Introduce bgsave cancel

src/rdb.c

@@ -3645,6 +3645,18 @@ void bgsaveCommand(client *c) {
     if (c->argc > 1) {
         if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr, "schedule")) {
             schedule = 1;
+        } else if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr, "cancel")) {
+            /* BGSAVE CANCEL
+             * Terminates an in progress BGSAVE */
+            if (server.child_type == CHILD_TYPE_RDB) {
+                /* There is an ongoing save */
+                serverLog(LL_NOTICE, "Background save requested to be canceled by user");
+                killRDBChild();
+                addReply(c, shared.ok);
+            } else {
+                addReplyError(c, "background save is currently not in progress");
+            }
+            return;
         } else {
             addReplyErrorObject(c, shared.syntaxerr);
             return;

tests/integration/rdb.tcl

@@ -170,6 +170,46 @@ start_server {} {
         }
         assert_equal [s rdb_changes_since_last_save] 0
     }
+
+    test {bgsave cancel aborts save} {
+        r config set save ""
+        # Generating RDB will take some 100 seconds
+        r config set rdb-key-save-delay 1000000
+        populate 100 "" 16
+
+        r bgsave
+        wait_for_condition 50 100 {
+            [s rdb_bgsave_in_progress] == 1
+        } else {
+            fail "bgsave not done"
+        }
+        set fork_child_pid [get_child_pid 0]
+
+        assert {[r bgsave cancel] eq {OK}}
+        set temp_rdb [file join [lindex [r config get dir] 1] temp-${fork_child_pid}.rdb]
+        # Temp rdb must be existed
+        wait_for_condition 50 100 {
+            ![file exists $temp_rdb]
+        } else {
+            fail "bgsave temp file was not deleted after cancel"
+        }
+    }
+
+    test {bgsave cancel response with error when no ongoing save} {
+        r config set save ""
+        # Generating RDB will take some 100 seconds
+        r config set rdb-key-save-delay 0
+
+        # Make sure no save is running and that bgsave return an error
+         wait_for_condition 50 100 {
+            [s rdb_bgsave_in_progress] == 0
+        } else {
+            fail "bgsave is currently running"
+        }
+        assert_error "ERR background save is currently not in progress" {r bgsave cancel}
+    }
+
+
 }
 
 test {client freed during loading} {