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| author | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2020-05-08 15:30:34 -0400 |
|---|---|---|
| committer | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2020-05-08 15:40:11 -0400 |
| commit | b060dbe0001a1d6bf26cd294710f3cb203868d46 (patch) | |
| tree | 6e9e980aa63ec1ec3655b93c92b9b5caa6689d38 /src/backend/access/transam/xlogutils.c | |
| parent | 871696ba20e0251e86041576373809d1c7ca161d (diff) | |
| download | postgresql-b060dbe0001a1d6bf26cd294710f3cb203868d46.tar.gz postgresql-b060dbe0001a1d6bf26cd294710f3cb203868d46.zip | |
Rework XLogReader callback system
Code review for 0dc8ead46363, prompted by a bug closed by 91c40548d5f7.
XLogReader's system for opening and closing segments had gotten too
complicated, with callbacks being passed at both the XLogReaderAllocate
level (read_page) as well as at the WALRead level (segment_open). This
was confusing and hard to follow, so restructure things so that these
callbacks are passed together at XLogReaderAllocate time, and add
another callback to the set (segment_close) to make it a coherent whole.
Also, ensure XLogReaderState is an argument to all the callbacks, so
that they can grab at the ->private data if necessary.
Document the whole arrangement more clearly.
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20200422175754.GA19858@alvherre.pgsql
Diffstat (limited to 'src/backend/access/transam/xlogutils.c')
| -rw-r--r-- | src/backend/access/transam/xlogutils.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c index 6cb143e161d..bbd801513a8 100644 --- a/src/backend/access/transam/xlogutils.c +++ b/src/backend/access/transam/xlogutils.c @@ -783,10 +783,10 @@ XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wa } } -/* openSegment callback for WALRead */ -static int -wal_segment_open(XLogSegNo nextSegNo, WALSegmentContext * segcxt, - TimeLineID *tli_p) +/* XLogReaderRoutine->segment_open callback for local pg_wal files */ +int +wal_segment_open(XLogReaderState *state, XLogSegNo nextSegNo, + WALSegmentContext *segcxt, TimeLineID *tli_p) { TimeLineID tli = *tli_p; char path[MAXPGPATH]; @@ -811,8 +811,17 @@ wal_segment_open(XLogSegNo nextSegNo, WALSegmentContext * segcxt, return -1; /* keep compiler quiet */ } +/* stock XLogReaderRoutine->segment_close callback */ +void +wal_segment_close(XLogReaderState *state) +{ + close(state->seg.ws_file); + /* need to check errno? */ + state->seg.ws_file = -1; +} + /* - * read_page callback for reading local xlog files + * XLogReaderRoutine->page_read callback for reading local xlog files * * Public because it would likely be very helpful for someone writing another * output method outside walsender, e.g. in a bgworker. @@ -937,8 +946,9 @@ read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, * as 'count', read the whole page anyway. It's guaranteed to be * zero-padded up to the page boundary if it's incomplete. */ - if (!WALRead(cur_page, targetPagePtr, XLOG_BLCKSZ, tli, &state->seg, - &state->segcxt, wal_segment_open, &errinfo)) + if (!WALRead(state, cur_page, targetPagePtr, XLOG_BLCKSZ, tli, + &state->seg, &state->segcxt, + &errinfo)) WALReadRaiseError(&errinfo); /* number of valid bytes in the buffer */ |