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-rw-r--r--src/backend/postmaster/pgarch.c718
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diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
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+/*-------------------------------------------------------------------------
+ *
+ * pgarch.c
+ *
+ * PostgreSQL WAL archiver
+ *
+ * All functions relating to archiver are included here
+ *
+ * - All functions executed by archiver process
+ *
+ * - archiver is forked from postmaster, and the two
+ * processes then communicate using signals. All functions
+ * executed by postmaster are included in this file.
+ *
+ * Initial author: Simon Riggs simon@2ndquadrant.com
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ * src/backend/postmaster/pgarch.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <fcntl.h>
+#include <signal.h>
+#include <time.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "access/xlog.h"
+#include "access/xlog_internal.h"
+#include "libpq/pqsignal.h"
+#include "miscadmin.h"
+#include "pgstat.h"
+#include "postmaster/interrupt.h"
+#include "postmaster/pgarch.h"
+#include "storage/fd.h"
+#include "storage/ipc.h"
+#include "storage/latch.h"
+#include "storage/pmsignal.h"
+#include "storage/proc.h"
+#include "storage/procsignal.h"
+#include "storage/shmem.h"
+#include "utils/guc.h"
+#include "utils/ps_status.h"
+
+
+/* ----------
+ * Timer definitions.
+ * ----------
+ */
+#define PGARCH_AUTOWAKE_INTERVAL 60 /* How often to force a poll of the
+ * archive status directory; in seconds. */
+#define PGARCH_RESTART_INTERVAL 10 /* How often to attempt to restart a
+ * failed archiver; in seconds. */
+
+/*
+ * Maximum number of retries allowed when attempting to archive a WAL
+ * file.
+ */
+#define NUM_ARCHIVE_RETRIES 3
+
+/*
+ * Maximum number of retries allowed when attempting to remove an
+ * orphan archive status file.
+ */
+#define NUM_ORPHAN_CLEANUP_RETRIES 3
+
+/* Shared memory area for archiver process */
+typedef struct PgArchData
+{
+ int pgprocno; /* pgprocno of archiver process */
+} PgArchData;
+
+
+/* ----------
+ * Local data
+ * ----------
+ */
+static time_t last_sigterm_time = 0;
+static PgArchData *PgArch = NULL;
+
+/*
+ * Flags set by interrupt handlers for later service in the main loop.
+ */
+static volatile sig_atomic_t ready_to_stop = false;
+
+/* ----------
+ * Local function forward declarations
+ * ----------
+ */
+static void pgarch_waken_stop(SIGNAL_ARGS);
+static void pgarch_MainLoop(void);
+static void pgarch_ArchiverCopyLoop(void);
+static bool pgarch_archiveXlog(char *xlog);
+static bool pgarch_readyXlog(char *xlog);
+static void pgarch_archiveDone(char *xlog);
+static void pgarch_die(int code, Datum arg);
+static void HandlePgArchInterrupts(void);
+
+/* Report shared memory space needed by PgArchShmemInit */
+Size
+PgArchShmemSize(void)
+{
+ Size size = 0;
+
+ size = add_size(size, sizeof(PgArchData));
+
+ return size;
+}
+
+/* Allocate and initialize archiver-related shared memory */
+void
+PgArchShmemInit(void)
+{
+ bool found;
+
+ PgArch = (PgArchData *)
+ ShmemInitStruct("Archiver Data", PgArchShmemSize(), &found);
+
+ if (!found)
+ {
+ /* First time through, so initialize */
+ MemSet(PgArch, 0, PgArchShmemSize());
+ PgArch->pgprocno = INVALID_PGPROCNO;
+ }
+}
+
+/*
+ * PgArchCanRestart
+ *
+ * Return true and archiver is allowed to restart if enough time has
+ * passed since it was launched last to reach PGARCH_RESTART_INTERVAL.
+ * Otherwise return false.
+ *
+ * This is a safety valve to protect against continuous respawn attempts if the
+ * archiver is dying immediately at launch. Note that since we will retry to
+ * launch the archiver from the postmaster main loop, we will get another
+ * chance later.
+ */
+bool
+PgArchCanRestart(void)
+{
+ static time_t last_pgarch_start_time = 0;
+ time_t curtime = time(NULL);
+
+ /*
+ * Return false and don't restart archiver if too soon since last archiver
+ * start.
