greenplumn receivelog 源码
greenplumn receivelog 代码
文件路径：/src/bin/pg_basebackup/receivelog.c
/*-------------------------------------------------------------------------
*
* receivelog.c - receive WAL files using the streaming
* replication protocol.
*
* Author: Magnus Hagander <magnus@hagander.net>
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/bin/pg_basebackup/receivelog.c
*-------------------------------------------------------------------------
*/
#include "postgres_fe.h"
#include <sys/stat.h>
#include <unistd.h>
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
/* local includes */
#include "receivelog.h"
#include "streamutil.h"
#include "libpq-fe.h"
#include "access/xlog_internal.h"
#include "common/file_utils.h"
#include "common/logging.h"
/* fd and filename for currently open WAL file */
static Walfile *walfile = NULL;
static char current_walfile_name[MAXPGPATH] = "";
static bool reportFlushPosition = false;
static XLogRecPtr lastFlushPosition = InvalidXLogRecPtr;
static bool still_sending = true; /* feedback still needs to be sent? */
static PGresult *HandleCopyStream(PGconn *conn, StreamCtl *stream,
XLogRecPtr *stoppos);
static int CopyStreamPoll(PGconn *conn, long timeout_ms, pgsocket stop_socket);
static int CopyStreamReceive(PGconn *conn, long timeout, pgsocket stop_socket,
char **buffer);
static bool ProcessKeepaliveMsg(PGconn *conn, StreamCtl *stream, char *copybuf,
int len, XLogRecPtr blockpos, TimestampTz *last_status);
static bool ProcessXLogDataMsg(PGconn *conn, StreamCtl *stream, char *copybuf, int len,
XLogRecPtr *blockpos);
static PGresult *HandleEndOfCopyStream(PGconn *conn, StreamCtl *stream, char *copybuf,
XLogRecPtr blockpos, XLogRecPtr *stoppos);
static bool CheckCopyStreamStop(PGconn *conn, StreamCtl *stream, XLogRecPtr blockpos,
XLogRecPtr *stoppos);
static long CalculateCopyStreamSleeptime(TimestampTz now, int standby_message_timeout,
TimestampTz last_status);
static bool ReadEndOfStreamingResult(PGresult *res, XLogRecPtr *startpos,
uint32 *timeline);
static bool
mark_file_as_archived(StreamCtl *stream, const char *fname)
{
Walfile *f;
static char tmppath[MAXPGPATH];
snprintf(tmppath, sizeof(tmppath), "archive_status/%s.done",
fname);
f = stream->walmethod->open_for_write(tmppath, NULL, 0);
if (f == NULL)
{
pg_log_error("could not create archive status file \"%s\": %s",
tmppath, stream->walmethod->getlasterror());
return false;
}
stream->walmethod->close(f, CLOSE_NORMAL);
return true;
}
/*
* Open a new WAL file in the specified directory.
*
* Returns true if OK; on failure, returns false after printing an error msg.
* On success, 'walfile' is set to the FD for the file, and the base filename
* (without partial_suffix) is stored in 'current_walfile_name'.
*
* The file will be padded to 16Mb with zeroes.
*/
static bool
open_walfile(StreamCtl *stream, XLogRecPtr startpoint)
{
Walfile *f;
char fn[MAXPGPATH];
ssize_t size;
XLogSegNo segno;
XLByteToSeg(startpoint, segno, WalSegSz);
XLogFileName(current_walfile_name, stream->timeline, segno, WalSegSz);
snprintf(fn, sizeof(fn), "%s%s", current_walfile_name,
stream->partial_suffix ? stream->partial_suffix : "");
/*
* When streaming to files, if an existing file exists we verify that it's
* either empty (just created), or a complete WalSegSz segment (in which
* case it has been created and padded). Anything else indicates a corrupt
* file.
*
* When streaming to tar, no file with this name will exist before, so we
* never have to verify a size.
