From cf5a1890592bfa2f45d306789533efba97496233 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 17 Apr 2018 16:10:42 -0400 Subject: [PATCH] Fix confusion on the padding of GIDs in on commit and abort records. Review of commit 1eb6d652: It's pointless to add padding to the GID fields, when the code that follows assumes that there is no alignment, and uses memcpy(). Remove the pointless padding. Update comments to note the new fields in the WAL records. Reviewed-by: Michael Paquier Discussion: https://www.postgresql.org/message-id/33b787bf-dc20-1161-54e9-3f3b607bf59d%40iki.fi --- src/backend/access/rmgrdesc/xactdesc.c | 16 ++++++++-------- src/backend/access/transam/twophase.c | 2 ++ src/backend/access/transam/xact.c | 24 ++---------------------- src/include/access/xact.h | 5 ++++- src/include/access/xlog_internal.h | 2 +- 5 files changed, 17 insertions(+), 32 deletions(-) diff --git a/src/backend/access/rmgrdesc/xactdesc.c b/src/backend/access/rmgrdesc/xactdesc.c index 9b40f447ff..6d5ebd475b 100644 --- a/src/backend/access/rmgrdesc/xactdesc.c +++ b/src/backend/access/rmgrdesc/xactdesc.c @@ -104,18 +104,18 @@ ParseCommitRecord(uint8 info, xl_xact_commit *xlrec, xl_xact_parsed_commit *pars if (parsed->xinfo & XACT_XINFO_HAS_GID) { - int gidlen; strlcpy(parsed->twophase_gid, data, sizeof(parsed->twophase_gid)); - gidlen = strlen(data) + 1; - data += MAXALIGN(gidlen); + data += strlen(data) + 1; } } + /* Note: no alignment is guaranteed after this point */ + if (parsed->xinfo & XACT_XINFO_HAS_ORIGIN) { xl_xact_origin xl_origin; - /* we're only guaranteed 4 byte alignment, so copy onto stack */ + /* no alignment is guaranteed, so copy onto stack */ memcpy(&xl_origin, data, sizeof(xl_origin)); parsed->origin_lsn = xl_origin.origin_lsn; @@ -188,18 +188,18 @@ ParseAbortRecord(uint8 info, xl_xact_abort *xlrec, xl_xact_parsed_abort *parsed) if (parsed->xinfo & XACT_XINFO_HAS_GID) { - int gidlen; strlcpy(parsed->twophase_gid, data, sizeof(parsed->twophase_gid)); - gidlen = strlen(data) + 1; - data += MAXALIGN(gidlen); + data += strlen(data) + 1; } } + /* Note: no alignment is guaranteed after this point */ + if (parsed->xinfo & XACT_XINFO_HAS_ORIGIN) { xl_xact_origin xl_origin; - /* we're only guaranteed 4 byte alignment, so copy onto stack */ + /* no alignment is guaranteed, so copy onto stack */ memcpy(&xl_origin, data, sizeof(xl_origin)); parsed->origin_lsn = xl_origin.origin_lsn; diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c index d6e4b7980f..5c05d545c4 100644 --- a/src/backend/access/transam/twophase.c +++ b/src/backend/access/transam/twophase.c @@ -1129,9 +1129,11 @@ EndPrepare(GlobalTransaction gxact) 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); diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 948733c1e3..4747353bb9 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -5245,9 +5245,7 @@ XactLogCommitRecord(TimestampTz commit_time, xl_xact_invals xl_invals; xl_xact_twophase xl_twophase; xl_xact_origin xl_origin; - uint8 info; - int gidlen = 0; Assert(CritSectionCount > 0); @@ -5313,10 +5311,7 @@ XactLogCommitRecord(TimestampTz commit_time, Assert(twophase_gid != NULL); if (XLogLogicalInfoActive()) - { xl_xinfo.xinfo |= XACT_XINFO_HAS_GID; - gidlen = strlen(twophase_gid) + 1; /* include '\0' */ - } } /* dump transaction origin information */ @@ -5370,12 +5365,7 @@ XactLogCommitRecord(TimestampTz