Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 640 insertions, 0 deletions

diff --git a/third_party/libwebrtc/rtc_base/thread.h b/third_party/libwebrtc/rtc_base/thread.h
new file mode 100644
index 0000000000..77ccc9e2ab
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/thread.h
@@ -0,0 +1,640 @@
+/*
+ *  Copyright 2004 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 RTC_BASE_THREAD_H_
+#define RTC_BASE_THREAD_H_
+
+#include <stdint.h>
+
+#include <list>
+#include <map>
+#include <memory>
+#include <queue>
+#include <set>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+
+#if defined(WEBRTC_POSIX)
+#include <pthread.h>
+#endif
+#include "absl/base/attributes.h"
+#include "absl/functional/any_invocable.h"
+#include "api/function_view.h"
+#include "api/task_queue/task_queue_base.h"
+#include "api/units/time_delta.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/deprecated/recursive_critical_section.h"
+#include "rtc_base/location.h"
+#include "rtc_base/message_handler.h"
+#include "rtc_base/platform_thread_types.h"
+#include "rtc_base/socket_server.h"
+#include "rtc_base/system/rtc_export.h"
+#include "rtc_base/thread_annotations.h"
+#include "rtc_base/thread_message.h"
+
+#if defined(WEBRTC_WIN)
+#include "rtc_base/win32.h"
+#endif
+
+#if RTC_DCHECK_IS_ON
+// Counts how many blocking Thread::Invoke or Thread::Send calls are made from
+// within a scope and logs the number of blocking calls at the end of the scope.
+#define RTC_LOG_THREAD_BLOCK_COUNT()                                        \
+  rtc::Thread::ScopedCountBlockingCalls blocked_call_count_printer(         \
+      [func = __func__](uint32_t actual_block, uint32_t could_block) {      \
+        auto total = actual_block + could_block;                            \
+        if (total) {                                                        \
+          RTC_LOG(LS_WARNING) << "Blocking " << func << ": total=" << total \
+                              << " (actual=" << actual_block                \
+                              << ", could=" << could_block << ")";          \
+        }                                                                   \
+      })
+
+// Adds an RTC_DCHECK_LE that checks that the number of blocking calls are
+// less than or equal to a specific value. Use to avoid regressing in the
+// number of blocking thread calls.
+// Note: Use of this macro, requires RTC_LOG_THREAD_BLOCK_COUNT() to be called
+// first.
+#define RTC_DCHECK_BLOCK_COUNT_NO_MORE_THAN(x)                               \
+  do {                                                                       \
+    blocked_call_count_printer.set_minimum_call_count_for_callback(x + 1);   \
+    RTC_DCHECK_LE(blocked_call_count_printer.GetTotalBlockedCallCount(), x); \
+  } while (0)
+#else
+#define RTC_LOG_THREAD_BLOCK_COUNT()
+#define RTC_DCHECK_BLOCK_COUNT_NO_MORE_THAN(x)
+#endif
+
+namespace rtc {
+
+class Thread;
+
+class RTC_EXPORT ThreadManager {
+ public:
+  static const int kForever = -1;
+
+  // Singleton, constructor and destructor are private.
+  static ThreadManager* Instance();
+
+  static void Add(Thread* message_queue);
+  static void Remove(Thread* message_queue);
+  static void Clear(MessageHandler* handler);
+
+  // For testing purposes, for use with a simulated clock.
+  // Ensures that all message queues have processed delayed messages
+  // up until the current point in time.
+  static void ProcessAllMessageQueuesForTesting();
+
+  Thread* CurrentThread();
+  void SetCurrentThread(Thread* thread);
+  // Allows changing the current thread, this is intended for tests where we
+  // want to simulate multiple threads running on a single physical thread.
+  void ChangeCurrentThreadForTest(Thread* thread);
+
+  // Returns a thread object with its thread_ ivar set
+  // to whatever the OS uses to represent the thread.
+  // If there already *is* a Thread object corresponding to this thread,
+  // this method will return that.  Otherwise it creates a new Thread
+  // object whose wrapped() method will return true, and whose
+  // handle will, on Win32, be opened with only synchronization privileges -
+  // if you need more privilegs, rather than changing this method, please
+  // write additional code to adjust the privileges, or call a different
+  // factory method of your own devising, because this one gets used in
+  // unexpected contexts (like inside browser plugins) and it would be a
+  // shame to break it.  It is also conceivable on Win32 that we won't even
+  // be able to get synchronization privileges, in which case the result
+  // will have a null handle.