*/
if (stream->walmethod->existsfile(fn))
{
size = stream->walmethod->get_file_size(fn);
if (size < 0)
{
pg_log_error("could not get size of write-ahead log file \"%s\": %s",
fn, stream->walmethod->getlasterror());
return false;
}
if (size == WalSegSz)
{
/* Already padded file. Open it for use */
f = stream->walmethod->open_for_write(current_walfile_name, stream->partial_suffix, 0);
if (f == NULL)
{
pg_log_error("could not open existing write-ahead log file \"%s\": %s",
fn, stream->walmethod->getlasterror());
return false;
}
/* fsync file in case of a previous crash */
if (stream->walmethod->sync(f) != 0)
{
pg_log_error("could not fsync existing write-ahead log file \"%s\": %s",
fn, stream->walmethod->getlasterror());
stream->walmethod->close(f, CLOSE_UNLINK);
return false;
}
walfile = f;
return true;
}
if (size != 0)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
pg_log_error(ngettext("write-ahead log file \"%s\" has %d byte, should be 0 or %d",
"write-ahead log file \"%s\" has %d bytes, should be 0 or %d",
size),
fn, (int) size, WalSegSz);
return false;
}
/* File existed and was empty, so fall through and open */
}
/* No file existed, so create one */
f = stream->walmethod->open_for_write(current_walfile_name,
stream->partial_suffix, WalSegSz);
if (f == NULL)
{
pg_log_error("could not open write-ahead log file \"%s\": %s",
fn, stream->walmethod->getlasterror());
return false;
}
walfile = f;
return true;
}
/*
* Close the current WAL file (if open), and rename it to the correct
* filename if it's complete. On failure, prints an error message to stderr
* and returns false, otherwise returns true.
*/
static bool
close_walfile(StreamCtl *stream, XLogRecPtr pos)
{
off_t currpos;
int r;
if (walfile == NULL)
return true;
currpos = stream->walmethod->get_current_pos(walfile);
if (currpos == -1)
{
pg_log_error("could not determine seek position in file \"%s\": %s",
current_walfile_name, stream->walmethod->getlasterror());
stream->walmethod->close(walfile, CLOSE_UNLINK);
walfile = NULL;
return false;
}
if (stream->partial_suffix)
{
if (currpos == WalSegSz)
r = stream->walmethod->close(walfile, CLOSE_NORMAL);
else
{
pg_log_info("not renaming \"%s%s\", segment is not complete",
current_walfile_name, stream->partial_suffix);
r = stream->walmethod->close(walfile, CLOSE_NO_RENAME);
}
}
else
r = stream->walmethod->close(walfile, CLOSE_NORMAL);
walfile = NULL;
if (r != 0)
{
pg_log_error("could not close file \"%s\": %s",
current_walfile_name, stream->walmethod->getlasterror());
return false;
}
/*
* Mark file as archived if requested by the caller - pg_basebackup needs
* to do so as files can otherwise get archived again after promotion of a
* new node. This is in line with walreceiver.c always doing a
* XLogArchiveForceDone() after a complete segment.
*/
if (currpos == WalSegSz && stream->mark_done)
{
/* writes error message if failed */
if (!mark_file_as_archived(stream, current_walfile_name))
return false;
}
lastFlushPosition = pos;
return true;
}
/*
* Check if a timeline history file exists.
*/
static bool
existsTimeLineHistoryFile(StreamCtl *stream)
{
char histfname[MAXFNAMELEN];
/*
* Timeline 1 never has a history file. We treat that as if it existed,
* since we never need to stream it.
*/
if (stream->timeline == 1)
return true;
TLHistoryFileName(histfname, stream->timeline);
return stream->walmethod->existsfile(histfname);
}
static bool
writeTimeLineHistoryFile(StreamCtl *stream, char *filename, char *content)
{
int size = strlen(content);
char histfname[MAXFNAMELEN];
Walfile *f;
/*
* Check that the server's idea of how timeline history files should be
* named matches ours.
*/
TLHistoryFileName(histfname, stream->timeline);
if (strcmp(histfname, filename) != 0)
{
pg_log_error("server reported unexpected history file name for timeline %u: %s",
stream->timeline, filename);
return false;
}
f = stream->walmethod->open_for_write(histfname, ".tmp", 0);
if (f == NULL)
{
pg_log_error("could not create timeline history file \"%s\": %s",
histfname, stream->walmethod->getlasterror());
return false;
}
if ((int) stream->walmethod->write(f, content, size) != size)
{
pg_log_error("could not write timeline history file \"%s\": %s",
histfname, stream->walmethod->getlasterror());
/*
* If we fail to make the file, delete it to release disk space
*/
stream->walmethod->close(f, CLOSE_UNLINK);
return false;
}
if (stream->walmethod->close(f, CLOSE_NORMAL) != 0)
{
pg_log_error("could not close file \"%s\": %s",
histfname, stream->walmethod->getlasterror());
return false;
}
/* Maintain archive_status, check close_walfile() for details. */
if (stream->mark_done)
{
/* writes error message if failed */
if (!mark_file_as_archived(stream, histfname))
return false;
}
return true;
}
/*
* Send a Standby Status Update message to server.
