Diskless replication: read report from child.

Author: antirez

src/rdb.c

@@ -1274,14 +1274,10 @@ void backgroundSaveDoneHandlerDisk(int exitcode, int bysignal) {
 
 /* A background saving child (BGSAVE) terminated its work. Handle this.
  * This function covers the case of RDB -> Salves socket transfers for
- * diskless replication.
- *
- * TODO:
- * 1) Read from the pipe the set of IDs which are fine. This should be
- *    just an uint32_t with the len, and N pid_t elements.
- * 2) Close all the slaves in state REDIS_REPL_WAIT_BGSAVE_END but are
- *    not reported as "transfer ok" by the child. */
+ * diskless replication. */
 void backgroundSaveDoneHandlerSocket(int exitcode, int bysignal) {
+    uint64_t *ok_slaves;
+
     if (!bysignal && exitcode == 0) {
         redisLog(REDIS_NOTICE,
             "Background RDB transfer terminated with success");
@@ -1294,18 +1290,64 @@ void backgroundSaveDoneHandlerSocket(int exitcode, int bysignal) {
     server.rdb_child_pid = -1;
     server.rdb_child_type = REDIS_RDB_CHILD_TYPE_NONE;
     server.rdb_save_time_start = -1;
-    /* Read the set of slave client IDs that currently received the full
-     * RDB payload, closing all the slaves which are not among the ones
-     * listed. */
-
-    /* TODO ... */
 
-    /* Close the pipe FDs. */
+    /* If the child returns an OK exit code, read the set of slave client
+     * IDs that received the full RDB payload, closing all the slaves
+     * which are not among the ones listed.
+     *
+     * If the process returned an error, consider the list of slaves that
+     * can continue to be emtpy, so that it's just a speical case of the
+     * normal code path. */
+    ok_slaves = zmalloc(sizeof(uint64_t)); /* Make space for the count. */
+    ok_slaves = 0;
+    if (!bysignal && exitcode == 0) {
+        int readlen = sizeof(uint64_t);
+
+        if (read(server.rdb_pipe_read_result_from_child, ok_slaves, readlen) !=
+                 readlen)
+        {
+            readlen = ok_slaves[0]*sizeof(uint64_t);
+
+            /* Make space for enough elements as specified by the first
+             * uint64_t element in the array. */
+            ok_slaves = zrealloc(ok_slaves,sizeof(uint64_t)+readlen);
+            if (readlen &&
+                read(server.rdb_pipe_read_result_from_child, ok_slaves+1,
+                     readlen) != readlen)
+            {
+                ok_slaves[0] = 0;
+            }
+        }
+    }
 
-    /* TODO ... */
+    close(server.rdb_pipe_read_result_from_child);
+    close(server.rdb_pipe_write_result_to_parent);
 
     /* We can continue the replication process with all the slaves that
-     * correctly received the full payload. */
+     * correctly received the full payload. Others are terminated. */
+    listNode *ln;
+    listIter li;
+
+    listRewind(server.slaves,&li);
+    while((ln = listNext(&li))) {
+        redisClient *slave = ln->value;
+
+        if (slave->replstate == REDIS_REPL_WAIT_BGSAVE_END) {
+            uint64_t j;
+
+            for (j = 1; j < ok_slaves[0]; j++) {
+                if (slave->id == ok_slaves[j]) break; /* Found in the OK list. */
+            }
+            if (j == ok_slaves[0]) {
+                redisLog(REDIS_WARNING,
+                "Closing slave %llu: child->slave RDB transfer failed.",
+                slave->id);
+                freeClient(slave);
+            }
+        }
+    }
+    zfree(ok_slaves);
+
     updateSlavesWaitingBgsave((!bysignal && exitcode == 0) ? REDIS_OK : REDIS_ERR, REDIS_RDB_CHILD_TYPE_SOCKET);
 }