Rename CriticalSection to RecursiveCriticalSection.

This name change communicates that the recursive critical section
should not be used for new code.
The relevant files are renamed rtc_base/critical_section* ->
rtc_base/deprecated/recursive_critical_section*

Bug: webrtc:11567
Change-Id: I73483a1c5e59c389407a981efbfc2cfe76ccdb43
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/179483
Commit-Queue: Markus Handell <handellm@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31754}

rtc_base/deprecated/recursive_critical_section_unittest.cc

@@ -0,0 +1,411 @@
+/*
+ *  Copyright 2014 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 "rtc_base/deprecated/recursive_critical_section.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <memory>
+#include <set>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#include "absl/base/attributes.h"
+#include "rtc_base/arraysize.h"
+#include "rtc_base/atomic_ops.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/event.h"
+#include "rtc_base/location.h"
+#include "rtc_base/message_handler.h"
+#include "rtc_base/platform_thread.h"
+#include "rtc_base/thread.h"
+#include "test/gtest.h"
+
+namespace rtc {
+
+namespace {
+
+const int kLongTime = 10000;  // 10 seconds
+const int kNumThreads = 16;
+const int kOperationsToRun = 1000;
+
+class UniqueValueVerifier {
+ public:
+  void Verify(const std::vector<int>& values) {
+    for (size_t i = 0; i < values.size(); ++i) {
+      std::pair<std::set<int>::iterator, bool> result =
+          all_values_.insert(values[i]);
+      // Each value should only be taken by one thread, so if this value
+      // has already been added, something went wrong.
+      EXPECT_TRUE(result.second)
+          << " Thread=" << Thread::Current() << " value=" << values[i];
+    }
+  }
+
+  void Finalize() {}
+
+ private:
+  std::set<int> all_values_;
+};
+
+class CompareAndSwapVerifier {
+ public:
+  CompareAndSwapVerifier() : zero_count_(0) {}
+
+  void Verify(const std::vector<int>& values) {
+    for (auto v : values) {
+      if (v == 0) {
+        EXPECT_EQ(0, zero_count_) << "Thread=" << Thread::Current();
+        ++zero_count_;
+      } else {
+        EXPECT_EQ(1, v) << " Thread=" << Thread::Current();
+      }
+    }
+  }
+
+  void Finalize() { EXPECT_EQ(1, zero_count_); }
+
+ private:
+  int zero_count_;
+};
+
+class RunnerBase : public MessageHandler {
+ public:
+  explicit RunnerBase(int value)
+      : threads_active_(0),
+        start_event_(true, false),
+        done_event_(true, false),
+        shared_value_(value) {}
+
+  bool Run() {
+    // Signal all threads to start.
+    start_event_.Set();
+
+    // Wait for all threads to finish.
+    return done_event_.Wait(kLongTime);
+  }
+
+  void SetExpectedThreadCount(int count) { threads_active_ = count; }
+
+  int shared_value() const { return shared_value_; }
+
+ protected:
+  // Derived classes must override OnMessage, and call BeforeStart and AfterEnd
+  // at the beginning and the end of OnMessage respectively.
+  void BeforeStart() { ASSERT_TRUE(start_event_.Wait(kLongTime)); }
+
+  // Returns true if all threads have finished.
+  bool AfterEnd() {
+    if (AtomicOps::Decrement(&threads_active_) == 0) {
+      done_event_.Set();
+      return true;
+    }
+    return false;
+  }
+
+  int threads_active_;
+  Event start_event_;
+  Event done_event_;
+  int shared_value_;
+};
+
+class RTC_LOCKABLE CriticalSectionLock {
+ public:
+  void Lock() RTC_EXCLUSIVE_LOCK_FUNCTION() { cs_.Enter(); }
+  void Unlock() RTC_UNLOCK_FUNCTION() { cs_.Leave(); }
+
+ private:
+  RecursiveCriticalSection cs_;
+};
+
+template <class Lock>
+class LockRunner : public RunnerBase {
+ public:
+  LockRunner() : RunnerBase(0) {}
+
+  void OnMessage(Message* msg) override {
+    BeforeStart();
+
+    lock_.Lock();
+
+    EXPECT_EQ(0, shared_value_);
+    int old = shared_value_;
+
+    // Use a loop to increase the chance of race.
+    for (int i = 0; i < kOperationsToRun; ++i) {
+      ++shared_value_;
+    }
+    EXPECT_EQ(old + kOperationsToRun, shared_value_);
+    shared_value_ = 0;
+
+    lock_.Unlock();
+
+    AfterEnd();
+  }
+
+ private:
+  Lock lock_;
+};
+
+template <class Op, class Verifier>
+class AtomicOpRunner : public RunnerBase {
+ public:
+  explicit AtomicOpRunner(int initial_value) : RunnerBase(initial_value) {}
+
+  void OnMessage(Message* msg) override {
+    BeforeStart();
+
+    std::vector<int> values;
+    values.reserve(kOperationsToRun);
+
+    // Generate a bunch of values by updating shared_value_ atomically.