*/
static bool
sendFeedback(PGconn *conn, XLogRecPtr blockpos, TimestampTz now, bool replyRequested)
{
char replybuf[1 + 8 + 8 + 8 + 8 + 1];
int len = 0;
replybuf[len] = 'r';
len += 1;
fe_sendint64(blockpos, &replybuf[len]); /* write */
len += 8;
if (reportFlushPosition)
fe_sendint64(lastFlushPosition, &replybuf[len]); /* flush */
else
fe_sendint64(InvalidXLogRecPtr, &replybuf[len]); /* flush */
len += 8;
fe_sendint64(InvalidXLogRecPtr, &replybuf[len]); /* apply */
len += 8;
fe_sendint64(now, &replybuf[len]); /* sendTime */
len += 8;
replybuf[len] = replyRequested ? 1 : 0; /* replyRequested */
len += 1;
if (PQputCopyData(conn, replybuf, len) <= 0 || PQflush(conn))
{
pg_log_error("could not send feedback packet: %s",
PQerrorMessage(conn));
return false;
}
return true;
}
/*
* Check that the server version we're connected to is supported by
* ReceiveXlogStream().
*
* If it's not, an error message is printed to stderr, and false is returned.
*/
bool
CheckServerVersionForStreaming(PGconn *conn)
{
int minServerMajor,
maxServerMajor;
int serverMajor;
/*
* The message format used in streaming replication changed in 9.3, so we
* cannot stream from older servers. And we don't support servers newer
* than the client; it might work, but we don't know, so err on the safe
* side.
*/
minServerMajor = 903;
maxServerMajor = PG_VERSION_NUM / 100;
serverMajor = PQserverVersion(conn) / 100;
if (serverMajor < minServerMajor)
{
const char *serverver = PQparameterStatus(conn, "server_version");
pg_log_error("incompatible server version %s; client does not support streaming from server versions older than %s",
serverver ? serverver : "'unknown'",
"9.3");
return false;
}
else if (serverMajor > maxServerMajor)
{
const char *serverver = PQparameterStatus(conn, "server_version");
pg_log_error("incompatible server version %s; client does not support streaming from server versions newer than %s",
serverver ? serverver : "'unknown'",
PG_VERSION);
return false;
}
return true;
}
/*
* Receive a log stream starting at the specified position.
*
* Individual parameters are passed through the StreamCtl structure.
*
* If sysidentifier is specified, validate that both the system
* identifier and the timeline matches the specified ones
* (by sending an extra IDENTIFY_SYSTEM command)
*
* All received segments will be written to the directory
* specified by basedir. This will also fetch any missing timeline history
* files.
*
* The stream_stop callback will be called every time data
* is received, and whenever a segment is completed. If it returns
* true, the streaming will stop and the function
* return. As long as it returns false, streaming will continue
* indefinitely.
*
* If stream_stop() checks for external input, stop_socket should be set to
* the FD it checks. This will allow such input to be detected promptly
* rather than after standby_message_timeout (which might be indefinite).
* Note that signals will interrupt waits for input as well, but that is
* race-y since a signal received while busy won't interrupt the wait.
*
* standby_message_timeout controls how often we send a message
* back to the master letting it know our progress, in milliseconds.
* Zero means no messages are sent.
* This message will only contain the write location, and never
* flush or replay.
*
* If 'partial_suffix' is not NULL, files are initially created with the
* given suffix, and the suffix is removed once the file is finished. That
* allows you to tell the difference between partial and completed files,
* so that you can continue later where you left.
*
* If 'synchronous' is true, the received WAL is flushed as soon as written,
* otherwise only when the WAL file is closed.
*
* Note: The WAL location *must* be at a log segment start!
*/
bool
ReceiveXlogStream(PGconn *conn, StreamCtl *stream)
{
char query[128];
char slotcmd[128];
PGresult *res;
XLogRecPtr stoppos;
/*
* The caller should've checked the server version already, but doesn't do
* any harm to check it here too.
