Pass Callback to TaskRunner by value and consume it on invocation (1)

third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.cc

 // Copyright 2015 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.
 
 #include "platform/scheduler/base/task_queue_impl.h"
 
+#include <utility>
+
 #include "base/format_macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
+#include "base/time/time.h"
 #include "base/trace_event/blame_context.h"
 #include "platform/scheduler/base/task_queue_manager.h"
 #include "platform/scheduler/base/task_queue_manager_delegate.h"
 #include "platform/scheduler/base/time_domain.h"
 #include "platform/scheduler/base/work_queue.h"
 
 namespace blink {
 namespace scheduler {
 
 // static
@@ skipping 89 matching lines @@
                   base::TimeTicks(),
                   true),
 #ifndef NDEBUG
       enqueue_order_set_(false),
 #endif
       enqueue_order_(0) {
   sequence_num = 0;
 }
 
 TaskQueueImpl::Task::Task(const tracked_objects::Location& posted_from,
-                          const base::Closure& task,
+                          base::Closure task,
                           base::TimeTicks desired_run_time,
                           EnqueueOrder sequence_number,
                           bool nestable)
-    : PendingTask(posted_from, task, desired_run_time, nestable),
+    : PendingTask(posted_from, std::move(task), desired_run_time, nestable),
 #ifndef NDEBUG
       enqueue_order_set_(false),
 #endif
       enqueue_order_(0) {
   sequence_num = sequence_number;
 }
 
 TaskQueueImpl::Task::Task(const tracked_objects::Location& posted_from,
-                          const base::Closure& task,
+                          base::Closure task,
                           base::TimeTicks desired_run_time,
                           EnqueueOrder sequence_number,
                           bool nestable,
                           EnqueueOrder enqueue_order)
-    : PendingTask(posted_from, task, desired_run_time, nestable),
+    : PendingTask(posted_from, std::move(task), desired_run_time, nestable),
 #ifndef NDEBUG
       enqueue_order_set_(true),
 #endif
       enqueue_order_(enqueue_order) {
   sequence_num = sequence_number;
 }
 
 TaskQueueImpl::AnyThread::AnyThread(TaskQueueManager* task_queue_manager,
                                     TimeDomain* time_domain)
     : task_queue_manager(task_queue_manager), time_domain(time_domain) {}
@@ skipping 35 matching lines @@
   any_thread().immediate_incoming_queue.clear();
   main_thread_only().immediate_work_queue.reset();
   main_thread_only().delayed_work_queue.reset();
 }
 
 bool TaskQueueImpl::RunsTasksOnCurrentThread() const {
   return base::PlatformThread::CurrentId() == thread_id_;
 }
 
 bool TaskQueueImpl::PostDelayedTask(const tracked_objects::Location& from_here,
-                                    const base::Closure& task,
+                                    base::Closure task,
                                     base::TimeDelta delay) {
   if (delay.is_zero())
-    return PostImmediateTaskImpl(from_here, task, TaskType::NORMAL);
+    return PostImmediateTaskImpl(from_here, std::move(task), TaskType::NORMAL);
 
-  return PostDelayedTaskImpl(from_here, task, delay, TaskType::NORMAL);
+  return PostDelayedTaskImpl(from_here, std::move(task), delay,
+                             TaskType::NORMAL);
 }
 
 bool TaskQueueImpl::PostNonNestableDelayedTask(
     const tracked_objects::Location& from_here,
-    const base::Closure& task,
+    base::Closure task,
     base::TimeDelta delay) {
   if (delay.is_zero())
-    return PostImmediateTaskImpl(from_here, task, TaskType::NON_NESTABLE);
+    return PostImmediateTaskImpl(from_here, std::move(task),
+                                 TaskType::NON_NESTABLE);
 
-  return PostDelayedTaskImpl(from_here, task, delay, TaskType::NON_NESTABLE);
+  return PostDelayedTaskImpl(from_here, std::move(task), delay,
+                             TaskType::NON_NESTABLE);
 }
 
 bool TaskQueueImpl::PostImmediateTaskImpl(
     const tracked_objects::Location& from_here,
-    const base::Closure& task,
+    base::Closure task,
     TaskType task_type) {
   base::AutoLock lock(any_thread_lock_);
   if (!any_thread().task_queue_manager)
     return false;
 
   EnqueueOrder sequence_number =
       any_thread().task_queue_manager->GetNextSequenceNumber();
 
