#include "postgres_fe.h"
#include <sys/stat.h>
#include <unistd.h>
#include "access/xlog_internal.h"
#include "common/file_utils.h"
#include "common/logging.h"
#include "libpq-fe.h"
#include "receivelog.h"
#include "streamutil.h"

Include dependency graph for receivelog.c:

Functions
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)

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)

static bool	open_walfile (StreamCtl *stream, XLogRecPtr startpoint)

static bool	close_walfile (StreamCtl *stream, XLogRecPtr pos)

static bool	existsTimeLineHistoryFile (StreamCtl *stream)

static bool	writeTimeLineHistoryFile (StreamCtl stream, char filename, char *content)

static bool	sendFeedback (PGconn *conn, XLogRecPtr blockpos, TimestampTz now, bool replyRequested)

bool	CheckServerVersionForStreaming (PGconn *conn)

bool	ReceiveXlogStream (PGconn conn, StreamCtl stream)

Variables
static Walfile *	walfile = NULL

static char	current_walfile_name [MAXPGPATH] = ""

static bool	reportFlushPosition = false

static XLogRecPtr	lastFlushPosition = InvalidXLogRecPtr

static bool	still_sending = true

Function Documentation

◆ CalculateCopyStreamSleeptime()

static long CalculateCopyStreamSleeptime	(	TimestampTz	now,
		int	standby_message_timeout,
		TimestampTz	last_status
	)

static

Definition at line 1244 of file receivelog.c.

 {
     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;
 }

References feTimestampDifference(), now(), standby_message_timeout, and still_sending.

Referenced by HandleCopyStream().

◆ CheckCopyStreamStop()

static bool CheckCopyStreamStop	(	PGconn *	conn,
		StreamCtl *	stream,
		XLogRecPtr	blockpos
	)

static

Definition at line 1219 of file receivelog.c.

 {
     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;
 }

References close_walfile(), conn, pg_log_error, PQerrorMessage(), PQflush(), PQputCopyEnd(), still_sending, StreamCtl::stream_stop, and StreamCtl::timeline.

Referenced by HandleCopyStream().

◆ CheckServerVersionForStreaming()

bool CheckServerVersionForStreaming ( PGconn * conn )

Definition at line 381 of file receivelog.c.

 {
     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;
 }

References conn, pg_log_error, PQparameterStatus(), and PQserverVersion().

Referenced by BaseBackup(), ReceiveXlogStream(), and StreamLog().

◆ close_walfile()

static bool close_walfile	(	StreamCtl *	stream,
		XLogRecPtr	pos
	)

static

Definition at line 191 of file receivelog.c.

 {
     char       *fn;
     off_t       currpos;
     int         r;
  
     if (walfile == NULL)
         return true;
  
     /* Note that this considers the compression used if necessary */
     fn = stream->walmethod->get_file_name(current_walfile_name,
                                           stream->partial_suffix);
  
     currpos = stream->walmethod->get_current_pos(walfile);
  
     if (currpos == -1)
     {
         pg_log_error("could not determine seek position in file \"%s\": %s",
                      fn, stream->walmethod->getlasterror());
         stream->walmethod->close(walfile, CLOSE_UNLINK);
         walfile = NULL;
  
         pg_free(fn);
         return false;
     }
  
     if (stream->partial_suffix)
     {
         if (currpos == WalSegSz)
             r = stream->walmethod->close(walfile, CLOSE_NORMAL);
         else
         {
             pg_log_info("not renaming \"%s\", segment is not complete", fn);
             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",
                      fn, stream->walmethod->getlasterror());
  
         pg_free(fn);
         return false;
     }
  
     pg_free(fn);
  
     /*
      * 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;
 }

References WalWriteMethod::close, CLOSE_NO_RENAME, CLOSE_NORMAL, CLOSE_UNLINK, current_walfile_name, fn(), WalWriteMethod::get_current_pos, WalWriteMethod::get_file_name, WalWriteMethod::getlasterror, lastFlushPosition, StreamCtl::mark_done, mark_file_as_archived(), StreamCtl::partial_suffix, pg_free(), pg_log_error, pg_log_info, walfile, StreamCtl::walmethod, and WalSegSz.

Referenced by CheckCopyStreamStop(), HandleEndOfCopyStream(), and ProcessXLogDataMsg().

◆ CopyStreamPoll()

static int CopyStreamPoll	(	PGconn *	conn,
		long	timeout_ms,
		pgsocket	stop_socket
	)

static

Definition at line 877 of file receivelog.c.

 {
     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("%s() failed: %m", "select");
         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 */
 }

References conn, EINTR, Max, pg_log_error, PGINVALID_SOCKET, PQerrorMessage(), PQsocket(), and select.

