1 files changed, 396 insertions, 0 deletions
diff --git a/base/message_loop/message_pump_win.h b/base/message_loop/message_pump_win.h
new file mode 100644
index 0000000..dbb41bd
--- /dev/null
+++ b/base/message_loop/message_pump_win.h
@@ -0,0 +1,396 @@
+// Copyright (c) 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_LOOP_MESSAGE_PUMP_WIN_H_
+#define BASE_MESSAGE_LOOP_MESSAGE_PUMP_WIN_H_
+
+#include <windows.h>
+
+#include <list>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop/message_pump.h"
+#include "base/message_loop/message_pump_dispatcher.h"
+#include "base/message_loop/message_pump_observer.h"
+#include "base/observer_list.h"
+#include "base/time.h"
+#include "base/win/scoped_handle.h"
+
+namespace base {
+
+// MessagePumpWin serves as the base for specialized versions of the MessagePump
+// for Windows. It provides basic functionality like handling of observers and
+// controlling the lifetime of the message pump.
+class BASE_EXPORT MessagePumpWin : public MessagePump {
+ public:
+  MessagePumpWin() : have_work_(0), state_(NULL) {}
+  virtual ~MessagePumpWin() {}
+
+  // Add an Observer, which will start receiving notifications immediately.
+  void AddObserver(MessagePumpObserver* observer);
+
+  // Remove an Observer.  It is safe to call this method while an Observer is
+  // receiving a notification callback.
+  void RemoveObserver(MessagePumpObserver* observer);
+
+  // Give a chance to code processing additional messages to notify the
+  // message loop observers that another message has been processed.
+  void WillProcessMessage(const MSG& msg);
+  void DidProcessMessage(const MSG& msg);
+
+  // Like MessagePump::Run, but MSG objects are routed through dispatcher.
+  void RunWithDispatcher(Delegate* delegate, MessagePumpDispatcher* dispatcher);
+
+  // MessagePump methods:
+  virtual void Run(Delegate* delegate) { RunWithDispatcher(delegate, NULL); }
+  virtual void Quit();
+
+ protected:
+  struct RunState {
+    Delegate* delegate;
+    MessagePumpDispatcher* dispatcher;
+
+    // Used to flag that the current Run() invocation should return ASAP.
+    bool should_quit;
+
+    // Used to count how many Run() invocations are on the stack.
+    int run_depth;
+  };
+
+  virtual void DoRunLoop() = 0;
+  int GetCurrentDelay() const;
+
+  ObserverList<MessagePumpObserver> observers_;
+
+  // The time at which delayed work should run.
+  TimeTicks delayed_work_time_;
+
+  // A boolean value used to indicate if there is a kMsgDoWork message pending
+  // in the Windows Message queue.  There is at most one such message, and it
+  // can drive execution of tasks when a native message pump is running.
+  LONG have_work_;
+
+  // State for the current invocation of Run.
+  RunState* state_;
+};
+
+//-----------------------------------------------------------------------------
+// MessagePumpForUI extends MessagePumpWin with methods that are particular to a
+// MessageLoop instantiated with TYPE_UI.
+//
+// MessagePumpForUI implements a "traditional" Windows message pump. It contains
+// a nearly infinite loop that peeks out messages, and then dispatches them.
+// Intermixed with those peeks are callouts to DoWork for pending tasks, and
+// DoDelayedWork for pending timers. When there are no events to be serviced,
+// this pump goes into a wait state. In most cases, this message pump handles
+// all processing.
+//
+// However, when a task, or windows event, invokes on the stack a native dialog
+// box or such, that window typically provides a bare bones (native?) message
+// pump.  That bare-bones message pump generally supports little more than a
+// peek of the Windows message queue, followed by a dispatch of the peeked
+// message.  MessageLoop extends that bare-bones message pump to also service
+// Tasks, at the cost of some complexity.
