pg_receivewal: Add --endpos option

This is primarily useful for making tests of this utility more
deterministic, to avoid the complexity of starting pg_receivewal as a
deamon in TAP tests.

While this is less useful than the equivalent pg_recvlogical option,
users can as well use it for example to enforce WAL streaming up to a
end-of-backup position, to save only a minimal amount of WAL.

Use this new option to stream WAL data in a deterministic way within a
new set of TAP tests.

Author: Michael Paquier <michael.paquier@gmail.com>

diff --git a/doc/src/sgml/ref/pg_receivewal.sgml b/doc/src/sgml/ref/pg_receivewal.sgml
index 7c82e36c7c86b97be0e6e61095133cebd6975f10..f0513dad2ae3efb0120bfe6afd3796aeb97184b5 100644 (file)
--- a/doc/src/sgml/ref/pg_receivewal.sgml
+++ b/doc/src/sgml/ref/pg_receivewal.sgml
@@ -98,6 +98,22 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-E <replaceable>lsn</replaceable></option></term>
+      <term><option>--endpos=<replaceable>lsn</replaceable></option></term>
+      <listitem>
+       <para>
+        Automatically stop replication and exit with normal exit status 0 when
+        receiving reaches the specified LSN.
+       </para>
+
+       <para>
+        If there is a record with LSN exactly equal to <replaceable>lsn</>,
+        the record will be processed.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--if-not-exists</option></term>
       <listitem>

diff --git a/src/bin/pg_basebackup/pg_receivewal.c b/src/bin/pg_basebackup/pg_receivewal.c
index 4a1a5658fb3d9a9af7a5526a1437540fc1b23273..710a33ab4d2de8124c6829993dbc7047119be798 100644 (file)
--- a/src/bin/pg_basebackup/pg_receivewal.c
+++ b/src/bin/pg_basebackup/pg_receivewal.c
@@ -36,12 +36,13 @@ static int  verbose = 0;
 static int compresslevel = 0;
 static int noloop = 0;
 static int standby_message_timeout = 10 * 1000;    /* 10 sec = default */
-static volatile bool time_to_abort = false;
+static volatile bool time_to_stop = false;
 static bool do_create_slot = false;
 static bool slot_exists_ok = false;
 static bool do_drop_slot = false;
 static bool synchronous = false;
 static char *replication_slot = NULL;
+static XLogRecPtr endpos = InvalidXLogRecPtr;
 
 
 static void usage(void);
@@ -77,6 +78,7 @@ usage(void)
    printf(_("  %s [OPTION]...\n"), progname);
    printf(_("\nOptions:\n"));
    printf(_("  -D, --directory=DIR    receive write-ahead log files into this directory\n"));
+   printf(_("  -E, --endpos=LSN       exit after receiving the specified LSN\n"));
    printf(_("      --if-not-exists    do not error if slot already exists when creating a slot\n"));
    printf(_("  -n, --no-loop          do not loop on connection lost\n"));
    printf(_("  -s, --status-interval=SECS\n"
@@ -112,6 +114,16 @@ stop_streaming(XLogRecPtr xlogpos, uint32 timeline, bool segment_finished)
                progname, (uint32) (xlogpos >> 32), (uint32) xlogpos,
                timeline);
 
+   if (!XLogRecPtrIsInvalid(endpos) && endpos < xlogpos)
+   {
+       if (verbose)
+           fprintf(stderr, _("%s: stopped streaming at %X/%X (timeline %u)\n"),
+                   progname, (uint32) (xlogpos >> 32), (uint32) xlogpos,
+                   timeline);
+       time_to_stop = true;
+       return true;
+   }
+
    /*
     * Note that we report the previous, not current, position here. After a
     * timeline switch, xlogpos points to the beginning of the segment because
@@ -128,7 +140,7 @@ stop_streaming(XLogRecPtr xlogpos, uint32 timeline, bool segment_finished)
    prevtimeline = timeline;
    prevpos = xlogpos;
 
-   if (time_to_abort)
+   if (time_to_stop)
    {
        if (verbose)
            fprintf(stderr, _("%s: received interrupt signal, exiting\n"),
@@ -448,7 +460,7 @@ StreamLog(void)
 static void
 sigint_handler(int signum)
 {
-   time_to_abort = true;
+   time_to_stop = true;
 }
 #endif
 
