First Commit

osdep/BlockingQueue.hpp

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+/*
+ * Copyright (c)2019 ZeroTier, Inc.
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file in the project's root directory.
+ *
+ * Change Date: 2026-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2.0 of the Apache License.
+ */
+/****/
+
+#ifndef ZT_BLOCKINGQUEUE_HPP
+#define ZT_BLOCKINGQUEUE_HPP
+
+#include <queue>
+#include <mutex>
+#include <condition_variable>
+#include <chrono>
+#include <atomic>
+#include <vector>
+
+namespace ZeroTier {
+
+/**
+ * Simple C++11 thread-safe queue
+ *
+ * Do not use in node/ since we have not gone C++11 there yet.
+ */
+template <class T>
+class BlockingQueue
+{
+public:
+	BlockingQueue(void) : r(true) {}
+
+	inline void post(T t)
+	{
+		std::lock_guard<std::mutex> lock(m);
+		q.push(t);
+		c.notify_one();
+	}
+
+	inline void postLimit(T t,const unsigned long limit)
+	{
+		std::unique_lock<std::mutex> lock(m);
+		for(;;) {
+			if (q.size() < limit) {
+				q.push(t);
+				c.notify_one();
+				break;
+			}
+			if (!r)
+				break;
+			gc.wait(lock);
+		}
+	}
+
+	inline void stop(void)
+	{
+		std::lock_guard<std::mutex> lock(m);
+		r = false;
+		c.notify_all();
+		gc.notify_all();
+	}
+
+	inline bool get(T &value)
+	{
+		std::unique_lock<std::mutex> lock(m);
+		if (!r)
+			return false;
+		while (q.empty()) {
+			c.wait(lock);
+			if (!r) {
+				gc.notify_all();
+				return false;
+			}
+		}
+		value = q.front();
+		q.pop();
+		gc.notify_all();
+		return true;
+	}
+
+	inline std::vector<T> drain()
+	{
+		std::vector<T> v;
+		while (!q.empty()) {
+			v.push_back(q.front());
+			q.pop();
+		}
+		return v;
+	}
+
+	enum TimedWaitResult
+	{
+		OK,
+		TIMED_OUT,
+		STOP
+	};
+
+	inline TimedWaitResult get(T &value,const unsigned long ms)
+	{
+		const std::chrono::milliseconds ms2{ms};
+		std::unique_lock<std::mutex> lock(m);
+		if (!r)
+			return STOP;
+		while (q.empty()) {
+			if (c.wait_for(lock,ms2) == std::cv_status::timeout)
+				return ((r) ? TIMED_OUT : STOP);
+			else if (!r)
+				return STOP;
+		}
+		value = q.front();
+		q.pop();
+		return OK;
+	}
+
+	inline size_t size() const {
+		return q.size();
+	}
+
+private:
+	std::queue<T> q;
+	mutable std::mutex m;
+	mutable std::condition_variable c,gc;
+	std::atomic_bool r;
+};
+
+} // namespace ZeroTier
+
+#endif