*/
if (!CheckServerVersionForStreaming(conn))
return false;
/*
* Decide whether we want to report the flush position. If we report the
* flush position, the primary will know what WAL we'll possibly
* re-request, and it can then remove older WAL safely. We must always do
* that when we are using slots.
*
* Reporting the flush position makes one eligible as a synchronous
* replica. People shouldn't include generic names in
* synchronous_standby_names, but we've protected them against it so far,
* so let's continue to do so unless specifically requested.
*/
if (stream->replication_slot != NULL)
{
reportFlushPosition = true;
sprintf(slotcmd, "SLOT \"%s\" ", stream->replication_slot);
}
else
{
if (stream->synchronous)
reportFlushPosition = true;
else
reportFlushPosition = false;
slotcmd[0] = 0;
}
if (stream->sysidentifier != NULL)
{
/* Validate system identifier hasn't changed */
res = PQexec(conn, "IDENTIFY_SYSTEM");
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
pg_log_error("could not send replication command \"%s\": %s",
"IDENTIFY_SYSTEM", PQerrorMessage(conn));
PQclear(res);
return false;
}
if (PQntuples(res) != 1 || PQnfields(res) < 3)
{
pg_log_error("could not identify system: got %d rows and %d fields, expected %d rows and %d or more fields",
PQntuples(res), PQnfields(res), 1, 3);
PQclear(res);
return false;
}
if (strcmp(stream->sysidentifier, PQgetvalue(res, 0, 0)) != 0)
{
pg_log_error("system identifier does not match between base backup and streaming connection");
PQclear(res);
return false;
}
if (stream->timeline > atoi(PQgetvalue(res, 0, 1)))
{
pg_log_error("starting timeline %u is not present in the server",
stream->timeline);
PQclear(res);
return false;
}
PQclear(res);
}
/*
* initialize flush position to starting point, it's the caller's
* responsibility that that's sane.
*/
lastFlushPosition = stream->startpos;
while (1)
{
/*
* Fetch the timeline history file for this timeline, if we don't have
* it already. When streaming log to tar, this will always return
* false, as we are never streaming into an existing file and
* therefore there can be no pre-existing timeline history file.
*/
if (!existsTimeLineHistoryFile(stream))
{
snprintf(query, sizeof(query), "TIMELINE_HISTORY %u", stream->timeline);
res = PQexec(conn, query);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
/* FIXME: we might send it ok, but get an error */
pg_log_error("could not send replication command \"%s\": %s",
"TIMELINE_HISTORY", PQresultErrorMessage(res));
PQclear(res);
return false;
}
/*
* The response to TIMELINE_HISTORY is a single row result set
* with two fields: filename and content
*/
if (PQnfields(res) != 2 || PQntuples(res) != 1)
{
pg_log_warning("unexpected response to TIMELINE_HISTORY command: got %d rows and %d fields, expected %d rows and %d fields",
PQntuples(res), PQnfields(res), 1, 2);
}
/* Write the history file to disk */
writeTimeLineHistoryFile(stream,
PQgetvalue(res, 0, 0),
PQgetvalue(res, 0, 1));
PQclear(res);
}
/*
* Before we start streaming from the requested location, check if the
* callback tells us to stop here.
*/
if (stream->stream_stop(stream->startpos, stream->timeline, false))
return true;
/* Initiate the replication stream at specified location */
snprintf(query, sizeof(query), "START_REPLICATION %s%X/%X TIMELINE %u",
slotcmd,
(uint32) (stream->startpos >> 32), (uint32) stream->startpos,
stream->timeline);
res = PQexec(conn, query);
if (PQresultStatus(res) != PGRES_COPY_BOTH)
{
pg_log_error("could not send replication command \"%s\": %s",
"START_REPLICATION", PQresultErrorMessage(res));
PQclear(res);
return false;
}
PQclear(res);
/* Stream the WAL */
res = HandleCopyStream(conn, stream, &stoppos);
if (res == NULL)
goto error;
/*
* Streaming finished.
*
* There are two possible reasons for that: a controlled shutdown, or
* we reached the end of the current timeline. In case of
* end-of-timeline, the server sends a result set after Copy has
* finished, containing information about the next timeline. Read
* that, and restart streaming from the next timeline. In case of
* controlled shutdown, stop here.
