Drop support for link-time injection of the rtc::TaskQueue::Impl

Bug: webrtc:10191
Change-Id: I1b975e8a2230dd45828a4e7f4d5a86f61164445a
Reviewed-on: https://webrtc-review.googlesource.com/c/124121
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26870}

api/task_queue/BUILD.gn

@@ -12,34 +12,26 @@ rtc_source_set("task_queue") {
   visibility = [ "*" ]
   public = [
     "queued_task.h",
-    "task_queue_priority.h",
-  ]
-}
-
-# TODO(bugs.webrtc.org/10191): Merge the target into task_queue target above
-# when support for link-time injection is dropped.
-rtc_source_set("task_queue_factory") {
-  visibility = [ "*" ]
-  public = [
     "task_queue_base.h",
     "task_queue_factory.h",
   ]
   sources = [
     "task_queue_base.cc",
-    "task_queue_impl.cc",
-    "task_queue_impl.h",
   ]
 
   deps = [
-    ":task_queue",
     "../../rtc_base:checks",
-    "../../rtc_base:rtc_task_queue_api",
     "//third_party/abseil-cpp/absl/base:config",
     "//third_party/abseil-cpp/absl/base:core_headers",
     "//third_party/abseil-cpp/absl/strings",
   ]
 }
 
+# TODO(danilchap): Remove this empty target when downstream project stop depending on it.
+rtc_source_set("task_queue_factory") {
+  visibility = [ "*" ]
+}
+
 rtc_source_set("task_queue_test") {
   visibility = [ "*" ]
   testonly = true
@@ -49,7 +41,6 @@ rtc_source_set("task_queue_test") {
   ]
   deps = [
     ":task_queue",
-    ":task_queue_factory",
     "../../rtc_base:rtc_event",
     "../../rtc_base:rtc_task_queue_api",
     "../../rtc_base:timeutils",
@@ -65,7 +56,7 @@ rtc_source_set("default_task_queue_factory") {
     "default_task_queue_factory.h",
   ]
   deps = [
-    ":task_queue_factory",
+    ":task_queue",
   ]
 
   # TODO(bugs.webrtc.org/10284): Include implementation unconditionally when
@@ -85,7 +76,7 @@ rtc_source_set("default_task_queue_factory_impl") {
     "../../rtc_base:rtc_task_queue_impl",
   ]
   deps = [
-    ":task_queue_factory",
+    ":task_queue",
   ]
   if (rtc_enable_libevent) {
     sources = [
@@ -141,7 +132,7 @@ rtc_source_set("global_task_queue_factory") {
   ]
   deps = [
     ":default_task_queue_factory",
-    ":task_queue_factory",
+    ":task_queue",
     "../../rtc_base:checks",
     "../../rtc_base:rtc_task_queue_api",
   ]

api/task_queue/DEPS

@@ -1,9 +1,4 @@
 specific_include_rules = {
-  # temporary include to support both rtc::TaskQueue::Current() and
-  # webrtc::TaskQueueBase::Current() for implementaions of the TaskQueueBase.
-  "task_queue_impl\.h": [
-    "+rtc_base/task_queue.h",
-  ],
   "task_queue_test\.h": [
     "+test/gtest.h",
   ],

api/task_queue/task_queue.cc

@@ -15,10 +15,6 @@
 namespace rtc {
 
 TaskQueue::TaskQueue(const char* queue_name, Priority priority)
-    // For backward compatibility impl_ need to be scoped_refptr<Impl>,
-    // But this implementation treat impl_ as
-    // std::unique_ptr<webrtc::TaskQueueBase, webrtc::TaskQueueDeleter> abusing
-    // fact that both classes are wrappers around raw pointer.
     : impl_(webrtc::GlobalTaskQueueFactory()
                 .CreateTaskQueue(queue_name, priority)
                 .release()) {
@@ -26,16 +22,7 @@ TaskQueue::TaskQueue(const char* queue_name, Priority priority)
 }
 
 TaskQueue::~TaskQueue() {
-  // TODO(danilchap): change impl_ to webrtc::TaskQueueBase* when dependenent
-  // projects stop using link-injection to override task queue and thus do not
-  // rely on exact TaskQueue layout.
-  // There might running task that tries to rescheduler itself to the TaskQueue
-  // and not yet away TaskQueue destructor is called.
-  // Calling back to TaskQueue::PostTask need impl_ pointer still be valid, so
-  // Start the destruction first, ...
   impl_->Delete();
-  // release the pointer later.
-  const_cast<rtc::scoped_refptr<Impl>&>(impl_).release();
 }
 
