Mac-specific CFRunLoop-based MessagePump implementation

base/message_pump_mac.h

+// 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.
+
+// The basis for all native run loops on the Mac is the CFRunLoop.  It can be
+// used directly, it can be used as the driving force behind the similar
+// Foundation NSRunLoop, and it can be used to implement higher-level event
+// loops such as the NSApplication event loop.
+//
+// This file introduces a basic CFRunLoop-based implementation of the
+// MessagePump interface called CFRunLoopBase.  CFRunLoopBase contains all
+// of the machinery necessary to dispatch events to a delegate, but does not
+// implement the specific run loop.  Concrete subclasses must provide their
+// own DoRun and Quit implementations.
+//
+// A concrete subclass that just runs a CFRunLoop loop is provided in
+// MessagePumpCFRunLoop.  For an NSRunLoop, the similar MessagePumpNSRunLoop
+// is provided.
+//
+// For the application's event loop, an implementation based on AppKit's
+// NSApplication event system is provided in MessagePumpNSApplication.
+//
+// Typically, MessagePumpNSApplication only makes sense on a Cocoa
+// application's main thread.  If a CFRunLoop-based message pump is needed on
+// any other thread, one of the other concrete subclasses is preferrable.
+// MessagePumpMac::Create is defined, which returns a new NSApplication-based
+// or NSRunLoop-based MessagePump subclass depending on which thread it is
+// called on.
+
+#ifndef BASE_MESSAGE_PUMP_MAC_H_
+#define BASE_MESSAGE_PUMP_MAC_H_
+
+#include "base/message_pump.h"
+
+#include <CoreFoundation/CoreFoundation.h>
+
+#include "base/time.h"
+
+namespace base {
+
+class MessagePumpCFRunLoopBase : public MessagePump {
+ public:
+  MessagePumpCFRunLoopBase();
+  virtual ~MessagePumpCFRunLoopBase();
+
+  // Subclasses should implement the work they need to do in MessagePump::Run
+  // in the DoRun method.  MessagePumpCFRunLoopBase::Run calls DoRun directly.
+  // This arrangement is used because MessagePumpCFRunLoopBase needs to set
+  // up and tear down things before and after the "meat" of DoRun.
+  virtual void Run(Delegate* delegate);
+  virtual void DoRun(Delegate* delegate) = 0;
+
+  virtual void ScheduleWork();
+  virtual void ScheduleDelayedWork(const Time& delayed_work_time);
+
+ protected:
+  // The thread's run loop.
+  CFRunLoopRef run_loop_;
+
+ private:
+  // Timer callback scheduled by ScheduleDelayedWork.  This does not do any
+  // work, but it signals delayed_work_source_ so that delayed work can be
+  // performed within the appropriate priority constraints.
+  static void RunDelayedWorkTimer(CFRunLoopTimerRef timer, void* info);
+
+  // Perform highest-priority work.  This is associated with work_source_
+  // signalled by ScheduleWork.
+  static void RunWork(void* info);
+
+  // Perform delayed-priority work.  This is associated with
+  // delayed_work_source_ signalled by RunDelayedWorkTimer, and is responsible
+  // for calling ScheduleDelayedWork again if appropriate.
+  static void RunDelayedWork(void* info);
+
+  // Observer callback responsible for performing idle-priority work, before
+  // the run loop goes to sleep.  Associated with idle_work_observer_.
+  static void RunIdleWork(CFRunLoopObserverRef observer,
+                          CFRunLoopActivity activity, void* info);
+
+  // The timer, sources, and observer are described above alongside their
+  // callbacks.
+  CFRunLoopTimerRef delayed_work_timer_;
+  CFRunLoopSourceRef work_source_;
+  CFRunLoopSourceRef delayed_work_source_;
+  CFRunLoopObserverRef idle_work_observer_;
+
+  // (weak) Delegate passed as an argument to the innermost Run call.
+  Delegate* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessagePumpCFRunLoopBase);
+};
+
+class MessagePumpCFRunLoop : public MessagePumpCFRunLoopBase {
+ public:
+  MessagePumpCFRunLoop();
+  virtual ~MessagePumpCFRunLoop();
+
+  virtual void DoRun(Delegate* delegate);
+  virtual void Quit();
+
+ private:
+  // Observer callback called when the run loop starts and stops, at the
+  // beginning and end of calls to CFRunLoopRun.  This is used to maintain
+  // nesting_level_ and to handle deferred loop quits.  Associated with
+  // enter_exit_observer_.
+  static void EnterExitRunLoop(CFRunLoopObserverRef observer,
+                               CFRunLoopActivity activity, void* info);
+
+  // Observer for EnterExitRunLoop.
+  CFRunLoopObserverRef enter_exit_observer_;
+
+  // The recursion depth of the currently-executing CFRunLoopRun loop on the
+  // run loop's thread.  0 if no run loops are running inside of whatever scope
+  // the object was created in.
+  int nesting_level_;
+
+  // The recursion depth (calculated in the same way as nesting_level_) of the
+  // innermost executing CFRunLoopRun loop started by a call to Run.
+  int innermost_quittable_;
+
+  // True if Quit is called to stop the innermost MessagePump
+  // (innermost_quittable_) but some other CFRunLoopRun loop (nesting_level_)
+  // is running inside the MessagePump's innermost Run call.
+  bool quit_pending_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessagePumpCFRunLoop);
+};
+
+class MessagePumpNSRunLoop : public MessagePumpCFRunLoopBase {
+ public:
+  MessagePumpNSRunLoop();
+  virtual ~MessagePumpNSRunLoop();
+
+  virtual void DoRun(Delegate* delegate);
+  virtual void Quit();
+
+ private:
+  // A source that doesn't do anything but provide something signalable
+  // attached to the run loop.  This source will be signalled when Quit
+  // is called, to cause the loop to wake up so that it can stop.
+  CFRunLoopSourceRef quit_source_;
+
+  // False after Quit is called.
+  bool keep_running_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessagePumpNSRunLoop);
+};
+
+class MessagePumpNSApplication : public MessagePumpCFRunLoopBase {
+ public:
+  MessagePumpNSApplication();
+
+  virtual void DoRun(Delegate* delegate);
+  virtual void Quit();
+
+ private:
+  // False after Quit is called.
+  bool keep_running_;
+
+  // True if DoRun is managing its own run loop as opposed to letting
+  // -[NSApplication run] handle it.  The outermost run loop in the application
+  // is managed by -[NSApplication run], inner run loops are handled by a loop
+  // in DoRun.
+  bool running_own_loop_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessagePumpNSApplication);
+};
+
+class MessagePumpMac {
+ public:
+  // Returns a new instance of MessagePumpNSApplication if called on the main
+  // thread.  Otherwise, returns a new instance of MessagePumpNSRunLoop.
+  static MessagePump* Create();
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(MessagePumpMac);
+};
+
+}  // namespace base
+
+#endif  // BASE_MESSAGE_PUMP_MAC_H_