*/
if (PQresultStatus(res) == PGRES_TUPLES_OK)
{
/*
* End-of-timeline. Read the next timeline's ID and starting
* position. Usually, the starting position will match the end of
* the previous timeline, but there are corner cases like if the
* server had sent us half of a WAL record, when it was promoted.
* The new timeline will begin at the end of the last complete
* record in that case, overlapping the partial WAL record on the
* old timeline.
*/
uint32 newtimeline;
bool parsed;
parsed = ReadEndOfStreamingResult(res, &stream->startpos, &newtimeline);
PQclear(res);
if (!parsed)
goto error;
/* Sanity check the values the server gave us */
if (newtimeline <= stream->timeline)
{
pg_log_error("server reported unexpected next timeline %u, following timeline %u",
newtimeline, stream->timeline);
goto error;
}
if (stream->startpos > stoppos)
{
pg_log_error("server stopped streaming timeline %u at %X/%X, but reported next timeline %u to begin at %X/%X",
stream->timeline, (uint32) (stoppos >> 32), (uint32) stoppos,
newtimeline, (uint32) (stream->startpos >> 32), (uint32) stream->startpos);
goto error;
}
/* Read the final result, which should be CommandComplete. */
res = PQgetResult(conn);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
pg_log_error("unexpected termination of replication stream: %s",
PQresultErrorMessage(res));
PQclear(res);
goto error;
}
PQclear(res);
/*
* Loop back to start streaming from the new timeline. Always
* start streaming at the beginning of a segment.
*/
stream->timeline = newtimeline;
stream->startpos = stream->startpos -
XLogSegmentOffset(stream->startpos, WalSegSz);
continue;
}
else if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
/*
* End of replication (ie. controlled shut down of the server).
*
* Check if the callback thinks it's OK to stop here. If not,
* complain.
*/
if (stream->stream_stop(stoppos, stream->timeline, false))
return true;
else
{
pg_log_error("replication stream was terminated before stop point");
goto error;
}
}
else
{
/* Server returned an error. */
pg_log_error("unexpected termination of replication stream: %s",
PQresultErrorMessage(res));
PQclear(res);
goto error;
}
}
error:
if (walfile != NULL && stream->walmethod->close(walfile, CLOSE_NO_RENAME) != 0)
pg_log_error("could not close file \"%s\": %s",
current_walfile_name, stream->walmethod->getlasterror());
walfile = NULL;
return false;
}
/*
* Helper function to parse the result set returned by server after streaming
* has finished. On failure, prints an error to stderr and returns false.
*/
static bool
ReadEndOfStreamingResult(PGresult *res, XLogRecPtr *startpos, uint32 *timeline)
{
uint32 startpos_xlogid,
startpos_xrecoff;
/*----------
* The result set consists of one row and two columns, e.g:
*
* next_tli | next_tli_startpos
* ----------+-------------------
* 4 | 0/9949AE0
*
* next_tli is the timeline ID of the next timeline after the one that
* just finished streaming. next_tli_startpos is the WAL location where
* the server switched to it.
*----------
*/
if (PQnfields(res) < 2 || PQntuples(res) != 1)
{
pg_log_error("unexpected result set after end-of-timeline: got %d rows and %d fields, expected %d rows and %d fields",
PQntuples(res), PQnfields(res), 1, 2);
return false;
}
*timeline = atoi(PQgetvalue(res, 0, 0));
if (sscanf(PQgetvalue(res, 0, 1), "%X/%X", &startpos_xlogid,
&startpos_xrecoff) != 2)
{
pg_log_error("could not parse next timeline's starting point \"%s\"",
PQgetvalue(res, 0, 1));
return false;
}
*startpos = ((uint64) startpos_xlogid << 32) | startpos_xrecoff;
return true;
}
/*
* The main loop of ReceiveXlogStream. Handles the COPY stream after
* initiating streaming with the START_REPLICATION command.
*
* If the COPY ends (not necessarily successfully) due a message from the
* server, returns a PGresult and sets *stoppos to the last byte written.
* On any other sort of error, returns NULL.
*/
static PGresult *
HandleCopyStream(PGconn *conn, StreamCtl *stream,
XLogRecPtr *stoppos)
{
char *copybuf = NULL;
TimestampTz last_status = -1;
XLogRecPtr blockpos = stream->startpos;
still_sending = true;
while (1)
{
int r;
TimestampTz now;
long sleeptime;
/*
* Check if we should continue streaming, or abort at this point.
