[threading linux] Implement suspendable pthreads

Use real-time event interrupt to communicate suspend in timely manner.
Use conditional_variable to implement suspend wait and resume trigger.

Ignore real-time event 36 in .gdbinit which is used to signal suspend.

Test suspending threads.

.gdbinit

@@ -4,3 +4,5 @@ handle SIG34 nostop noprint
 handle SIG35 nostop noprint
 # Ignore PosixThread exit event
 handle SIG32 nostop noprint
+# Ignore PosixThread suspend event
+handle SIG36 nostop noprint

src/xenia/base/testing/threading_test.cc

@@ -759,8 +759,29 @@ TEST_CASE("Create and Run Thread", "Thread") {
 }
 
 TEST_CASE("Test Suspending Thread", "Thread") {
-  // TODO(bwrsandman): Test suspension and resume
-  REQUIRE(true);
+  std::unique_ptr<Thread> thread;
+  WaitResult result;
+  Thread::CreationParameters params = {};
+  auto func = [] { Sleep(20ms); };
+
+  // Create initially suspended
+  params.create_suspended = true;
+  thread = threading::Thread::Create(params, func);
+  result = threading::Wait(thread.get(), false, 50ms);
+  REQUIRE(result == threading::WaitResult::kTimeout);
+  thread->Resume();
+  result = threading::Wait(thread.get(), false, 50ms);
+  REQUIRE(result == threading::WaitResult::kSuccess);
+  params.create_suspended = false;
+
+  // Create and then suspend
+  thread = threading::Thread::Create(params, func);
+  thread->Suspend();
+  result = threading::Wait(thread.get(), false, 50ms);
+  REQUIRE(result == threading::WaitResult::kTimeout);
+  thread->Resume();
+  result = threading::Wait(thread.get(), false, 50ms);
+  REQUIRE(result == threading::WaitResult::kSuccess);
 }
 
 TEST_CASE("Test Thread QueueUserCallback", "Thread") {

src/xenia/base/threading_posix.cc

@@ -38,7 +38,7 @@ inline timespec DurationToTimeSpec(
 // This implementation uses the SIGRTMAX - SIGRTMIN to signal to a thread
 // gdb tip, for SIG = SIGRTMIN + SignalType : handle SIG nostop
 // lldb tip, for SIG = SIGRTMIN + SignalType : process handle SIG -s false
-enum class SignalType { kHighResolutionTimer, kTimer, k_Count };
+enum class SignalType { kHighResolutionTimer, kTimer, kThreadSuspend, k_Count };
 
 int GetSystemSignal(SignalType num) {
   auto result = SIGRTMIN + static_cast<int>(num);
@@ -430,6 +430,7 @@ class PosixCondition<Timer> : public PosixConditionBase {
 
 struct ThreadStartData {
   std::function<void()> start_routine;
+  bool create_suspended;
   Thread* thread_obj;
 };
 
@@ -438,6 +439,7 @@ class PosixCondition<Thread> : public PosixConditionBase {
   enum class State {
     kUninitialized,
     kRunning,
+    kSuspended,
     kFinished,
   };
 
@@ -449,7 +451,7 @@ class PosixCondition<Thread> : public PosixConditionBase {
         state_(State::kUninitialized) {}
   bool Initialize(Thread::CreationParameters params,
                   ThreadStartData* start_data) {
-    assert_false(params.create_suspended);
+    start_data->create_suspended = params.create_suspended;
     pthread_attr_t attr;
     if (pthread_attr_init(&attr) != 0) return false;
     if (pthread_attr_setstacksize(&attr, params.stack_size) != 0) {
@@ -570,15 +572,23 @@ class PosixCondition<Thread> : public PosixConditionBase {
   }
 
   bool Resume(uint32_t* out_new_suspend_count = nullptr) {
-    // TODO(bwrsandman)
-    assert_always();
-    return false;
+    // TODO(bwrsandman): implement suspend_count
+    assert_null(out_new_suspend_count);
+    WaitStarted();
+    std::unique_lock<std::mutex> lock(state_mutex_);
+    if (state_ != State::kSuspended) return false;
+    state_ = State::kRunning;
+    state_signal_.notify_all();
+    return true;
   }
 
