add basic backup support to block driver

[qemu.git] / main-loop.c

diff --git a/main-loop.c b/main-loop.c
index 7dba6f6e3511a678502fb232f6f88762ee2d9724..6f52ac39bc7f6bfede652230bbad4a80ce44b6c5 100644 (file)
--- a/main-loop.c
+++ b/main-loop.c
@@ -23,14 +23,14 @@
  */
 
 #include "qemu-common.h"
-#include "qemu-timer.h"
+#include "qemu/timer.h"
 #include "slirp/slirp.h"
-#include "main-loop.h"
-#include "qemu-aio.h"
+#include "qemu/main-loop.h"
+#include "block/aio.h"
 
 #ifndef _WIN32
 
-#include "compatfd.h"
+#include "qemu/compatfd.h"
 
 /* If we have signalfd, we mask out the signals we want to handle and then
  * use signalfd to listen for them.  We rely on whatever the current signal
@@ -330,7 +330,7 @@ void qemu_fd_register(int fd)
 static int os_host_main_loop_wait(uint32_t timeout)
 {
     GMainContext *context = g_main_context_default();
-    int ret, i;
+    int select_ret, g_poll_ret, ret, i;
     PollingEntry *pe;
     WaitObjects *w = &wait_objects;
     gint poll_timeout;
@@ -345,13 +345,6 @@ static int os_host_main_loop_wait(uint32_t timeout)
         return ret;
     }
 
-    if (nfds >= 0) {
-        ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
-        if (ret != 0) {
-            timeout = 0;
-        }
-    }
-
     g_main_context_prepare(context, &max_priority);
     n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
                                       poll_fds, ARRAY_SIZE(poll_fds));
@@ -367,9 +360,9 @@ static int os_host_main_loop_wait(uint32_t timeout)
     }
 
     qemu_mutex_unlock_iothread();
-    ret = g_poll(poll_fds, n_poll_fds + w->num, poll_timeout);
+    g_poll_ret = g_poll(poll_fds, n_poll_fds + w->num, poll_timeout);
     qemu_mutex_lock_iothread();
-    if (ret > 0) {
+    if (g_poll_ret > 0) {
         for (i = 0; i < w->num; i++) {
             w->revents[i] = poll_fds[n_poll_fds + i].revents;
         }
@@ -384,12 +377,18 @@ static int os_host_main_loop_wait(uint32_t timeout)
         g_main_context_dispatch(context);
     }
 
-    /* If an edge-triggered socket event occurred, select will return a
-     * positive result on the next iteration.  We do not need to do anything
-     * here.
+    /* Call select after g_poll to avoid a useless iteration and therefore
+     * improve socket latency.
      */
 
-    return ret;
+    if (nfds >= 0) {
+        select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
+        if (select_ret != 0) {
+            timeout = 0;
+        }
+    }
+
+    return select_ret || g_poll_ret;
 }
 #endif