 // static

api/task_queue/task_queue_base.h

@@ -13,7 +13,12 @@
 #include <memory>
 
 #include "api/task_queue/queued_task.h"
-#include "api/task_queue/task_queue_impl.h"
+
+// TODO(bugs.webrtc.org/10191): Remove when
+// rtc::TaskQueue* rtc::TaskQueue::Current() is unused.
+namespace rtc {
+class TaskQueue;
+}  // namespace rtc
 
 namespace webrtc {
 
@@ -21,10 +26,7 @@ namespace webrtc {
 // in FIFO order and that tasks never overlap. Tasks may always execute on the
 // same worker thread and they may not. To DCHECK that tasks are executing on a
 // known task queue, use IsCurrent().
-// TODO(bugs.webrtc.org/10191): Remove inheritence from rtc::TaskQueue::Impl
+class TaskQueueBase {
-// when all implementations switch to use TaskQueueFactory instead of link-time
-// injection.
-class TaskQueueBase : public rtc::TaskQueue::Impl {
  public:
   // Starts destruction of the task queue.
   // On return ensures no task are running and no new tasks are able to start
@@ -35,7 +37,7 @@ class TaskQueueBase : public rtc::TaskQueue::Impl {
   // TaskQueue is deallocated and thus should not call any methods after Delete.
   // Code running on the TaskQueue should not call Delete, but can assume
   // TaskQueue still exists and may call other methods, e.g. PostTask.
-  void Delete() override = 0;
+  virtual void Delete() = 0;
 
   // Schedules a task to execute. Tasks are executed in FIFO order.
   // If |task->Run()| returns true, task is deleted on the task queue
@@ -45,19 +47,17 @@ class TaskQueueBase : public rtc::TaskQueue::Impl {
   // TaskQueue or it may happen asynchronously after TaskQueue is deleted.
   // This may vary from one implementation to the next so assumptions about
   // lifetimes of pending tasks should not be made.
-  void PostTask(std::unique_ptr<QueuedTask> task) override = 0;
+  virtual void PostTask(std::unique_ptr<QueuedTask> task) = 0;
 
   // Schedules a task to execute a specified number of milliseconds from when
   // the call is made. The precision should be considered as "best effort"
   // and in some cases, such as on Windows when all high precision timers have
   // been used up, can be off by as much as 15 millseconds.
-  void PostDelayedTask(std::unique_ptr<QueuedTask> task,
+  virtual void PostDelayedTask(std::unique_ptr<QueuedTask> task,
-                       uint32_t milliseconds) override = 0;
+                               uint32_t milliseconds) = 0;
 
-  // Until all TaskQueue implementations switch to  using CurrentTaskQueueSetter
+  // Returns the task queue that is running the current thread.
-  // below, this function may return nullptr even if code is executed by a
+  // Returns nullptr if this thread is not associated with any task queue.
-  // TaskQueue. Keep using rtc::TaskQueue::Current() until bugs.webrtc.org/10191
-  // is resolved.
   static TaskQueueBase* Current();
   bool IsCurrent() const { return Current() == this; }
 
@@ -75,7 +75,11 @@ class TaskQueueBase : public rtc::TaskQueue::Impl {
 
   // Users of the TaskQueue should call Delete instead of directly deleting
   // this object.
-  ~TaskQueueBase() override = default;
+  virtual ~TaskQueueBase() = default;
+
+ private:
+  friend class rtc::TaskQueue;
+  rtc::TaskQueue* task_queue_ = nullptr;
 };
 
 struct TaskQueueDeleter {

api/task_queue/task_queue_factory.h

@@ -14,15 +14,15 @@
 
 #include "absl/strings/string_view.h"
 #include "api/task_queue/task_queue_base.h"
-#include "api/task_queue/task_queue_priority.h"
 
 namespace webrtc {
 
+// The implementation of this interface must be thread-safe.
 class TaskQueueFactory {
  public:
   // TaskQueue priority levels. On some platforms these will map to thread
   // priorities, on others such as Mac and iOS, GCD queue priorities.
-  using Priority = ::webrtc::TaskQueuePriority;
+  enum class Priority { NORMAL = 0, HIGH, LOW };
 
   virtual ~TaskQueueFactory() = default;
   virtual std::unique_ptr<TaskQueueBase, TaskQueueDeleter> CreateTaskQueue(

api/task_queue/task_queue_impl.cc

@@ -1,31 +0,0 @@
-/*
- *  Copyright 2019 The WebRTC Project Authors. All rights reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-#include "api/task_queue/task_queue_impl.h"
-
-#include "rtc_base/checks.h"
-
-namespace rtc {
-
-// Fake ref counting: implementers of the TaskQueueBase shouldn't expect it is
-// stored in a refererence counter pointer.
-void TaskQueue::Impl::AddRef() {
-  // AddRef should be called exactly once by rtc::TaskQueue constructor when
-  // raw pointer converted into scoped_refptr<Impl>,
-  // just before TaskQueue constructor assign task_queue_ member.
-  RTC_CHECK(task_queue_ == nullptr);
-}
-
-void TaskQueue::Impl::Release() {
-  // TaskQueue destructor manually destroyes this object, thus Release should
-  // never be called.
-  RTC_CHECK(false);
-}
-
-}  // namespace rtc