Referenced by CopyStreamReceive().

◆ CopyStreamReceive()

static int CopyStreamReceive	(	PGconn *	conn,
		long	timeout,
		pgsocket	stop_socket,
		char **	buffer
	)

static

Definition at line 939 of file receivelog.c.

 {
     char       *copybuf = NULL;
     int         rawlen;
  
     if (*buffer != NULL)
         PQfreemem(*buffer);
     *buffer = NULL;
  
     /* Try to receive a CopyData message */
     rawlen = PQgetCopyData(conn, &copybuf, 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, &copybuf, 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;
 }

References conn, copybuf, CopyStreamPoll(), pg_log_error, PQconsumeInput(), PQerrorMessage(), PQfreemem(), and PQgetCopyData().

Referenced by HandleCopyStream().

◆ existsTimeLineHistoryFile()

static bool existsTimeLineHistoryFile ( StreamCtl * stream )

static

Definition at line 265 of file receivelog.c.

 {
     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);
 }

References WalWriteMethod::existsfile, MAXFNAMELEN, StreamCtl::timeline, TLHistoryFileName, and StreamCtl::walmethod.

Referenced by ReceiveXlogStream().

◆ HandleCopyStream()

static PGresult * HandleCopyStream	(	PGconn *	conn,
		StreamCtl *	stream,
		XLogRecPtr *	stoppos
	)

static

Definition at line 751 of file receivelog.c.

 {
     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))
             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_fatal("could not fsync file \"%s\": %s",
                          current_walfile_name, stream->walmethod->getlasterror());
             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 primary
          */
         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, &copybuf);
         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))
                     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, &copybuf);
         }
     }
  
 error:
     if (copybuf != NULL)
         PQfreemem(copybuf);
     return NULL;
 }

References CalculateCopyStreamSleeptime(), CheckCopyStreamStop(), conn, copybuf, CopyStreamReceive(), current_walfile_name, error(), feGetCurrentTimestamp(), feTimestampDifferenceExceeds(), WalWriteMethod::getlasterror, HandleEndOfCopyStream(), lastFlushPosition, now(), pg_fatal, pg_log_error, PQfreemem(), ProcessKeepaliveMsg(), ProcessXLogDataMsg(), res, sendFeedback(), StreamCtl::standby_message_timeout, StreamCtl::startpos, still_sending, StreamCtl::stop_socket, WalWriteMethod::sync, StreamCtl::synchronous, walfile, and StreamCtl::walmethod.

Referenced by ReceiveXlogStream().

◆ HandleEndOfCopyStream()

static PGresult * HandleEndOfCopyStream	(	PGconn *	conn,
		StreamCtl *	stream,
		char *	copybuf,
		XLogRecPtr	blockpos,
		XLogRecPtr *	stoppos
	)

static

Definition at line 1178 of file receivelog.c.

 {
     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;
 }

References close_walfile(), conn, copybuf, pg_log_error, PGRES_COPY_IN, PQclear(), PQerrorMessage(), PQflush(), PQfreemem(), PQgetResult(), PQputCopyEnd(), PQresultStatus(), res, and still_sending.

Referenced by HandleCopyStream().

◆ mark_file_as_archived()

static bool mark_file_as_archived	(	StreamCtl *	stream,
		const char *	fname
	)

static

Definition at line 57 of file receivelog.c.

 {
     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;
     }
  
     if (stream->walmethod->close(f, CLOSE_NORMAL) != 0)
     {
         pg_log_error("could not close archive status file \"%s\": %s",
                      tmppath, stream->walmethod->getlasterror());
         return false;
     }
  
     return true;
 }

References WalWriteMethod::close, CLOSE_NORMAL, WalWriteMethod::getlasterror, MAXPGPATH, WalWriteMethod::open_for_write, pg_log_error, snprintf, and StreamCtl::walmethod.

Referenced by close_walfile(), and writeTimeLineHistoryFile().

◆ open_walfile()

static bool open_walfile	(	StreamCtl *	stream,
		XLogRecPtr	startpoint
	)

static

Definition at line 93 of file receivelog.c.

