added cache-flush-delay configuration directive. Don't BGSAVE when using diskstore

src/config.c

@@ -250,6 +250,9 @@ void loadServerConfig(char *filename) {
             server.ds_path = sdsnew(argv[1]);
         } else if (!strcasecmp(argv[0],"cache-max-memory") && argc == 2) {
             server.cache_max_memory = memtoll(argv[1],NULL);
+        } else if (!strcasecmp(argv[0],"cache-flush-delay") && argc == 2) {
+            server.cache_flush_delay = atoi(argv[1]);
+            if (server.cache_flush_delay < 0) server.cache_flush_delay = 0;
         } else if (!strcasecmp(argv[0],"hash-max-zipmap-entries") && argc == 2) {
             server.hash_max_zipmap_entries = memtoll(argv[1], NULL);
         } else if (!strcasecmp(argv[0],"hash-max-zipmap-value") && argc == 2) {

src/redis.c

@@ -596,7 +596,7 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
             }
             updateDictResizePolicy();
         }
-    } else {
+    } else if (!server.ds_enabled) {
         /* If there is not a background saving in progress check if
          * we have to save now */
          time_t now = time(NULL);