+ */
+ if ((unsigned int) (curtime - last_pgarch_start_time) <
+ (unsigned int) PGARCH_RESTART_INTERVAL)
+ return false;
+
+ last_pgarch_start_time = curtime;
+ return true;
+}
+
+
+/* Main entry point for archiver process */
+void
+PgArchiverMain(void)
+{
+ /*
+ * Ignore all signals usually bound to some action in the postmaster,
+ * except for SIGHUP, SIGTERM, SIGUSR1, SIGUSR2, and SIGQUIT.
+ */
+ pqsignal(SIGHUP, SignalHandlerForConfigReload);
+ pqsignal(SIGINT, SIG_IGN);
+ pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
+ /* SIGQUIT handler was already set up by InitPostmasterChild */
+ pqsignal(SIGALRM, SIG_IGN);
+ pqsignal(SIGPIPE, SIG_IGN);
+ pqsignal(SIGUSR1, procsignal_sigusr1_handler);
+ pqsignal(SIGUSR2, pgarch_waken_stop);
+
+ /* Reset some signals that are accepted by postmaster but not here */
+ pqsignal(SIGCHLD, SIG_DFL);
+
+ /* Unblock signals (they were blocked when the postmaster forked us) */
+ PG_SETMASK(&UnBlockSig);
+
+ /* We shouldn't be launched unnecessarily. */
+ Assert(XLogArchivingActive());
+
+ /* Arrange to clean up at archiver exit */
+ on_shmem_exit(pgarch_die, 0);
+
+ /*
+ * Advertise our pgprocno so that backends can use our latch to wake us up
+ * while we're sleeping.
+ */
+ PgArch->pgprocno = MyProc->pgprocno;
+
+ pgarch_MainLoop();
+
+ proc_exit(0);
+}
+
+/*
+ * Wake up the archiver
+ */
+void
+PgArchWakeup(void)
+{
+ int arch_pgprocno = PgArch->pgprocno;
+
+ /*
+ * We don't acquire ProcArrayLock here. It's actually fine because
+ * procLatch isn't ever freed, so we just can potentially set the wrong
+ * process' (or no process') latch. Even in that case the archiver will
+ * be relaunched shortly and will start archiving.
+ */
+ if (arch_pgprocno != INVALID_PGPROCNO)
+ SetLatch(&ProcGlobal->allProcs[arch_pgprocno].procLatch);
+}
+
+
+/* SIGUSR2 signal handler for archiver process */
+static void
+pgarch_waken_stop(SIGNAL_ARGS)
+{
+ int save_errno = errno;
+
+ /* set flag to do a final cycle and shut down afterwards */
+ ready_to_stop = true;
+ SetLatch(MyLatch);
+
+ errno = save_errno;
+}
+
+/*
+ * pgarch_MainLoop
+ *
+ * Main loop for archiver
+ */
+static void
+pgarch_MainLoop(void)
+{
+ pg_time_t last_copy_time = 0;
+ bool time_to_stop;
+
+ /*
+ * There shouldn't be anything for the archiver to do except to wait for a
+ * signal ... however, the archiver exists to protect our data, so she
+ * wakes up occasionally to allow herself to be proactive.
+ */
+ do
+ {
+ ResetLatch(MyLatch);
+
+ /* When we get SIGUSR2, we do one more archive cycle, then exit */
+ time_to_stop = ready_to_stop;
+
+ /* Check for barrier events and config update */
+ HandlePgArchInterrupts();
+
+ /*
+ * If we've gotten SIGTERM, we normally just sit and do nothing until
+ * SIGUSR2 arrives. However, that means a random SIGTERM would
+ * disable archiving indefinitely, which doesn't seem like a good
+ * idea. If more than 60 seconds pass since SIGTERM, exit anyway, so
+ * that the postmaster can start a new archiver if needed.
+ */
+ if (ShutdownRequestPending)
+ {
+ time_t curtime = time(NULL);
+
+ if (last_sigterm_time == 0)
+ last_sigterm_time = curtime;
+ else if ((unsigned int) (curtime - last_sigterm_time) >=
+ (unsigned int) 60)
+ break;
+ }
+
+ /* Do what we're here for */
+ pgarch_ArchiverCopyLoop();
+ last_copy_time = time(NULL);
+
+ /*
+ * Sleep until a signal is received, or until a poll is forced by
+ * PGARCH_AUTOWAKE_INTERVAL having passed since last_copy_time, or
+ * until postmaster dies.