 {
     Walfile    *f;
     char       *fn;
     ssize_t     size;
     XLogSegNo   segno;
  
     XLByteToSeg(startpoint, segno, WalSegSz);
     XLogFileName(current_walfile_name, stream->timeline, segno, WalSegSz);
  
     /* Note that this considers the compression used if necessary */
     fn = stream->walmethod->get_file_name(current_walfile_name,
                                           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. Compressed files have no need for padding, so just ignore this
      * case.
      *
      * When streaming to tar, no file with this name will exist before, so we
      * never have to verify a size.
      */
     if (stream->walmethod->compression_algorithm() == PG_COMPRESSION_NONE &&
         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());
             pg_free(fn);
             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());
                 pg_free(fn);
                 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);
                 exit(1);
             }
  
             walfile = f;
             pg_free(fn);
             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 %zd byte, should be 0 or %d",
                                   "write-ahead log file \"%s\" has %zd bytes, should be 0 or %d",
                                   size),
                          fn, size, WalSegSz);
             pg_free(fn);
             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());
         pg_free(fn);
         return false;
     }
  
     pg_free(fn);
     walfile = f;
     return true;
 }

References WalWriteMethod::close, CLOSE_UNLINK, WalWriteMethod::compression_algorithm, current_walfile_name, WalWriteMethod::existsfile, exit(), fn(), WalWriteMethod::get_file_name, WalWriteMethod::get_file_size, WalWriteMethod::getlasterror, ngettext, WalWriteMethod::open_for_write, StreamCtl::partial_suffix, PG_COMPRESSION_NONE, pg_free(), pg_log_error, WalWriteMethod::sync, StreamCtl::timeline, walfile, StreamCtl::walmethod, WalSegSz, XLByteToSeg, and XLogFileName.

Referenced by ProcessXLogDataMsg().

◆ ProcessKeepaliveMsg()

static bool ProcessKeepaliveMsg	(	PGconn *	conn,
		StreamCtl *	stream,
		char *	copybuf,
		int	len,
		XLogRecPtr	blockpos,
		TimestampTz *	last_status
	)

static

Definition at line 994 of file receivelog.c.

 {
     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_fatal("could not fsync file \"%s\": %s",
                          current_walfile_name, stream->walmethod->getlasterror());
             lastFlushPosition = blockpos;
         }
  
         now = feGetCurrentTimestamp();
         if (!sendFeedback(conn, blockpos, now, false))
             return false;
         *last_status = now;
     }
  
     return true;
 }

References conn, copybuf, current_walfile_name, feGetCurrentTimestamp(), WalWriteMethod::getlasterror, lastFlushPosition, len, now(), pg_fatal, pg_log_error, reportFlushPosition, sendFeedback(), still_sending, WalWriteMethod::sync, walfile, and StreamCtl::walmethod.

Referenced by HandleCopyStream().

◆ ProcessXLogDataMsg()

static bool ProcessXLogDataMsg	(	PGconn *	conn,
		StreamCtl *	stream,
		char *	copybuf,
		int	len,
		XLogRecPtr *	blockpos
	)

static

Definition at line 1048 of file receivelog.c.

 {
     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(&copybuf[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 %d 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;
 }

References close_walfile(), conn, copybuf, current_walfile_name, fe_recvint64(), WalWriteMethod::get_current_pos, WalWriteMethod::getlasterror, len, open_walfile(), pg_log_error, PQerrorMessage(), PQflush(), PQputCopyEnd(), still_sending, StreamCtl::stream_stop, StreamCtl::timeline, walfile, StreamCtl::walmethod, WalSegSz, WalWriteMethod::write, and XLogSegmentOffset.

Referenced by HandleCopyStream().

◆ ReadEndOfStreamingResult()

static bool ReadEndOfStreamingResult	(	PGresult *	res,
		XLogRecPtr *	startpos,
		uint32 *	timeline
	)

static

Definition at line 705 of file receivelog.c.

 {
     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;
 }

References pg_log_error, PQgetvalue(), PQnfields(), PQntuples(), res, and startpos.

Referenced by ReceiveXlogStream().

◆ ReceiveXlogStream()

bool ReceiveXlogStream	(	PGconn *	conn,
		StreamCtl *	stream
	)

Definition at line 459 of file receivelog.c.

 {
     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)
     {
         char       *sysidentifier = NULL;
         TimeLineID  servertli;
  
         /*
          * Get the server system identifier and timeline, and validate them.
          */
         if (!RunIdentifySystem(conn, &sysidentifier, &servertli, NULL, NULL))
         {
             pg_free(sysidentifier);
             return false;
         }
  
         if (strcmp(stream->sysidentifier, sysidentifier) != 0)
         {
             pg_log_error("system identifier does not match between base backup and streaming connection");
             pg_free(sysidentifier);
             return false;
         }
         pg_free(sysidentifier);
  
         if (stream->timeline > servertli)
         {
             pg_log_error("starting timeline %u is not present in the server",
                          stream->timeline);
             return false;
         }
     }
  
     /*
      * 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,
                  LSN_FORMAT_ARGS(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, LSN_FORMAT_ARGS(stoppos),
                              newtimeline, LSN_FORMAT_ARGS(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;
 }