*/
if (!CheckCopyStreamStop(conn, stream, blockpos, stoppos))
goto error;
now = feGetCurrentTimestamp();
/*
* If synchronous option is true, issue sync command as soon as there
* are WAL data which has not been flushed yet.
*/
if (stream->synchronous && lastFlushPosition < blockpos && walfile != NULL)
{
if (stream->walmethod->sync(walfile) != 0)
{
pg_log_error("could not fsync file \"%s\": %s",
current_walfile_name, stream->walmethod->getlasterror());
goto error;
}
lastFlushPosition = blockpos;
/*
* Send feedback so that the server sees the latest WAL locations
* immediately.
*/
if (!sendFeedback(conn, blockpos, now, false))
goto error;
last_status = now;
}
/*
* Potentially send a status message to the master
*/
if (still_sending && stream->standby_message_timeout > 0 &&
feTimestampDifferenceExceeds(last_status, now,
stream->standby_message_timeout))
{
/* Time to send feedback! */
if (!sendFeedback(conn, blockpos, now, false))
goto error;
last_status = now;
}
/*
* Calculate how long send/receive loops should sleep
*/
sleeptime = CalculateCopyStreamSleeptime(now, stream->standby_message_timeout,
last_status);
r = CopyStreamReceive(conn, sleeptime, stream->stop_socket, ©buf);
while (r != 0)
{
if (r == -1)
goto error;
if (r == -2)
{
PGresult *res = HandleEndOfCopyStream(conn, stream, copybuf, blockpos, stoppos);
if (res == NULL)
goto error;
else
return res;
}
/* Check the message type. */
if (copybuf[0] == 'k')
{
if (!ProcessKeepaliveMsg(conn, stream, copybuf, r, blockpos,
&last_status))
goto error;
}
else if (copybuf[0] == 'w')
{
if (!ProcessXLogDataMsg(conn, stream, copybuf, r, &blockpos))
goto error;
/*
* Check if we should continue streaming, or abort at this
* point.
*/
if (!CheckCopyStreamStop(conn, stream, blockpos, stoppos))
goto error;
}
else
{
pg_log_error("unrecognized streaming header: \"%c\"",
copybuf[0]);
goto error;
}
/*
* Process the received data, and any subsequent data we can read
* without blocking.
*/
r = CopyStreamReceive(conn, 0, stream->stop_socket, ©buf);
}
}
error:
if (copybuf != NULL)
PQfreemem(copybuf);
return NULL;
}
/*
* Wait until we can read a CopyData message,
* or timeout, or occurrence of a signal or input on the stop_socket.
* (timeout_ms < 0 means wait indefinitely; 0 means don't wait.)
*
* Returns 1 if data has become available for reading, 0 if timed out
* or interrupted by signal or stop_socket input, and -1 on an error.
*/
static int
CopyStreamPoll(PGconn *conn, long timeout_ms, pgsocket stop_socket)
{
int ret;
fd_set input_mask;
int connsocket;
int maxfd;
struct timeval timeout;
struct timeval *timeoutptr;
connsocket = PQsocket(conn);
if (connsocket < 0)
{
pg_log_error("invalid socket: %s", PQerrorMessage(conn));
return -1;
}
FD_ZERO(&input_mask);
FD_SET(connsocket, &input_mask);
maxfd = connsocket;
if (stop_socket != PGINVALID_SOCKET)
{
FD_SET(stop_socket, &input_mask);
maxfd = Max(maxfd, stop_socket);
}
if (timeout_ms < 0)
timeoutptr = NULL;
else
{
timeout.tv_sec = timeout_ms / 1000L;
timeout.tv_usec = (timeout_ms % 1000L) * 1000L;
timeoutptr = &timeout;
}
ret = select(maxfd + 1, &input_mask, NULL, NULL, timeoutptr);
if (ret < 0)
{
if (errno == EINTR)
return 0; /* Got a signal, so not an error */
pg_log_error("select() failed: %m");
return -1;
}
if (ret > 0 && FD_ISSET(connsocket, &input_mask))
return 1; /* Got input on connection socket */
return 0; /* Got timeout or input on stop_socket */
}
/*
* Receive CopyData message available from XLOG stream, blocking for
* maximum of 'timeout' ms.