+ */
+ if (!time_to_stop) /* Don't wait during last iteration */
+ {
+ pg_time_t curtime = (pg_time_t) time(NULL);
+ int timeout;
+
+ timeout = PGARCH_AUTOWAKE_INTERVAL - (curtime - last_copy_time);
+ if (timeout > 0)
+ {
+ int rc;
+
+ rc = WaitLatch(MyLatch,
+ WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
+ timeout * 1000L,
+ WAIT_EVENT_ARCHIVER_MAIN);
+ if (rc & WL_POSTMASTER_DEATH)
+ time_to_stop = true;
+ }
+ }
+
+ /*
+ * The archiver quits either when the postmaster dies (not expected)
+ * or after completing one more archiving cycle after receiving
+ * SIGUSR2.
+ */
+ } while (!time_to_stop);
+}
+
+/*
+ * pgarch_ArchiverCopyLoop
+ *
+ * Archives all outstanding xlogs then returns
+ */
+static void
+pgarch_ArchiverCopyLoop(void)
+{
+ char xlog[MAX_XFN_CHARS + 1];
+
+ /*
+ * loop through all xlogs with archive_status of .ready and archive
+ * them...mostly we expect this to be a single file, though it is possible
+ * some backend will add files onto the list of those that need archiving
+ * while we are still copying earlier archives
+ */
+ while (pgarch_readyXlog(xlog))
+ {
+ int failures = 0;
+ int failures_orphan = 0;
+
+ for (;;)
+ {
+ struct stat stat_buf;
+ char pathname[MAXPGPATH];
+
+ /*
+ * Do not initiate any more archive commands after receiving
+ * SIGTERM, nor after the postmaster has died unexpectedly. The
+ * first condition is to try to keep from having init SIGKILL the
+ * command, and the second is to avoid conflicts with another
+ * archiver spawned by a newer postmaster.
+ */
+ if (ShutdownRequestPending || !PostmasterIsAlive())
+ return;
+
+ /*
+ * Check for barrier events and config update. This is so that
+ * we'll adopt a new setting for archive_command as soon as
+ * possible, even if there is a backlog of files to be archived.
+ */
+ HandlePgArchInterrupts();
+
+ /* can't do anything if no command ... */
+ if (!XLogArchiveCommandSet())
+ {
+ ereport(WARNING,
+ (errmsg("archive_mode enabled, yet archive_command is not set")));
+ return;
+ }
+
+ /*
+ * Since archive status files are not removed in a durable manner,
+ * a system crash could leave behind .ready files for WAL segments
+ * that have already been recycled or removed. In this case,
+ * simply remove the orphan status file and move on. unlink() is
+ * used here as even on subsequent crashes the same orphan files
+ * would get removed, so there is no need to worry about
+ * durability.
+ */
+ snprintf(pathname, MAXPGPATH, XLOGDIR "/%s", xlog);
+ if (stat(pathname, &stat_buf) != 0 && errno == ENOENT)
+ {
+ char xlogready[MAXPGPATH];
+
+ StatusFilePath(xlogready, xlog, ".ready");
+ if (unlink(xlogready) == 0)
+ {
+ ereport(WARNING,
+ (errmsg("removed orphan archive status file \"%s\"",
+ xlogready)));
+
+ /* leave loop and move to the next status file */
+ break;
+ }
+
+ if (++failures_orphan >= NUM_ORPHAN_CLEANUP_RETRIES)
+ {
+ ereport(WARNING,
+ (errmsg("removal of orphan archive status file \"%s\" failed too many times, will try again later",
+ xlogready)));
+
+ /* give up cleanup of orphan status files */
+ return;
+ }
+
+ /* wait a bit before retrying */
+ pg_usleep(1000000L);
+ continue;
+ }
+
+ if (pgarch_archiveXlog(xlog))
+ {
+ /* successful */
+ pgarch_archiveDone(xlog);
+
+ /*
+ * Tell the collector about the WAL file that we successfully
+ * archived
+ */
+ pgstat_send_archiver(xlog, false);
+
+ break; /* out of inner retry loop */
+ }
+ else
+ {
+ /*
+ * Tell the collector about the WAL file that we failed to
+ * archive
+ */
+ pgstat_send_archiver(xlog, true);
+
+ if (++failures >= NUM_ARCHIVE_RETRIES)
+ {
+ ereport(WARNING,
