databases/rrdtool: add new port option LOCKTIMEOUT

By default, RRDTool tries to lock RRD file and fails
if it cannot obtain the lock immediately.

New build option LOCKTIMEOUT (disabled by default)
allows to change this behavior and specify
a time interval (in seconds) with environment variable
RRDTOOL_LOCK_TIMEOUT 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.

The patch documents the feature in the manual page and HTML docs.

Default build is not affected, so PORTREVISION not bumped.

2 files changed, 83 insertions, 1 deletions

diff --git a/databases/rrdtool/Makefile b/databases/rrdtool/Makefile
index 88591c7e5ada..8d53ecfd2265 100644
--- a/databases/rrdtool/Makefile
+++ b/databases/rrdtool/Makefile
@@ -26,12 +26,13 @@ CPE_VENDOR=	rrdtool_project
 
 PORTEXAMPLES=	cgi-demo.cgi
 
-OPTIONS_DEFINE=	DEJAVU GRAPH MMAP NLS PERL PYTHON \
+OPTIONS_DEFINE=	DEJAVU GRAPH MMAP LOCKTIMEOUT NLS PERL PYTHON \
 		RUBY EXAMPLES DOCS
 OPTIONS_DEFAULT=DEJAVU GRAPH MMAP PERL
 OPTIONS_SUB=	yes
 GRAPH_DESC=	Enable the rrdtool graph command (needs cairo)
 DEJAVU_DESC=	Use DejaVu fonts (requires X11)
+LOCKTIMEOUT_DESC=Enable the patch for lock timeout
 MMAP_DESC=	Use mmap in rrd_update
 PERL_DESC=	Build PERL module
 PYTHON_DESC=	Build PYTHON bindings
@@ -46,6 +47,7 @@ GRAPH_CONFIGURE_OFF=	--disable-rrdcgi --disable-rrd_graph
 GRAPH_LIB_DEPENDS=	libfreetype.so:print/freetype2 \
 			libpng.so:graphics/png
 GRAPH_USE=		GNOME=cairo,pango
+LOCKTIMEOUT_EXTRA_PATCHES=${PATCHDIR}/extra-patch-locktimeout
 MMAP_CONFIGURE_ENABLE=	mmap
 NLS_CONFIGURE_ENABLE=	nls
 NLS_USE=		GNOME=intltool
diff --git a/databases/rrdtool/files/extra-patch-locktimeout b/databases/rrdtool/files/extra-patch-locktimeout
new file mode 100644
index 000000000000..9d6d4607a7fb
--- /dev/null
+++ b/databases/rrdtool/files/extra-patch-locktimeout
@@ -0,0 +1,80 @@
+--- 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,