dbi plugin: register one read callback for each database block

By using a distinct read callback for each database block, collectd
will be able to query several databases in parallel. This is useful if
the plugin should handle many queries. This lets the user split them in
chunks and speed up the retrieval.

diff --git a/src/dbi.c b/src/dbi.c
index 45e0d31..779c723 100644 (file)
--- a/src/dbi.c
+++ b/src/dbi.c
@@ -68,6 +68,8 @@ static size_t            queries_num   = 0;
 static cdbi_database_t **databases     = NULL;
 static size_t            databases_num = 0;
 
+static int cdbi_read_database (user_data_t *ud);
+
 /*
  * Functions
  */
@@ -369,9 +371,24 @@ static int cdbi_config_add_database (oconfig_item_t *ci) /* {{{ */
     }
     else
     {
+      user_data_t ud;
+      char *name = NULL;
+
       databases = temp;
       databases[databases_num] = db;
       databases_num++;
+
+      memset (&ud, 0, sizeof (ud));
+      ud.data = (void *) db;
+      ud.free_func = NULL;
+      name = ssnprintf_alloc("dbi:%s", db->name);
+
+      plugin_register_complex_read (/* group = */ NULL,
+          /* name = */ name ? name : db->name,
+          /* callback = */ cdbi_read_database,
+          /* interval = */ NULL,
+          /* user_data = */ &ud);
+      free (name);
     }
   }
 
@@ -758,8 +775,9 @@ static int cdbi_connect_database (cdbi_database_t *db) /* {{{ */
   return (0);
 } /* }}} int cdbi_connect_database */
 
-static int cdbi_read_database (cdbi_database_t *db) /* {{{ */
+static int cdbi_read_database (user_data_t *ud) /* {{{ */
 {
+  cdbi_database_t *db = (cdbi_database_t *) ud->data;
   size_t i;
   int success;
   int status;
@@ -798,29 +816,6 @@ static int cdbi_read_database (cdbi_database_t *db) /* {{{ */
   return (0);
 } /* }}} int cdbi_read_database */
 
-static int cdbi_read (void) /* {{{ */
-{
-  size_t i;
-  int success = 0;
-  int status;
-
-  for (i = 0; i < databases_num; i++)
-  {
-    status = cdbi_read_database (databases[i]);
-    if (status == 0)
-      success++;
-  }
-
-  if (success == 0)
-  {
-    ERROR ("dbi plugin: No database could be read. Will return an error so "
-        "the plugin will be delayed.");
-    return (-1);
-  }
-
-  return (0);
-} /* }}} int cdbi_read */
-
 static int cdbi_shutdown (void) /* {{{ */
 {
   size_t i;
@@ -848,7 +843,6 @@ void module_register (void) /* {{{ */
 {
   plugin_register_complex_config ("dbi", cdbi_config);
   plugin_register_init ("dbi", cdbi_init);
-  plugin_register_read ("dbi", cdbi_read);
   plugin_register_shutdown ("dbi", cdbi_shutdown);
 } /* }}} void module_register */