+//
+// The basic structure of the extension (refered to as a sub-pump) is that a
+// special message, kMsgHaveWork, is repeatedly injected into the Windows
+// Message queue.  Each time the kMsgHaveWork message is peeked, checks are
+// made for an extended set of events, including the availability of Tasks to
+// run.
+//
+// After running a task, the special message kMsgHaveWork is again posted to
+// the Windows Message queue, ensuring a future time slice for processing a
+// future event.  To prevent flooding the Windows Message queue, care is taken
+// to be sure that at most one kMsgHaveWork message is EVER pending in the
+// Window's Message queue.
+//
+// There are a few additional complexities in this system where, when there are
+// no Tasks to run, this otherwise infinite stream of messages which drives the
+// sub-pump is halted.  The pump is automatically re-started when Tasks are
+// queued.
+//
+// A second complexity is that the presence of this stream of posted tasks may
+// prevent a bare-bones message pump from ever peeking a WM_PAINT or WM_TIMER.
+// Such paint and timer events always give priority to a posted message, such as
+// kMsgHaveWork messages.  As a result, care is taken to do some peeking in
+// between the posting of each kMsgHaveWork message (i.e., after kMsgHaveWork
+// is peeked, and before a replacement kMsgHaveWork is posted).
+//
+// NOTE: Although it may seem odd that messages are used to start and stop this
+// flow (as opposed to signaling objects, etc.), it should be understood that
+// the native message pump will *only* respond to messages.  As a result, it is
+// an excellent choice.  It is also helpful that the starter messages that are
+// placed in the queue when new task arrive also awakens DoRunLoop.
+//
+class BASE_EXPORT MessagePumpForUI : public MessagePumpWin {
+ public:
+  // A MessageFilter implements the common Peek/Translate/Dispatch code to deal
+  // with windows messages.
+  // This abstraction is used to inject TSF message peeking. See
+  // TextServicesMessageFilter.
+  class BASE_EXPORT MessageFilter {
+   public:
+    virtual ~MessageFilter() {}
+    // Implements the functionality exposed by the OS through PeekMessage.
+    virtual BOOL DoPeekMessage(MSG* msg,
+                               HWND window_handle,
+                               UINT msg_filter_min,
+                               UINT msg_filter_max,
+                               UINT remove_msg) {
+      return PeekMessage(msg, window_handle, msg_filter_min, msg_filter_max,
+                         remove_msg);
+    }
+    // Returns true if |message| was consumed by the filter and no extra
+    // processing is required. If this method returns false, it is the
+    // responsibility of the caller to ensure that normal processing takes
+    // place.
+    // The priority to consume messages is the following:
+    // - Native Windows' message filter (CallMsgFilter).
+    // - MessageFilter::ProcessMessage.
+    // - MessagePumpDispatcher.
+    // - TranslateMessage / DispatchMessage.
+    virtual bool ProcessMessage(const MSG& msg) { return false;}
+  };
+  // The application-defined code passed to the hook procedure.
+  static const int kMessageFilterCode = 0x5001;
+
+  MessagePumpForUI();
+  virtual ~MessagePumpForUI();
+
+  // Sets a new MessageFilter. MessagePumpForUI takes ownership of
+  // |message_filter|. When SetMessageFilter is called, old MessageFilter is
+  // deleted.
+  void SetMessageFilter(scoped_ptr<MessageFilter> message_filter);
+
+  // MessagePump methods:
+  virtual void ScheduleWork();
+  virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time);
+
+  // Applications can call this to encourage us to process all pending WM_PAINT
+  // messages.  This method will process all paint messages the Windows Message
+  // queue can provide, up to some fixed number (to avoid any infinite loops).
+  void PumpOutPendingPaintMessages();
+
+ private:
+  static LRESULT CALLBACK WndProcThunk(HWND window_handle,
+                                       UINT message,
+                                       WPARAM wparam,
+                                       LPARAM lparam);
+  virtual void DoRunLoop();
+  void InitMessageWnd();
+  void WaitForWork();
+  void HandleWorkMessage();
+  void HandleTimerMessage();
+  bool ProcessNextWindowsMessage();
+  bool ProcessMessageHelper(const MSG& msg);
+  bool ProcessPumpReplacementMessage();
+
+  // Atom representing the registered window class.
