make connectWithMaster error message less confusing

* close tempfile when done bgsave

* declare getTempFileName

* open close child pipes in correct place

* assert no existing child pipe when opening new child pipe

src/childinfo.cpp

@@ -42,6 +42,7 @@ typedef struct {
  * RDB / AOF saving process from the child to the parent (for instance
  * the amount of copy on write memory used) */
 void openChildInfoPipe(void) {
+    serverAssert(g_pserver->child_info_pipe[0] == -1);
     if (pipe(g_pserver->child_info_pipe) == -1) {
         /* On error our two file descriptors should be still set to -1,
          * but we call anyway closeChildInfoPipe() since can't hurt. */

src/rdb.cpp

@@ -1490,7 +1490,7 @@ int rdbSaveFile(char *filename, const redisDbPersistentDataSnapshot **rgpdb, rdb
     rio rdb;
     int error = 0;
 
-    snprintf(tmpfile,sizeof(tmpfile),"temp-%d-%d.rdb", getpid(), g_pserver->rdbThreadVars.tmpfileNum);
+    getTempFileName(tmpfile, g_pserver->rdbThreadVars.tmpfileNum);
     fp = fopen(tmpfile,"w");
     if (!fp) {
         char *cwdp = getcwd(cwd,MAXPATHLEN);
@@ -1660,12 +1660,14 @@ int launchRdbSaveThread(pthread_t &child, rdbSaveInfo *rsi)
         pthread_attr_t tattr;
         pthread_attr_init(&tattr);
         pthread_attr_setstacksize(&tattr, 1 << 23); // 8 MB
+        openChildInfoPipe();
         if (pthread_create(&child, &tattr, rdbSaveThread, args)) {
             pthread_attr_destroy(&tattr);
             for (int idb = 0; idb < cserver.dbnum; ++idb)
                 g_pserver->db[idb]->endSnapshot(args->rgpdb[idb]);
             args->~rdbSaveThreadArgs();
             zfree(args);
+            closeChildInfoPipe();
             return C_ERR;
         }
         pthread_attr_destroy(&tattr);
@@ -1683,13 +1685,11 @@ int rdbSaveBackground(rdbSaveInfo *rsi) {
 
     g_pserver->dirty_before_bgsave = g_pserver->dirty;
     g_pserver->lastbgsave_try = time(NULL);
-    openChildInfoPipe();
 
     start = ustime();
     latencyStartMonitor(g_pserver->rdb_save_latency);
 
     if (launchRdbSaveThread(child, rsi) != C_OK) {
-        closeChildInfoPipe();
         g_pserver->lastbgsave_status = C_ERR;
         serverLog(LL_WARNING,"Can't save in background: fork: %s",
             strerror(errno));

src/rdb.h

@@ -151,6 +151,7 @@ int rdbLoad(rdbSaveInfo *rsi, int rdbflags);
 int rdbLoadFile(const char *filename, rdbSaveInfo *rsi, int rdbflags);
 int rdbSaveBackground(rdbSaveInfo *rsi);
 int rdbSaveToSlavesSockets(rdbSaveInfo *rsi);
+void getTempFileName(char tmpfile[], int tmpfileNum);
 void rdbRemoveTempFile(pid_t childpid, int from_signal);
 int rdbSave(const redisDbPersistentDataSnapshot **rgpdb, rdbSaveInfo *rsi);
 int rdbSaveFile(char *filename, const redisDbPersistentDataSnapshot **rgpdb, rdbSaveInfo *rsi);

src/replication.cpp

@@ -3797,9 +3797,11 @@ int connectWithMaster(redisMaster *mi) {
     connSetPrivateData(mi->repl_transfer_s, mi);
     if (connConnect(mi->repl_transfer_s, mi->masterhost, mi->masterport,
                 NET_FIRST_BIND_ADDR, syncWithMaster) == C_ERR) {
-        int sev = g_pserver->enable_multimaster ? LL_NOTICE : LL_WARNING;   // with multimaster its not unheard of to intentiallionall have downed masters
-        serverLog(sev,"Unable to connect to MASTER: %s",
-                connGetLastError(mi->repl_transfer_s));
+        const char *err = "Unknown Error";
+        if (mi->repl_transfer_s->last_errno != 0)
+            err = connGetLastError(mi->repl_transfer_s);
+        int sev = g_pserver->enable_multimaster ? LL_NOTICE : LL_WARNING;   // with multimaster its not unheard of to intentionally have downed masters
+        serverLog(sev, "Unable to connect to MASTER: %s", err);
         connClose(mi->repl_transfer_s);
         mi->repl_transfer_s = NULL;
         return C_ERR;