live: add ping responder capability for live nodes

Author: justinclift

common/live_types.go

@@ -39,7 +39,7 @@ type JobResponseDBCreate struct {
 	NodeName string `json:"node_name"`
 }
 
-// JobResponseDBError holds the structure used when our job queue backend only needs to response with an error field (empty or not)
+// JobResponseDBError holds the structure used when our job queue backend only needs to respond with an error field (empty or not)
 type JobResponseDBError struct {
 	Err string `json:"error"`
 }

common/memcache.go

@@ -82,7 +82,7 @@ func ConnectCache() (err error) {
 }
 
 // DeleteCacheItem deletes the cached item with the given key if it exists
-func DeleteCacheItem(cacheKey string) (error) {
+func DeleteCacheItem(cacheKey string) error {
 	err := memCache.Delete(cacheKey)
 
 	// We don't care about cache misses

common/postgresql_live.go

@@ -222,7 +222,13 @@ func JobQueueCheck() {
 			}
 
 		case "ping":
-			// TODO: Write a ping responder so we can internally check if live nodes are responding
+			// This just returns an empty response
+			var response JobResponseDBError
+			responsePayload, err = json.Marshal(response)
+			if err != nil {
+				log.Printf("%s: error when serialising ping response json: %s", config.Conf.Live.Nodename, err)
+				responsePayload = []byte(fmt.Sprintf(`{"error": "%s"}`, err))
+			}
 
 		case "query":
 			if JobQueueDebug > 0 {