From 323cbe7c7ddcf18aaf24b7f6d682a45a61d4e31b Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Thu, 8 Apr 2021 23:03:23 +1200 Subject: Remove read_page callback from XLogReader. Previously, the XLogReader module would fetch new input data using a callback function. Redesign the interface so that it tells the caller to insert more data with a special return value instead. This API suits later patches for prefetching, encryption and maybe other future projects that would otherwise require continually extending the callback interface. As incidental cleanup work, move global variables readOff, readLen and readSegNo inside XlogReaderState. Author: Kyotaro HORIGUCHI Author: Heikki Linnakangas (parts of earlier version) Reviewed-by: Antonin Houska Reviewed-by: Alvaro Herrera Reviewed-by: Takashi Menjo Reviewed-by: Andres Freund Reviewed-by: Thomas Munro Discussion: https://postgr.es/m/20190418.210257.43726183.horiguchi.kyotaro%40lab.ntt.co.jp --- src/backend/access/transam/xlogutils.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) (limited to 'src/backend/access/transam/xlogutils.c') diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c index d17d660f460..e5de26dce54 100644 --- a/src/backend/access/transam/xlogutils.c +++ b/src/backend/access/transam/xlogutils.c @@ -686,8 +686,7 @@ XLogTruncateRelation(RelFileNode rnode, ForkNumber forkNum, void XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wantLength) { - const XLogRecPtr lastReadPage = (state->seg.ws_segno * - state->segcxt.ws_segsize + state->segoff); + const XLogRecPtr lastReadPage = state->readPagePtr; Assert(wantPage != InvalidXLogRecPtr && wantPage % XLOG_BLCKSZ == 0); Assert(wantLength <= XLOG_BLCKSZ); @@ -702,7 +701,7 @@ XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wa * current TLI has since become historical. */ if (lastReadPage == wantPage && - state->readLen != 0 && + state->page_verified && lastReadPage + state->readLen >= wantPage + Min(wantLength, XLOG_BLCKSZ - 1)) return; @@ -824,10 +823,12 @@ wal_segment_close(XLogReaderState *state) * exists for normal backends, so we have to do a check/sleep/repeat style of * loop for now. */ -int -read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, - int reqLen, XLogRecPtr targetRecPtr, char *cur_page) +bool +read_local_xlog_page(XLogReaderState *state) { + XLogRecPtr targetPagePtr = state->readPagePtr; + int reqLen = state->reqLen; + char *cur_page = state->readBuf; XLogRecPtr read_upto, loc; TimeLineID tli; @@ -926,7 +927,8 @@ read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, else if (targetPagePtr + reqLen > read_upto) { /* not enough data there */ - return -1; + XLogReaderSetInputData(state, -1); + return false; } else { @@ -939,12 +941,14 @@ 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(state, cur_page, targetPagePtr, XLOG_BLCKSZ, tli, - &errinfo)) + if (!WALRead(state, wal_segment_open, wal_segment_close, + cur_page, targetPagePtr, XLOG_BLCKSZ, tli, &errinfo)) WALReadRaiseError(&errinfo); /* number of valid bytes in the buffer */ - return count; + state->readPagePtr = targetPagePtr; + XLogReaderSetInputData(state, count); + return true; } /* -- cgit v1.2.3