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--- src/rrd_open.c.orig 2019-05-28 01:48:09.000000000 +0700
+++ src/rrd_open.c 2022-07-11 00:05:29.242533000 +0700
@@ -32,6 +32,16 @@
#include "rrd_rados.h"
#endif
+#include <signal.h>
+/*
+ * Signal handler for SIGALRM.
+ */
+static void
+timeout(int sig)
+{
+ (void)sig;
+}
+
#define MEMBLK 8192
#ifdef _WIN32
@@ -776,8 +786,9 @@ int rrd_rwlock(
return 0;
}
#endif
- int rcstat;
+ int rcstat, waitsec;
rrd_simple_file_t *rrd_simple_file;
+ char *endptr, *pwaitsec;
rrd_simple_file = (rrd_simple_file_t *) rrd_file->pvt;
#ifdef USE_WINDOWS_LOCK
@@ -786,6 +797,25 @@ int rrd_rwlock(
/* Silence unused parameter compiler warning */
(void) writelock;
#else
+ if ((pwaitsec = getenv("RRDTOOL_LOCK_TIMEOUT")) != NULL) {
+ waitsec = strtol(pwaitsec, &endptr, 0);
+ if (*endptr == '\0' && waitsec >= 0) {
+ if (waitsec > 0) { /* Set up a timeout. */
+ struct sigaction act;
+
+ act.sa_handler = timeout;
+ sigemptyset(&act.sa_mask);
+ act.sa_flags = SA_RESETHAND; /* Note that we do not set SA_RESTART. */
+ sigaction(SIGALRM, &act, NULL);
+ alarm(waitsec);
+ }
+ rcstat = flock(rrd_simple_file->fd, writelock ? LOCK_EX : LOCK_SH);
+ if (waitsec > 0)
+ alarm(0);
+
+ return (rcstat);
+ }
+ }
{
struct flock lock;
--- doc/rrdtool.pod.orig 2019-02-04 20:54:28.000000000 +0700
+++ doc/rrdtool.pod 2022-07-11 00:37:16.486373000 +0700
@@ -321,6 +321,21 @@
L<rrdcached>, a caching daemon for RRDtool which may help you lessen the
stress on your disks.
+=head1 ENVIRONMENT
+
+=over 8
+
+=item RRDTOOL_LOCK_TIMEOUT
+
+By default, B<RRDtool> tries to lock RRD file and fails
+if it cannot obtain the lock immediately.
+This variable allows to change this behavior and specify
+a time interval in seconds to wait for lock if the file is busy.
+It will fail if the lock cannot be obtained in time.
+Zero value makes it wait for the lock indefinitely.
+
+=back
+
=head1 SEE ALSO
rrdcreate, rrdupdate, rrdgraph, rrddump, rrdfetch, rrdtune, rrdlast, rrdxport,
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