+  Thread* WrapCurrentThread();
+  void UnwrapCurrentThread();
+
+#if RTC_DCHECK_IS_ON
+  // Registers that a Send operation is to be performed between `source` and
+  // `target`, while checking that this does not cause a send cycle that could
+  // potentially cause a deadlock.
+  void RegisterSendAndCheckForCycles(Thread* source, Thread* target);
+#endif
+
+ private:
+  ThreadManager();
+  ~ThreadManager();
+
+  ThreadManager(const ThreadManager&) = delete;
+  ThreadManager& operator=(const ThreadManager&) = delete;
+
+  void SetCurrentThreadInternal(Thread* thread);
+  void AddInternal(Thread* message_queue);
+  void RemoveInternal(Thread* message_queue);
+  void ClearInternal(MessageHandler* handler);
+  void ProcessAllMessageQueuesInternal();
+#if RTC_DCHECK_IS_ON
+  void RemoveFromSendGraph(Thread* thread) RTC_EXCLUSIVE_LOCKS_REQUIRED(crit_);
+#endif
+
+  // This list contains all live Threads.
+  std::vector<Thread*> message_queues_ RTC_GUARDED_BY(crit_);
+
+  // Methods that don't modify the list of message queues may be called in a
+  // re-entrant fashion. "processing_" keeps track of the depth of re-entrant
+  // calls.
+  RecursiveCriticalSection crit_;
+  size_t processing_ RTC_GUARDED_BY(crit_) = 0;
+#if RTC_DCHECK_IS_ON
+  // Represents all thread seand actions by storing all send targets per thread.
+  // This is used by RegisterSendAndCheckForCycles. This graph has no cycles
+  // since we will trigger a CHECK failure if a cycle is introduced.
+  std::map<Thread*, std::set<Thread*>> send_graph_ RTC_GUARDED_BY(crit_);
+#endif
+
+#if defined(WEBRTC_POSIX)
+  pthread_key_t key_;
+#endif
+
+#if defined(WEBRTC_WIN)
+  const DWORD key_;
+#endif
+};
+
+// WARNING! SUBCLASSES MUST CALL Stop() IN THEIR DESTRUCTORS!  See ~Thread().
+
+class RTC_LOCKABLE RTC_EXPORT Thread : public webrtc::TaskQueueBase {
+ public:
+  static const int kForever = -1;
+
+  // Create a new Thread and optionally assign it to the passed
+  // SocketServer. Subclasses that override Clear should pass false for
+  // init_queue and call DoInit() from their constructor to prevent races
+  // with the ThreadManager using the object while the vtable is still
+  // being created.
+  explicit Thread(SocketServer* ss);
+  explicit Thread(std::unique_ptr<SocketServer> ss);
+
+  // Constructors meant for subclasses; they should call DoInit themselves and
+  // pass false for `do_init`, so that DoInit is called only on the fully
+  // instantiated class, which avoids a vptr data race.
+  Thread(SocketServer* ss, bool do_init);
+  Thread(std::unique_ptr<SocketServer> ss, bool do_init);
+
+  // NOTE: ALL SUBCLASSES OF Thread MUST CALL Stop() IN THEIR DESTRUCTORS (or
+  // guarantee Stop() is explicitly called before the subclass is destroyed).
+  // This is required to avoid a data race between the destructor modifying the
+  // vtable, and the Thread::PreRun calling the virtual method Run().
+
+  // NOTE: SUBCLASSES OF Thread THAT OVERRIDE Clear MUST CALL
+  // DoDestroy() IN THEIR DESTRUCTORS! This is required to avoid a data race
+  // between the destructor modifying the vtable, and the ThreadManager
+  // calling Clear on the object from a different thread.
+  ~Thread() override;
+
+  Thread(const Thread&) = delete;
+  Thread& operator=(const Thread&) = delete;
+
+  static std::unique_ptr<Thread> CreateWithSocketServer();
+  static std::unique_ptr<Thread> Create();
+  static Thread* Current();
+
+  // Used to catch performance regressions. Use this to disallow blocking calls
+  // (Invoke) for a given scope.  If a synchronous call is made while this is in
+  // effect, an assert will be triggered.
+  // Note that this is a single threaded class.
