[threading linux] Make PosixCondition base class

Add PosixConditionBase as base class for Waitables to use common
primitives mutex and conditional variable
Add abstract signaled() and post_execution() to use single WaitMultiple
implementation.

src/xenia/base/threading_posix.cc

@@ -164,31 +164,8 @@ std::unique_ptr<HighResolutionTimer> HighResolutionTimer::CreateRepeating(
   return std::unique_ptr<HighResolutionTimer>(timer.release());
 }
 
-// There really is no native POSIX handle for a single wait/signal construct
-// pthreads is at a lower level with more handles for such a mechanism.
-// This simple wrapper class functions as our handle and uses conditional
-// variables for waits and signals.
-class PosixCondition {
+class PosixConditionBase {
  public:
-  PosixCondition(bool manual_reset, bool initial_state)
-      : signal_(initial_state), manual_reset_(manual_reset) {}
-  virtual ~PosixCondition() = default;
-
-  void Signal() {
-    auto lock = std::unique_lock<std::mutex>(mutex_);
-    signal_ = true;
-    if (manual_reset_) {
-      cond_.notify_all();
-    } else {
-      cond_.notify_one();
-    }
-  }
-
-  void Reset() {
-    auto lock = std::unique_lock<std::mutex>(mutex_);
-    signal_ = false;
-  }
-
   WaitResult Wait(std::chrono::milliseconds timeout) {
     bool executed;
     auto predicate = [this] { return this->signaled(); };
@@ -212,9 +189,9 @@ class PosixCondition {
   }
 
   static std::pair<WaitResult, size_t> WaitMultiple(
-      std::vector<PosixCondition*> handles, bool wait_all,
+      std::vector<PosixConditionBase*>&& handles, bool wait_all,
       std::chrono::milliseconds timeout) {
-    using iter_t = decltype(handles)::const_iterator;
+    using iter_t = std::vector<PosixConditionBase*>::const_iterator;
     bool executed;
     auto predicate = [](auto h) { return h->signaled(); };
 
@@ -225,7 +202,10 @@ class PosixCondition {
       return operation(handles.cbegin(), handles.cend(), predicate);
     };
 
-    std::unique_lock<std::mutex> lock(PosixCondition::mutex_);
+    // TODO(bwrsandman, Triang3l) This is controversial, see issue #1677
+    // This will probably cause a deadlock on the next thread doing any waiting
+    // if the thread is suspended between locking and waiting
+    std::unique_lock<std::mutex> lock(PosixConditionBase::mutex_);
 
     // Check if the aggregate lambda (all or any) is already satisfied
     if (aggregate()) {
@@ -234,11 +214,11 @@ class PosixCondition {
       // If the aggregate is not yet satisfied and the timeout is infinite,
       // wait without timeout.
       if (timeout == std::chrono::milliseconds::max()) {
-        PosixCondition::cond_.wait(lock, aggregate);
+        PosixConditionBase::cond_.wait(lock, aggregate);
         executed = true;
       } else {
         // Wait with timeout.
-        executed = PosixCondition::cond_.wait_for(lock, timeout, aggregate);
+        executed = PosixConditionBase::cond_.wait_for(lock, timeout, aggregate);
       }
     }
     if (executed) {
@@ -258,22 +238,58 @@ class PosixCondition {
     }
   }
 