commit_time, { XLogRegisterData((char *) (&xl_twophase), sizeof(xl_xact_twophase)); if (xl_xinfo.xinfo & XACT_XINFO_HAS_GID) - { - static const char zeroes[MAXIMUM_ALIGNOF] = { 0 }; - XLogRegisterData((char*) twophase_gid, gidlen); - if (MAXALIGN(gidlen) != gidlen) - XLogRegisterData((char*) zeroes, MAXALIGN(gidlen) - gidlen); - } + XLogRegisterData((char *) twophase_gid, strlen(twophase_gid)); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_ORIGIN) @@ -5409,7 +5399,6 @@ XactLogAbortRecord(TimestampTz abort_time, xl_xact_origin xl_origin; uint8 info; - int gidlen = 0; Assert(CritSectionCount > 0); @@ -5448,10 +5437,7 @@ XactLogAbortRecord(TimestampTz abort_time, Assert(twophase_gid != NULL); if (XLogLogicalInfoActive()) - { xl_xinfo.xinfo |= XACT_XINFO_HAS_GID; - gidlen = strlen(twophase_gid) + 1; /* include '\0' */ - } } if (TransactionIdIsValid(twophase_xid) && XLogLogicalInfoActive()) @@ -5487,7 +5473,6 @@ XactLogAbortRecord(TimestampTz abort_time, if (xl_xinfo.xinfo & XACT_XINFO_HAS_DBINFO) XLogRegisterData((char *) (&xl_dbinfo), sizeof(xl_dbinfo)); - if (xl_xinfo.xinfo & XACT_XINFO_HAS_SUBXACTS) { XLogRegisterData((char *) (&xl_subxacts), @@ -5508,12 +5493,7 @@ XactLogAbortRecord(TimestampTz abort_time, { XLogRegisterData((char *) (&xl_twophase), sizeof(xl_xact_twophase)); if (xl_xinfo.xinfo & XACT_XINFO_HAS_GID) - { - static const char zeroes[MAXIMUM_ALIGNOF] = { 0 }; - XLogRegisterData((char*) twophase_gid, gidlen); - if (MAXALIGN(gidlen) != gidlen) - XLogRegisterData((char*) zeroes, MAXALIGN(gidlen) - gidlen); - } + XLogRegisterData((char *) twophase_gid, strlen(twophase_gid) + 1); } if (xl_xinfo.xinfo & XACT_XINFO_HAS_ORIGIN) diff --git a/src/include/access/xact.h b/src/include/access/xact.h index a46396f2d9..3661b8d090 100644 --- a/src/include/access/xact.h +++ b/src/include/access/xact.h @@ -269,6 +269,7 @@ typedef struct xl_xact_commit /* xl_xact_relfilenodes follows if XINFO_HAS_RELFILENODES */ /* xl_xact_invals follows if XINFO_HAS_INVALS */ /* xl_xact_twophase follows if XINFO_HAS_TWOPHASE */ + /* twophase_gid follows if XINFO_HAS_GID. As a null-terminated string. */ /* xl_xact_origin follows if XINFO_HAS_ORIGIN, stored unaligned! */ } xl_xact_commit; #define MinSizeOfXactCommit (offsetof(xl_xact_commit, xact_time) + sizeof(TimestampTz)) @@ -278,11 +279,13 @@ typedef struct xl_xact_abort TimestampTz xact_time; /* time of abort */ /* xl_xact_xinfo follows if XLOG_XACT_HAS_INFO */ - /* No db_info required */ + /* xl_xact_dbinfo follows if XINFO_HAS_DBINFO */ /* xl_xact_subxacts follows if HAS_SUBXACT */ /* xl_xact_relfilenodes follows if HAS_RELFILENODES */ /* No invalidation messages needed. */ /* xl_xact_twophase follows if XINFO_HAS_TWOPHASE */ + /* twophase_gid follows if XINFO_HAS_GID. As a null-terminated string. */ + /* xl_xact_origin follows if XINFO_HAS_ORIGIN, stored unaligned! */ } xl_xact_abort; #define MinSizeOfXactAbort sizeof(xl_xact_abort) diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h index a5c074642f..7c766836db 100644 --- a/src/include/access/xlog_internal.h +++ b/src/include/access/xlog_internal.h @@ -31,7 +31,7 @@ /* * Each page of XLOG file has a header like this: */ -#define XLOG_PAGE_MAGIC 0xD097 /* can be used as WAL version indicator */ +#define XLOG_PAGE_MAGIC 0xD098 /* can be used as WAL version indicator */ typedef struct XLogPageHeaderData { -- 2.40.0