+  class ScopedDisallowBlockingCalls {
+   public:
+    ScopedDisallowBlockingCalls();
+    ScopedDisallowBlockingCalls(const ScopedDisallowBlockingCalls&) = delete;
+    ScopedDisallowBlockingCalls& operator=(const ScopedDisallowBlockingCalls&) =
+        delete;
+    ~ScopedDisallowBlockingCalls();
+
+   private:
+    Thread* const thread_;
+    const bool previous_state_;
+  };
+
+#if RTC_DCHECK_IS_ON
+  class ScopedCountBlockingCalls {
+   public:
+    ScopedCountBlockingCalls(std::function<void(uint32_t, uint32_t)> callback);
+    ScopedCountBlockingCalls(const ScopedDisallowBlockingCalls&) = delete;
+    ScopedCountBlockingCalls& operator=(const ScopedDisallowBlockingCalls&) =
+        delete;
+    ~ScopedCountBlockingCalls();
+
+    uint32_t GetBlockingCallCount() const;
+    uint32_t GetCouldBeBlockingCallCount() const;
+    uint32_t GetTotalBlockedCallCount() const;
+
+    void set_minimum_call_count_for_callback(uint32_t minimum) {
+      min_blocking_calls_for_callback_ = minimum;
+    }
+
+   private:
+    Thread* const thread_;
+    const uint32_t base_blocking_call_count_;
+    const uint32_t base_could_be_blocking_call_count_;
+    // The minimum number of blocking calls required in order to issue the
+    // result_callback_. This is used by RTC_DCHECK_BLOCK_COUNT_NO_MORE_THAN to
+    // tame log spam.
+    // By default we always issue the callback, regardless of callback count.
+    uint32_t min_blocking_calls_for_callback_ = 0;
+    std::function<void(uint32_t, uint32_t)> result_callback_;
+  };
+
+  uint32_t GetBlockingCallCount() const;
+  uint32_t GetCouldBeBlockingCallCount() const;
+#endif
+
+  SocketServer* socketserver();
+
+  // Note: The behavior of Thread has changed.  When a thread is stopped,
+  // futher Posts and Sends will fail.  However, any pending Sends and *ready*
+  // Posts (as opposed to unexpired delayed Posts) will be delivered before
+  // Get (or Peek) returns false.  By guaranteeing delivery of those messages,
+  // we eliminate the race condition when an MessageHandler and Thread
+  // may be destroyed independently of each other.
+  virtual void Quit();
+  virtual bool IsQuitting();
+  virtual void Restart();
+  // Not all message queues actually process messages (such as SignalThread).
+  // In those cases, it's important to know, before posting, that it won't be
+  // Processed.  Normally, this would be true until IsQuitting() is true.
+  virtual bool IsProcessingMessagesForTesting();
+
+  // Get() will process I/O until:
+  //  1) A message is available (returns true)
+  //  2) cmsWait seconds have elapsed (returns false)
+  //  3) Stop() is called (returns false)
+  virtual bool Get(Message* pmsg,
+                   int cmsWait = kForever,
+                   bool process_io = true);
+  virtual bool Peek(Message* pmsg, int cmsWait = 0);
+  // `time_sensitive` is deprecated and should always be false.
+  virtual void Post(const Location& posted_from,
+                    MessageHandler* phandler,
+                    uint32_t id = 0,
+                    MessageData* pdata = nullptr,
+                    bool time_sensitive = false);
+  virtual void PostDelayed(const Location& posted_from,
+                           int delay_ms,
+                           MessageHandler* phandler,
+                           uint32_t id = 0,
+                           MessageData* pdata = nullptr);
+  virtual void PostAt(const Location& posted_from,
+                      int64_t run_at_ms,
+                      MessageHandler* phandler,
+                      uint32_t id = 0,
+                      MessageData* pdata = nullptr);
+  virtual void Clear(MessageHandler* phandler,
+                     uint32_t id = MQID_ANY,
+                     MessageList* removed = nullptr);
+  virtual void Dispatch(Message* pmsg);
+
+  // Amount of time until the next message can be retrieved
+  virtual int GetDelay();
+
+  bool empty() const { return size() == 0u; }
+  size_t size() const {
+    CritScope cs(&crit_);
+    return messages_.size() + delayed_messages_.size() + (fPeekKeep_ ? 1u : 0u);
+  }
+
+  // Internally posts a message which causes the doomed object to be deleted
+  template <class T>
+  void Dispose(T* doomed) {
+    if (doomed) {
+      Post(RTC_FROM_HERE, nullptr, MQID_DISPOSE, new DisposeData<T>(doomed));
+    }
+  }
+
+  bool IsCurrent() const;
+
+  // Sleeps the calling thread for the specified number of milliseconds, during
+  // which time no processing is performed. Returns false if sleeping was
+  // interrupted by a signal (POSIX only).