+  ATOM atom_;
+
+  // A hidden message-only window.
+  HWND message_hwnd_;
+
+  scoped_ptr<MessageFilter> message_filter_;
+};
+
+//-----------------------------------------------------------------------------
+// MessagePumpForIO extends MessagePumpWin with methods that are particular to a
+// MessageLoop instantiated with TYPE_IO. This version of MessagePump does not
+// deal with Windows mesagges, and instead has a Run loop based on Completion
+// Ports so it is better suited for IO operations.
+//
+class BASE_EXPORT MessagePumpForIO : public MessagePumpWin {
+ public:
+  struct IOContext;
+
+  // Clients interested in receiving OS notifications when asynchronous IO
+  // operations complete should implement this interface and register themselves
+  // with the message pump.
+  //
+  // Typical use #1:
+  //   // Use only when there are no user's buffers involved on the actual IO,
+  //   // so that all the cleanup can be done by the message pump.
+  //   class MyFile : public IOHandler {
+  //     MyFile() {
+  //       ...
+  //       context_ = new IOContext;
+  //       context_->handler = this;
+  //       message_pump->RegisterIOHandler(file_, this);
+  //     }
+  //     ~MyFile() {
+  //       if (pending_) {
+  //         // By setting the handler to NULL, we're asking for this context
+  //         // to be deleted when received, without calling back to us.
+  //         context_->handler = NULL;
+  //       } else {
+  //         delete context_;
+  //      }
+  //     }
+  //     virtual void OnIOCompleted(IOContext* context, DWORD bytes_transfered,
+  //                                DWORD error) {
+  //         pending_ = false;
+  //     }
+  //     void DoSomeIo() {
+  //       ...
+  //       // The only buffer required for this operation is the overlapped
+  //       // structure.
+  //       ConnectNamedPipe(file_, &context_->overlapped);
+  //       pending_ = true;
+  //     }
+  //     bool pending_;
+  //     IOContext* context_;
+  //     HANDLE file_;
+  //   };
+  //
+  // Typical use #2:
+  //   class MyFile : public IOHandler {
+  //     MyFile() {
+  //       ...
+  //       message_pump->RegisterIOHandler(file_, this);
+  //     }
+  //     // Plus some code to make sure that this destructor is not called
+  //     // while there are pending IO operations.
+  //     ~MyFile() {
+  //     }
+  //     virtual void OnIOCompleted(IOContext* context, DWORD bytes_transfered,
+  //                                DWORD error) {
+  //       ...
+  //       delete context;
+  //     }
+  //     void DoSomeIo() {
+  //       ...
+  //       IOContext* context = new IOContext;
+  //       // This is not used for anything. It just prevents the context from
+  //       // being considered "abandoned".
+  //       context->handler = this;
+  //       ReadFile(file_, buffer, num_bytes, &read, &context->overlapped);
+  //     }
+  //     HANDLE file_;
+  //   };
+  //
+  // Typical use #3:
+  // Same as the previous example, except that in order to deal with the
+  // requirement stated for the destructor, the class calls WaitForIOCompletion
+  // from the destructor to block until all IO finishes.
+  //     ~MyFile() {
+  //       while(pending_)
+  //         message_pump->WaitForIOCompletion(INFINITE, this);
+  //     }
+  //
+  class IOHandler {
+   public:
+    virtual ~IOHandler() {}
+    // This will be called once the pending IO operation associated with
+    // |context| completes. |error| is the Win32 error code of the IO operation
+    // (ERROR_SUCCESS if there was no error). |bytes_transfered| will be zero
+    // on error.
+    virtual void OnIOCompleted(IOContext* context, DWORD bytes_transfered,
+                               DWORD error) = 0;
+  };
+
+  // An IOObserver is an object that receives IO notifications from the
+  // MessagePump.
+  //
+  // NOTE: An IOObserver implementation should be extremely fast!