*
* If data was received, returns the length of the data. *buffer is set to
* point to a buffer holding the received message. The buffer is only valid
* until the next CopyStreamReceive call.
*
* Returns 0 if no data was available within timeout, or if wait was
* interrupted by signal or stop_socket input.
* -1 on error. -2 if the server ended the COPY.
*/
static int
CopyStreamReceive(PGconn *conn, long timeout, pgsocket stop_socket,
char **buffer)
{
char *copybuf = NULL;
int rawlen;
if (*buffer != NULL)
PQfreemem(*buffer);
*buffer = NULL;
/* Try to receive a CopyData message */
rawlen = PQgetCopyData(conn, ©buf, 1);
if (rawlen == 0)
{
int ret;
/*
* No data available. Wait for some to appear, but not longer than
* the specified timeout, so that we can ping the server. Also stop
* waiting if input appears on stop_socket.
*/
ret = CopyStreamPoll(conn, timeout, stop_socket);
if (ret <= 0)
return ret;
/* Now there is actually data on the socket */
if (PQconsumeInput(conn) == 0)
{
pg_log_error("could not receive data from WAL stream: %s",
PQerrorMessage(conn));
return -1;
}
/* Now that we've consumed some input, try again */
rawlen = PQgetCopyData(conn, ©buf, 1);
if (rawlen == 0)
return 0;
}
if (rawlen == -1) /* end-of-streaming or error */
return -2;
if (rawlen == -2)
{
pg_log_error("could not read COPY data: %s", PQerrorMessage(conn));
return -1;
}
/* Return received messages to caller */
*buffer = copybuf;
return rawlen;
}
/*
* Process the keepalive message.
*/
static bool
ProcessKeepaliveMsg(PGconn *conn, StreamCtl *stream, char *copybuf, int len,
XLogRecPtr blockpos, TimestampTz *last_status)
{
int pos;
bool replyRequested;
TimestampTz now;
/*
* Parse the keepalive message, enclosed in the CopyData message. We just
* check if the server requested a reply, and ignore the rest.
*/
pos = 1; /* skip msgtype 'k' */
pos += 8; /* skip walEnd */
pos += 8; /* skip sendTime */
if (len < pos + 1)
{
pg_log_error("streaming header too small: %d", len);
return false;
}
replyRequested = copybuf[pos];
/* If the server requested an immediate reply, send one. */
if (replyRequested && still_sending)
{
if (reportFlushPosition && lastFlushPosition < blockpos &&
walfile != NULL)
{
/*
* If a valid flush location needs to be reported, flush the
* current WAL file so that the latest flush location is sent back
* to the server. This is necessary to see whether the last WAL
* data has been successfully replicated or not, at the normal
* shutdown of the server.
*/
if (stream->walmethod->sync(walfile) != 0)
{
pg_log_error("could not fsync file \"%s\": %s",
current_walfile_name, stream->walmethod->getlasterror());
return false;
}
lastFlushPosition = blockpos;
}
now = feGetCurrentTimestamp();
if (!sendFeedback(conn, blockpos, now, false))
return false;
*last_status = now;
}
return true;
}
/*
* Process XLogData message.
*/
static bool
ProcessXLogDataMsg(PGconn *conn, StreamCtl *stream, char *copybuf, int len,
XLogRecPtr *blockpos)
{
int xlogoff;
int bytes_left;
int bytes_written;
int hdr_len;
/*
* Once we've decided we don't want to receive any more, just ignore any
* subsequent XLogData messages.
*/
if (!(still_sending))
return true;
/*
* Read the header of the XLogData message, enclosed in the CopyData
* message. We only need the WAL location field (dataStart), the rest of
* the header is ignored.
*/
hdr_len = 1; /* msgtype 'w' */
hdr_len += 8; /* dataStart */
hdr_len += 8; /* walEnd */
hdr_len += 8; /* sendTime */
if (len < hdr_len)
{
pg_log_error("streaming header too small: %d", len);
return false;
}
*blockpos = fe_recvint64(©buf[1]);
/* Extract WAL location for this block */
xlogoff = XLogSegmentOffset(*blockpos, WalSegSz);
/*
* Verify that the initial location in the stream matches where we think
* we are.
