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--- cyrus-imapd-2.1.3/lib/lock_flock.c Tue Oct 2 16:08:13 2001
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+++ cyrus-imapd-2.1.3-patched/lib/lock_flock.c Tue Apr 16 09:44:58 2002
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@@ -51,6 +51,10 @@
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#endif
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#include "lock.h"
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+#include <syslog.h>
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+
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+/* Locking timeout parameter */
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+#define MAXTIME 99
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const char *lock_method_desc = "flock";
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@@ -69,6 +73,18 @@
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* 'failaction' is provided, it is filled in with a pointer to a fixed
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* string naming the action that failed.
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*
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+ * Modified by jwade 4/16/2002 to work around seen file locking problem
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+ * Added locking timeout parameter to allow processes that are
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+ * waiting for a lock to eventually time out
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+ *
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+ * Calls flock() in non-blocking fashion and then retries until a
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+ * maximum delay is reached or the lock succeeds.
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+ *
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+ * As written, uses a quadratic backoff on retries with MAXTIME being
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+ * the longest interval delay. Total delay time is the sum of the squares
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+ * of all integers whose square is less than MAXTIME. In the case of
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+ * MAXTIME = 99 this is 0+1+4+9+16+25+36+49+64+81= 285 Seconds
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+ * This time is arbitrary and can be adjusted
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*/
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int lock_reopen(fd, filename, sbuf, failaction)
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int fd;
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@@ -79,17 +95,29 @@
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int r;
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struct stat sbuffile, sbufspare;
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int newfd;
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+ int delay=0, i=0;
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if (!sbuf) sbuf = &sbufspare;
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- for (;;) {
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- r = flock(fd, LOCK_EX);
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+ for(i=0,delay=0;;) {
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+ r = flock(fd, LOCK_EX|LOCK_NB);
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if (r == -1) {
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- if (errno == EINTR) continue;
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- if (failaction) *failaction = "locking";
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+ if (errno == EINTR) {
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+ continue;
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+ }
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+ else if ((errno == EWOULDBLOCK) && (delay < MAXTIME)) {
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+ syslog(LOG_DEBUG, "lock: reopen-blocked sleeping for %d on interval %d (%d, %s)" , delay, i, fd, filename);
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+ sleep(delay);
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+ i++;
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+ delay = i*i;
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+ continue;
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+ }
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+ if (failaction) {
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+ if (delay >= MAXTIME) *failaction = "locking_timeout";
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+ else *failaction = "locking";
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+ }
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return -1;
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}
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-
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fstat(fd, sbuf);
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r = stat(filename, &sbuffile);
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if (r == -1) {
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@@ -97,9 +125,7 @@
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flock(fd, LOCK_UN);
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return -1;
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}
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-
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if (sbuf->st_ino == sbuffile.st_ino) return 0;
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-
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newfd = open(filename, O_RDWR);
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if (newfd == -1) {
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if (failaction) *failaction = "opening";
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