Give a CFRunLoop to the IO message loop type on Mac OS X.

base/message_pump_mac.h

Index: base/message_pump_mac.h
===================================================================
--- base/message_pump_mac.h	(revision 90809)
+++ base/message_pump_mac.h	(working copy)
@@ -32,6 +32,7 @@
 #pragma once
 
 #include "base/message_pump.h"
+#include "base/observer_list.h"
 
 #include <CoreFoundation/CoreFoundation.h>
 
@@ -58,9 +59,107 @@
   // Needs access to CreateAutoreleasePool.
   friend class MessagePumpScopedAutoreleasePool;
  public:
+  class IOObserver {
+   public:
+    IOObserver() {}
+
+    // An IOObserver is an object that receives IO notifications from the
+    // MessagePump.
+    //
+    // NOTE: An IOObserver implementation should be extremely fast!
+    virtual void WillProcessIOEvent() = 0;
+    virtual void DidProcessIOEvent() = 0;
+
+   protected:
+    virtual ~IOObserver() {}
+  };
+
+  // Used with WatchFileDescptor to asynchronously monitor the I/O readiness of
+  // a File Descriptor.
+  class Watcher {
+   public:
+    virtual ~Watcher() {}
+    // Called from MessageLoop::Run when an FD can be read from/written to
+    // without blocking
+    virtual void OnFileCanReadWithoutBlocking(int fd) = 0;
+    virtual void OnFileCanWriteWithoutBlocking(int fd) = 0;
+  };
+
+  // Object returned by WatchFileDescriptor to manage further watching.
+  class FileDescriptorWatcher {
+   public:
+    FileDescriptorWatcher();
+    ~FileDescriptorWatcher();  // Implicitly calls StopWatchingFileDescriptor.
+
+    // NOTE: These methods aren't called StartWatching()/StopWatching() to
+    // avoid confusion with the win32 ObjectWatcher class.
+
+    // Stop watching the FD, always safe to call.  No-op if there's nothing
+    // to do.
+    bool StopWatchingFileDescriptor();
+
+   private:
+    friend class MessagePumpCFRunLoopBase;
+
+    // Called by MessagePumpCFRunLoopBase, ownership of |fdref| and |fd_source|
+    // is transferred to this object.
+    void Init(CFFileDescriptorRef fdref,
+              CFOptionFlags callback_types,
+              CFRunLoopSourceRef fd_source,
+              bool is_persistent);
+
+    // Used by MessagePumpCFRunLoopBase to take ownership of fdref_.
+    CFFileDescriptorRef ReleaseCFFileDescriptor();
+
+    void set_pump(MessagePumpCFRunLoopBase* pump) { pump_ = pump; }
+    MessagePumpCFRunLoopBase* pump() { return pump_; }
+
+    void set_watcher(Watcher* watcher) { watcher_ = watcher; }
+
+    void OnFileCanReadWithoutBlocking(int fd, MessagePumpCFRunLoopBase* pump);
+    void OnFileCanWriteWithoutBlocking(int fd, MessagePumpCFRunLoopBase* pump);
+
+    bool is_persistent_;  // false if this event is one-shot.
+    CFFileDescriptorRef fdref_;
+    CFOptionFlags callback_types_;
+    CFRunLoopSourceRef fd_source_;
+    MessagePumpCFRunLoopBase* pump_;
+    Watcher* watcher_;
+
+    DISALLOW_COPY_AND_ASSIGN(FileDescriptorWatcher);
+  };
+
+  enum Mode {
+    WATCH_READ = 1 << 0,
+    WATCH_WRITE = 1 << 1,
+    WATCH_READ_WRITE = WATCH_READ | WATCH_WRITE
+  };
+
   MessagePumpCFRunLoopBase();
   virtual ~MessagePumpCFRunLoopBase();
 
+  // Have the current thread's message loop watch for a a situation in which
+  // reading/writing to the FD can be performed without blocking.
+  // Callers must provide a preallocated FileDescriptorWatcher object which
+  // can later be used to manage the lifetime of this event.
+  // If a FileDescriptorWatcher is passed in which is already attached to
+  // an event, then the effect is cumulative i.e. after the call |controller|
+  // will watch both the previous event and the new one.
+  // If an error occurs while calling this method in a cumulative fashion, the
+  // event previously attached to |controller| is aborted.
+  // Returns true on success.
+  // Must be called on the same thread the message_pump is running on.
+  bool WatchFileDescriptor(int fd,
+                           bool persistent,
+                           Mode mode,
+                           FileDescriptorWatcher *controller,
+                           Watcher *delegate);
+
+  void RemoveRunLoopSource(CFRunLoopSourceRef source);
+
+  void AddIOObserver(IOObserver* obs);
+  void RemoveIOObserver(IOObserver* obs);
+
   // 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
@@ -84,6 +183,13 @@
   virtual NSAutoreleasePool* CreateAutoreleasePool();
 
  private:
+  void WillProcessIOEvent();
+  void DidProcessIOEvent();
+
+  static void HandleFdIOEvent(CFFileDescriptorRef fdref,
+                              CFOptionFlags callback_types,
+                              void* context);
+
   // Timer callback scheduled by ScheduleDelayedWork.  This does not do any
   // work, but it signals work_source_ so that delayed work can be performed
   // within the appropriate priority constraints.
@@ -184,6 +290,9 @@
   bool delegateless_work_;
   bool delegateless_idle_work_;
 
+  ObserverList<IOObserver> io_observers_;
+  ThreadChecker watch_file_descriptor_caller_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(MessagePumpCFRunLoopBase);
 };