PPAPI: Get TrackedCallback ready for running on non-main threads.

ppapi/shared_impl/tracked_callback.h

 // 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 PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_
 #define PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_
 
 #include <map>
 #include <set>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
 #include "base/synchronization/condition_variable.h"
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/shared_impl/ppapi_shared_export.h"
 
 namespace ppapi {
 
 class CallbackTracker;
 class Resource;
@@ skipping 42 matching lines @@
 
   // These run the callback in an abortive manner, or post a task to do so (but
   // immediately marking the callback as to be aborted).
   void Abort();
   void PostAbort();
 
   // Run the callback with the given result. If the callback had previously been
   // marked as to be aborted (by |PostAbort()|), |result| will be ignored and
   // the callback will be run with result |PP_ERROR_ABORTED|.
   //
-  // See also ClearAndRun().
+  // Run() will invoke the call immediately, if invoked from the target thread
+  // (as determined by target_loop_). If invoked on a different thread, the
+  // callback will be scheduled to run later on target_loop_.
+  // TODO(dmichael): Make the above part about different threads actually true.
   void Run(int32_t result);
+  // PostRun is like Run(), except it guarantees that the callback will be run
+  // later. In particular, if you invoke PostRun on the same thread on which the
+  // callback is targeted to run, it will *not* be run immediately.
   void PostRun(int32_t result);
 
   void BlockUntilRun();
 
   // Returns the ID of the resource which "owns" the callback, or 0 if the
   // callback is not associated with any resource.
   PP_Resource resource_id() const { return resource_id_; }
 
   // Returns true if the callback was completed (possibly aborted).
   bool completed() const { return completed_; }
 
   // Returns true if the callback was or should be aborted; this will be the
   // case whenever |Abort()| or |PostAbort()| is called before a non-abortive
   // completion.
   bool aborted() const { return aborted_; }
 
   // Helper to determine if the given callback is set and not yet completed.
   // The normal pattern is to use a scoped_refptr to hold a callback. This
   // function tells you if the operation is currently in progress by checking
   // both the null-ness of the scoped_refptr, as well as the completion state
   // of the callback (which may still be out-standing via a PostAbort).
   static bool IsPending(const scoped_refptr<TrackedCallback>& callback);
 
-  // Runs the given callback, clearing the given scoped_refptr before execution.
-  // This is useful for cases where there can be only one pending callback, and
-  // the presence of the callback indicates one is pending. Such code would
-  // normally want to clear it before execution so the plugin can issue a new
-  // request.
-  static void ClearAndRun(scoped_refptr<TrackedCallback>* callback,
-                          int32_t result);
-
-  // Same as ClearAndRun except it calls Abort().
-  static void ClearAndAbort(scoped_refptr<TrackedCallback>* callback);
-
  protected:
   bool is_blocking() {
     return !callback_.func;
   }
   bool is_required() {
     return (callback_.func &&
             !(callback_.flags & PP_COMPLETIONCALLBACK_FLAG_OPTIONAL));
   }
   bool is_optional() {
     return (callback_.func &&
@@ skipping 12 matching lines @@
 
   // Mark this object as complete and remove it from the tracker. This must only
   // be called once. Note that running this may result in this object being
   // deleted (so keep a reference if it'll still be needed).
   void MarkAsCompleted();
 
   // This class is ref counted.
   friend class base::RefCountedThreadSafe<TrackedCallback>;
   virtual ~TrackedCallback();
 
-  // Factory used by |PostAbort()| and |PostRun()|. Note that it's safe to
-  // cancel any pending posted tasks on destruction -- before it's destroyed,
-  // the "owning" |CallbackTracker| must have gone through and done
-  // (synchronous) |Abort()|s.
-  base::WeakPtrFactory<TrackedCallback> weak_ptr_factory_;
+  // Flag used by |PostAbort()| and |PostRun()| to check that we don't schedule
+  // the callback more than once.
+  bool is_scheduled_;
 
   scoped_refptr<CallbackTracker> tracker_;
   PP_Resource resource_id_;
   bool completed_;
   bool aborted_;
   PP_CompletionCallback callback_;
 
   int32_t result_for_blocked_callback_;
   // Used for pausing/waking the blocked thread if this is a blocking completion
   // callback. Note that in-process, there is no lock, blocking callbacks are
   // not allowed, and therefore this pointer will be NULL.
   scoped_ptr<base::ConditionVariable> operation_completed_condvar_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(TrackedCallback);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_TRACKED_CALLBACK_H_