api/task_queue/task_queue_impl.h

@@ -1,40 +0,0 @@
-/*
- *  Copyright 2019 The WebRTC Project Authors. All rights reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef API_TASK_QUEUE_TASK_QUEUE_IMPL_H_
-#define API_TASK_QUEUE_TASK_QUEUE_IMPL_H_
-
-#include <memory>
-
-#include "api/task_queue/queued_task.h"
-#include "rtc_base/task_queue.h"
-
-// TODO(danilchap): Remove Impl and dependency on rtc::TaskQueue when custom
-// implementations switch to use global factories that creates TaskQueue
-// instead of using link-time injection.
-class rtc::TaskQueue::Impl {
- public:
-  virtual void Delete() = 0;
-  virtual void PostTask(std::unique_ptr<QueuedTask> task) = 0;
-  virtual void PostDelayedTask(std::unique_ptr<QueuedTask> task,
-                               uint32_t milliseconds) = 0;
-
-  void AddRef();
-  void Release();
-
- protected:
-  virtual ~Impl() = default;
-
- private:
-  friend class rtc::TaskQueue;
-  rtc::TaskQueue* task_queue_ = nullptr;
-};
-
-#endif  // API_TASK_QUEUE_TASK_QUEUE_IMPL_H_

api/task_queue/task_queue_priority.h

@@ -1,21 +0,0 @@
-/*
- *  Copyright 2019 The WebRTC Project Authors. All rights reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-#ifndef API_TASK_QUEUE_TASK_QUEUE_PRIORITY_H_
-#define API_TASK_QUEUE_TASK_QUEUE_PRIORITY_H_
-
-namespace webrtc {
-
-// TODO(bugs.webrtc.org/10191): Move as member class of TaskQueueFactory when
-// rtc::TaskQueue would be able to depende on it.
-enum class TaskQueuePriority { NORMAL = 0, HIGH, LOW };
-
-}  // namespace webrtc
-
-#endif  // API_TASK_QUEUE_TASK_QUEUE_PRIORITY_H_

rtc_base/BUILD.gn

@@ -498,7 +498,6 @@ rtc_source_set("rtc_task_queue_api") {
   ]
   deps = [
     ":macromagic",
-    "../api:scoped_refptr",
     "../api/task_queue",
     "system:rtc_export",
     "//third_party/abseil-cpp/absl/memory",
@@ -522,7 +521,6 @@ if (rtc_enable_libevent) {
       ":safe_conversions",
       ":timeutils",
       "../api/task_queue",
-      "../api/task_queue:task_queue_factory",
       "//third_party/abseil-cpp/absl/memory",
       "//third_party/abseil-cpp/absl/strings",
     ]
@@ -543,7 +541,6 @@ if (is_mac || is_ios) {
       ":checks",
       ":logging",
       "../api/task_queue",
-      "../api/task_queue:task_queue_factory",
       "//third_party/abseil-cpp/absl/memory",
       "//third_party/abseil-cpp/absl/strings",
     ]
@@ -568,7 +565,6 @@ if (is_win) {
       ":safe_conversions",
       ":timeutils",
       "../api/task_queue",
-      "../api/task_queue:task_queue_factory",
       "//third_party/abseil-cpp/absl/memory",
       "//third_party/abseil-cpp/absl/strings",
     ]
@@ -592,7 +588,6 @@ rtc_source_set("rtc_task_queue_stdlib") {
     ":safe_conversions",
     ":timeutils",
     "../api/task_queue",
-    "../api/task_queue:task_queue_factory",
     "//third_party/abseil-cpp/absl/memory",
     "//third_party/abseil-cpp/absl/strings",
   ]

rtc_base/task_queue.h

@@ -17,9 +17,9 @@
 #include <utility>
 
 #include "absl/memory/memory.h"
-#include "api/scoped_refptr.h"
 #include "api/task_queue/queued_task.h"
-#include "api/task_queue/task_queue_priority.h"
+#include "api/task_queue/task_queue_base.h"
+#include "api/task_queue/task_queue_factory.h"
 #include "rtc_base/constructor_magic.h"
 #include "rtc_base/system/rtc_export.h"
 #include "rtc_base/thread_annotations.h"
@@ -143,8 +143,7 @@ class RTC_LOCKABLE RTC_EXPORT TaskQueue {
  public:
   // TaskQueue priority levels. On some platforms these will map to thread
   // priorities, on others such as Mac and iOS, GCD queue priorities.
-  using Priority = ::webrtc::TaskQueuePriority;
+  using Priority = ::webrtc::TaskQueueFactory::Priority;
-  class Impl;
 
   explicit TaskQueue(const char* queue_name,
                      Priority priority = Priority::NORMAL);
@@ -188,15 +187,7 @@ class RTC_LOCKABLE RTC_EXPORT TaskQueue {
   }
 
  private:
-  // TODO(danilchap): Remove when external implementaions of TaskQueue remove
+  webrtc::TaskQueueBase* const impl_;
-  // these two functions.
-  void PostTaskAndReply(std::unique_ptr<QueuedTask> task,
-                        std::unique_ptr<QueuedTask> reply,
-                        TaskQueue* reply_queue);
-  void PostTaskAndReply(std::unique_ptr<QueuedTask> task,
-                        std::unique_ptr<QueuedTask> reply);
-
-  const scoped_refptr<Impl> impl_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(TaskQueue);
 };