+  class IOObserver {
+   public:
+    IOObserver() {}
+
+    virtual void WillProcessIOEvent() = 0;
+    virtual void DidProcessIOEvent() = 0;
+
+   protected:
+    virtual ~IOObserver() {}
+  };
+
+  // The extended context that should be used as the base structure on every
+  // overlapped IO operation. |handler| must be set to the registered IOHandler
+  // for the given file when the operation is started, and it can be set to NULL
+  // before the operation completes to indicate that the handler should not be
+  // called anymore, and instead, the IOContext should be deleted when the OS
+  // notifies the completion of this operation. Please remember that any buffers
+  // involved with an IO operation should be around until the callback is
+  // received, so this technique can only be used for IO that do not involve
+  // additional buffers (other than the overlapped structure itself).
+  struct IOContext {
+    OVERLAPPED overlapped;
+    IOHandler* handler;
+  };
+
+  MessagePumpForIO();
+  virtual ~MessagePumpForIO() {}
+
+  // MessagePump methods:
+  virtual void ScheduleWork();
+  virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time);
+
+  // Register the handler to be used when asynchronous IO for the given file
+  // completes. The registration persists as long as |file_handle| is valid, so
+  // |handler| must be valid as long as there is pending IO for the given file.
+  void RegisterIOHandler(HANDLE file_handle, IOHandler* handler);
+
+  // Register the handler to be used to process job events. The registration
+  // persists as long as the job object is live, so |handler| must be valid
+  // until the job object is destroyed. Returns true if the registration
+  // succeeded, and false otherwise.
+  bool RegisterJobObject(HANDLE job_handle, IOHandler* handler);
+
+  // Waits for the next IO completion that should be processed by |filter|, for
+  // up to |timeout| milliseconds. Return true if any IO operation completed,
+  // regardless of the involved handler, and false if the timeout expired. If
+  // the completion port received any message and the involved IO handler
+  // matches |filter|, the callback is called before returning from this code;
+  // if the handler is not the one that we are looking for, the callback will
+  // be postponed for another time, so reentrancy problems can be avoided.
+  // External use of this method should be reserved for the rare case when the
+  // caller is willing to allow pausing regular task dispatching on this thread.
+  bool WaitForIOCompletion(DWORD timeout, IOHandler* filter);
+
+  void AddIOObserver(IOObserver* obs);
+  void RemoveIOObserver(IOObserver* obs);
+
+ private:
+  struct IOItem {
+    IOHandler* handler;
+    IOContext* context;
+    DWORD bytes_transfered;
+    DWORD error;
+
+    // In some cases |context| can be a non-pointer value casted to a pointer.
+    // |has_valid_io_context| is true if |context| is a valid IOContext
+    // pointer, and false otherwise.
+    bool has_valid_io_context;
+  };
+
+  virtual void DoRunLoop();
+  void WaitForWork();
+  bool MatchCompletedIOItem(IOHandler* filter, IOItem* item);
+  bool GetIOItem(DWORD timeout, IOItem* item);
+  bool ProcessInternalIOItem(const IOItem& item);
+  void WillProcessIOEvent();
+  void DidProcessIOEvent();
+
+  // Converts an IOHandler pointer to a completion port key.
+  // |has_valid_io_context| specifies whether completion packets posted to
+  // |handler| will have valid OVERLAPPED pointers.
+  static ULONG_PTR HandlerToKey(IOHandler* handler, bool has_valid_io_context);
+
+  // Converts a completion port key to an IOHandler pointer.
+  static IOHandler* KeyToHandler(ULONG_PTR key, bool* has_valid_io_context);
+
+  // The completion port associated with this thread.
+  win::ScopedHandle port_;
+  // This list will be empty almost always. It stores IO completions that have
+  // not been delivered yet because somebody was doing cleanup.
+  std::list<IOItem> completed_io_;
+
+  ObserverList<IOObserver> io_observers_;
+};
+
+}  // namespace base
+
+#endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_WIN_H_