ping plugin: Add the hosts during initialization, not when reading the config file.

Since adding a host to liboping might block when no nameserver can be reached
or another problem occures (normally this means network misconfiguration) it's
not the best idea to do this when reading the config file. At that point we
didn't fork to the background yet, so the boot process may hang which is not good.

Also, hosts that cannot be added right away are tried again in increasing intervals.

diff --git a/src/ping.c b/src/ping.c
index 8e2c50b..2a2f03e 100644 (file)
--- a/src/ping.c
+++ b/src/ping.c
@@ -31,7 +31,17 @@
 #include <netinet/in.h>
 #include "liboping/oping.h"
 
+struct hostlist_s
+{
+       char *host;
+       int   wait_time;
+       int   wait_left;
+       struct hostlist_s *next;
+};
+typedef struct hostlist_s hostlist_t;
+
 static pingobj_t *pingobj = NULL;
+static hostlist_t *hosts = NULL;
 
 static char *file_template = "ping-%s.rrd";
 
@@ -50,9 +60,59 @@ static char *config_keys[] =
 };
 static int config_keys_num = 2;
 
+static void add_hosts (void)
+{
+       hostlist_t *hl_this;
+       hostlist_t *hl_prev;
+
+       int step = atoi (COLLECTD_STEP);
+
+       hl_this = hosts;
+       hl_prev = NULL;
+       while (hl_this != NULL)
+       {
+               DBG ("host = %s, wait_left = %i, wait_time = %i, next = %p",
+                               hl_this->host, hl_this->wait_left, hl_this->wait_time, (void *) hl_this->next);
+
+               if (hl_this->wait_left <= 0)
+               {
+                       if (ping_host_add (pingobj, hl_this->host) == 0)
+                       {
+                               DBG ("Successfully added host %s", hl_this->host);
+                               /* Remove the host from the linked list */
+                               if (hl_prev != NULL)
+                                       hl_prev->next = hl_this->next;
+                               else
+                                       hosts = hl_this->next;
+                               free (hl_this->host);
+                               free (hl_this);
+                               hl_this = (hl_prev != NULL) ? hl_prev : hosts;
+                       }
+                       else
+                       {
+                               hl_this->wait_left = hl_this->wait_time;
+                               hl_this->wait_time *= 2;
+                               if (hl_this->wait_time > 86400)
+                                       hl_this->wait_time = 86400;
+                       }
+               }
+               else
+               {
+                       hl_this->wait_left -= step;
+               }
+
+               if (hl_this != NULL)
+               {
+                       hl_prev = hl_this;
+                       hl_this = hl_this->next;
+               }
+       }
+}
+
 static void ping_init (void)
 {
-       return;
+       if (hosts != NULL)
+               add_hosts ();
 }
 
 static int ping_config (char *key, char *value)
@@ -69,12 +129,29 @@ static int ping_config (char *key, char *value)
 
        if (strcasecmp (key, "host") == 0)
        {
-               if (ping_host_add (pingobj, value) < 0)
+               hostlist_t *hl;
+               char *host;
+               int step = atoi (COLLECTD_STEP);
+
+               if ((hl = (hostlist_t *) malloc (sizeof (hostlist_t))) == NULL)
                {
-                       syslog (LOG_WARNING, "ping: `ping_host_add' failed: %s",
-                                       ping_get_error (pingobj));
+                       syslog (LOG_ERR, "ping plugin: malloc failed: %s",
+                                       strerror (errno));
+                       return (1);
+               }
+               if ((host = strdup (value)) == NULL)
+               {
+                       free (hl);
+                       syslog (LOG_ERR, "ping plugin: strdup failed: %s",
+                                       strerror (errno));
                        return (1);
                }
+
+               hl->host = host;
+               hl->wait_time = 2 * step;
+               hl->wait_left = 0;
+               hl->next = hosts;
+               hosts = hl;
        }
        else if (strcasecmp (key, "ttl") == 0)
        {
@@ -130,6 +207,9 @@ static void ping_read (void)
        if (pingobj == NULL)
                return;
 
+       if (hosts != NULL)
+               add_hosts ();
+
        if (ping_send (pingobj) < 0)
        {
                syslog (LOG_ERR, "ping: `ping_send' failed: %s",