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Diffstat (limited to 'src/backend/utils/init/miscinit.c')
-rw-r--r--src/backend/utils/init/miscinit.c180
1 files changed, 144 insertions, 36 deletions
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index 0ecfa272440..c6192aa0c6e 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.61 2001/01/27 00:05:31 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.62 2001/03/13 01:17:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -41,7 +41,8 @@ unsigned char RecodeBackTable[128];
ProcessingMode Mode = InitProcessing;
-/* Note: we rely on this to initialize as zeroes */
+/* Note: we rely on these to initialize as zeroes */
+static char directoryLockFile[MAXPGPATH];
static char socketLockFile[MAXPGPATH];
@@ -458,6 +459,9 @@ GetUserName(Oid userid)
* The path is also just for informational purposes (so that a socket lockfile
* can be more easily traced to the associated postmaster).
*
+ * A data-directory lockfile can optionally contain a third line, containing
+ * the key and ID for the shared memory block used by this postmaster.
+ *
* On successful lockfile creation, a proc_exit callback to remove the
* lockfile is automatically created.
*-------------------------------------------------------------------------
@@ -476,16 +480,18 @@ UnlinkLockFile(int status, Datum filename)
/*
* Create a lockfile, if possible
*
- * Call CreateLockFile with the name of the lockfile to be created. If
- * successful, it returns zero. On detecting a collision, it returns
- * the PID or negated PID of the lockfile owner --- the caller is responsible
- * for producing an appropriate error message.
+ * Call CreateLockFile with the name of the lockfile to be created.
+ * Returns true if successful, false if not (with a message on stderr).
+ *
+ * amPostmaster is used to determine how to encode the output PID.
+ * isDDLock and refName are used to determine what error message to produce.
*/
-static int
-CreateLockFile(const char *filename, bool amPostmaster)
+static bool
+CreateLockFile(const char *filename, bool amPostmaster,
+ bool isDDLock, const char *refName)
{
int fd;
- char buffer[MAXPGPATH + 32];
+ char buffer[MAXPGPATH + 100];
int len;
int encoded_pid;
pid_t other_pid;
@@ -539,11 +545,61 @@ CreateLockFile(const char *filename, bool amPostmaster)
{
if (kill(other_pid, 0) == 0 ||
errno != ESRCH)
- return encoded_pid; /* lockfile belongs to a live process */
+ {
+ /* lockfile belongs to a live process */
+ fprintf(stderr, "Lock file \"%s\" already exists.\n",
+ filename);
+ if (isDDLock)
+ fprintf(stderr,
+ "Is another %s (pid %d) running in \"%s\"?\n",
+ (encoded_pid < 0 ? "postgres" : "postmaster"),
+ other_pid, refName);
+ else
+ fprintf(stderr,
+ "Is another %s (pid %d) using \"%s\"?\n",
+ (encoded_pid < 0 ? "postgres" : "postmaster"),
+ other_pid, refName);
+ return false;
+ }
+ }
+
+ /*
+ * No, the creating process did not exist. However, it could be that
+ * the postmaster crashed (or more likely was kill -9'd by a clueless
+ * admin) but has left orphan backends behind. Check for this by
+ * looking to see if there is an associated shmem segment that is
+ * still in use.
+ */
+ if (isDDLock)
+ {
+ char *ptr;
+ unsigned long shmKey,
+ shmId;
+
+ ptr = strchr(buffer, '\n');
+ if (ptr != NULL &&
+ (ptr = strchr(ptr+1, '\n')) != NULL)
+ {
+ ptr++;
+ if (sscanf(ptr, "%lu %lu", &shmKey, &shmId) == 2)
+ {
+ if (SharedMemoryIsInUse((IpcMemoryKey) shmKey,
+ (IpcMemoryId) shmId))
+ {
+ fprintf(stderr,
+ "Found a pre-existing shared memory block (ID %d) still in use.\n"
+ "If you're sure there are no old backends still running,\n"
+ "remove the shared memory block with ipcrm(1), or just\n"
+ "delete \"%s\".\n",
+ (int) shmId, filename);
+ return false;
+ }
+ }
+ }
}
/*
- * No, the process did not exist. Unlink the file and try again to
+ * Looks like nobody's home. Unlink the file and try again to
* create it. Need a loop because of possible race condition against
* other would-be creators.
