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

base/task_scheduler/scheduler_worker_pool_impl.cc

 // Copyright 2016 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 "base/task_scheduler/scheduler_worker_pool_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
@@ skipping 41 matching lines @@
   // long as |worker_pool| is alive.
   // TODO(robliao): Find a concrete way to manage |worker_pool|'s memory.
   SchedulerParallelTaskRunner(const TaskTraits& traits,
                               SchedulerWorkerPool* worker_pool)
       : traits_(traits), worker_pool_(worker_pool) {
     DCHECK(worker_pool_);
   }
 
   // TaskRunner:
   bool PostDelayedTask(const tracked_objects::Location& from_here,
-                       const Closure& closure,
+                       Closure closure,
                        TimeDelta delay) override {
     // Post the task as part of a one-off single-task Sequence.
     return worker_pool_->PostTaskWithSequence(
-        MakeUnique<Task>(from_here, closure, traits_, delay),
+        MakeUnique<Task>(from_here, std::move(closure), traits_, delay),
         make_scoped_refptr(new Sequence), nullptr);
   }
 
   bool RunsTasksOnCurrentThread() const override {
     return tls_current_worker_pool.Get().Get() == worker_pool_;
   }
 
  private:
   ~SchedulerParallelTaskRunner() override = default;
 
@@ skipping 10 matching lines @@
   // so long as |worker_pool| is alive.
   // TODO(robliao): Find a concrete way to manage |worker_pool|'s memory.
   SchedulerSequencedTaskRunner(const TaskTraits& traits,
                                SchedulerWorkerPool* worker_pool)
       : traits_(traits), worker_pool_(worker_pool) {
     DCHECK(worker_pool_);
   }
 
   // SequencedTaskRunner:
   bool PostDelayedTask(const tracked_objects::Location& from_here,
-                       const Closure& closure,
+                       Closure closure,
                        TimeDelta delay) override {
-    std::unique_ptr<Task> task(new Task(from_here, closure, traits_, delay));
+    std::unique_ptr<Task> task(
+        new Task(from_here, std::move(closure), traits_, delay));
     task->sequenced_task_runner_ref = this;
 
     // Post the task as part of |sequence_|.
     return worker_pool_->PostTaskWithSequence(std::move(task), sequence_,
                                               nullptr);
   }
 
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
-                                  const Closure& closure,
+                                  Closure closure,
                                   base::TimeDelta delay) override {
     // Tasks are never nested within the task scheduler.
-    return PostDelayedTask(from_here, closure, delay);
+    return PostDelayedTask(from_here, std::move(closure), delay);
   }
 
   bool RunsTasksOnCurrentThread() const override {
     // TODO(fdoray): Rename TaskRunner::RunsTaskOnCurrentThread() to something
     // that reflects this behavior more accurately. crbug.com/646905
     return sequence_->token() == SequenceToken::GetForCurrentThread();
   }
 
  private:
   ~SchedulerSequencedTaskRunner() override = default;
@@ skipping 27 matching lines @@
   // Constructs a SchedulerSingleThreadTaskRunner which can be used to post
   // tasks so long as |worker_pool| and |worker| are alive.
   // TODO(robliao): Find a concrete way to manage the memory of |worker_pool|
   // and |worker|.
   SchedulerSingleThreadTaskRunner(const TaskTraits& traits,
                                   SchedulerWorkerPool* worker_pool,
                                   SchedulerWorker* worker);
 
   // SingleThreadTaskRunner:
   bool PostDelayedTask(const tracked_objects::Location& from_here,
-                       const Closure& closure,
+                       Closure closure,
                        TimeDelta delay) override {
-    std::unique_ptr<Task> task(new Task(from_here, closure, traits_, delay));
+    std::unique_ptr<Task> task(
+        new Task(from_here, std::move(closure), traits_, delay));
     task->single_thread_task_runner_ref = this;
 
     // Post the task to be executed by |worker_| as part of |sequence_|.
     return worker_pool_->PostTaskWithSequence(std::move(task), sequence_,
                                               worker_);
   }
 
   bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here,
-                                  const Closure& closure,
+                                  Closure closure,
                                   base::TimeDelta delay) override {
     // Tasks are never nested within the task scheduler.
-    return PostDelayedTask(from_here, closure, delay);
+    return PostDelayedTask(from_here, std::move(closure), delay);
   }
 
   bool RunsTasksOnCurrentThread() const override {
     // Even though this is a SingleThreadTaskRunner, test the actual sequence
     // instead of the assigned worker so that another task randomly assigned
     // to the same worker doesn't return true by happenstance.
     return sequence_->token() == SequenceToken::GetForCurrentThread();
   }
 
  private:
@@ skipping 575 matching lines @@
   AutoSchedulerLock auto_lock(idle_workers_stack_lock_);
   idle_workers_stack_.Remove(worker);
 }
 
 bool SchedulerWorkerPoolImpl::CanWorkerDetachForTesting() {
   return !worker_detachment_disallowed_.IsSet();
 }
 
 }  // namespace internal
 }  // namespace base