Make sync RDB deletion configurable. Default to no.

src/config.c

@@ -2084,6 +2084,7 @@ standardConfig configs[] = {
     createBoolConfig("always-show-logo", NULL, IMMUTABLE_CONFIG, server.always_show_logo, 0, NULL, NULL),
     createBoolConfig("protected-mode", NULL, MODIFIABLE_CONFIG, server.protected_mode, 1, NULL, NULL),
     createBoolConfig("rdbcompression", NULL, MODIFIABLE_CONFIG, server.rdb_compression, 1, NULL, NULL),
+    createBoolConfig("rdb-del-sync-files", NULL, MODIFIABLE_CONFIG, server.rdb_del_sync_files, 0, NULL, NULL),
     createBoolConfig("activerehashing", NULL, MODIFIABLE_CONFIG, server.activerehashing, 1, NULL, NULL),
     createBoolConfig("stop-writes-on-bgsave-error", NULL, MODIFIABLE_CONFIG, server.stop_writes_on_bgsave_err, 1, NULL, NULL),
     createBoolConfig("dynamic-hz", NULL, MODIFIABLE_CONFIG, server.dynamic_hz, 1, NULL, NULL), /* Adapt hz to # of clients.*/

src/replication.c

@@ -625,8 +625,12 @@ int startBgsaveForReplication(int mincapa) {
     }
 
     /* If we succeeded to start a BGSAVE with disk target, let's remember
-     * this fact, so that we can later delete the file if needed. */
+     * this fact, so that we can later delete the file if needed. Note
-    if (retval == C_OK && !socket_target) RDBGeneratedByReplication = 1;
+     * that we don't set the flag to 1 if the feature is disabled, otherwise
+     * it would never be cleared: the file is not deleted. This way if
+     * the user enables it later with CONFIG SET, we are fine. */
+    if (retval == C_OK && !socket_target && server.rdb_del_sync_files)
+        RDBGeneratedByReplication = 1;
 
     /* If we failed to BGSAVE, remove the slaves waiting for a full
      * resynchronization from the list of slaves, inform them with
@@ -926,6 +930,17 @@ void putSlaveOnline(client *slave) {
  * to take RDB files around, this violates certain policies in certain
  * environments. */
 void removeRDBUsedToSyncReplicas(void) {
+    /* If the feature is disabled, return ASAP but also clear the
+     * RDBGeneratedByReplication flag in case it was set. Otherwise if the
+     * feature was enabled, but gets disabled later with CONFIG SET, the
+     * flag may remain set to one: then next time the feature is re-enabled
+     * via CONFIG SET we have have it set even if no RDB was generated
+     * because of replication recently. */
+    if (!server.rdb_del_sync_files) {
+        RDBGeneratedByReplication = 0;
+        return;
+    }
+
     if (allPersistenceDisabled() && RDBGeneratedByReplication) {
         client *slave;
         listNode *ln;
@@ -1713,7 +1728,7 @@ void readSyncBulkPayload(connection *conn) {
                 "Failed trying to load the MASTER synchronization "
                 "DB from disk");
             cancelReplicationHandshake();
-            if (allPersistenceDisabled()) {
+            if (server.rdb_del_sync_files && allPersistenceDisabled()) {
                 serverLog(LL_NOTICE,"Removing the RDB file obtained from "
                                     "the master. This replica has persistence "
                                     "disabled");
@@ -1725,7 +1740,7 @@ void readSyncBulkPayload(connection *conn) {
         }
 
         /* Cleanup. */
-        if (allPersistenceDisabled()) {
+        if (server.rdb_del_sync_files && allPersistenceDisabled()) {
             serverLog(LL_NOTICE,"Removing the RDB file obtained from "
                                 "the master. This replica has persistence "
                                 "disabled");

src/server.h

@@ -1202,6 +1202,8 @@ struct redisServer {
     char *rdb_filename;             /* Name of RDB file */
     int rdb_compression;            /* Use compression in RDB? */
     int rdb_checksum;               /* Use RDB checksum? */
+    int rdb_del_sync_files;         /* Remove RDB files used only for SYNC if
+                                       the instance does not use persistence. */
     time_t lastsave;                /* Unix time of last successful save */
     time_t lastbgsave_try;          /* Unix time of last attempted bgsave */
     time_t rdb_save_time_last;      /* Time used by last RDB save run. */