+  static bool SleepMs(int millis);
+
+  // Sets the thread's name, for debugging. Must be called before Start().
+  // If `obj` is non-null, its value is appended to `name`.
+  const std::string& name() const { return name_; }
+  bool SetName(absl::string_view name, const void* obj);
+
+  // Sets the expected processing time in ms. The thread will write
+  // log messages when Invoke() takes more time than this.
+  // Default is 50 ms.
+  void SetDispatchWarningMs(int deadline);
+
+  // Starts the execution of the thread.
+  bool Start();
+
+  // Tells the thread to stop and waits until it is joined.
+  // Never call Stop on the current thread.  Instead use the inherited Quit
+  // function which will exit the base Thread without terminating the
+  // underlying OS thread.
+  virtual void Stop();
+
+  // By default, Thread::Run() calls ProcessMessages(kForever).  To do other
+  // work, override Run().  To receive and dispatch messages, call
+  // ProcessMessages occasionally.
+  virtual void Run();
+
+  virtual void Send(const Location& posted_from,
+                    MessageHandler* phandler,
+                    uint32_t id = 0,
+                    MessageData* pdata = nullptr);
+
+  // Convenience method to invoke a functor on another thread.  Caller must
+  // provide the `ReturnT` template argument, which cannot (easily) be deduced.
+  // Uses Send() internally, which blocks the current thread until execution
+  // is complete.
+  // Ex: bool result = thread.Invoke<bool>(RTC_FROM_HERE,
+  // &MyFunctionReturningBool);
+  // NOTE: This function can only be called when synchronous calls are allowed.
+  // See ScopedDisallowBlockingCalls for details.
+  // NOTE: Blocking invokes are DISCOURAGED, consider if what you're doing can
+  // be achieved with PostTask() and callbacks instead.
+  template <
+      class ReturnT,
+      typename = typename std::enable_if<!std::is_void<ReturnT>::value>::type>
+  ReturnT Invoke(const Location& posted_from, FunctionView<ReturnT()> functor) {
+    ReturnT result;
+    InvokeInternal(posted_from, [functor, &result] { result = functor(); });
+    return result;
+  }
+
+  template <
+      class ReturnT,
+      typename = typename std::enable_if<std::is_void<ReturnT>::value>::type>
+  void Invoke(const Location& posted_from, FunctionView<void()> functor) {
+    InvokeInternal(posted_from, functor);
+  }
+
+  // Allows invoke to specified `thread`. Thread never will be dereferenced and
+  // will be used only for reference-based comparison, so instance can be safely
+  // deleted. If NDEBUG is defined and RTC_DCHECK_IS_ON is undefined do
+  // nothing.
+  void AllowInvokesToThread(Thread* thread);
+
+  // If NDEBUG is defined and RTC_DCHECK_IS_ON is undefined do nothing.
+  void DisallowAllInvokes();
+  // Returns true if `target` was allowed by AllowInvokesToThread() or if no
+  // calls were made to AllowInvokesToThread and DisallowAllInvokes. Otherwise
+  // returns false.
+  // If NDEBUG is defined and RTC_DCHECK_IS_ON is undefined always returns
+  // true.
+  bool IsInvokeToThreadAllowed(rtc::Thread* target);
+
+  // From TaskQueueBase
+  void Delete() override;
+  void PostTask(absl::AnyInvocable<void() &&> task) override;
+  void PostDelayedTask(absl::AnyInvocable<void() &&> task,
+                       webrtc::TimeDelta delay) override;
+  void PostDelayedHighPrecisionTask(absl::AnyInvocable<void() &&> task,
+                                    webrtc::TimeDelta delay) override;
+
+  // ProcessMessages will process I/O and dispatch messages until:
+  //  1) cms milliseconds have elapsed (returns true)
+  //  2) Stop() is called (returns false)
+  bool ProcessMessages(int cms);
+
+  // Returns true if this is a thread that we created using the standard
+  // constructor, false if it was created by a call to
+  // ThreadManager::WrapCurrentThread().  The main thread of an application
+  // is generally not owned, since the OS representation of the thread
+  // obviously exists before we can get to it.