@@ -460,6 +472,7 @@ main(int argc, char **argv)
        {"version", no_argument, NULL, 'V'},
        {"directory", required_argument, NULL, 'D'},
        {"dbname", required_argument, NULL, 'd'},
+       {"endpos", required_argument, NULL, 'E'},
        {"host", required_argument, NULL, 'h'},
        {"port", required_argument, NULL, 'p'},
        {"username", required_argument, NULL, 'U'},
@@ -481,6 +494,7 @@ main(int argc, char **argv)
    int         c;
    int         option_index;
    char       *db_name;
+   uint32      hi, lo;
 
    progname = get_progname(argv[0]);
    set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_basebackup"));
@@ -500,7 +514,7 @@ main(int argc, char **argv)
        }
    }
 
-   while ((c = getopt_long(argc, argv, "D:d:h:p:U:s:S:nwWvZ:",
+   while ((c = getopt_long(argc, argv, "D:d:E:h:p:U:s:S:nwWvZ:",
                            long_options, &option_index)) != -1)
    {
        switch (c)
@@ -544,6 +558,16 @@ main(int argc, char **argv)
            case 'S':
                replication_slot = pg_strdup(optarg);
                break;
+           case 'E':
+               if (sscanf(optarg, "%X/%X", &hi, &lo) != 2)
+               {
+                   fprintf(stderr,
+                           _("%s: could not parse end position \"%s\"\n"),
+                           progname, optarg);
+                   exit(1);
+               }
+               endpos = ((uint64) hi) << 32 | lo;
+               break;
            case 'n':
                noloop = 1;
                break;
@@ -714,11 +738,11 @@ main(int argc, char **argv)
    while (true)
    {
        StreamLog();
-       if (time_to_abort)
+       if (time_to_stop)
        {
            /*
-            * We've been Ctrl-C'ed. That's not an error, so exit without an
-            * errorcode.
+            * We've been Ctrl-C'ed or end of streaming position has been
+            * willingly reached, so exit without an error code.
             */
            exit(0);
        }

diff --git a/src/bin/pg_basebackup/t/020_pg_receivewal.pl b/src/bin/pg_basebackup/t/020_pg_receivewal.pl
index b4cb6f729dc722105a9a7aca7e2b602523f6c651..101a36466d075aab98b266633c4be90802cf98a1 100644 (file)
--- a/src/bin/pg_basebackup/t/020_pg_receivewal.pl
+++ b/src/bin/pg_basebackup/t/020_pg_receivewal.pl
@@ -1,8 +1,51 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 8;
+use PostgresNode;
+use Test::More tests => 14;
 
 program_help_ok('pg_receivewal');
 program_version_ok('pg_receivewal');
 program_options_handling_ok('pg_receivewal');
+
+my $primary = get_new_node('primary');
+$primary->init(allows_streaming => 1);
+$primary->start;
+
+my $stream_dir = $primary->basedir . '/archive_wal';
+mkdir($stream_dir);
+
+# Sanity checks for command line options.
+$primary->command_fails(['pg_receivewal'],
+   'pg_receivewal needs target directory specified');
+$primary->command_fails(
+   [ 'pg_receivewal', '-D', $stream_dir, '--create-slot', '--drop-slot' ],
+   'failure if both --create-slot and --drop-slot specified');
+$primary->command_fails(
+   [ 'pg_receivewal', '-D', $stream_dir, '--create-slot' ],
+   'failure if --create-slot specified without --slot');
+
+# Slot creation and drop
+my $slot_name = 'test';
+$primary->command_ok(
+   [ 'pg_receivewal', '--slot', $slot_name, '--create-slot' ],
+   'creating a replication slot');
+$primary->command_ok([ 'pg_receivewal', '--slot', $slot_name, '--drop-slot' ],
+   'dropping a replication slot');
+
+# Generate some WAL.  Use --synchronous at the same time to add more
+# code coverage.  Switch to the next segment first so that subsequent
+# restarts of pg_receivewal will see this segment as full..
+$primary->psql('postgres', 'CREATE TABLE test_table(x integer);');
+$primary->psql('postgres', 'SELECT pg_switch_wal();');
+my $nextlsn =
+  $primary->safe_psql('postgres', 'SELECT pg_current_wal_insert_lsn();');
+chomp($nextlsn);
+$primary->psql('postgres',
+   'INSERT INTO test_table VALUES (generate_series(1,100));');
+
+# Stream up to the given position.
+$primary->command_ok(
+   [   'pg_receivewal', '-D',     $stream_dir,     '--verbose',
+       '--endpos',      $nextlsn, '--synchronous', '--no-loop' ],
+   'streaming some WAL with --synchronous');