References CheckServerVersionForStreaming(), WalWriteMethod::close, CLOSE_NO_RENAME, conn, current_walfile_name, error(), existsTimeLineHistoryFile(), WalWriteMethod::getlasterror, HandleCopyStream(), lastFlushPosition, LSN_FORMAT_ARGS, pg_free(), pg_log_error, pg_log_warning, PGRES_COMMAND_OK, PGRES_COPY_BOTH, PGRES_TUPLES_OK, PQclear(), PQexec(), PQgetResult(), PQgetvalue(), PQnfields(), PQntuples(), PQresultErrorMessage(), PQresultStatus(), ReadEndOfStreamingResult(), StreamCtl::replication_slot, reportFlushPosition, res, RunIdentifySystem(), snprintf, sprintf, StreamCtl::startpos, StreamCtl::stream_stop, StreamCtl::synchronous, StreamCtl::sysidentifier, StreamCtl::timeline, walfile, StreamCtl::walmethod, WalSegSz, writeTimeLineHistoryFile(), and XLogSegmentOffset.

Referenced by LogStreamerMain(), and StreamLog().

◆ sendFeedback()

static bool sendFeedback	(	PGconn *	conn,
		XLogRecPtr	blockpos,
		TimestampTz	now,
		bool	replyRequested
	)

static

Definition at line 343 of file receivelog.c.

 {
     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;
 }

References conn, fe_sendint64(), InvalidXLogRecPtr, lastFlushPosition, len, now(), pg_log_error, PQerrorMessage(), PQflush(), PQputCopyData(), and reportFlushPosition.

Referenced by HandleCopyStream(), and ProcessKeepaliveMsg().

◆ writeTimeLineHistoryFile()

static bool writeTimeLineHistoryFile	(	StreamCtl *	stream,
		char *	filename,
		char *	content
	)

static

Definition at line 282 of file receivelog.c.

 {
     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;
 }

References WalWriteMethod::close, CLOSE_NORMAL, CLOSE_UNLINK, filename, WalWriteMethod::getlasterror, StreamCtl::mark_done, mark_file_as_archived(), MAXFNAMELEN, WalWriteMethod::open_for_write, pg_log_error, StreamCtl::timeline, TLHistoryFileName, StreamCtl::walmethod, and WalWriteMethod::write.

Referenced by ReceiveXlogStream().

Variable Documentation

◆ current_walfile_name

char current_walfile_name[MAXPGPATH] = ""

static

Definition at line 32 of file receivelog.c.

Referenced by close_walfile(), HandleCopyStream(), open_walfile(), ProcessKeepaliveMsg(), ProcessXLogDataMsg(), and ReceiveXlogStream().

◆ lastFlushPosition

XLogRecPtr lastFlushPosition = InvalidXLogRecPtr

static

Definition at line 34 of file receivelog.c.

Referenced by close_walfile(), HandleCopyStream(), ProcessKeepaliveMsg(), ReceiveXlogStream(), and sendFeedback().

◆ reportFlushPosition

bool reportFlushPosition = false

static

Definition at line 33 of file receivelog.c.

Referenced by ProcessKeepaliveMsg(), ReceiveXlogStream(), and sendFeedback().

◆ still_sending

bool still_sending = true

static

Definition at line 36 of file receivelog.c.

Referenced by CalculateCopyStreamSleeptime(), CheckCopyStreamStop(), HandleCopyStream(), HandleEndOfCopyStream(), ProcessKeepaliveMsg(), and ProcessXLogDataMsg().

◆ walfile

Walfile* walfile = NULL

static

Definition at line 31 of file receivelog.c.

Referenced by CleanupPriorWALFiles(), close_walfile(), HandleCopyStream(), open_walfile(), ProcessKeepaliveMsg(), ProcessXLogDataMsg(), and ReceiveXlogStream().

Functions

Variables

Function Documentation

◆ CalculateCopyStreamSleeptime()

◆ CheckCopyStreamStop()

◆ CheckServerVersionForStreaming()

◆ close_walfile()

◆ CopyStreamPoll()

◆ CopyStreamReceive()

◆ existsTimeLineHistoryFile()

◆ HandleCopyStream()

◆ HandleEndOfCopyStream()

◆ mark_file_as_archived()

◆ open_walfile()

◆ ProcessKeepaliveMsg()

◆ ProcessXLogDataMsg()

◆ ReadEndOfStreamingResult()

◆ ReceiveXlogStream()

◆ sendFeedback()

◆ writeTimeLineHistoryFile()

Variable Documentation

◆ current_walfile_name

◆ lastFlushPosition

◆ reportFlushPosition

◆ still_sending

◆ walfile