Provide an iOS message pump for IO implementation.

base/message_pump_io_ios.h

+// Copyright 2012 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 BASE_MESSAGE_PUMP_IO_IOS_H_
+#define BASE_MESSAGE_PUMP_IO_IOS_H_
+
+#include "base/mac/scoped_cffiledescriptorref.h"
+#include "base/mac/scoped_cftyperef.h"
+#include "base/message_pump_mac.h"
+#include "base/observer_list.h"
+
+namespace base {
+
+// This file introduces a class to monitor sockets and issue callbacks when
+// sockets are ready for I/O on iOS.
+class MessagePumpIOSForIO : public MessagePumpNSRunLoop {
+ 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 MessagePumpIOSForIO;
+
+    // Called by MessagePumpIOSForIO, ownership of |fdref| and |fd_source|
+    // is transferred to this object.
+    void Init(CFFileDescriptorRef fdref,
+              CFOptionFlags callback_types,
+              CFRunLoopSourceRef fd_source,
+              bool is_persistent);
+
+    void set_pump(MessagePumpIOSForIO* pump) { pump_ = pump; }
+    MessagePumpIOSForIO* pump() const { return pump_; }
+
+    void set_watcher(Watcher* watcher) { watcher_ = watcher; }
+
+    void OnFileCanReadWithoutBlocking(int fd, MessagePumpIOSForIO* pump);
+    void OnFileCanWriteWithoutBlocking(int fd, MessagePumpIOSForIO* pump);
+
+    bool is_persistent_;  // false if this event is one-shot.
+    base::mac::ScopedCFFileDescriptorRef fdref_;
+    CFOptionFlags callback_types_;
+    base::mac::ScopedCFTypeRef<CFRunLoopSourceRef> fd_source_;
+    MessagePumpIOSForIO* pump_;
+    Watcher* watcher_;
+
+    DISALLOW_COPY_AND_ASSIGN(FileDescriptorWatcher);
+  };
+
+  enum Mode {
+    WATCH_READ = 1 << 0,
+    WATCH_WRITE = 1 << 1
+  };
+
+  MessagePumpIOSForIO();
+
+  // 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,

[Mark Mentovai, 2012/11/20 22:29:27]

This should be an int argument. A variable of enum type can only legally store
the values enumerated in the type. A compiler, assuming that those are the only
possible values, might optimize away code that considers that mode might be READ
| WRITE. If you accept this argument as an int or some other integral type, this
isn’t a problem.

[blundell, 2012/11/21 16:56:52]

Thanks for the catch! Done.

On 2012/11/20 22:29:27, Mark Mentovai wrote:

+                           FileDescriptorWatcher *controller,
+                           Watcher *delegate);
+
+  void RemoveRunLoopSource(CFRunLoopSourceRef source);
+
+  void AddIOObserver(IOObserver* obs);
+  void RemoveIOObserver(IOObserver* obs);
+
+ protected:
+  virtual ~MessagePumpIOSForIO();
+
+ private:
+  void WillProcessIOEvent();
+  void DidProcessIOEvent();
+
+  static void HandleFdIOEvent(CFFileDescriptorRef fdref,
+                              CFOptionFlags callback_types,
+                              void* context);
+
+  ObserverList<IOObserver> io_observers_;
+  ThreadChecker watch_file_descriptor_caller_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessagePumpIOSForIO);
+};
+
+}  // namespace base
+
+#endif // BASE_MESSAGE_PUMP_IO_IOS_H_