Multicast bandwidth accounting work in progress, and some config field changes and cleanup.

node/BandwidthAccount.hpp

@@ -0,0 +1,132 @@
+/*
+ * 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_BWACCOUNT_HPP
+#define _ZT_BWACCOUNT_HPP
+
+#include <math.h>
+
+#include "Constants.hpp"
+#include "Utils.hpp"
+
+#ifdef __WINDOWS__
+#define fmin(a,b) (((a) <= (b)) ? (a) : (b))
+#define fmax(a,b) (((a) >= (b)) ? (a) : (b))
+#endif
+
+namespace ZeroTier {
+
+/**
+ * Bandwidth account used for rate limiting multicast groups
+ *
+ * This is used to apply a bank account model to multicast groups. Each
+ * multicast packet counts against a balance, which accrues at a given
+ * rate in bytes per second. Debt is possible. These parameters are
+ * configurable.
+ *
+ * A bank account model permits bursting behavior, which correctly models
+ * how OSes and apps typically use multicast. It's common for things to
+ * spew lots of multicast messages at once, wait a while, then do it
+ * again. A consistent bandwidth limit model doesn't fit.
+ */
+class BandwidthAccount
+{
+public:
+	/**
+	 * Rate of balance accrual and min/max
+	 */
+	struct Accrual
+	{
+		/**
+		 * Rate of balance accrual in bytes per second
+		 */
+		double bytesPerSecond;
+
+		/**
+		 * Maximum balance that can ever be accrued (should be > 0.0)
+		 */
+		double maxBalance;
+
+		/**
+		 * Minimum balance, or maximum allowable "debt" (should be <= 0.0)
+		 */
+		double minBalance;
+	};
+
+	/**
+	 * Create an uninitialized account
+	 *
+	 * init() must be called before this is used.
+	 */
+	BandwidthAccount() throw() {}
+
+	/**
+	 * Create and initialize
+	 *
+	 * @param preload Initial balance to place in account
+	 */
+	BandwidthAccount(double preload)
+		throw()
+	{
+		init(preload);
+	}
+
+	/**
+	 * Initialize or re-initialize account
+	 *
+	 * @param preload Initial balance to place in account
+	 */
+	inline void init(double preload)
+		throw()
+	{
+		_lastTime = Utils::nowf();
+		_balance = preload;
+	}
+
+	/**
+	 * Update balance by accruing and then deducting
+	 *
+	 * @param ar Current rate of accrual
+	 * @param deduct Amount to deduct, or 0.0 to just update
+	 * @return New balance with deduction applied
+	 */
+	inline double update(const Accrual &ar,double deduct)
+		throw()
+	{
+		double lt = _lastTime;
+		double now = _lastTime = Utils::nowf();
+		return (_balance = fmax(ar.minBalance,fmin(ar.maxBalance,(_balance + (ar.bytesPerSecond * (now - lt))) - deduct)));
+	}
+
+private:
+	double _lastTime;
+	double _balance;
+};
+
+} // namespace ZeroTier
+
+#endif