[glib] gsocket: always try before waiting for condition

[Paolo Borelli <pborelli src gnome org>]

commit cf03e824780d4ca58de664737bf5ba9ed416cfa2
Author: Ignacio Casal Quinteiro <icq gnome org>
Date:   Mon Dec 22 16:38:50 2014 +0100

    gsocket: always try before waiting for condition
    
    When implementing blocking operations on top of
    nonblocking sockets we should always first try to
    perform the operation and then if needed handle
    EAGAIN and wait with g_socket_wait_condition.
    This is an optimization since we avoid calling
    wait condition when it is not needed, but most
    importantly this fixes hangs on win32 where some
    events (in particular FD_WRITE) are only emitted
    after the operation fails with EWOULDBLOCK.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=732439
    https://bugzilla.gnome.org/show_bug.cgi?id=741707

 gio/gsocket.c |  147 ++++++++++++++++++++++++++++++---------------------------
 1 files changed, 77 insertions(+), 70 deletions(-)
---
diff --git a/gio/gsocket.c b/gio/gsocket.c
index d9e135d..f144674 100644
--- a/gio/gsocket.c
+++ b/gio/gsocket.c
@@ -2230,31 +2230,31 @@ g_socket_accept (GSocket       *socket,
 
   while (TRUE)
     {
-      if (socket->priv->blocking &&
-         !g_socket_condition_wait (socket,
-                                   G_IO_IN, cancellable, error))
-       return NULL;
-
       if ((ret = accept (socket->priv->fd, NULL, 0)) < 0)
        {
          int errsv = get_socket_errno ();
 
-         win32_unset_event_mask (socket, FD_ACCEPT);
-
          if (errsv == EINTR)
            continue;
 
-         if (socket->priv->blocking)
-           {
 #ifdef WSAEWOULDBLOCK
-             if (errsv == WSAEWOULDBLOCK)
-               continue;
+          if (errsv == WSAEWOULDBLOCK)
 #else
-             if (errsv == EWOULDBLOCK ||
-                 errsv == EAGAIN)
-               continue;
+          if (errsv == EWOULDBLOCK ||
+              errsv == EAGAIN)
 #endif
-           }
+            {
+              win32_unset_event_mask (socket, FD_ACCEPT);
+
+              if (socket->priv->blocking)
+                {
+                  if (!g_socket_condition_wait (socket,
+                                                G_IO_IN, cancellable, error))
+                    return NULL;
+
+                  continue;
+                }
+            }
 
          g_set_error (error, G_IO_ERROR,
                       socket_io_error_from_errno (errsv),
@@ -2368,6 +2368,8 @@ g_socket_connect (GSocket         *socket,
          if (errsv == WSAEWOULDBLOCK)
 #endif
            {
+              win32_unset_event_mask (socket, FD_CONNECT);
+
              if (socket->priv->blocking)
                {
                  if (g_socket_condition_wait (socket, G_IO_OUT, cancellable, error))
@@ -2602,11 +2604,6 @@ g_socket_receive_with_blocking (GSocket       *socket,
 
   while (1)
     {
-      if (blocking &&
-         !g_socket_condition_wait (socket,
-                                   G_IO_IN, cancellable, error))
-       return -1;
-
       if ((ret = recv (socket->priv->fd, buffer, size, 0)) < 0)
        {
          int errsv = get_socket_errno ();
@@ -2614,17 +2611,24 @@ g_socket_receive_with_blocking (GSocket       *socket,
          if (errsv == EINTR)
            continue;
 
-         if (blocking)
-           {
 #ifdef WSAEWOULDBLOCK
-             if (errsv == WSAEWOULDBLOCK)
-               continue;
+          if (errsv == WSAEWOULDBLOCK)
 #else
-             if (errsv == EWOULDBLOCK ||
-                 errsv == EAGAIN)
-               continue;
+          if (errsv == EWOULDBLOCK ||
+              errsv == EAGAIN)
 #endif
-           }
+            {
+              win32_unset_event_mask (socket, FD_READ);
+
+              if (blocking)
+                {
+                  if (!g_socket_condition_wait (socket,
+                                                G_IO_IN, cancellable, error))
+                    return -1;
+
+                  continue;
+                }
+            }
 
          win32_unset_event_mask (socket, FD_READ);
 
