Merge pull request #1610 from fireice-uk/dev2.4.4

release 2.4.4

1 files changed, 96 insertions, 0 deletions

diff --git a/xmrstak/cpputil/read_write_lock.h b/xmrstak/cpputil/read_write_lock.h
new file mode 100644
index 0000000..9139dfd
--- /dev/null
+++ b/xmrstak/cpputil/read_write_lock.h
@@ -0,0 +1,96 @@
+/* MIT License
+ *
+ * Copyright (c) 2018 Will Zhang
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#pragma once
+
+#include <mutex>
+#include <condition_variable>
+
+namespace cpputil
+{
+
+class RWLock
+{
+ public:
+	RWLock() : status_(0), waiting_readers_(0), waiting_writers_(0) {}
+	RWLock(const RWLock&) = delete;
+	RWLock(RWLock&&) = delete;
+	RWLock& operator = (const RWLock&) = delete;
+	RWLock& operator = (RWLock&&) = delete;
+
+	void ReadLock()
+	{
+		std::unique_lock<std::mutex> lck(mtx_);
+		waiting_readers_ += 1;
+		read_cv_.wait(lck, [&]() { return waiting_writers_ == 0 && status_ >= 0; });
+		waiting_readers_ -= 1;
+		status_ += 1;
+	}
+
+	void WriteLock()
+	{
+		std::unique_lock<std::mutex> lck(mtx_);
+		waiting_writers_ += 1;
+		write_cv_.wait(lck, [&]() { return status_ == 0; });
+		waiting_writers_ -= 1;
+		status_ = -1;
+	}
+
+	void UnLock()
+	{
+		std::unique_lock<std::mutex> lck(mtx_);
+		if (status_ == -1) {
+			status_ = 0;
+		} 
+		else
+		{
+			status_ -= 1;
+		}
+		if (waiting_writers_ > 0)
+		{
+			if (status_ == 0)
+			{
+				write_cv_.notify_one();
+			}
+		} 
+		else
+		{
+			read_cv_.notify_all();
+		}
+	}
+
+ private:
+	/** status of the lock
+	 * -1    : one writer
+	 * 0     : no reader and no writer
+	 * n > 0 : n reader
+	 */
+	int32_t status_;
+	int32_t waiting_readers_;
+	int32_t waiting_writers_;
+	std::mutex mtx_;
+	std::condition_variable read_cv_;
+	std::condition_variable write_cv_;
+};
+
+}  // namespace cpputil