diff options
Diffstat (limited to 'common')
| -rw-r--r-- | common/ChangeLog | 5 | ||||
| -rw-r--r-- | common/dotlock.c | 119 |
2 files changed, 87 insertions, 37 deletions
diff --git a/common/ChangeLog b/common/ChangeLog index e0fc2dddc..0f66a4122 100644 --- a/common/ChangeLog +++ b/common/ChangeLog @@ -1,3 +1,8 @@ +2011-09-28 Werner Koch <wk@g10code.com> + + * dotlock.c (dotlock_take, dotlock_take_unix, dotlock_take_w32): + Implement arbitrary timeout values. + 2011-09-27 Werner Koch <wk@g10code.com> * dotlock.c (dotlock_take_unix): Check only the link count and not diff --git a/common/dotlock.c b/common/dotlock.c index 97a3f7462..e3e9fa3d2 100644 --- a/common/dotlock.c +++ b/common/dotlock.c @@ -87,8 +87,10 @@ This function will wait until the lock is acquired. If an unexpected error occurs if will return non-zero and set ERRNO. If - you pass (0) instead of (-1) the function does not wait if the file - is already locked but returns -1 and sets ERRNO to EACCES. + you pass (0) instead of (-1) the function does not wait in case the + file is already locked but returns -1 and sets ERRNO to EACCES. + Any other positive value for the second parameter is considered a + timeout valuie in milliseconds. To release the lock you call: @@ -805,15 +807,20 @@ dotlock_destroy (dotlock_t h) #ifdef HAVE_POSIX_SYSTEM -/* Unix specific code of make_dotlock. Returns 0 on success, -1 on - error and 1 to try again. */ +/* Unix specific code of make_dotlock. Returns 0 on success and -1 on + error. */ static int -dotlock_take_unix (dotlock_t h, long timeout, int *backoff) +dotlock_take_unix (dotlock_t h, long timeout) { - int pid; + int wtime = 0; + int sumtime = 0; + int pid; + int lastpid = -1; + int ownerchanged; const char *maybe_dead=""; int same_node; + again: if (h->use_o_excl) { /* No hardlink support - use open(O_EXCL). */ @@ -889,7 +896,7 @@ dotlock_take_unix (dotlock_t h, long timeout, int *backoff) return -1; } my_info_0 ("lockfile disappeared\n"); - return 1; /* Try again. */ + goto again; } else if ( pid == getpid() && same_node ) { @@ -904,24 +911,49 @@ dotlock_take_unix (dotlock_t h, long timeout, int *backoff) of the stale file tries to lock right at the same time as we. */ my_info_1 (_("removing stale lockfile (created by %d)\n"), pid); unlink (h->lockname); - return 1; /* Try again. */ + goto again; } - if ( timeout == -1 ) + if (lastpid == -1) + lastpid = pid; + ownerchanged = (pid != lastpid); + + if (timeout) { - /* Wait until lock has been released. */ struct timeval tv; - my_info_3 (_("waiting for lock (held by %d%s) %s...\n"), - pid, maybe_dead, maybe_deadlock(h)? _("(deadlock?) "):""); + /* Wait until lock has been released. We use increasing retry + intervals of 50ms, 100ms, 200ms, 400ms, 800ms, 2s, 4s and 8s + but reset it if the lock owner meanwhile changed. */ + if (!wtime || ownerchanged) + wtime = 50; + else if (wtime < 800) + wtime *= 2; + else if (wtime == 800) + wtime = 2000; + else if (wtime < 8000) + wtime *= 2; + + if (timeout > 0) + { + if (wtime > timeout) + wtime = timeout; + timeout -= wtime; + } + + sumtime += wtime; + if (sumtime >= 1500) + { + sumtime = 0; + my_info_3 (_("waiting for lock (held by %d%s) %s...\n"), + pid, maybe_dead, maybe_deadlock(h)? _("(deadlock?) "):""); + } + - /* We can't use sleep, cause signals may be blocked. */ - tv.tv_sec = 1 + *backoff; - tv.tv_usec = 0; + tv.tv_sec = wtime / 1000; + tv.tv_usec = (wtime % 1000) * 1000; select (0, NULL, NULL, NULL, &tv); - if ( *backoff < 10 ) - ++*backoff; - return 1; /* Try again. */ + goto again; } jnlib_set_errno (EACCES); @@ -931,14 +963,16 @@ dotlock_take_unix (dotlock_t h, long timeout, int *backoff) #ifdef HAVE_DOSISH_SYSTEM -/* Windows specific code of make_dotlock. Returns 0 on success, -1 on - error and 1 to try again. */ +/* Windows specific code of make_dotlock. Returns 0 on success and -1 on + error. */ static int -dotlock_take_w32 (dotlock_t h, long timeout, int *backoff) +dotlock_take_w32 (dotlock_t h, long timeout) { + int wtime = 0; int w32err; OVERLAPPED ovl; + again: /* Lock one byte at offset 0. The offset is given by OVL. */ memset (&ovl, 0, sizeof ovl); if (LockFileEx (h->lockhd, (LOCKFILE_EXCLUSIVE_LOCK @@ -956,14 +990,31 @@ dotlock_take_w32 (dotlock_t h, long timeout, int *backoff) return -1; } - if ( timeout == -1 ) + if (timeout) { - /* Wait until lock has been released. */ - my_info_1 (_("waiting for lock %s...\n"), h->lockname); - Sleep ((1 + *backoff)*1000); - if ( *backoff < 10 ) - ++*backoff; - return 1; /* Try again. */ + /* Wait until lock has been released. We use retry intervals of + 50ms, 100ms, 200ms, 400ms, 800ms, 2s, 4s and 8s. */ + if (!wtime) + wtime = 50; + else if (wtime < 800) + wtime *= 2; + else if (wtime == 800) + wtime = 2000; + else if (wtime < 8000) + wtime *= 2; + + if (timeout > 0) + { + if (wtime > timeout) + wtime = timeout; + timeout -= wtime; + } + + if (wtime >= 800) + my_info_1 (_("waiting for lock %s...\n"), h->lockname); + + Sleep (wtime); + goto again; } return -1; @@ -973,12 +1024,10 @@ dotlock_take_w32 (dotlock_t h, long timeout, int *backoff) /* Take a lock on H. A value of 0 for TIMEOUT returns immediately if the lock can't be taked, -1 waits forever (hopefully not), other - values are reserved (planned to be timeouts in milliseconds). - Returns: 0 on success */ + values wait for TIMEOUT milliseconds. Returns: 0 on success */ int dotlock_take (dotlock_t h, long timeout) { - int backoff = 0; int ret; if ( h->disable ) @@ -990,15 +1039,11 @@ dotlock_take (dotlock_t h, long timeout) return 0; } - do - { #ifdef HAVE_DOSISH_SYSTEM - ret = dotlock_take_w32 (h, timeout, &backoff); + ret = dotlock_take_w32 (h, timeout); #else /*!HAVE_DOSISH_SYSTEM*/ - ret = dotlock_take_unix (h, timeout, &backoff); + ret = dotlock_take_unix (h, timeout); #endif /*!HAVE_DOSISH_SYSTEM*/ - } - while (ret == 1); return ret; } |