+    for (int i = 0; i < kOperationsToRun; ++i) {
+      values.push_back(Op::AtomicOp(&shared_value_));
+    }
+
+    {  // Add them all to the set.
+      CritScope cs(&all_values_crit_);
+      verifier_.Verify(values);
+    }
+
+    if (AfterEnd()) {
+      verifier_.Finalize();
+    }
+  }
+
+ private:
+  RecursiveCriticalSection all_values_crit_;
+  Verifier verifier_;
+};
+
+struct IncrementOp {
+  static int AtomicOp(int* i) { return AtomicOps::Increment(i); }
+};
+
+struct DecrementOp {
+  static int AtomicOp(int* i) { return AtomicOps::Decrement(i); }
+};
+
+struct CompareAndSwapOp {
+  static int AtomicOp(int* i) { return AtomicOps::CompareAndSwap(i, 0, 1); }
+};
+
+void StartThreads(std::vector<std::unique_ptr<Thread>>* threads,
+                  MessageHandler* handler) {
+  for (int i = 0; i < kNumThreads; ++i) {
+    std::unique_ptr<Thread> thread(Thread::Create());
+    thread->Start();
+    thread->Post(RTC_FROM_HERE, handler);
+    threads->push_back(std::move(thread));
+  }
+}
+
+}  // namespace
+
+TEST(AtomicOpsTest, Simple) {
+  int value = 0;
+  EXPECT_EQ(1, AtomicOps::Increment(&value));
+  EXPECT_EQ(1, value);
+  EXPECT_EQ(2, AtomicOps::Increment(&value));
+  EXPECT_EQ(2, value);
+  EXPECT_EQ(1, AtomicOps::Decrement(&value));
+  EXPECT_EQ(1, value);
+  EXPECT_EQ(0, AtomicOps::Decrement(&value));
+  EXPECT_EQ(0, value);
+}
+
+TEST(AtomicOpsTest, SimplePtr) {
+  class Foo {};
+  Foo* volatile foo = nullptr;
+  std::unique_ptr<Foo> a(new Foo());
+  std::unique_ptr<Foo> b(new Foo());
+  // Reading the initial value should work as expected.
+  EXPECT_TRUE(rtc::AtomicOps::AcquireLoadPtr(&foo) == nullptr);
+  // Setting using compare and swap should work.
+  EXPECT_TRUE(rtc::AtomicOps::CompareAndSwapPtr(
+                  &foo, static_cast<Foo*>(nullptr), a.get()) == nullptr);
+  EXPECT_TRUE(rtc::AtomicOps::AcquireLoadPtr(&foo) == a.get());
+  // Setting another value but with the wrong previous pointer should fail
+  // (remain a).
+  EXPECT_TRUE(rtc::AtomicOps::CompareAndSwapPtr(
+                  &foo, static_cast<Foo*>(nullptr), b.get()) == a.get());
+  EXPECT_TRUE(rtc::AtomicOps::AcquireLoadPtr(&foo) == a.get());
+  // Replacing a with b should work.
+  EXPECT_TRUE(rtc::AtomicOps::CompareAndSwapPtr(&foo, a.get(), b.get()) ==
+              a.get());
+  EXPECT_TRUE(rtc::AtomicOps::AcquireLoadPtr(&foo) == b.get());
+}
+
+TEST(AtomicOpsTest, Increment) {
+  // Create and start lots of threads.
+  AtomicOpRunner<IncrementOp, UniqueValueVerifier> runner(0);
+  std::vector<std::unique_ptr<Thread>> threads;
+  StartThreads(&threads, &runner);
+  runner.SetExpectedThreadCount(kNumThreads);
+
+  // Release the hounds!
+  EXPECT_TRUE(runner.Run());
+  EXPECT_EQ(kOperationsToRun * kNumThreads, runner.shared_value());
+}
+
+TEST(AtomicOpsTest, Decrement) {
+  // Create and start lots of threads.
+  AtomicOpRunner<DecrementOp, UniqueValueVerifier> runner(kOperationsToRun *
+                                                          kNumThreads);
+  std::vector<std::unique_ptr<Thread>> threads;
+  StartThreads(&threads, &runner);
+  runner.SetExpectedThreadCount(kNumThreads);
+
+  // Release the hounds!
+  EXPECT_TRUE(runner.Run());
+  EXPECT_EQ(0, runner.shared_value());
+}
+
+TEST(AtomicOpsTest, CompareAndSwap) {
+  // Create and start lots of threads.
