rrdtool plugin: Serialise access to the cache and to the function from the librrd.

diff --git a/src/rrdtool.c b/src/rrdtool.c
index 3bb8e0754439bcf9846a113faf2fa6f4770f93c8..6dc14c763d01dffa8434f82874cdda2da48058a4 100644 (file)
--- a/src/rrdtool.c
+++ b/src/rrdtool.c
@@ -24,6 +24,10 @@
 #include "common.h"
 #include "utils_avltree.h"
 
+#if HAVE_PTHREAD_H
+# include <pthread.h>
+#endif
+
 /*
  * Private types
  */
@@ -78,6 +82,7 @@ static int         cache_timeout = 0;
 static int         cache_flush_timeout = 0;
 static time_t      cache_flush_last;
 static avl_tree_t *cache = NULL;
+static pthread_mutex_t cache_lock = PTHREAD_MUTEX_INITIALIZER;
 
 /* * * * * * * * * *
  * WARNING:  Magic *
@@ -485,6 +490,9 @@ static int rrd_write_cache_entry (const char *filename, rrd_cache_t *rc)
 
        int i;
 
+       if (rc->values_num < 1)
+               return (0);
+
        argc = rc->values_num + 2;
        argv = (char **) malloc ((argc + 1) * sizeof (char *));
        if (argv == NULL)
@@ -507,10 +515,15 @@ static int rrd_write_cache_entry (const char *filename, rrd_cache_t *rc)
        optind = 0; /* bug in librrd? */
        rrd_clear_error ();
        status = rrd_update (argc, argv);
+       if (status != 0)
+       {
+               WARNING ("rrd_update failed: %s: %s",
+                               filename, rrd_get_error ());
+               status = -1;
+       }
 
        free (argv);
        free (fn);
-
        /* Free the value list of `rc' */
        for (i = 0; i < rc->values_num; i++)
                free (rc->values[i]);
@@ -518,14 +531,7 @@ static int rrd_write_cache_entry (const char *filename, rrd_cache_t *rc)
        rc->values = NULL;
        rc->values_num = 0;
 
-       if (status != 0)
-       {
-               WARNING ("rrd_update failed: %s: %s",
-                               filename, rrd_get_error ());
-               return (-1);
-       }
-
-       return (0);
+       return (status);
 } /* int rrd_write_cache_entry */
 
 static void rrd_cache_flush (int timeout)
@@ -630,15 +636,20 @@ static int rrd_write (const data_set_t *ds, const value_list_t *vl)
                return (-1);
        }
 
+       pthread_mutex_lock (&cache_lock);
        rc = rrd_cache_insert (filename, values);
        if (rc == NULL)
+       {
+               pthread_mutex_unlock (&cache_lock);
                return (-1);
+       }
 
        if (cache == NULL)
        {
                rrd_write_cache_entry (filename, rc);
                /* rc's value-list is free's by `rrd_write_cache_entry' */
                sfree (rc);
+               pthread_mutex_unlock (&cache_lock);
                return (0);
        }
 
@@ -654,6 +665,7 @@ static int rrd_write (const data_set_t *ds, const value_list_t *vl)
        if ((now - cache_flush_last) >= cache_flush_timeout)
                rrd_cache_flush (cache_flush_timeout);
 
+       pthread_mutex_unlock (&cache_lock);
        return (0);
 } /* int rrd_write */
 
@@ -754,10 +766,12 @@ static int rrd_config (const char *key, const char *value)
 
 static int rrd_shutdown (void)
 {
+       pthread_mutex_lock (&cache_lock);
        rrd_cache_flush (-1);
        if (cache != NULL)
                avl_destroy (cache);
        cache = NULL;
+       pthread_mutex_unlock (&cache_lock);
 
        return (0);
 } /* int rrd_shutdown */
@@ -778,6 +792,7 @@ static int rrd_init (void)
                                "smaller than your `interval'. This will "
                                "create needlessly big RRD-files.");
 
+       pthread_mutex_lock (&cache_lock);
        if (cache_timeout < 2)
        {
                cache_timeout = 0;
@@ -792,8 +807,10 @@ static int rrd_init (void)
                cache_flush_last = time (NULL);
                plugin_register_shutdown ("rrdtool", rrd_shutdown);
        }
+       pthread_mutex_unlock (&cache_lock);
 
-       DEBUG ("datadir = %s; stepsize = %i; heartbeat = %i; rrarows = %i; xff = %lf;",
+       DEBUG ("rrdtool plugin: rrd_init: datadir = %s; stepsize = %i;"
+                       " heartbeat = %i; rrarows = %i; xff = %lf;",
                        (datadir == NULL) ? "(null)" : datadir,
                        stepsize, heartbeat, rrarows, xff);