   bool Suspend(uint32_t* out_previous_suspend_count = nullptr) {
-    // TODO(bwrsandman)
-    assert_always();
-    return false;
+    // TODO(bwrsandman): implement suspend_count
+    assert_null(out_previous_suspend_count);
+    WaitStarted();
+    int result =
+        pthread_kill(thread_, GetSystemSignal(SignalType::kThreadSuspend));
+    return result == 0;
   }
 
   void Terminate(int exit_code) {
@@ -606,6 +616,13 @@ class PosixCondition<Thread> : public PosixConditionBase {
                        [this] { return state_ != State::kUninitialized; });
   }
 
+  /// Set state to suspended and wait until it reset by another thread
+  void WaitSuspended() {
+    std::unique_lock<std::mutex> lock(state_mutex_);
+    state_ = State::kSuspended;
+    state_signal_.wait(lock, [this] { return state_ != State::kSuspended; });
+  }
+
  private:
   static void* ThreadStartRoutine(void* parameter);
   inline bool signaled() const override { return signaled_; }
@@ -618,7 +635,7 @@ class PosixCondition<Thread> : public PosixConditionBase {
   pthread_t thread_;
   bool signaled_;
   int exit_code_;
-  State state_;
+  volatile State state_;
   mutable std::mutex state_mutex_;
   mutable std::condition_variable state_signal_;
 };
@@ -786,7 +803,8 @@ class PosixThread : public PosixConditionHandle<Thread> {
 
   bool Initialize(CreationParameters params,
                   std::function<void()> start_routine) {
-    auto start_data = new ThreadStartData({std::move(start_routine), this});
+    auto start_data =
+        new ThreadStartData({std::move(start_routine), false, this});
     return handle_.Initialize(params, start_data);
   }
 
@@ -824,6 +842,8 @@ class PosixThread : public PosixConditionHandle<Thread> {
   }
 
   void Terminate(int exit_code) override { handle_.Terminate(exit_code); }
+
+  void WaitSuspended() { handle_.WaitSuspended(); }
 };
 
 thread_local PosixThread* current_thread_ = nullptr;
@@ -840,12 +860,20 @@ void* PosixCondition<Thread>::ThreadStartRoutine(void* parameter) {
 
   auto thread = dynamic_cast<PosixThread*>(start_data->thread_obj);
   auto start_routine = std::move(start_data->start_routine);
+  auto create_suspended = start_data->create_suspended;
   delete start_data;
 
   current_thread_ = thread;
   {
     std::unique_lock<std::mutex> lock(thread->handle_.state_mutex_);
-    thread->handle_.state_ = State::kRunning;
+    if (create_suspended) {
+      thread->handle_.state_ = State::kSuspended;
+      thread->handle_.state_signal_.wait(lock, [thread] {
+        return thread->handle_.state_ != State::kSuspended;
+      });
+    } else {
+      thread->handle_.state_ = State::kRunning;
+    }
     thread->handle_.state_signal_.notify_all();
   }
 
@@ -867,6 +895,7 @@ void* PosixCondition<Thread>::ThreadStartRoutine(void* parameter) {
 
 std::unique_ptr<Thread> Thread::Create(CreationParameters params,
                                        std::function<void()> start_routine) {
+  install_signal_handler(SignalType::kThreadSuspend);
   auto thread = std::make_unique<PosixThread>();
   if (!thread->Initialize(params, std::move(start_routine))) return nullptr;
   assert_not_null(thread);
@@ -914,6 +943,10 @@ static void signal_handler(int signal, siginfo_t* info, void* /*context*/) {
           static_cast<PosixCondition<Timer>*>(info->si_value.sival_ptr);
       pTimer->CompletionRoutine();
     } break;
+    case SignalType::kThreadSuspend: {
+      assert_not_null(current_thread_);
+      current_thread_->WaitSuspended();
+    } break;
     default:
       assert_always();
   }