postgresql plugin: Reinitialize a database after reconnecting.

During initialization we get the right version of each query definition. After
reconnecting, the PostgreSQL server version might have changed, so we might
need to update some of the query definitions.

diff --git a/src/postgresql.c b/src/postgresql.c
index 6c8b814..ccd357c 100644 (file)
--- a/src/postgresql.c
+++ b/src/postgresql.c
@@ -112,6 +112,7 @@ typedef struct {
 
        /* user configuration */
        c_psql_query_t **queries;
+       int             *hidden_queries;
        int              queries_num;
 
        char *host;
@@ -223,8 +224,9 @@ static c_psql_database_t *c_psql_database_new (const char *name)
 
        db->max_params_num = 0;
 
-       db->queries     = NULL;
-       db->queries_num = 0;
+       db->queries        = NULL;
+       db->hidden_queries = NULL;
+       db->queries_num    = 0;
 
        db->database   = sstrdup (name);
        db->host       = NULL;
@@ -240,12 +242,42 @@ static c_psql_database_t *c_psql_database_new (const char *name)
        return db;
 } /* c_psql_database_new */
 
+static void c_psql_database_init (c_psql_database_t *db, int server_version)
+{
+       int i;
+
+       /* Get the right version of each query definition. */
+       for (i = 0; i < db->queries_num; ++i) {
+               c_psql_query_t *tmp;
+
+               tmp = c_psql_query_get (db->queries[i]->name, server_version);
+
+               if (tmp == db->queries[i])
+                       continue;
+
+               if (NULL == tmp) {
+                       log_err ("Query \"%s\" not found for server version %i - "
+                                       "please check your configuration.",
+                                       db->queries[i]->name, server_version);
+                       /* By hiding the query (rather than removing it from the list) we
+                        * don't lose it in case a reconnect to an available version
+                        * happens at a later time. */
+                       db->hidden_queries[i] = 1;
+                       continue;
+               }
+
+               db->hidden_queries[i] = 0;
+               db->queries[i] = tmp;
+       }
+} /* c_psql_database_init */
+
 static void c_psql_database_delete (c_psql_database_t *db)
 {
        PQfinish (db->conn);
        db->conn = NULL;
 
        sfree (db->queries);
+       sfree (db->hidden_queries);
        db->queries_num = 0;
 
        sfree (db->database);
@@ -343,6 +375,11 @@ static int c_psql_check_connection (c_psql_database_t *db)
                                        db->proto_version);
        }
 
+       /* We might have connected to a different PostgreSQL version, so we
+        * need to reinitialize stuff. */
+       if (c_would_release (&db->conn_complaint))
+               c_psql_database_init (db, PQserverVersion (db->conn));
+
        c_release (LOG_INFO, &db->conn_complaint,
                        "Successfully reconnected to database %s", PQdb (db->conn));
        return 0;
@@ -395,6 +432,9 @@ static int c_psql_exec_query (c_psql_database_t *db, int idx)
        if (idx >= db->queries_num)
                return -1;
 
+       if (0 != db->hidden_queries[idx])
+               return 0;
+
        query = db->queries[idx];
 
        if (3 <= db->proto_version)
@@ -548,8 +588,6 @@ static int c_psql_init (void)
                char *server_host;
                int   server_version;
 
-               int j;
-
                /* this will happen during reinitialization */
                if (NULL != db->conn) {
                        c_psql_check_connection (db);
@@ -590,32 +628,7 @@ static int c_psql_init (void)
                        log_warn ("Protocol version %d does not support parameters.",
                                        db->proto_version);
 
-               /* Now that we know the PostgreSQL server version, we can get the
-                * right version of each query definition. */
-               for (j = 0; j < db->queries_num; ++j) {
-                       c_psql_query_t *tmp;
-
-                       tmp = c_psql_query_get (db->queries[j]->name, server_version);
-
-                       if (tmp == db->queries[j])
-                               continue;
-
-                       if (NULL == tmp) {
-                               log_err ("Query \"%s\" not found for server version %i - "
-                                               "please check your configuration.",
-                                               db->queries[j]->name, server_version);
-
-                               if (db->queries_num - j - 1 > 0)
-                                       memmove (db->queries + j, db->queries + j + 1,
-                                                       (db->queries_num - j - 1) * sizeof (*db->queries));
-
-                               --db->queries_num;
-                               --j;
-                               continue;
-                       }
-
-                       db->queries[j] = tmp;
-               }
+               c_psql_database_init (db, server_version);
        }
 
        plugin_register_read ("postgresql", c_psql_read);
@@ -757,7 +770,7 @@ static int c_psql_config_query (oconfig_item_t *ci)
 {
        c_psql_query_t *query;
 
-       int i;
+       int status = 0, i;
 
        if ((1 != ci->values_num)
                        || (OCONFIG_TYPE_STRING != ci->values[0].type)) {
@@ -797,26 +810,27 @@ static int c_psql_config_query (oconfig_item_t *ci)
                                && (query->min_pg_version <= q->max_pg_version)) {
                        log_err ("Ignoring redefinition (with overlapping version ranges) "
                                        "of query \"%s\".", query->name);
-                       c_psql_query_delete (query);
-                       --queries_num;
-                       return 1;
+                       status = 1;
+                       break;
                }
        }
 
        if (query->min_pg_version > query->max_pg_version) {
                log_err ("Query \"%s\": MinPGVersion > MaxPGVersion.",
                                query->name);
-               c_psql_query_delete (query);
-               --queries_num;
-               return 1;
+               status = 1;
        }
 
        if (NULL == query->stmt) {
                log_err ("Query \"%s\" does not include an SQL query statement - "
                                "please check your configuration.", query->name);
+               status = 1;
+       }
+
+       if (0 != status) {
                c_psql_query_delete (query);
                --queries_num;
-               return 1;
+               return status;
        }
        return 0;
 } /* c_psql_config_query */
@@ -862,8 +876,15 @@ static int c_psql_config_database (oconfig_item_t *ci)
                for (i = 0; i < def_queries_num; ++i)
                        set_query (db, def_queries[i]);
        }
+
+       db->hidden_queries = (int *)calloc (db->queries_num,
+                       sizeof (*db->hidden_queries));
+       if (NULL == db->hidden_queries) {
+               log_err ("Out of memory.");
+               exit (5);
+       }
        return 0;
-}
+} /* c_psql_config_database */
 
 static int c_psql_config (oconfig_item_t *ci)
 {