The Tor Browser: ipc/chromium/src/base/message_pump.h@6474c204b198 (annotated)

ipc/chromium/src/base/message_pump.h@6474c204b198 (annotated)

ipc/chromium/src/base/message_pump.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright (c) 2006-2008 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.
 #ifndef BASE_MESSAGE_PUMP_H_
 #define BASE_MESSAGE_PUMP_H_
 #include "base/ref_counted.h"
 namespace base {
 class TimeTicks;
 class MessagePump : public RefCountedThreadSafe<MessagePump> {
  public:
   // Please see the comments above the Run method for an illustration of how
   // these delegate methods are used.
   class Delegate {
    public:
     virtual ~Delegate() {}
     // Called from within Run in response to ScheduleWork or when the message
     // pump would otherwise call DoDelayedWork.  Returns true to indicate that
     // work was done.  DoDelayedWork will not be called if DoWork returns true.
     virtual bool DoWork() = 0;
     // Called from within Run in response to ScheduleDelayedWork or when the
     // message pump would otherwise sleep waiting for more work.  Returns true
     // to indicate that delayed work was done.  DoIdleWork will not be called
     // if DoDelayedWork returns true.  Upon return |next_delayed_work_time|
     // indicates the time when DoDelayedWork should be called again.  If
     // |next_delayed_work_time| is null (per Time::is_null), then the queue of
     // future delayed work (timer events) is currently empty, and no additional
     // calls to this function need to be scheduled.
     virtual bool DoDelayedWork(TimeTicks* next_delayed_work_time) = 0;
     // Called from within Run just before the message pump goes to sleep.
     // Returns true to indicate that idle work was done.
     virtual bool DoIdleWork() = 0;
   };
   virtual ~MessagePump() {}
   // The Run method is called to enter the message pump's run loop.
   //
   // Within the method, the message pump is responsible for processing native
   // messages as well as for giving cycles to the delegate periodically.  The
   // message pump should take care to mix delegate callbacks with native
   // message processing so neither type of event starves the other of cycles.
   //
   // The anatomy of a typical run loop:
   //
   //   for (;;) {
   //     bool did_work = DoInternalWork();
   //     if (should_quit_)
   //       break;
   //
   //     did_work |= delegate_->DoWork();
   //     if (should_quit_)
   //       break;
   //
   //     did_work |= delegate_->DoDelayedWork();
   //     if (should_quit_)
   //       break;
   //
   //     if (did_work)
   //       continue;
   //
   //     did_work = delegate_->DoIdleWork();
   //     if (should_quit_)
   //       break;
   //
   //     if (did_work)
   //       continue;
   //
   //     WaitForWork();
   //   }
   //
   // Here, DoInternalWork is some private method of the message pump that is
   // responsible for dispatching the next UI message or notifying the next IO
   // completion (for example).  WaitForWork is a private method that simply
   // blocks until there is more work of any type to do.
   //
   // Notice that the run loop cycles between calling DoInternalWork, DoWork,
   // and DoDelayedWork methods.  This helps ensure that neither work queue
   // starves the other.  This is important for message pumps that are used to
   // drive animations, for example.
   //
   // Notice also that after each callout to foreign code, the run loop checks
   // to see if it should quit.  The Quit method is responsible for setting this
   // flag.  No further work is done once the quit flag is set.
   //
   // NOTE: Care must be taken to handle Run being called again from within any
   // of the callouts to foreign code.  Native message pumps may also need to
   // deal with other native message pumps being run outside their control
   // (e.g., the MessageBox API on Windows pumps UI messages!).  To be specific,
   // the callouts (DoWork and DoDelayedWork) MUST still be provided even in
   // nested sub-loops that are "seemingly" outside the control of this message
   // pump.  DoWork in particular must never be starved for time slices unless
   // it returns false (meaning it has run out of things to do).
   //
   virtual void Run(Delegate* delegate) = 0;
   // Quit immediately from the most recently entered run loop.  This method may
   // only be used on the thread that called Run.
   virtual void Quit() = 0;
   // Schedule a DoWork callback to happen reasonably soon.  Does nothing if a
   // DoWork callback is already scheduled.  This method may be called from any
   // thread.  Once this call is made, DoWork should not be "starved" at least
   // until it returns a value of false.
   virtual void ScheduleWork() = 0;
   // This method may only called from the thread that called Run.
   //
   // Ensure that DoWork will be called if a nested loop is entered.
   // If a MessagePump can already guarantee that DoWork will be called
   // "reasonably soon", this method can be a no-op to avoid expensive
   // atomic tests and/or syscalls required for ScheduleWork().
   virtual void ScheduleWorkForNestedLoop() { ScheduleWork(); };
   // Schedule a DoDelayedWork callback to happen at the specified time,
   // cancelling any pending DoDelayedWork callback.  This method may only be
   // used on the thread that called Run.
   virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time) = 0;
 };
 }  // namespace base
 #endif  // BASE_MESSAGE_PUMP_H_

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ipc/chromium/src/base/message_pump.h@6474c204b198 (annotated)

ipc/chromium/src/base/message_pump.h