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35739b87dc
A new callback named startup_cb, called shortly after a module is
loaded, is added. This makes possible the initialization of any
additional state data required by a module. This initial state data can
be saved in a ArchiveModuleState, that is now passed down to all the
callbacks that can be defined in a module. With this design, it is
possible to have a per-module state, aimed at opening the door to the
support of more than one archive module.
The initialization of the callbacks is changed so as
_PG_archive_module_init() does not anymore give in input a
ArchiveModuleCallbacks that a module has to fill in with callback
definitions. Instead, a module now needs to return a const
ArchiveModuleCallbacks.
All the structure and callback definitions of archive modules are moved
into their own header, named archive_module.h, from pgarch.h.
Command-based archiving follows the same line, with a new set of files
named shell_archive.{c,h}.
There are a few more items that are under discussion to improve the
design of archive modules, like the fact that basic_archive calls
sigsetjmp() by itself to define its own error handling flow. These will
be adjusted later, the changes done here cover already a good portion
of what has been discussed.
Any modules created for v15 will need to be adjusted to this new
design.
Author: Nathan Bossart
Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/20230130194810.6fztfgbn32e7qarj@awork3.anarazel.de
141 lines
3.6 KiB
C
141 lines
3.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* shell_archive.c
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*
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* This archiving function uses a user-specified shell command (the
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* archive_command GUC) to copy write-ahead log files. It is used as the
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* default, but other modules may define their own custom archiving logic.
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*
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* Copyright (c) 2022-2023, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/backend/archive/shell_archive.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <sys/wait.h>
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#include "access/xlog.h"
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#include "archive/archive_module.h"
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#include "archive/shell_archive.h"
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#include "common/percentrepl.h"
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#include "pgstat.h"
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static bool shell_archive_configured(ArchiveModuleState *state);
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static bool shell_archive_file(ArchiveModuleState *state,
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const char *file,
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const char *path);
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static void shell_archive_shutdown(ArchiveModuleState *state);
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static const ArchiveModuleCallbacks shell_archive_callbacks = {
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.startup_cb = NULL,
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.check_configured_cb = shell_archive_configured,
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.archive_file_cb = shell_archive_file,
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.shutdown_cb = shell_archive_shutdown
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};
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const ArchiveModuleCallbacks *
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shell_archive_init(void)
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{
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return &shell_archive_callbacks;
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}
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static bool
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shell_archive_configured(ArchiveModuleState *state)
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{
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return XLogArchiveCommand[0] != '\0';
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}
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static bool
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shell_archive_file(ArchiveModuleState *state, const char *file,
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const char *path)
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{
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char *xlogarchcmd;
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char *nativePath = NULL;
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int rc;
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if (path)
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{
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nativePath = pstrdup(path);
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make_native_path(nativePath);
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}
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xlogarchcmd = replace_percent_placeholders(XLogArchiveCommand,
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"archive_command", "fp",
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file, nativePath);
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if (nativePath)
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pfree(nativePath);
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ereport(DEBUG3,
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(errmsg_internal("executing archive command \"%s\"",
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xlogarchcmd)));
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fflush(NULL);
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pgstat_report_wait_start(WAIT_EVENT_ARCHIVE_COMMAND);
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rc = system(xlogarchcmd);
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pgstat_report_wait_end();
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if (rc != 0)
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{
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/*
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* If either the shell itself, or a called command, died on a signal,
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* abort the archiver. We do this because system() ignores SIGINT and
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* SIGQUIT while waiting; so a signal is very likely something that
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* should have interrupted us too. Also die if the shell got a hard
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* "command not found" type of error. If we overreact it's no big
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* deal, the postmaster will just start the archiver again.
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*/
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int lev = wait_result_is_any_signal(rc, true) ? FATAL : LOG;
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if (WIFEXITED(rc))
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{
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ereport(lev,
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(errmsg("archive command failed with exit code %d",
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WEXITSTATUS(rc)),
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errdetail("The failed archive command was: %s",
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xlogarchcmd)));
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}
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else if (WIFSIGNALED(rc))
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{
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#if defined(WIN32)
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ereport(lev,
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(errmsg("archive command was terminated by exception 0x%X",
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WTERMSIG(rc)),
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errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value."),
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errdetail("The failed archive command was: %s",
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xlogarchcmd)));
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#else
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ereport(lev,
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(errmsg("archive command was terminated by signal %d: %s",
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WTERMSIG(rc), pg_strsignal(WTERMSIG(rc))),
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errdetail("The failed archive command was: %s",
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xlogarchcmd)));
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#endif
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}
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else
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{
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ereport(lev,
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(errmsg("archive command exited with unrecognized status %d",
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rc),
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errdetail("The failed archive command was: %s",
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xlogarchcmd)));
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}
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return false;
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}
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pfree(xlogarchcmd);
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elog(DEBUG1, "archived write-ahead log file \"%s\"", file);
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return true;
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}
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static void
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shell_archive_shutdown(ArchiveModuleState *state)
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{
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elog(DEBUG1, "archiver process shutting down");
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}
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