Fix query cache lock file handling.

Query cache module creates a lock file under logdir for concurrency
control. However, there were bugs in the handling:

1) Garbage file "QUERY_CACHE_LOCK_FILE" was created by pgpool main
   process.

2) The lock file was not removed upon pgpool shutdown.

This commit fixes the bugs.

Author: Tatsuo Ishii <ishii@postgresql.org>
Reported-by: Bo Peng <pengbo@sraoss.co.jp>
Reviewed-by: Bo Peng <pengbo@sraoss.co.jp>
Backpatch-through: v4.4

diff --git a/src/main/pgpool_main.c b/src/main/pgpool_main.c
index 40376b2f80be3c4f8da44cf7ef5e2dae0295e335..c73296665be3f3c140908a9d013ca7a79bb0da1b 100644 (file)
--- a/src/main/pgpool_main.c
+++ b/src/main/pgpool_main.c
@@ -306,6 +306,12 @@ PgpoolMain(bool discard_status, bool clear_memcache_oidmaps)
         */
        volatile bool first = true;
 
+       /*
+        * Query cache lock file path. This should be declared as "static" because
+        * the path is passed to be registered using on_proc_exit().
+        */
+       static char query_cache_lock_path[MAXPGPATH];
+
        processState = INITIALIZING;
 
        /*
@@ -512,23 +518,23 @@ PgpoolMain(bool discard_status, bool clear_memcache_oidmaps)
        }
 
        /* For query cache concurrency control */
-       if (pool_config->memory_cache_enabled)
+       if (pool_config->memory_cache_enabled || pool_config->enable_shared_relcache)
        {
-               char            path[1024];
                int                     lfd;
 
-               snprintf(path, sizeof(path), "%s/QUERY_CACHE_LOCK_FILE", pool_config->logdir);
-               lfd = open(path, O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR);
+               snprintf(query_cache_lock_path, sizeof(query_cache_lock_path),
+                                "%s/%s", pool_config->logdir, QUERY_CACHE_LOCK_FILE);
+               lfd = open(query_cache_lock_path, O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR);
                if (lfd == -1)
                {
                        ereport(FATAL,
-                                       (errmsg("Failed to open lock file for query cache \"%s\"", path),
+                                       (errmsg("Failed to open lock file for query cache \"%s\"", query_cache_lock_path),
                                         errdetail("%m")));
                }
                close(lfd);
 
                /* Register file unlink at exit */
-               on_proc_exit(FileUnlink, (Datum) path);
+               on_proc_exit(FileUnlink, (Datum) query_cache_lock_path);
        }
 
        /*
@@ -1652,14 +1658,14 @@ failover(void)
                 */
                if (failover_context.request_details & REQ_DETAIL_PROMOTE)
                {
-                       promote_node = failover_context.node_id_set[0]; /* requested node */
+                       promote_node = failover_context.node_id_set[0]; /* requested node */
                        for (i = 0; i < failover_context.node_count; i++)
                        {
                                failover_context.node_id_set[i] = REAL_PRIMARY_NODE_ID;
                        }
                }
 
-               node_id = failover_context.node_id_set[0];              /* set target node id */
+               node_id = failover_context.node_id_set[0];      /* set target node id */
 
                /* failback request? */
                if (failover_context.reqkind == NODE_UP_REQUEST)