+  // You cannot call Start on non-owned threads.
+  bool IsOwned();
+
+  // Expose private method IsRunning() for tests.
+  //
+  // DANGER: this is a terrible public API.  Most callers that might want to
+  // call this likely do not have enough control/knowledge of the Thread in
+  // question to guarantee that the returned value remains true for the duration
+  // of whatever code is conditionally executing because of the return value!
+  bool RunningForTest() { return IsRunning(); }
+
+  // These functions are public to avoid injecting test hooks. Don't call them
+  // outside of tests.
+  // This method should be called when thread is created using non standard
+  // method, like derived implementation of rtc::Thread and it can not be
+  // started by calling Start(). This will set started flag to true and
+  // owned to false. This must be called from the current thread.
+  bool WrapCurrent();
+  void UnwrapCurrent();
+
+  // Sets the per-thread allow-blocking-calls flag to false; this is
+  // irrevocable. Must be called on this thread.
+  void DisallowBlockingCalls() { SetAllowBlockingCalls(false); }
+
+ protected:
+  class CurrentThreadSetter : CurrentTaskQueueSetter {
+   public:
+    explicit CurrentThreadSetter(Thread* thread)
+        : CurrentTaskQueueSetter(thread),
+          manager_(rtc::ThreadManager::Instance()),
+          previous_(manager_->CurrentThread()) {
+      manager_->ChangeCurrentThreadForTest(thread);
+    }
+    ~CurrentThreadSetter() { manager_->ChangeCurrentThreadForTest(previous_); }
+
+   private:
+    rtc::ThreadManager* const manager_;
+    rtc::Thread* const previous_;
+  };
+
+  // DelayedMessage goes into a priority queue, sorted by trigger time. Messages
+  // with the same trigger time are processed in num_ (FIFO) order.
+  class DelayedMessage {
+   public:
+    DelayedMessage(int64_t delay,
+                   int64_t run_time_ms,
+                   uint32_t num,
+                   const Message& msg)
+        : delay_ms_(delay),
+          run_time_ms_(run_time_ms),
+          message_number_(num),
+          msg_(msg) {}
+
+    bool operator<(const DelayedMessage& dmsg) const {
+      return (dmsg.run_time_ms_ < run_time_ms_) ||
+             ((dmsg.run_time_ms_ == run_time_ms_) &&
+              (dmsg.message_number_ < message_number_));
+    }
+
+    int64_t delay_ms_;  // for debugging
+    int64_t run_time_ms_;
+    // Monotonicaly incrementing number used for ordering of messages
+    // targeted to execute at the same time.
+    uint32_t message_number_;
+    Message msg_;
+  };
+
+  class PriorityQueue : public std::priority_queue<DelayedMessage> {
+   public:
+    container_type& container() { return c; }
+    void reheap() { make_heap(c.begin(), c.end(), comp); }
+  };
+
+  void DoDelayPost(const Location& posted_from,
+                   int64_t cmsDelay,
+                   int64_t tstamp,
+                   MessageHandler* phandler,
+                   uint32_t id,
+                   MessageData* pdata);
+
+  // Perform initialization, subclasses must call this from their constructor
+  // if false was passed as init_queue to the Thread constructor.
+  void DoInit();
+
+  // Does not take any lock. Must be called either while holding crit_, or by
+  // the destructor (by definition, the latter has exclusive access).
+  void ClearInternal(MessageHandler* phandler,
+                     uint32_t id,
+                     MessageList* removed) RTC_EXCLUSIVE_LOCKS_REQUIRED(&crit_);
+
+  // Perform cleanup; subclasses must call this from the destructor,
+  // and are not expected to actually hold the lock.
+  void DoDestroy() RTC_EXCLUSIVE_LOCKS_REQUIRED(&crit_);
+
+  void WakeUpSocketServer();
+
+  // Same as WrapCurrent except that it never fails as it does not try to
+  // acquire the synchronization access of the thread. The caller should never
+  // call Stop() or Join() on this thread.
+  void SafeWrapCurrent();
+
+  // Blocks the calling thread until this thread has terminated.
+  void Join();
+
+  static void AssertBlockingIsAllowedOnCurrentThread();
+
+  friend class ScopedDisallowBlockingCalls;
+
+  RecursiveCriticalSection* CritForTest() { return &crit_; }
+
+ private:
+  static const int kSlowDispatchLoggingThreshold = 50;  // 50 ms
+
+  // Sets the per-thread allow-blocking-calls flag and returns the previous
+  // value. Must be called on this thread.
