Add RateLimiter for rate limiting multicast, not tested yet.

node/RateLimiter.hpp

@@ -0,0 +1,125 @@
+/*
+ * ZeroTier One - Global Peer to Peer Ethernet
+ * Copyright (C) 2012-2013  ZeroTier Networks LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * --
+ *
+ * ZeroTier may be used and distributed under the terms of the GPLv3, which
+ * are available at: http://www.gnu.org/licenses/gpl-3.0.html
+ *
+ * If you would like to embed ZeroTier into a commercial application or
+ * redistribute it in a modified binary form, please contact ZeroTier Networks
+ * LLC. Start here: http://www.zerotier.com/
+ */
+
+#ifndef _ZT_RATELIMITER_HPP
+#define _ZT_RATELIMITER_HPP
+
+#include <math.h>
+#include "Utils.hpp"
+
+namespace ZeroTier {
+
+/**
+ * Burstable rate limiter
+ *
+ * This limits a transfer rate to a maximum bytes per second using an
+ * accounting method based on a balance rather than accumulating an
+ * average rate. The result is a burstable rate limit rather than a
+ * continuous rate limit; the link being limited may use all its balance
+ * at once or slowly over time. Balance constantly replenishes over time
+ * up to a configurable maximum balance.
+ */
+class RateLimiter
+{
+public:
+	/**
+	 * Create an uninitialized rate limiter
+	 *
+	 * init() must be called before this is used.
+	 */
+	RateLimiter() throw() {}
+
+	/**
+	 * @param bytesPerSecond Bytes per second to permit (average)
+	 * @param preload Initial balance to place in account
+	 * @param max Maximum balance to permit to ever accrue (max burst)
+	 */
+	RateLimiter(double bytesPerSecond,double preload,double max)
+		throw()
+	{
+		init(bytesPerSecond,preload,max);
+	}
+
+	/**
+	 * Initialize or re-initialize rate limiter
+	 *
+	 * @param bytesPerSecond Bytes per second to permit (average)
+	 * @param preload Initial balance to place in account
+	 * @param max Maximum balance to permit to ever accrue (max burst)
+	 */
+	inline void init(double bytesPerSecond,double preload,double max)
+		throw()
+	{
+		_bytesPerSecond = bytesPerSecond;
+		_lastTime = Utils::nowf();
+		_balance = preload;
+		_max = max;
+	}
+
+	/**
+	 * Update balance based on current clock
+	 *
+	 * This can be called at any time to check the current balance without
+	 * affecting the behavior of gate().
+	 *
+	 * @return New balance
+	 */
+	inline double updateBalance()
+		throw()
+	{
+		double now = Utils::nowf();
+		double b = _balance = fmin(_max,_balance + (_bytesPerSecond * (now - _lastTime)));
+		_lastTime = now;
+		return b;
+	}
+
+	/**
+	 * Test balance and update / deduct if there is enough to transfer 'bytes'
+	 *
+	 * @param bytes Number of bytes that we wish to transfer
+	 * @return True if balance was sufficient (balance is updated), false if not (balance unchanged)
+	 */
+	inline bool gate(double bytes)
+		throw()
+	{
+		if (updateBalance() >= bytes) {
+			_balance -= bytes;
+			return true;
+		}
+		return false;
+	}
+
+private:
+	double _bytesPerSecond;
+	double _lastTime;
+	double _balance;
+	double _max;
+};
+
+} // namespace ZeroTier
+
+#endif