cleanup and refactoring

raytracer/nvpro_core/nvh/threading.hpp

@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2022, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * SPDX-FileCopyrightText: Copyright (c) 2014-2021 NVIDIA CORPORATION
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include <thread>
+#include <condition_variable>
+#include <mutex>
+
+namespace nvh {
+
+using DefaultDelayClock    = std::chrono::steady_clock;
+using DefaultDelayDuration = std::chrono::nanoseconds;
+
+/** @DOC_START
+ # class nvh::delayed_call 
+ Class returned by delay_noreturn_for to track the thread created and possibly reset the
+ delay timer.
+@DOC_END */
+template <class Clock = DefaultDelayClock, class Duration = std::chrono::duration<double>>
+class delayed_call
+{
+  template <class ClockT, class DurationT, class Function, class... Args>
+  friend delayed_call<ClockT, DurationT> delay_noreturn_for(const DurationT& sleep_duration, Function&& f, Args&&... args);
+
+public:
+  /** Update the thread to make the call sleep_duration from now
+     * 
+     * \return True if the delay was updated before the callback was called. False otherwise.
+     */
+  bool delay_for(const Duration& sleep_duration)
+  {
+    bool result = false;
+    if(m_delay)
+    {
+      std::lock_guard<std::mutex> lock(m_delay->mutex);
+      if(!m_delay->started)
+      {
+        auto prevUntil = m_delay->until;
+        m_delay->until = Clock::now() + sleep_duration;
+
+        // No need to wake up the other thread if the delay is longer. It'll keep looping while dirty is set.
+        if(prevUntil < m_delay->until)
+          m_delay->dirty = true;
+        else
+          m_delay->cv.notify_all();
+      }
+      result = !m_delay->started;
+    }
+    return result;
+  }
+
+  /** Cancel a delayed call
+     * 
+     * \return True if the call was cancelled before running. False otherwise.
+     */
+  bool cancel()
+  {
+    bool result = false;
+    if(m_delay)
+    {
+      std::lock_guard<std::mutex> lock(m_delay->mutex);
+      if(!m_delay->started)
+      {
+        m_delay->cancelled = true;
+        m_delay->cv.notify_all();
+      }
+      result = !m_delay->started;
+    }
+    return result;
+  }
+
+  delayed_call() = default;
+  delayed_call(delayed_call&& other) { *this = std::move(other); }
+  ~delayed_call() = default;
+
+  delayed_call& operator=(delayed_call&& other)
+  {
+    m_delay = std::move(other.m_delay);
+    return *this;
+  }
+
+  // This class is movable only
+  delayed_call(const delayed_call& other)            = delete;
+  delayed_call& operator=(const delayed_call& other) = delete;
+
+private:
+  struct DelayData
+  {
+    std::chrono::time_point<Clock, Duration> until;
+    std::thread                              thread;
+    std::mutex                               mutex;
+    std::condition_variable                  cv;
+    bool                                     dirty     = true;
+    bool                                     cancelled = false;
+    bool                                     started   = false;
+
+    ~DelayData()
+    {
+      if(thread.joinable())
+        thread.join();
+    }
+  };
+
+  template <class Function, class... Args>
+  static void delayEntry(DelayData* delay, Function&& f, Args&&... args)
+  {
+    {
+      std::unique_lock<std::mutex> lock(delay->mutex);
+      std::cv_status               status = std::cv_status::no_timeout;
+      while(!delay->cancelled && (delay->dirty || status == std::cv_status::no_timeout))
+      {
+        delay->dirty = false;
+        status       = delay->cv.wait_until(lock, delay->until);
+      }
+      if(delay->cancelled)
+        return;
+      delay->started = true;
+    }
+
+    // Ignore the return value. Need to keep a std::future object if not.
+    (void)f(std::forward<Args>(args)...);
+  }
+
+  std::unique_ptr<DelayData> m_delay;
+
+  template <class Function, class... Args>
+  delayed_call(const Duration& sleep_duration, Function&& f, Args&&... args)
+      : m_delay(std::make_unique<DelayData>())
+  {
+    m_delay->until = Clock::now() + sleep_duration;
+    m_delay->thread =
+        std::thread(delayed_call::delayEntry<std::remove_reference_t<Function>&&, std::remove_reference_t<Args>&&...>,
+                    m_delay.get(), std::forward<Function>(f), std::forward<Args>(args)...);
+  }
+};
+
+/** @DOC_START
+ Delay a call to a void function for sleep_duration.
+ 
+ `return`: A delayed_call object that holds the running thread.
+
+Example:
+ ```cpp
+ // Create or update a delayed call to callback. Useful to consolidate multiple events into one call.
+ if(!m_delayedCall.delay_for(delay))
+   m_delayedCall = nvh::delay_noreturn_for(delay, callback);
+ ```
+@DOC_END */
+template <class Clock = DefaultDelayClock, class Duration = DefaultDelayDuration, class Function, class... Args>
+delayed_call<Clock, Duration> delay_noreturn_for(const Duration& sleep_duration, Function&& f, Args&&... args)
+{
+  return delayed_call<Clock, Duration>(sleep_duration, std::forward<Function>(f), std::forward<Args>(args)...);
+}
+
+}  // namespace nvh