empty the queue soon.
10781120
*/
1079-
HASH_SEQ_STATUShstat;
1080-
PendingOperationEntry*entry;
1121+
while (!ForwardFsyncRequest(rnode,FORGET_RELATION_FSYNC))
1122+
pg_usleep(10000L);/* 10 msec seems a good number */
1123+
/*
1124+
* Note we don't wait for the bgwriter to actually absorb the
1125+
* revoke message; see mdsync() for the implications.
1126+
*/
1127+
}
1128+
}
10811129

1082-
hash_seq_init(&hstat,pendingOpsTable);
1083-
while ((entry= (PendingOperationEntry*)hash_seq_search(&hstat))!=NULL)
1084-
{
1085-
if (RelFileNodeEquals(entry->tag.rnode,rnode))
1086-
{
1087-
/* Okay, delete this entry */
1088-
if (hash_search(pendingOpsTable,&entry->tag,
1089-
HASH_REMOVE,NULL)==NULL)
1090-
elog(ERROR,"pendingOpsTable corrupted");
1091-
}
1092-
}
1130+
/*
1131+
* ForgetDatabaseFsyncRequests -- ensure any fsyncs for a DB are forgotten
1132+
*/
1133+
void
1134+
ForgetDatabaseFsyncRequests(Oiddbid)
1135+
{
1136+
RelFileNodernode;
1137+
1138+
rnode.dbNode=dbid;
1139+
rnode.spcNode=0;
1140+
rnode.relNode=0;
1141+
1142+
if (pendingOpsTable)
1143+
{
1144+
/* standalone backend or startup process: fsync state is local */
1145+
RememberFsyncRequest(rnode,FORGET_DATABASE_FSYNC);
1146+
}
1147+
elseif (IsUnderPostmaster)
1148+
{
1149+
/* see notes in ForgetRelationFsyncRequests */
1150+
while (!ForwardFsyncRequest(rnode,FORGET_DATABASE_FSYNC))
1151+
pg_usleep(10000L);/* 10 msec seems a good number */
10931152
}
10941153
}
10951154

1155+
10961156
/*
10971157
*_fdvec_alloc() -- Make a MdfdVec object.
10981158
*/

‎src/include/storage/smgr.h

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/storage/smgr.h,v 1.57 2007/01/05 22:19:58 momjian Exp $
10+
* $PostgreSQL: pgsql/src/include/storage/smgr.h,v 1.58 2007/01/17 16:25:01 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -106,6 +106,8 @@ extern void mdimmedsync(SMgrRelation reln);
106106
externvoidmdsync(void);
107107

108108
externvoidRememberFsyncRequest(RelFileNodernode,BlockNumbersegno);
109+
externvoidForgetRelationFsyncRequests(RelFileNodernode);
110+
externvoidForgetDatabaseFsyncRequests(Oiddbid);
109111

110112
/* smgrtype.c */
111113
externDatumsmgrout(PG_FUNCTION_ARGS);

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