@@ -2777,11 +2781,6 @@ g_socket_send_with_blocking (GSocket       *socket,
 
   while (1)
     {
-      if (blocking &&
-         !g_socket_condition_wait (socket,
-                                   G_IO_OUT, cancellable, error))
-       return -1;
-
       if ((ret = send (socket->priv->fd, buffer, size, G_SOCKET_DEFAULT_SEND_FLAGS)) < 0)
        {
          int errsv = get_socket_errno ();
@@ -2790,21 +2789,23 @@ g_socket_send_with_blocking (GSocket       *socket,
            continue;
 
 #ifdef WSAEWOULDBLOCK
-         if (errsv == WSAEWOULDBLOCK)
-           win32_unset_event_mask (socket, FD_WRITE);
-#endif
-
-         if (blocking)
-           {
-#ifdef WSAEWOULDBLOCK
-             if (errsv == WSAEWOULDBLOCK)
-               continue;
+          if (errsv == WSAEWOULDBLOCK)
 #else
-             if (errsv == EWOULDBLOCK ||
-                 errsv == EAGAIN)
-               continue;
+          if (errsv == EWOULDBLOCK ||
+              errsv == EAGAIN)
 #endif
-           }
+            {
+              win32_unset_event_mask (socket, FD_WRITE);
+
+              if (blocking)
+                {
+                  if (!g_socket_condition_wait (socket,
+                                                G_IO_OUT, cancellable, error))
+                    return -1;
+
+                  continue;
+                }
+            }
 
          g_set_error (error, G_IO_ERROR,
                       socket_io_error_from_errno (errsv),
@@ -3874,11 +3875,6 @@ g_socket_send_message (GSocket                *socket,
 
     while (1)
       {
-       if (socket->priv->blocking &&
-           !g_socket_condition_wait (socket,
-                                     G_IO_OUT, cancellable, error))
-         return -1;
-
        result = sendmsg (socket->priv->fd, &msg, flags | G_SOCKET_DEFAULT_SEND_FLAGS);
        if (result < 0)
          {
@@ -3890,7 +3886,13 @@ g_socket_send_message (GSocket                *socket,
            if (socket->priv->blocking &&
                (errsv == EWOULDBLOCK ||
                 errsv == EAGAIN))
-             continue;
+              {
+                if (!g_socket_condition_wait (socket,
+                                              G_IO_OUT, cancellable, error))
+                  return -1;
+
+                continue;
+              }
 
            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
@@ -3942,11 +3944,6 @@ g_socket_send_message (GSocket                *socket,
 
     while (1)
       {
-       if (socket->priv->blocking &&
-           !g_socket_condition_wait (socket,
-                                     G_IO_OUT, cancellable, error))
-         return -1;
-
        if (address)
          result = WSASendTo (socket->priv->fd,
                              bufs, num_vectors,
@@ -3967,11 +3964,18 @@ g_socket_send_message (GSocket                *socket,
              continue;
 
            if (errsv == WSAEWOULDBLOCK)
-             win32_unset_event_mask (socket, FD_WRITE);
+              {
+                win32_unset_event_mask (socket, FD_WRITE);
 
-           if (socket->priv->blocking &&
-               errsv == WSAEWOULDBLOCK)
-             continue;
+                if (socket->priv->blocking)
+                  {
+                    if (!g_socket_condition_wait (socket,
+                                                  G_IO_OUT, cancellable, error))
+                      return -1;
+
+                    continue;
+                  }
+              }
 
            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
@@ -4634,11 +4638,6 @@ g_socket_receive_message (GSocket                 *socket,
     /* do it */
     while (1)
       {
-       if (socket->priv->blocking &&
-           !g_socket_condition_wait (socket,
-                                     G_IO_IN, cancellable, error))
-         return -1;
-
        addrlen = sizeof addr;
        if (address)
          result = WSARecvFrom (socket->priv->fd,
@@ -4658,11 +4657,19 @@ g_socket_receive_message (GSocket                 *socket,
            if (errsv == WSAEINTR)
              continue;
 
-           win32_unset_event_mask (socket, FD_READ);
+            if (errsv == WSAEWOULDBLOCK)
+              {
+                win32_unset_event_mask (socket, FD_READ);
 
-           if (socket->priv->blocking &&
-               errsv == WSAEWOULDBLOCK)
-             continue;
+                if (socket->priv->blocking)
+                  {
+                    if (!g_socket_condition_wait (socket,
+                                                  G_IO_IN, cancellable, error))
+                      return -1;
+
+                    continue;
+                  }
+              }
 
            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),