diskless replication rdb transfer uses pipe, and writes to sockets form the parent process.

misc:
- handle SSL_has_pending by iterating though these in beforeSleep, and setting timeout of 0 to aeProcessEvents
- fix issue with epoll signaling EPOLLHUP and EPOLLERR only to the write handlers. (needed to detect the rdb pipe was closed)
- add key-load-delay config for testing
- trim connShutdown which is no longer needed
- rioFdsetWrite -> rioFdWrite - simplified since there's no longer need to write to multiple FDs
- don't detect rdb child exited (don't call wait3) until we detect the pipe is closed
- Cleanup bad optimization from rio.c, add another one

src/server.c

@@ -1746,6 +1746,48 @@ void updateCachedTime(void) {
     server.daylight_active = tm.tm_isdst;
 }
 
+void checkChildrenDone(void) {
+    int statloc;
+    pid_t pid;
+
+    /* If we have a diskless rdb child (note that we support only one concurrent
+     * child), we want to avoid collecting it's exit status and acting on it
+     * as long as we didn't finish to drain the pipe, since then we're at risk
+     * of starting a new fork and a new pipe before we're done with the previous
+     * one. */
+    if (server.rdb_child_pid != -1 && server.rdb_pipe_conns)
+        return;
+
+    if ((pid = wait3(&statloc,WNOHANG,NULL)) != 0) {
+        int exitcode = WEXITSTATUS(statloc);
+        int bysignal = 0;
+
+        if (WIFSIGNALED(statloc)) bysignal = WTERMSIG(statloc);
+
+        if (pid == -1) {
+            serverLog(LL_WARNING,"wait3() returned an error: %s. "
+                "rdb_child_pid = %d, aof_child_pid = %d",
+                strerror(errno),
+                (int) server.rdb_child_pid,
+                (int) server.aof_child_pid);
+        } else if (pid == server.rdb_child_pid) {
+            backgroundSaveDoneHandler(exitcode,bysignal);
+            if (!bysignal && exitcode == 0) receiveChildInfo();
+        } else if (pid == server.aof_child_pid) {
+            backgroundRewriteDoneHandler(exitcode,bysignal);
+            if (!bysignal && exitcode == 0) receiveChildInfo();
+        } else {
+            if (!ldbRemoveChild(pid)) {
+                serverLog(LL_WARNING,
+                    "Warning, detected child with unmatched pid: %ld",
+                    (long)pid);
+            }
+        }
+        updateDictResizePolicy();
+        closeChildInfoPipe();
+    }
+}
+
 /* This is our timer interrupt, called server.hz times per second.
  * Here is where we do a number of things that need to be done asynchronously.
  * For instance:
@@ -1898,37 +1940,7 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
     if (server.rdb_child_pid != -1 || server.aof_child_pid != -1 ||
         ldbPendingChildren())
     {
-        int statloc;
-        pid_t pid;
-
-        if ((pid = wait3(&statloc,WNOHANG,NULL)) != 0) {
-            int exitcode = WEXITSTATUS(statloc);
-            int bysignal = 0;
-
-            if (WIFSIGNALED(statloc)) bysignal = WTERMSIG(statloc);
-
-            if (pid == -1) {
-                serverLog(LL_WARNING,"wait3() returned an error: %s. "
-                    "rdb_child_pid = %d, aof_child_pid = %d",
-                    strerror(errno),
-                    (int) server.rdb_child_pid,
-                    (int) server.aof_child_pid);
-            } else if (pid == server.rdb_child_pid) {
-                backgroundSaveDoneHandler(exitcode,bysignal);
-                if (!bysignal && exitcode == 0) receiveChildInfo();
-            } else if (pid == server.aof_child_pid) {
-                backgroundRewriteDoneHandler(exitcode,bysignal);
-                if (!bysignal && exitcode == 0) receiveChildInfo();
-            } else {
-                if (!ldbRemoveChild(pid)) {
-                    serverLog(LL_WARNING,
-                        "Warning, detected child with unmatched pid: %ld",
-                        (long)pid);
-                }
-            }
-            updateDictResizePolicy();
-            closeChildInfoPipe();
-        }
+        checkChildrenDone();
     } else {
         /* If there is not a background saving/rewrite in progress check if
          * we have to save/rewrite now. */
@@ -2081,6 +2093,11 @@ void beforeSleep(struct aeEventLoop *eventLoop) {
     /* Handle writes with pending output buffers. */
     handleClientsWithPendingWritesUsingThreads();
 
+    /* TODO: How do i handle write barriers flag */
+    tlsProcessPendingData();
+    /* If tls already has pending unread data don't sleep at all. */
+    aeDontWait(server.el, tlsHasPendingData());
+
     /* Close clients that need to be closed asynchronous */
     freeClientsInAsyncFreeQueue();
 
@@ -2280,6 +2297,7 @@ void initServerConfig(void) {
     server.aof_rewrite_incremental_fsync = CONFIG_DEFAULT_AOF_REWRITE_INCREMENTAL_FSYNC;
     server.rdb_save_incremental_fsync = CONFIG_DEFAULT_RDB_SAVE_INCREMENTAL_FSYNC;
     server.rdb_key_save_delay = CONFIG_DEFAULT_RDB_KEY_SAVE_DELAY;
+    server.key_load_delay = CONFIG_DEFAULT_KEY_LOAD_DELAY;
     server.aof_load_truncated = CONFIG_DEFAULT_AOF_LOAD_TRUNCATED;
     server.aof_use_rdb_preamble = CONFIG_DEFAULT_AOF_USE_RDB_PREAMBLE;
     server.pidfile = NULL;
@@ -2813,6 +2831,11 @@ void initServer(void) {
     server.rdb_child_pid = -1;
     server.aof_child_pid = -1;
     server.rdb_child_type = RDB_CHILD_TYPE_NONE;
+    server.rdb_pipe_conns = NULL;
+    server.rdb_pipe_numconns = 0;
+    server.rdb_pipe_numconns_writing = 0;
+    server.rdb_pipe_buff = NULL;
+    server.rdb_pipe_bufflen = 0;
     server.rdb_bgsave_scheduled = 0;
     server.child_info_pipe[0] = -1;
     server.child_info_pipe[1] = -1;