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Refactor pg_receivexlog main loop code, for readability, take 2.
Previously the source codes for processing the received data and handling the end of stream were included in pg_receivexlog main loop. This commit splits out them as separate functions. This is useful for improving the readability of main loop code and making the future pg_receivexlog-related patch simpler.
This commit is contained in:
Fujii Masao
parent
e3da0d4d1a
commit
6805e02c66
@ -31,12 +31,23 @@ static char current_walfile_name[MAXPGPATH] = "";
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static bool reportFlushPosition = false;
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static XLogRecPtr lastFlushPosition = InvalidXLogRecPtr;
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static bool still_sending = true; /* feedback still needs to be sent? */
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static PGresult *HandleCopyStream(PGconn *conn, XLogRecPtr startpos,
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uint32 timeline, char *basedir,
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stream_stop_callback stream_stop, int standby_message_timeout,
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char *partial_suffix, XLogRecPtr *stoppos);
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static int CopyStreamPoll(PGconn *conn, long timeout_ms);
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static int CopyStreamReceive(PGconn *conn, long timeout, char **buffer);
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static bool ProcessKeepaliveMsg(PGconn *conn, char *copybuf, int len,
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XLogRecPtr blockpos, int64 *last_status);
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static bool ProcessXLogDataMsg(PGconn *conn, char *copybuf, int len,
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XLogRecPtr *blockpos, uint32 timeline,
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char *basedir, stream_stop_callback stream_stop,
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char *partial_suffix);
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static PGresult *HandleEndOfCopyStream(PGconn *conn, char *copybuf,
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XLogRecPtr blockpos, char *basedir, char *partial_suffix,
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XLogRecPtr *stoppos);
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static bool ReadEndOfStreamingResult(PGresult *res, XLogRecPtr *startpos,
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uint32 *timeline);
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@ -740,16 +751,13 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
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char *copybuf = NULL;
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int64 last_status = -1;
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XLogRecPtr blockpos = startpos;
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bool still_sending = true;
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still_sending = true;
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while (1)
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{
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int r;
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int xlogoff;
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int bytes_left;
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int bytes_written;
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int64 now;
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int hdr_len;
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long sleeptime;
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/*
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@ -818,198 +826,26 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
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goto error;
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if (r == -2)
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{
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PGresult *res = PQgetResult(conn);
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/*
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* The server closed its end of the copy stream. If we haven't
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* closed ours already, we need to do so now, unless the server
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* threw an error, in which case we don't.
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*/
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if (still_sending)
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{
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if (!close_walfile(basedir, partial_suffix, blockpos))
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{
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/* Error message written in close_walfile() */
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PQclear(res);
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goto error;
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}
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if (PQresultStatus(res) == PGRES_COPY_IN)
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{
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if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
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{
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fprintf(stderr,
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_("%s: could not send copy-end packet: %s"),
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progname, PQerrorMessage(conn));
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PQclear(res);
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goto error;
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}
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PQclear(res);
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res = PQgetResult(conn);
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}
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still_sending = false;
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}
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if (copybuf != NULL)
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PQfreemem(copybuf);
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copybuf = NULL;
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*stoppos = blockpos;
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return res;
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PGresult *res = HandleEndOfCopyStream(conn, copybuf, blockpos,
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basedir, partial_suffix, stoppos);
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if (res == NULL)
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goto error;
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else
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return res;
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}
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/* Check the message type. */
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if (copybuf[0] == 'k')
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{
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int pos;
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bool replyRequested;
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/*
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* Parse the keepalive message, enclosed in the CopyData message.
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* We just check if the server requested a reply, and ignore the
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* rest.
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*/
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pos = 1; /* skip msgtype 'k' */
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pos += 8; /* skip walEnd */
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pos += 8; /* skip sendTime */
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if (r < pos + 1)
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{
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fprintf(stderr, _("%s: streaming header too small: %d\n"),
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progname, r);
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if (!ProcessKeepaliveMsg(conn, copybuf, r, blockpos,
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&last_status))
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goto error;
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}
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replyRequested = copybuf[pos];
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/* If the server requested an immediate reply, send one. */
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if (replyRequested && still_sending)
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{
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now = feGetCurrentTimestamp();
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if (!sendFeedback(conn, blockpos, now, false))
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goto error;
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last_status = now;
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}
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}
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else if (copybuf[0] == 'w')
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{
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/*
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* Once we've decided we don't want to receive any more, just
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* ignore any subsequent XLogData messages.
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*/
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if (!still_sending)
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continue;
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/*
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* Read the header of the XLogData message, enclosed in the
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* CopyData message. We only need the WAL location field
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* (dataStart), the rest of the header is ignored.