*/
@@ -576,28 +632,19 @@ CreateLockFile(const char *filename, bool amPostmaster)
*/
on_proc_exit(UnlinkLockFile, PointerGetDatum(strdup(filename)));
- return 0; /* Success! */
+ return true; /* Success! */
}
bool
CreateDataDirLockFile(const char *datadir, bool amPostmaster)
{
char lockfile[MAXPGPATH];
- int encoded_pid;
snprintf(lockfile, sizeof(lockfile), "%s/postmaster.pid", datadir);
- encoded_pid = CreateLockFile(lockfile, amPostmaster);
- if (encoded_pid != 0)
- {
- fprintf(stderr, "Lock file \"%s\" already exists.\n", lockfile);
- if (encoded_pid < 0)
- fprintf(stderr, "Is another postgres (pid %d) running in \"%s\"?\n",
- -encoded_pid, datadir);
- else
- fprintf(stderr, "Is another postmaster (pid %d) running in \"%s\"?\n",
- encoded_pid, datadir);
+ if (! CreateLockFile(lockfile, amPostmaster, true, datadir))
return false;
- }
+ /* Save name of lockfile for RecordSharedMemoryInLockFile */
+ strcpy(directoryLockFile, lockfile);
return true;
}
@@ -605,21 +652,10 @@ bool
CreateSocketLockFile(const char *socketfile, bool amPostmaster)
{
char lockfile[MAXPGPATH];
- int encoded_pid;
snprintf(lockfile, sizeof(lockfile), "%s.lock", socketfile);
- encoded_pid = CreateLockFile(lockfile, amPostmaster);
- if (encoded_pid != 0)
- {
- fprintf(stderr, "Lock file \"%s\" already exists.\n", lockfile);
- if (encoded_pid < 0)
- fprintf(stderr, "Is another postgres (pid %d) using \"%s\"?\n",
- -encoded_pid, socketfile);
- else
- fprintf(stderr, "Is another postmaster (pid %d) using \"%s\"?\n",
- encoded_pid, socketfile);
+ if (! CreateLockFile(lockfile, amPostmaster, false, socketfile))
return false;
- }
/* Save name of lockfile for TouchSocketLockFile */
strcpy(socketLockFile, lockfile);
return true;
@@ -650,6 +686,78 @@ TouchSocketLockFile(void)
}
}
+/*
+ * Append information about a shared memory segment to the data directory
+ * lock file (if we have created one).
+ *
+ * This may be called multiple times in the life of a postmaster, if we
+ * delete and recreate shmem due to backend crash. Therefore, be prepared
+ * to overwrite existing information. (As of 7.1, a postmaster only creates
+ * one shm seg anyway; but for the purposes here, if we did have more than
+ * one then any one of them would do anyway.)
+ */
+void
+RecordSharedMemoryInLockFile(IpcMemoryKey shmKey, IpcMemoryId shmId)
+{
+ int fd;
+ int len;
+ char *ptr;
+ char buffer[BLCKSZ];
+
+ /*
+ * Do nothing if we did not create a lockfile (probably because we
+ * are running standalone).
+ */
+ if (directoryLockFile[0] == '\0')
+ return;
+
+ fd = open(directoryLockFile, O_RDWR | PG_BINARY, 0);
+ if (fd < 0)
+ {
+ elog(DEBUG, "Failed to rewrite %s: %m", directoryLockFile);
+ return;
+ }
+ len = read(fd, buffer, sizeof(buffer) - 100);
+ if (len <= 0)
+ {
+ elog(DEBUG, "Failed to read %s: %m", directoryLockFile);
+ close(fd);
+ return;
+ }
+ buffer[len] = '\0';
+ /*
+ * Skip over first two lines (PID and path).
+ */
+ ptr = strchr(buffer, '\n');
+ if (ptr == NULL ||
+ (ptr = strchr(ptr+1, '\n')) == NULL)
+ {
+ elog(DEBUG, "Bogus data in %s", directoryLockFile);
+ close(fd);
+ return;
+ }
+ ptr++;
+ /*
+ * Append shm key and ID. Format to try to keep it the same length
+ * always (trailing junk won't hurt, but might confuse humans).
+ */
+ sprintf(ptr, "%9lu %9lu\n",
+ (unsigned long) shmKey, (unsigned long) shmId);
+ /*
+ * And rewrite the data. Since we write in a single kernel call,
+ * this update should appear atomic to onlookers.
+ */
+ len = strlen(buffer);
+ if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
+ (int) write(fd, buffer, len) != len)
+ {
+ elog(DEBUG, "Failed to write %s: %m", directoryLockFile);
+ close(fd);
+ return;
+ }
+ close(fd);
+}
+
/*-------------------------------------------------------------------------
* Version checking support
generated by cgit v1.2.3 (git 2.46.0) at 2025-08-13 05:39:04 +0000