+ (errmsg("archiving write-ahead log file \"%s\" failed too many times, will try again later",
+ xlog)));
+ return; /* give up archiving for now */
+ }
+ pg_usleep(1000000L); /* wait a bit before retrying */
+ }
+ }
+ }
+}
+
+/*
+ * pgarch_archiveXlog
+ *
+ * Invokes system(3) to copy one archive file to wherever it should go
+ *
+ * Returns true if successful
+ */
+static bool
+pgarch_archiveXlog(char *xlog)
+{
+ char xlogarchcmd[MAXPGPATH];
+ char pathname[MAXPGPATH];
+ char activitymsg[MAXFNAMELEN + 16];
+ char *dp;
+ char *endp;
+ const char *sp;
+ int rc;
+
+ snprintf(pathname, MAXPGPATH, XLOGDIR "/%s", xlog);
+
+ /*
+ * construct the command to be executed
+ */
+ dp = xlogarchcmd;
+ endp = xlogarchcmd + MAXPGPATH - 1;
+ *endp = '\0';
+
+ for (sp = XLogArchiveCommand; *sp; sp++)
+ {
+ if (*sp == '%')
+ {
+ switch (sp[1])
+ {
+ case 'p':
+ /* %p: relative path of source file */
+ sp++;
+ strlcpy(dp, pathname, endp - dp);
+ make_native_path(dp);
+ dp += strlen(dp);
+ break;
+ case 'f':
+ /* %f: filename of source file */
+ sp++;
+ strlcpy(dp, xlog, endp - dp);
+ dp += strlen(dp);
+ break;
+ case '%':
+ /* convert %% to a single % */
+ sp++;
+ if (dp < endp)
+ *dp++ = *sp;
+ break;
+ default:
+ /* otherwise treat the % as not special */
+ if (dp < endp)
+ *dp++ = *sp;
+ break;
+ }
+ }
+ else
+ {
+ if (dp < endp)
+ *dp++ = *sp;
+ }
+ }
+ *dp = '\0';
+
+ ereport(DEBUG3,
+ (errmsg_internal("executing archive command \"%s\"",
+ xlogarchcmd)));
+
+ /* Report archive activity in PS display */
+ snprintf(activitymsg, sizeof(activitymsg), "archiving %s", xlog);
+ set_ps_display(activitymsg);
+
+ rc = system(xlogarchcmd);
+ if (rc != 0)
+ {
+ /*
+ * If either the shell itself, or a called command, died on a signal,
+ * abort the archiver. We do this because system() ignores SIGINT and
+ * SIGQUIT while waiting; so a signal is very likely something that
+ * should have interrupted us too. Also die if the shell got a hard
+ * "command not found" type of error. If we overreact it's no big
+ * deal, the postmaster will just start the archiver again.
+ */
+ int lev = wait_result_is_any_signal(rc, true) ? FATAL : LOG;
+
+ if (WIFEXITED(rc))
+ {
+ ereport(lev,
+ (errmsg("archive command failed with exit code %d",
+ WEXITSTATUS(rc)),
+ errdetail("The failed archive command was: %s",
+ xlogarchcmd)));
+ }
+ else if (WIFSIGNALED(rc))
+ {
+#if defined(WIN32)
+ ereport(lev,
+ (errmsg("archive command was terminated by exception 0x%X",
+ WTERMSIG(rc)),
+ errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value."),
+ errdetail("The failed archive command was: %s",
+ xlogarchcmd)));
+#else
+ ereport(lev,
+ (errmsg("archive command was terminated by signal %d: %s",
+ WTERMSIG(rc), pg_strsignal(WTERMSIG(rc))),
+ errdetail("The failed archive command was: %s",
+ xlogarchcmd)));
+#endif
+ }
+ else
+ {
+ ereport(lev,
+ (errmsg("archive command exited with unrecognized status %d",
+ rc),
+ errdetail("The failed archive command was: %s",
+ xlogarchcmd)));
+ }
+
+ snprintf(activitymsg, sizeof(activitymsg), "failed on %s", xlog);
+ set_ps_display(activitymsg);
+
+ return false;
+ }
+ elog(DEBUG1, "archived write-ahead log file \"%s\"", xlog);
+
+ snprintf(activitymsg, sizeof(activitymsg), "last was %s", xlog);
+ set_ps_display(activitymsg);
+
+ return true;
+}
+
+/*
+ * pgarch_readyXlog
+ *
+ * Return name of the oldest xlog file that has not yet been archived.
+ * No notification is set that file archiving is now in progress, so
+ * this would need to be extended if multiple concurrent archival
+ * tasks were created. If a failure occurs, we will completely
+ * re-copy the file at the next available opportunity.