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*/
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hdr_len = 1; /* msgtype 'w' */
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hdr_len += 8; /* dataStart */
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hdr_len += 8; /* walEnd */
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hdr_len += 8; /* sendTime */
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if (r < hdr_len)
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{
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fprintf(stderr, _("%s: streaming header too small: %d\n"),
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progname, r);
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if (!ProcessXLogDataMsg(conn, copybuf, r, &blockpos,
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timeline, basedir, stream_stop, partial_suffix))
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goto error;
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}
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blockpos = fe_recvint64(©buf[1]);
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/* Extract WAL location for this block */
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xlogoff = blockpos % XLOG_SEG_SIZE;
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/*
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* Verify that the initial location in the stream matches where we
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* think we are.
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*/
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if (walfile == -1)
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{
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/* No file open yet */
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if (xlogoff != 0)
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{
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fprintf(stderr,
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_("%s: received transaction log record for offset %u with no file open\n"),
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progname, xlogoff);
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goto error;
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}
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}
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else
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{
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/* More data in existing segment */
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/* XXX: store seek value don't reseek all the time */
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if (lseek(walfile, 0, SEEK_CUR) != xlogoff)
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{
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fprintf(stderr,
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_("%s: got WAL data offset %08x, expected %08x\n"),
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progname, xlogoff, (int) lseek(walfile, 0, SEEK_CUR));
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goto error;
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}
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}
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bytes_left = r - hdr_len;
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bytes_written = 0;
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while (bytes_left)
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{
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int bytes_to_write;
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/*
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* If crossing a WAL boundary, only write up until we reach
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* XLOG_SEG_SIZE.
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*/
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if (xlogoff + bytes_left > XLOG_SEG_SIZE)
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bytes_to_write = XLOG_SEG_SIZE - xlogoff;
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else
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bytes_to_write = bytes_left;
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if (walfile == -1)
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{
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if (!open_walfile(blockpos, timeline,
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basedir, partial_suffix))
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{
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/* Error logged by open_walfile */
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goto error;
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}
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}
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if (write(walfile,
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copybuf + hdr_len + bytes_written,
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bytes_to_write) != bytes_to_write)
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{
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fprintf(stderr,
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_("%s: could not write %u bytes to WAL file \"%s\": %s\n"),
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progname, bytes_to_write, current_walfile_name,
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strerror(errno));
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goto error;
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}
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/* Write was successful, advance our position */
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bytes_written += bytes_to_write;
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bytes_left -= bytes_to_write;
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blockpos += bytes_to_write;
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xlogoff += bytes_to_write;
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/* Did we reach the end of a WAL segment? */
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if (blockpos % XLOG_SEG_SIZE == 0)
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{
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if (!close_walfile(basedir, partial_suffix, blockpos))
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/* Error message written in close_walfile() */
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goto error;
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xlogoff = 0;
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if (still_sending && stream_stop(blockpos, timeline, true))
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{
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if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
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{
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fprintf(stderr, _("%s: could not send copy-end packet: %s"),
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progname, PQerrorMessage(conn));
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goto error;
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}
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still_sending = false;
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break; /* ignore the rest of this XLogData packet */
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}
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}
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}
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/* No more data left to write, receive next copy packet */
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}
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else
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{
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@ -1135,3 +971,225 @@ CopyStreamReceive(PGconn *conn, long timeout, char **buffer)
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*buffer = copybuf;
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return rawlen;
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}
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/*
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* Process the keepalive message.
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*/
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static bool
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ProcessKeepaliveMsg(PGconn *conn, char *copybuf, int len,
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XLogRecPtr blockpos, int64 *last_status)
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{
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int pos;
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bool replyRequested;
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int64 now;
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/*
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* Parse the keepalive message, enclosed in the CopyData message.
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* We just check if the server requested a reply, and ignore the
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* rest.
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*/
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pos = 1; /* skip msgtype 'k' */
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pos += 8; /* skip walEnd */
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pos += 8; /* skip sendTime */
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if (len < pos + 1)
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{
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fprintf(stderr, _("%s: streaming header too small: %d\n"),
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progname, len);
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return false;
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}
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replyRequested = copybuf[pos];
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/* If the server requested an immediate reply, send one. */
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if (replyRequested && still_sending)
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{
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now = feGetCurrentTimestamp();
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if (!sendFeedback(conn, blockpos, now, false))
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return false;
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*last_status = now;
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}
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return true;
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}
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/*
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* Process XLogData message.