+  AtomicOpRunner<CompareAndSwapOp, CompareAndSwapVerifier> runner(0);
+  std::vector<std::unique_ptr<Thread>> threads;
+  StartThreads(&threads, &runner);
+  runner.SetExpectedThreadCount(kNumThreads);
+
+  // Release the hounds!
+  EXPECT_TRUE(runner.Run());
+  EXPECT_EQ(1, runner.shared_value());
+}
+
+TEST(RecursiveCriticalSectionTest, Basic) {
+  // Create and start lots of threads.
+  LockRunner<CriticalSectionLock> runner;
+  std::vector<std::unique_ptr<Thread>> threads;
+  StartThreads(&threads, &runner);
+  runner.SetExpectedThreadCount(kNumThreads);
+
+  // Release the hounds!
+  EXPECT_TRUE(runner.Run());
+  EXPECT_EQ(0, runner.shared_value());
+}
+
+class PerfTestData {
+ public:
+  PerfTestData(int expected_count, Event* event)
+      : cache_line_barrier_1_(),
+        cache_line_barrier_2_(),
+        expected_count_(expected_count),
+        event_(event) {
+    cache_line_barrier_1_[0]++;  // Avoid 'is not used'.
+    cache_line_barrier_2_[0]++;  // Avoid 'is not used'.
+  }
+  ~PerfTestData() {}
+
+  void AddToCounter(int add) {
+    rtc::CritScope cs(&lock_);
+    my_counter_ += add;
+    if (my_counter_ == expected_count_)
+      event_->Set();
+  }
+
+  int64_t total() const {
+    // Assume that only one thread is running now.
+    return my_counter_;
+  }
+
+ private:
+  uint8_t cache_line_barrier_1_[64];
+  RecursiveCriticalSection lock_;
+  uint8_t cache_line_barrier_2_[64];
+  int64_t my_counter_ = 0;
+  const int expected_count_;
+  Event* const event_;
+};
+
+class PerfTestThread {
+ public:
+  PerfTestThread() : thread_(&ThreadFunc, this, "CsPerf") {}
+
+  void Start(PerfTestData* data, int repeats, int id) {
+    RTC_DCHECK(!thread_.IsRunning());
+    RTC_DCHECK(!data_);
+    data_ = data;
+    repeats_ = repeats;
+    my_id_ = id;
+    thread_.Start();
+  }
+
+  void Stop() {
+    RTC_DCHECK(thread_.IsRunning());
+    RTC_DCHECK(data_);
+    thread_.Stop();
+    repeats_ = 0;
+    data_ = nullptr;
+    my_id_ = 0;
+  }
+
+ private:
+  static void ThreadFunc(void* param) {
+    PerfTestThread* me = static_cast<PerfTestThread*>(param);
+    for (int i = 0; i < me->repeats_; ++i)
+      me->data_->AddToCounter(me->my_id_);
+  }
+
+  PlatformThread thread_;
+  PerfTestData* data_ = nullptr;
+  int repeats_ = 0;
+  int my_id_ = 0;
+};
+
+// Comparison of output of this test as tested on a MacBook Pro, 13-inch,
+// 2017, 3,5 GHz Intel Core i7, 16 GB 2133 MHz LPDDR3,
+// running macOS Mojave, 10.14.3.
+//
+// Native mutex implementation using fair policy (previously macOS default):
+// Approximate CPU usage:
+// real    4m54.612s
+// user    1m20.575s
+// sys     3m48.872s
+// Unit test output:
+// [       OK ] RecursiveCriticalSectionTest.Performance (294375 ms)
+//
+// Native mutex implementation using first fit policy (current macOS default):
+// Approximate CPU usage:
+// real    0m11.535s
+// user    0m12.738s
+// sys     0m31.207s
+// Unit test output:
+// [       OK ] RecursiveCriticalSectionTest.Performance (11444 ms)
+//
+// Special partially spin lock based implementation:
+// Approximate CPU usage:
+// real    0m2.113s
+// user    0m3.014s
+// sys     0m4.495s
+// Unit test output:
+// [       OK ] RecursiveCriticalSectionTest.Performance (1885 ms)
+//
+// The test is disabled by default to avoid unecessarily loading the bots.
+TEST(RecursiveCriticalSectionTest, DISABLED_Performance) {
+  PerfTestThread threads[8];
+  Event event;
+
+  static const int kThreadRepeats = 10000000;
+  static const int kExpectedCount = kThreadRepeats * arraysize(threads);
+  PerfTestData test_data(kExpectedCount, &event);
+
+  for (auto& t : threads)
+    t.Start(&test_data, kThreadRepeats, 1);
+
+  event.Wait(Event::kForever);
+
+  for (auto& t : threads)
+    t.Stop();
+}
+
+}  // namespace rtc