From 66cebbda350c3895eb3291cb2f195ed2542c72ac Mon Sep 17 00:00:00 2001
From: Danil Chapovalov <danilchap@webrtc.org>
Date: Thu, 9 Nov 2017 18:44:31 +0100
Subject: [PATCH] Remove aggressive thread checker from WeakPtrReference

This allows to create WeakPtr and dereference it on different threads.
Fix test to validate it.

Bug: webrtc:8517
Change-Id: Idaf0bbdcf14bffbe43cb5fb6514041e8fa746004
Reviewed-on: https://webrtc-review.googlesource.com/21700
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20634}
---
 rtc_base/weak_ptr.cc          |  4 ----
 rtc_base/weak_ptr.h           |  1 -
 rtc_base/weak_ptr_unittest.cc | 22 +++++++++++++++-------
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/rtc_base/weak_ptr.cc b/rtc_base/weak_ptr.cc
index 453a22e8e4..c76256a092 100644
--- a/rtc_base/weak_ptr.cc
+++ b/rtc_base/weak_ptr.cc
@@ -52,16 +52,13 @@ bool WeakReference::is_valid() const {
 }
 
 WeakReferenceOwner::WeakReferenceOwner() {
-  checker_.Detach();
 }
 
 WeakReferenceOwner::~WeakReferenceOwner() {
-  RTC_DCHECK(checker_.CalledSequentially());
   Invalidate();
 }
 
 WeakReference WeakReferenceOwner::GetRef() const {
-  RTC_DCHECK(checker_.CalledSequentially());
   // If we hold the last reference to the Flag then create a new one.
   if (!HasRefs())
     flag_ = new RefCountedObject<WeakReference::Flag>();
@@ -70,7 +67,6 @@ WeakReference WeakReferenceOwner::GetRef() const {
 }
 
 void WeakReferenceOwner::Invalidate() {
-  RTC_DCHECK(checker_.CalledSequentially());
   if (flag_.get()) {
     flag_->Invalidate();
     flag_ = nullptr;
diff --git a/rtc_base/weak_ptr.h b/rtc_base/weak_ptr.h
index 4950dfc19e..8acfab0f03 100644
--- a/rtc_base/weak_ptr.h
+++ b/rtc_base/weak_ptr.h
@@ -135,7 +135,6 @@ class WeakReferenceOwner {
   void Invalidate();
 
  private:
-  SequencedTaskChecker checker_;
   mutable scoped_refptr<RefCountedObject<WeakReference::Flag>> flag_;
 };
 
diff --git a/rtc_base/weak_ptr_unittest.cc b/rtc_base/weak_ptr_unittest.cc
index 0a2dceaf57..c22032b2f5 100644
--- a/rtc_base/weak_ptr_unittest.cc
+++ b/rtc_base/weak_ptr_unittest.cc
@@ -221,13 +221,21 @@ TEST(WeakPtrTest, ObjectAndWeakPtrOnDifferentThreads) {
 }
 
 TEST(WeakPtrTest, WeakPtrInitiateAndUseOnDifferentThreads) {
-  // Test that it is OK to create an object that has a WeakPtr member on one
-  // thread, but use it on another.  This tests that we do not trip runtime
-  // checks that ensure that a WeakPtr is not used by multiple threads.
-  std::unique_ptr<Arrow> arrow(NewObjectCreatedOnTaskQueue<Arrow>());
-  TargetWithFactory target;
-  arrow->target = target.factory.GetWeakPtr();
-  EXPECT_EQ(&target, arrow->target.get());
+  // Test that it is OK to create a WeakPtr on one thread, but use it on
+  // another. This tests that we do not trip runtime checks that ensure that a
+  // WeakPtr is not used by multiple threads.
+  auto target = rtc::MakeUnique<TargetWithFactory>();
+  // Create weak ptr on main thread
+  WeakPtr<Target> weak_ptr = target->factory.GetWeakPtr();
+  rtc::TaskQueue queue("queue");
+  rtc::Event done(false, false);
+  queue.PostTask([&] {
+    // Dereference and invalide weak_ptr on another thread.
+    EXPECT_EQ(weak_ptr.get(), target.get());
+    target.reset();
+    done.Set();
+  });
+  EXPECT_TRUE(done.Wait(1000));
 }
 
 }  // namespace rtc