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*/
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static bool
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ProcessXLogDataMsg(PGconn *conn, char *copybuf, int len,
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XLogRecPtr *blockpos, uint32 timeline,
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char *basedir, stream_stop_callback stream_stop,
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char *partial_suffix)
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{
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int xlogoff;
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int bytes_left;
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int bytes_written;
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int hdr_len;
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/*
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* Once we've decided we don't want to receive any more, just
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* ignore any subsequent XLogData messages.
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*/
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if (!(still_sending))
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return true;
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/*
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* Read the header of the XLogData message, enclosed in the
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* CopyData message. We only need the WAL location field
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* (dataStart), the rest of the header is ignored.
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*/
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hdr_len = 1; /* msgtype 'w' */
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hdr_len += 8; /* dataStart */
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hdr_len += 8; /* walEnd */
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hdr_len += 8; /* sendTime */
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if (len < hdr_len)
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{
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fprintf(stderr, _("%s: streaming header too small: %d\n"),
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progname, len);
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return false;
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}
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*blockpos = fe_recvint64(©buf[1]);
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/* Extract WAL location for this block */
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xlogoff = *blockpos % XLOG_SEG_SIZE;
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/*
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* Verify that the initial location in the stream matches where we
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* think we are.
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*/
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if (walfile == -1)
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{
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/* No file open yet */
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if (xlogoff != 0)
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{
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fprintf(stderr,
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_("%s: received transaction log record for offset %u with no file open\n"),
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progname, xlogoff);
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return false;
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}
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}
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else
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{
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/* More data in existing segment */
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/* XXX: store seek value don't reseek all the time */
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if (lseek(walfile, 0, SEEK_CUR) != xlogoff)
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{
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fprintf(stderr,
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_("%s: got WAL data offset %08x, expected %08x\n"),
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progname, xlogoff, (int) lseek(walfile, 0, SEEK_CUR));
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return false;
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}
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}
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bytes_left = len - hdr_len;
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bytes_written = 0;
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while (bytes_left)
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{
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int bytes_to_write;
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/*
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* If crossing a WAL boundary, only write up until we reach
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* XLOG_SEG_SIZE.
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*/
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if (xlogoff + bytes_left > XLOG_SEG_SIZE)
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bytes_to_write = XLOG_SEG_SIZE - xlogoff;
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else
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bytes_to_write = bytes_left;
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if (walfile == -1)
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{
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if (!open_walfile(*blockpos, timeline,
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basedir, partial_suffix))
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{
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/* Error logged by open_walfile */
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return false;
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}
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}
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if (write(walfile,
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copybuf + hdr_len + bytes_written,
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bytes_to_write) != bytes_to_write)
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{
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fprintf(stderr,
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_("%s: could not write %u bytes to WAL file \"%s\": %s\n"),
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progname, bytes_to_write, current_walfile_name,
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strerror(errno));
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return false;
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}
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/* Write was successful, advance our position */
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bytes_written += bytes_to_write;
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bytes_left -= bytes_to_write;
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*blockpos += bytes_to_write;
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xlogoff += bytes_to_write;
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/* Did we reach the end of a WAL segment? */
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if (*blockpos % XLOG_SEG_SIZE == 0)
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{
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if (!close_walfile(basedir, partial_suffix, *blockpos))
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/* Error message written in close_walfile() */
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return false;
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xlogoff = 0;
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if (still_sending && stream_stop(*blockpos, timeline, true))
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{
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if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
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{
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fprintf(stderr, _("%s: could not send copy-end packet: %s"),
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progname, PQerrorMessage(conn));
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return false;
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}
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still_sending = false;
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return true; /* ignore the rest of this XLogData packet */
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}
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}
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}
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/* No more data left to write, receive next copy packet */
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return true;
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}
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/*
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* Handle end of the copy stream.
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*/
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static PGresult *
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HandleEndOfCopyStream(PGconn *conn, char *copybuf,
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XLogRecPtr blockpos, char *basedir, char *partial_suffix,
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XLogRecPtr *stoppos)
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{
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PGresult *res = PQgetResult(conn);
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/*
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* The server closed its end of the copy stream. If we haven't
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* closed ours already, we need to do so now, unless the server
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* threw an error, in which case we don't.
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*/
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if (still_sending)
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{
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if (!close_walfile(basedir, partial_suffix, blockpos))
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{
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/* Error message written in close_walfile() */
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PQclear(res);
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return NULL;
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}
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if (PQresultStatus(res) == PGRES_COPY_IN)
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{
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if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
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{
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fprintf(stderr,
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_("%s: could not send copy-end packet: %s"),
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progname, PQerrorMessage(conn));
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PQclear(res);
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return NULL;
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}
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res = PQgetResult(conn);
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}
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still_sending = false;
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}
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if (copybuf != NULL)
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PQfreemem(copybuf);
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*stoppos = blockpos;
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return res;
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}
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