*/
if (walfile == NULL)
{
/* No file open yet */
if (xlogoff != 0)
{
pg_log_error("received write-ahead log record for offset %u with no file open",
xlogoff);
return false;
}
}
else
{
/* More data in existing segment */
if (stream->walmethod->get_current_pos(walfile) != xlogoff)
{
pg_log_error("got WAL data offset %08x, expected %08x",
xlogoff, (int) stream->walmethod->get_current_pos(walfile));
return false;
}
}
bytes_left = len - hdr_len;
bytes_written = 0;
while (bytes_left)
{
int bytes_to_write;
/*
* If crossing a WAL boundary, only write up until we reach wal
* segment size.
*/
if (xlogoff + bytes_left > WalSegSz)
bytes_to_write = WalSegSz - xlogoff;
else
bytes_to_write = bytes_left;
if (walfile == NULL)
{
if (!open_walfile(stream, *blockpos))
{
/* Error logged by open_walfile */
return false;
}
}
if (stream->walmethod->write(walfile, copybuf + hdr_len + bytes_written,
bytes_to_write) != bytes_to_write)
{
pg_log_error("could not write %u bytes to WAL file \"%s\": %s",
bytes_to_write, current_walfile_name,
stream->walmethod->getlasterror());
return false;
}
/* Write was successful, advance our position */
bytes_written += bytes_to_write;
bytes_left -= bytes_to_write;
*blockpos += bytes_to_write;
xlogoff += bytes_to_write;
/* Did we reach the end of a WAL segment? */
if (XLogSegmentOffset(*blockpos, WalSegSz) == 0)
{
if (!close_walfile(stream, *blockpos))
/* Error message written in close_walfile() */
return false;
xlogoff = 0;
if (still_sending && stream->stream_stop(*blockpos, stream->timeline, true))
{
if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
{
pg_log_error("could not send copy-end packet: %s",
PQerrorMessage(conn));
return false;
}
still_sending = false;
return true; /* ignore the rest of this XLogData packet */
}
}
}
/* No more data left to write, receive next copy packet */
return true;
}
/*
* Handle end of the copy stream.
*/
static PGresult *
HandleEndOfCopyStream(PGconn *conn, StreamCtl *stream, char *copybuf,
XLogRecPtr blockpos, XLogRecPtr *stoppos)
{
PGresult *res = PQgetResult(conn);
/*
* The server closed its end of the copy stream. If we haven't closed
* ours already, we need to do so now, unless the server threw an error,
* in which case we don't.
*/
if (still_sending)
{
if (!close_walfile(stream, blockpos))
{
/* Error message written in close_walfile() */
PQclear(res);
return NULL;
}
if (PQresultStatus(res) == PGRES_COPY_IN)
{
if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
{
pg_log_error("could not send copy-end packet: %s",
PQerrorMessage(conn));
PQclear(res);
return NULL;
}
res = PQgetResult(conn);
}
still_sending = false;
}
if (copybuf != NULL)
PQfreemem(copybuf);
*stoppos = blockpos;
return res;
}
/*
* Check if we should continue streaming, or abort at this point.
*/
static bool
CheckCopyStreamStop(PGconn *conn, StreamCtl *stream, XLogRecPtr blockpos,
XLogRecPtr *stoppos)
{
if (still_sending && stream->stream_stop(blockpos, stream->timeline, false))
{
if (!close_walfile(stream, blockpos))
{
/* Potential error message is written by close_walfile */
return false;
}
if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
{
pg_log_error("could not send copy-end packet: %s",
PQerrorMessage(conn));
return false;
}
still_sending = false;
}
return true;
}
/*
* Calculate how long send/receive loops should sleep
*/
static long
CalculateCopyStreamSleeptime(TimestampTz now, int standby_message_timeout,
TimestampTz last_status)
{
TimestampTz status_targettime = 0;
long sleeptime;
if (standby_message_timeout && still_sending)
status_targettime = last_status +
(standby_message_timeout - 1) * ((int64) 1000);
if (status_targettime > 0)
{
long secs;
int usecs;
feTimestampDifference(now,
status_targettime,
&secs,
&usecs);
/* Always sleep at least 1 sec */
if (secs <= 0)
{
secs = 1;
usecs = 0;
}
sleeptime = secs * 1000 + usecs / 1000;
}
else
sleeptime = -1;
return sleeptime;
}
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