+ protected:
+  inline virtual bool signaled() const = 0;
+  inline virtual void post_execution() = 0;
+  static std::condition_variable cond_;
+  static std::mutex mutex_;
+};
+
+std::condition_variable PosixConditionBase::cond_;
+std::mutex PosixConditionBase::mutex_;
+
+// There really is no native POSIX handle for a single wait/signal construct
+// pthreads is at a lower level with more handles for such a mechanism.
+// This simple wrapper class functions as our handle and uses conditional
+// variables for waits and signals.
+template <typename T>
+class PosixCondition {};
+
+template <>
+class PosixCondition<Event> : public PosixConditionBase {
+ public:
+  PosixCondition(bool manual_reset, bool initial_state)
+      : signal_(initial_state), manual_reset_(manual_reset) {}
+  virtual ~PosixCondition() = default;
+
+  void Signal() {
+    auto lock = std::unique_lock<std::mutex>(mutex_);
+    signal_ = true;
+    if (manual_reset_) {
+      cond_.notify_all();
+    } else {
+      // FIXME(bwrsandman): Potential cause for deadlock
+      // See issue #1678 for possible fix and discussion
+      cond_.notify_one();
+    }
+  }
+
+  void Reset() {
+    auto lock = std::unique_lock<std::mutex>(mutex_);
+    signal_ = false;
+  }
+
  private:
-  inline bool signaled() const { return signal_; }
-  inline void post_execution() {
+  inline bool signaled() const override { return signal_; }
+  inline void post_execution() override {
     if (!manual_reset_) {
       signal_ = false;
     }
   }
   bool signal_;
   const bool manual_reset_;
-  static std::condition_variable cond_;
-  static std::mutex mutex_;
 };
 
-std::condition_variable PosixCondition::cond_;
-std::mutex PosixCondition::mutex_;
-
 // Native posix thread handle
 template <typename T>
 class PosixThreadHandle : public T {
@@ -294,21 +310,41 @@ class PosixThreadHandle : public T {
 template <typename T>
 class PosixConditionHandle : public T {
  public:
-  PosixConditionHandle(bool manual_reset, bool initial_state)
-      : handle_(manual_reset, initial_state) {}
+  PosixConditionHandle(bool manual_reset, bool initial_state);
   ~PosixConditionHandle() override = default;
 
  protected:
   void* native_handle() const override {
-    return reinterpret_cast<void*>(const_cast<PosixCondition*>(&handle_));
+    return reinterpret_cast<void*>(const_cast<PosixCondition<T>*>(&handle_));
   }
 
-  PosixCondition handle_;
+  PosixCondition<T> handle_;
 };
 
+template <>
+PosixConditionHandle<Semaphore>::PosixConditionHandle(bool manual_reset,
+                                                      bool initial_state)
+    : handle_() {}
+
+template <>
+PosixConditionHandle<Mutant>::PosixConditionHandle(bool manual_reset,
+                                                   bool initial_state)
+    : handle_() {}
+
+template <>
+PosixConditionHandle<Timer>::PosixConditionHandle(bool manual_reset,
+                                                  bool initial_state)
+    : handle_() {}
+
+template <>
+PosixConditionHandle<Event>::PosixConditionHandle(bool manual_reset,
+                                                  bool initial_state)
+    : handle_(manual_reset, initial_state) {}
+
 WaitResult Wait(WaitHandle* wait_handle, bool is_alertable,
                 std::chrono::milliseconds timeout) {
-  auto handle = reinterpret_cast<PosixCondition*>(wait_handle->native_handle());
+  auto handle =
+      reinterpret_cast<PosixConditionBase*>(wait_handle->native_handle());
   return handle->Wait(timeout);
 }
 
@@ -325,12 +361,13 @@ std::pair<WaitResult, size_t> WaitMultiple(WaitHandle* wait_handles[],
                                            size_t wait_handle_count,
                                            bool wait_all, bool is_alertable,
                                            std::chrono::milliseconds timeout) {
-  std::vector<PosixCondition*> handles(wait_handle_count);
+  std::vector<PosixConditionBase*> handles(wait_handle_count);
   for (int i = 0u; i < wait_handle_count; ++i) {
     handles[i] =
-        reinterpret_cast<PosixCondition*>(wait_handles[i]->native_handle());
+        reinterpret_cast<PosixConditionBase*>(wait_handles[i]->native_handle());
   }
-  return PosixCondition::WaitMultiple(handles, wait_all, timeout);
+  return PosixConditionBase::WaitMultiple(std::move(handles), wait_all,
+                                          timeout);
 }
 
 class PosixEvent : public PosixConditionHandle<Event> {