+ *
+ * It is important that we return the oldest, so that we archive xlogs
+ * in order that they were written, for two reasons:
+ * 1) to maintain the sequential chain of xlogs required for recovery
+ * 2) because the oldest ones will sooner become candidates for
+ * recycling at time of checkpoint
+ *
+ * NOTE: the "oldest" comparison will consider any .history file to be older
+ * than any other file except another .history file. Segments on a timeline
+ * with a smaller ID will be older than all segments on a timeline with a
+ * larger ID; the net result being that past timelines are given higher
+ * priority for archiving. This seems okay, or at least not obviously worth
+ * changing.
+ */
+static bool
+pgarch_readyXlog(char *xlog)
+{
+ /*
+ * open xlog status directory and read through list of xlogs that have the
+ * .ready suffix, looking for earliest file. It is possible to optimise
+ * this code, though only a single file is expected on the vast majority
+ * of calls, so....
+ */
+ char XLogArchiveStatusDir[MAXPGPATH];
+ DIR *rldir;
+ struct dirent *rlde;
+ bool found = false;
+ bool historyFound = false;
+
+ snprintf(XLogArchiveStatusDir, MAXPGPATH, XLOGDIR "/archive_status");
+ rldir = AllocateDir(XLogArchiveStatusDir);
+
+ while ((rlde = ReadDir(rldir, XLogArchiveStatusDir)) != NULL)
+ {
+ int basenamelen = (int) strlen(rlde->d_name) - 6;
+ char basename[MAX_XFN_CHARS + 1];
+ bool ishistory;
+
+ /* Ignore entries with unexpected number of characters */
+ if (basenamelen < MIN_XFN_CHARS ||
+ basenamelen > MAX_XFN_CHARS)
+ continue;
+
+ /* Ignore entries with unexpected characters */
+ if (strspn(rlde->d_name, VALID_XFN_CHARS) < basenamelen)
+ continue;
+
+ /* Ignore anything not suffixed with .ready */
+ if (strcmp(rlde->d_name + basenamelen, ".ready") != 0)
+ continue;
+
+ /* Truncate off the .ready */
+ memcpy(basename, rlde->d_name, basenamelen);
+ basename[basenamelen] = '\0';
+
+ /* Is this a history file? */
+ ishistory = IsTLHistoryFileName(basename);
+
+ /*
+ * Consume the file to archive. History files have the highest
+ * priority. If this is the first file or the first history file
+ * ever, copy it. In the presence of a history file already chosen as
+ * target, ignore all other files except history files which have been
+ * generated for an older timeline than what is already chosen as
+ * target to archive.
+ */
+ if (!found || (ishistory && !historyFound))
+ {
+ strcpy(xlog, basename);
+ found = true;
+ historyFound = ishistory;
+ }
+ else if (ishistory || !historyFound)
+ {
+ if (strcmp(basename, xlog) < 0)
+ strcpy(xlog, basename);
+ }
+ }
+ FreeDir(rldir);
+
+ return found;
+}
+
+/*
+ * pgarch_archiveDone
+ *
+ * Emit notification that an xlog file has been successfully archived.
+ * We do this by renaming the status file from NNN.ready to NNN.done.
+ * Eventually, a checkpoint process will notice this and delete both the
+ * NNN.done file and the xlog file itself.
+ */
+static void
+pgarch_archiveDone(char *xlog)
+{
+ char rlogready[MAXPGPATH];
+ char rlogdone[MAXPGPATH];
+
+ StatusFilePath(rlogready, xlog, ".ready");
+ StatusFilePath(rlogdone, xlog, ".done");
+ (void) durable_rename(rlogready, rlogdone, WARNING);
+}
+
+
+/*
+ * pgarch_die
+ *
+ * Exit-time cleanup handler
+ */
+static void
+pgarch_die(int code, Datum arg)
+{
+ PgArch->pgprocno = INVALID_PGPROCNO;
+}
+
+/*
+ * Interrupt handler for WAL archiver process.
+ *
+ * This is called in the loops pgarch_MainLoop and pgarch_ArchiverCopyLoop.
+ * It checks for barrier events and config update, but not shutdown request
+ * because how to handle shutdown request is different between those loops.
+ */
+static void
+HandlePgArchInterrupts(void)
+{
+ if (ProcSignalBarrierPending)
+ ProcessProcSignalBarrier();
+
+ if (ConfigReloadPending)
+ {
+ ConfigReloadPending = false;
+ ProcessConfigFile(PGC_SIGHUP);
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-20 17:10:26 +0000