-  PushOntoImmediateIncomingQueueLocked(
-      from_here,
-      task,
-      base::TimeTicks(),
-      sequence_number,
-      task_type != TaskType::NON_NESTABLE);
+  PushOntoImmediateIncomingQueueLocked(from_here, std::move(task),
+                                       base::TimeTicks(), sequence_number,
+                                       task_type != TaskType::NON_NESTABLE);
   return true;
 }
 
 bool TaskQueueImpl::PostDelayedTaskImpl(
     const tracked_objects::Location& from_here,
-    const base::Closure& task,
+    base::Closure task,
     base::TimeDelta delay,
     TaskType task_type) {
   DCHECK_GT(delay, base::TimeDelta());
   if (base::PlatformThread::CurrentId() == thread_id_) {
     // Lock-free fast path for delayed tasks posted from the main thread.
     if (!main_thread_only().task_queue_manager)
       return false;
 
     EnqueueOrder sequence_number =
         main_thread_only().task_queue_manager->GetNextSequenceNumber();
 
     base::TimeTicks time_domain_now = main_thread_only().time_domain->Now();
     base::TimeTicks time_domain_delayed_run_time = time_domain_now + delay;
     PushOntoDelayedIncomingQueueFromMainThread(
-        Task(from_here, task, time_domain_delayed_run_time, sequence_number,
-             task_type != TaskType::NON_NESTABLE),
+        Task(from_here, std::move(task), time_domain_delayed_run_time,
+             sequence_number, task_type != TaskType::NON_NESTABLE),
         time_domain_now);
   } else {
     // NOTE posting a delayed task from a different thread is not expected to
     // be common. This pathway is less optimal than perhaps it could be
     // because it causes two main thread tasks to be run.  Should this
     // assumption prove to be false in future, we may need to revisit this.
     base::AutoLock lock(any_thread_lock_);
     if (!any_thread().task_queue_manager)
       return false;
 
     EnqueueOrder sequence_number =
         any_thread().task_queue_manager->GetNextSequenceNumber();
 
     base::TimeTicks time_domain_now = any_thread().time_domain->Now();
     base::TimeTicks time_domain_delayed_run_time = time_domain_now + delay;
     PushOntoDelayedIncomingQueueLocked(
-        Task(from_here, task, time_domain_delayed_run_time, sequence_number,
-             task_type != TaskType::NON_NESTABLE));
+        Task(from_here, std::move(task), time_domain_delayed_run_time,
+             sequence_number, task_type != TaskType::NON_NESTABLE));
   }
   return true;
 }
 
 void TaskQueueImpl::PushOntoDelayedIncomingQueueFromMainThread(
     Task pending_task, base::TimeTicks now) {
   base::TimeTicks delayed_run_time = pending_task.delayed_run_time;
   main_thread_only().task_queue_manager->DidQueueTask(pending_task);
   main_thread_only().delayed_incoming_queue.push(std::move(pending_task));
 
@@ skipping 41 matching lines @@
   } else {
     // If |delayed_run_time| is in the future we can queue it as normal.
     PushOntoDelayedIncomingQueueFromMainThread(std::move(pending_task),
                                                time_domain_now);
   }
   TraceQueueSize(false);
 }
 
 void TaskQueueImpl::PushOntoImmediateIncomingQueueLocked(
     const tracked_objects::Location& posted_from,
-    const base::Closure& task,
+    base::Closure task,
     base::TimeTicks desired_run_time,
     EnqueueOrder sequence_number,
     bool nestable) {
   // If the |immediate_incoming_queue| is empty we need a DoWork posted to make
   // it run.
   if (any_thread().immediate_incoming_queue.empty()) {
     // However there's no point posting a DoWork for a blocked queue. NB we can
     // only tell if it's disabled from the main thread.
     bool queue_is_blocked =
         RunsTasksOnCurrentThread() &&
         (!IsQueueEnabled() || main_thread_only().current_fence);
     any_thread().task_queue_manager->OnQueueHasIncomingImmediateWork(
         this, sequence_number, queue_is_blocked);
     any_thread().time_domain->OnQueueHasImmediateWork(this);
   }
   any_thread().immediate_incoming_queue.emplace_back(
-      posted_from, task, desired_run_time, sequence_number, nestable,
+      posted_from, std::move(task), desired_run_time, sequence_number, nestable,
       sequence_number);
   any_thread().task_queue_manager->DidQueueTask(
       any_thread().immediate_incoming_queue.back());
   TraceQueueSize(true);
 }
 
 void TaskQueueImpl::ReloadImmediateWorkQueueIfEmpty() {
   if (!main_thread_only().immediate_work_queue->Empty())
     return;
 
@@ skipping 522 matching lines @@
 
 void TaskQueueImpl::PushImmediateIncomingTaskForTest(
     TaskQueueImpl::Task&& task) {
   base::AutoLock lock(any_thread_lock_);
   any_thread().immediate_incoming_queue.push_back(std::move(task));
 }
 
 }  // namespace internal
 }  // namespace scheduler
 }  // namespace blink