+  bool SetAllowBlockingCalls(bool allow);
+
+#if defined(WEBRTC_WIN)
+  static DWORD WINAPI PreRun(LPVOID context);
+#else
+  static void* PreRun(void* pv);
+#endif
+
+  // ThreadManager calls this instead WrapCurrent() because
+  // ThreadManager::Instance() cannot be used while ThreadManager is
+  // being created.
+  // The method tries to get synchronization rights of the thread on Windows if
+  // `need_synchronize_access` is true.
+  bool WrapCurrentWithThreadManager(ThreadManager* thread_manager,
+                                    bool need_synchronize_access);
+
+  // Return true if the thread is currently running.
+  bool IsRunning();
+
+  void InvokeInternal(const Location& posted_from,
+                      rtc::FunctionView<void()> functor);
+
+  // Called by the ThreadManager when being set as the current thread.
+  void EnsureIsCurrentTaskQueue();
+
+  // Called by the ThreadManager when being unset as the current thread.
+  void ClearCurrentTaskQueue();
+
+  bool fPeekKeep_;
+  Message msgPeek_;
+  MessageList messages_ RTC_GUARDED_BY(crit_);
+  PriorityQueue delayed_messages_ RTC_GUARDED_BY(crit_);
+  uint32_t delayed_next_num_ RTC_GUARDED_BY(crit_);
+#if RTC_DCHECK_IS_ON
+  uint32_t blocking_call_count_ RTC_GUARDED_BY(this) = 0;
+  uint32_t could_be_blocking_call_count_ RTC_GUARDED_BY(this) = 0;
+  std::vector<Thread*> allowed_threads_ RTC_GUARDED_BY(this);
+  bool invoke_policy_enabled_ RTC_GUARDED_BY(this) = false;
+#endif
+  RecursiveCriticalSection crit_;
+  bool fInitialized_;
+  bool fDestroyed_;
+
+  std::atomic<int> stop_;
+
+  // The SocketServer might not be owned by Thread.
+  SocketServer* const ss_;
+  // Used if SocketServer ownership lies with `this`.
+  std::unique_ptr<SocketServer> own_ss_;
+
+  std::string name_;
+
+  // TODO(tommi): Add thread checks for proper use of control methods.
+  // Ideally we should be able to just use PlatformThread.
+
+#if defined(WEBRTC_POSIX)
+  pthread_t thread_ = 0;
+#endif
+
+#if defined(WEBRTC_WIN)
+  HANDLE thread_ = nullptr;
+  DWORD thread_id_ = 0;
+#endif
+
+  // Indicates whether or not ownership of the worker thread lies with
+  // this instance or not. (i.e. owned_ == !wrapped).
+  // Must only be modified when the worker thread is not running.
+  bool owned_ = true;
+
+  // Only touched from the worker thread itself.
+  bool blocking_calls_allowed_ = true;
+
+  std::unique_ptr<TaskQueueBase::CurrentTaskQueueSetter>
+      task_queue_registration_;
+
+  friend class ThreadManager;
+
+  int dispatch_warning_ms_ RTC_GUARDED_BY(this) = kSlowDispatchLoggingThreshold;
+};
+
+// AutoThread automatically installs itself at construction
+// uninstalls at destruction, if a Thread object is
+// _not already_ associated with the current OS thread.
+//
+// NOTE: *** This class should only be used by tests ***
+//
+class AutoThread : public Thread {
+ public:
+  AutoThread();
+  ~AutoThread() override;
+
+  AutoThread(const AutoThread&) = delete;
+  AutoThread& operator=(const AutoThread&) = delete;
+};
+
+// AutoSocketServerThread automatically installs itself at
+// construction and uninstalls at destruction. If a Thread object is
+// already associated with the current OS thread, it is temporarily
+// disassociated and restored by the destructor.
+
+class AutoSocketServerThread : public Thread {
+ public:
+  explicit AutoSocketServerThread(SocketServer* ss);
+  ~AutoSocketServerThread() override;
+
+  AutoSocketServerThread(const AutoSocketServerThread&) = delete;
+  AutoSocketServerThread& operator=(const AutoSocketServerThread&) = delete;
+
+ private:
+  rtc::Thread* old_thread_;
+};
+}  // namespace rtc
+
+#endif  // RTC_BASE_THREAD_H_