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

native_client_sdk/src/libraries/nacl_io/event_emitter.h

+/* 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.
+ */
+#ifndef LIBRARIES_NACL_IO_EVENT_EMITTER_H_
+#define LIBRARIES_NACL_IO_EVENT_EMITTER_H_
+
+#include <stdint.h>
+
+#include <map>
+#include <set>
+
+#include "nacl_io/error.h"
+
+#include "sdk_util/ref_object.h"
+#include "sdk_util/scoped_ref.h"
+#include "sdk_util/simple_lock.h"
+
+
+namespace nacl_io {
+
+class EventEmitter;
+class EventListener;
+
+// A ref counted object (non POD derived from RefObject) for storing the
+// state of a single signal request.  Requests are unique to any
+// FD/EventListener pair.
+struct EventInfo : public sdk_util::RefObject {
+  // User provied data to be returned on EventListener::Wait
+  uint64_t user_data;
+
+  // Bitfield of enum KernelEventType currently signaled.
+  uint32_t events;
+
+  // Bitfield of enum KernelEventType that can signal.
+  uint32_t filter;
+
+  // We do not use a ScopedRef to prevent circular references.
+  EventEmitter* emitter;
+  EventListener* listener;
+  uint32_t id;
+};
+
+typedef sdk_util::ScopedRef<EventInfo> ScopedEventInfo;
+
+// Provide comparison for std::map and std::set
+bool operator<(const ScopedEventInfo& src_a, const ScopedEventInfo& src_b);
+
+typedef std::map<int, ScopedEventInfo> EventInfoMap_t;
+typedef std::set<ScopedEventInfo> EventInfoSet_t;
+
+// EventEmitter
+//
+// The EventEmitter class provides notification of events to EventListeners
+// by registering EventInfo objects and signaling the EventListener
+// whenever thier state is changed.
+//
+// See "Kernel Events" in event_listener.h for additional information.
+class EventEmitter : public sdk_util::RefObject {
+ protected:
+  // Called automatically prior to delete to inform the EventListeners that
+  // this EventEmitter is abandoning an associated EventInfo.
+  virtual void Destroy();
+
+ private:
+  // Register or unregister an EventInfo.  The lock of the EventListener
+  // associated with this EventInfo must be held prior to calling these
+  // functions.  These functions are private to ensure they are called by the
+  // EventListener.
+  void RegisterEventInfo(const ScopedEventInfo& info);
+  void UnregisterEventInfo(const ScopedEventInfo& info);
+
+ public:
+  // Returns the current state of the emitter as KernelEventType bitfield.
+  virtual uint32_t GetEventStatus() = 0;
+
+  // Returns the type of the emitter (compatible with st_mode in stat)
+  virtual int GetType() = 0;
+
+ protected:
+  // Called by the thread causing the Event.
+  void RaiseEvent(uint32_t events);
+
+  // Provided to allow one EventEmitter to register the same EventInfo with
+  // a child EventEmitter so that they can both signal the EventListener.
+  // Called after registering locally, but while lock is still held.
+  virtual void ChainRegisterEventInfo(const ScopedEventInfo& event);
+
+  // Called before unregistering locally, but while lock is still held.
+  virtual void ChainUnregisterEventInfo(const ScopedEventInfo& event);
+
+private:
+  sdk_util::SimpleLock emitter_lock_;
+  EventInfoSet_t events_;
+  friend class EventListener;
+};
+
+typedef sdk_util::ScopedRef<EventEmitter> ScopedEventEmitter;
+
+}  // namespace nacl_io
+
+
+#endif  // LIBRARIES_NACL_IO_EVENT_EMITTER_H_