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Commita31ff70

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Make ascii-art in comments pgindent-safe, and some other formatting changes.
Kevin Grittner
1 parentfc1286d commita31ff70

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1 file changed

+17
-13
lines changed

1 file changed

+17
-13
lines changed

‎src/backend/storage/lmgr/predicate.c

Lines changed: 17 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -3814,7 +3814,7 @@ FlagRWConflict(SERIALIZABLEXACT *reader, SERIALIZABLEXACT *writer)
38143814
SetRWConflict(reader,writer);
38153815
}
38163816

3817-
/*
3817+
/*----------------------------------------------------------------------------
38183818
* We are about to add a RW-edge to the dependency graph - check that we don't
38193819
* introduce a dangerous structure by doing so, and abort one of the
38203820
* transactions if so.
@@ -3823,13 +3823,14 @@ FlagRWConflict(SERIALIZABLEXACT *reader, SERIALIZABLEXACT *writer)
38233823
* in the dependency graph:
38243824
*
38253825
*Tin ------> Tpivot ------> Tout
3826-
* rw rw
3826+
* rw rw
38273827
*
38283828
* Furthermore, Tout must commit first.
38293829
*
38303830
* One more optimization is that if Tin is declared READ ONLY (or commits
38313831
* without writing), we can only have a problem if Tout committed before Tin
38323832
* acquired its snapshot.
3833+
*----------------------------------------------------------------------------
38333834
*/
38343835
staticvoid
38353836
OnConflict_CheckForSerializationFailure(constSERIALIZABLEXACT*reader,
@@ -3842,32 +3843,34 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader,
38423843

38433844
failure= false;
38443845

3845-
/*
3846+
/*------------------------------------------------------------------------
38463847
* Check for already-committed writer with rw-conflict out flagged
38473848
* (conflict-flag on W means that T2 committed before W):
38483849
*
38493850
*R ------> W ------> T2
3850-
*rw rw
3851+
*rw rw
38513852
*
38523853
* That is a dangerous structure, so we must abort. (Since the writer
38533854
* has already committed, we must be the reader)
3855+
*------------------------------------------------------------------------
38543856
*/
38553857
if (SxactIsCommitted(writer)
38563858
&& (SxactHasConflictOut(writer)||SxactHasSummaryConflictOut(writer)))
38573859
failure= true;
38583860

3859-
/*
3861+
/*------------------------------------------------------------------------
38603862
* Check whether the writer has become a pivot with an out-conflict
38613863
* committed transaction (T2), and T2 committed first:
38623864
*
38633865
*R ------> W ------> T2
3864-
*rw rw
3866+
*rw rw
38653867
*
38663868
* Because T2 must've committed first, there is no anomaly if:
38673869
* - the reader committed before T2
38683870
* - the writer committed before T2
38693871
* - the reader is a READ ONLY transaction and the reader was concurrent
38703872
* with T2 (= reader acquired its snapshot before T2 committed)
3873+
*------------------------------------------------------------------------
38713874
*/
38723875
if (!failure)
38733876
{
@@ -3891,7 +3894,7 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader,
38913894
&& (!SxactIsCommitted(writer)
38923895
||t2->commitSeqNo <=writer->commitSeqNo)
38933896
&& (!SxactIsReadOnly(reader)
3894-
||t2->commitSeqNo <=reader->SeqNo.lastCommitBeforeSnapshot))
3897+
||t2->commitSeqNo <=reader->SeqNo.lastCommitBeforeSnapshot))
38953898
{
38963899
failure= true;
38973900
break;
@@ -3903,16 +3906,17 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader,
39033906
}
39043907
}
39053908

3906-
/*
3909+
/*------------------------------------------------------------------------
39073910
* Check whether the reader has become a pivot with a committed writer:
39083911
*
39093912
*T0 ------> R ------> W
3910-
* rw rw
3913+
* rw rw
39113914
*
39123915
* Because W must've committed first for an anomaly to occur, there is no
39133916
* anomaly if:
39143917
* - T0 committed before the writer
39153918
* - T0 is READ ONLY, and overlaps the writer
3919+
*------------------------------------------------------------------------
39163920
*/
39173921
if (!failure&&SxactIsCommitted(writer)&& !SxactIsReadOnly(reader))
39183922
{
@@ -3934,7 +3938,7 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader,
39343938
&& (!SxactIsCommitted(t0)
39353939
||t0->commitSeqNo >=writer->commitSeqNo)
39363940
&& (!SxactIsReadOnly(t0)
3937-
||t0->SeqNo.lastCommitBeforeSnapshot >=writer->commitSeqNo))
3941+
||t0->SeqNo.lastCommitBeforeSnapshot >=writer->commitSeqNo))
39383942
{
39393943
failure= true;
39403944
break;
@@ -3950,8 +3954,8 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader,
39503954
{
39513955
/*
39523956
* We have to kill a transaction to avoid a possible anomaly from
3953-
* occurring. If the writer is us, we can just ereport() to cause
3954-
*atransaction abort. Otherwise we flag the writer for termination,
3957+
* occurring. If the writer is us, we can just ereport() to cause a
3958+
* transaction abort. Otherwise we flag the writer for termination,
39553959
* causing it to abort when it tries to commit. However, if the writer
39563960
* is a prepared transaction, already prepared, we can't abort it
39573961
* anymore, so we have to kill the reader instead.
@@ -3962,7 +3966,7 @@ OnConflict_CheckForSerializationFailure(const SERIALIZABLEXACT *reader,
39623966
ereport(ERROR,
39633967
(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
39643968
errmsg("could not serialize access due to read/write dependencies among transactions"),
3965-
errdetail("Cancelled on identification as a pivot, during write."),
3969+
errdetail("Cancelled on identification as a pivot, during write."),
39663970
errhint("The transaction might succeed if retried.")));
39673971
}
39683972
elseif (SxactIsPrepared(writer))

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