Simplify failure codepaths of MessagePumpLibevent::WatchFileDescriptor()

base/message_pump_libevent.cc

 // Copyright (c) 2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/message_pump_libevent.h"
 
 #include <errno.h>
 #include <fcntl.h>
 
 #include "eintr_wrapper.h"
@@ skipping 143 matching lines @@
   DCHECK(mode == WATCH_READ || mode == WATCH_WRITE || mode == WATCH_READ_WRITE);
 
   int event_mask = persistent ? EV_PERSIST : 0;
   if ((mode & WATCH_READ) != 0) {
     event_mask |= EV_READ;
   }
   if ((mode & WATCH_WRITE) != 0) {
     event_mask |= EV_WRITE;
   }
 
-  // |should_delete_event| is true if we're modifying an event that's currently
-  // active in |controller|.
-  // If we're modifying an existing event and there's an error then we need to
-  // tell libevent to clean it up via event_delete() before returning.
-  bool should_delete_event = true;
   scoped_ptr<event> evt(controller->ReleaseEvent());
   if (evt.get() == NULL) {
-    should_delete_event = false;
     // Ownership is transferred to the controller.
     evt.reset(new event);
   } else {
-    // It's illegal to use this function to listen on 2 separate fds with the
-    // same |controller|.
-    if (EVENT_FD(evt.get()) != fd) {
-      NOTREACHED() << "FDs don't match" << EVENT_FD(evt.get()) << "!=" << fd;
-      return false;
-    }
-
     // Make sure we don't pick up any funky internal libevent masks.
     int old_interest_mask = evt.get()->ev_events &
         (EV_READ | EV_WRITE | EV_PERSIST);
 
     // Combine old/new event masks.
     event_mask |= old_interest_mask;
 
     // Must disarm the event before we can reuse it.
     event_del(evt.get());
+
+    // It's illegal to use this function to listen on 2 separate fds with the
+    // same |controller|.
+    if (EVENT_FD(evt.get()) != fd) {
+      NOTREACHED() << "FDs don't match" << EVENT_FD(evt.get()) << "!=" << fd;
+      return false;
+    }
   }
 
   // Set current interest mask and message pump for this event.
-  event_set(evt.get(), fd, event_mask, OnLibeventNotification,
-            delegate);
+  event_set(evt.get(), fd, event_mask, OnLibeventNotification, delegate);
 
   // Tell libevent which message pump this socket will belong to when we add it.
   if (event_base_set(event_base_, evt.get()) != 0) {
-    if (should_delete_event) {
-      event_del(evt.get());
-    }
     return false;
   }
 
   // Add this socket to the list of monitored sockets.
   if (event_add(evt.get(), NULL) != 0) {
-    if (should_delete_event) {
-      event_del(evt.get());
-    }
     return false;
   }
 
   // Transfer ownership of evt to controller.
   controller->Init(evt.release(), persistent);
   return true;
 }
 
 
 void MessagePumpLibevent::OnLibeventNotification(int fd, short flags,
@@ skipping 76 matching lines @@
 }
 
 void MessagePumpLibevent::ScheduleDelayedWork(const Time& delayed_work_time) {
   // We know that we can't be blocked on Wait right now since this method can
   // only be called on the same thread as Run, so we only need to update our
   // record of how long to sleep when we do sleep.
   delayed_work_time_ = delayed_work_time;
 }
 
 }  // namespace base