[NaCl SDK} Add EventListener and EventEmitter to support epoll.

native_client_sdk/src/libraries/nacl_io/event_emitter.cc

+/* Copyright (c) 2013 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 <assert.h>
+
+#include "nacl_io/event_emitter.h"
+#include "nacl_io/event_listener.h"
+
+#include "sdk_util/auto_lock.h"
+
+bool operator<(const ScopedEventInfo& src_a, const ScopedEventInfo& src_b) {
+  return src_a.get() < src_b.get();
+}
+
+void EventEmitter::Destroy() {
+  // We can not grab the EmitterLock prior to grabbing the EventListener lock,
+  // however the ref count proves this is the only thread which has a
+  // reference to the emitter at this point so accessing events_ is safe.
+  EventInfoSet_t::iterator it;
+  for (it = events_.begin(); it != events_.end(); it++) {
+    ScopedEventInfo info = *it;
+    info->listener->AbandonedEventInfo(info);
+  }
+}
+
+void EventEmitter::RegisterEventInfo(const ScopedEventInfo& info) {
+  AutoLock lock(emitter_lock_);
+
+  events_.insert(info);
+  ChainRegister(info);
+}
+
+void EventEmitter::UnregisterEventInfo(const ScopedEventInfo& info) {
+  AutoLock lock(emitter_lock_);
+
+  ChainUnregister(info);
+  events_.erase(info);
+}
+void EventEmitter::RaiseEvent(uint32_t event_bits) {
+  AutoLock lock(emitter_lock_);
+
+  EventInfoSet_t::iterator it;
+  for (it = events_.begin(); it != events_.end(); it++) {
+    // If this event is allowed by the filter, signal it
+    ScopedEventInfo info = *it;
+    if (info->filter & event_bits) {
+      info->events |= event_bits & info->filter;
+      info->listener->Signal(info);
+    }
+  }
+}
+
+void EventEmitter::ChainRegister(const ScopedEventInfo& info) {}
+void EventEmitter::ChainUnregister(const ScopedEventInfo& info) {}