--- /dev/null
+/*
+ * Copyright (c) 2003-2005 The BISON Project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+package peersim.transport;
+
+
+/**
+ * This static singleton emulates an underlying router network
+ * of fixed size, and stores the latency measurements for all pairs
+ * of routers.
+ *
+ * @author Alberto Montresor
+ * @version $Revision: 1.6 $
+ */
+public class E2ENetwork
+{
+
+//---------------------------------------------------------------------
+//Fields
+//---------------------------------------------------------------------
+
+/**
+ * True if latency between nodes is considered symmetric. False otherwise.
+ */
+private static boolean symm;
+
+/**
+ * Size of the router network.
+ */
+private static int size;
+
+/**
+ * Latency distances between nodes.
+ */
+private static int[][] array;
+
+//---------------------------------------------------------------------
+//Initialization
+//---------------------------------------------------------------------
+
+/** Disable instance construction */
+private E2ENetwork() {}
+
+//---------------------------------------------------------------------
+//Methods
+//---------------------------------------------------------------------
+
+/**
+ * Resets the network, by creating a triangular (if symm is true) or
+ * a rectangular (if symm is false) array of integers. Initially all
+ * latencies between any pairs are set to be 0.
+ * @param size the number or routers
+ * @param symm if latency is symmetric between all pairs of routers
+ */
+public static void reset(int size, boolean symm)
+{
+ E2ENetwork.symm = symm;
+ E2ENetwork.size = size;
+ array = new int[size][];
+ for (int i=0; i < size; i++) {
+ if (symm)
+ array[i] = new int[i];
+ else
+ array[i] = new int[size];
+ }
+}
+
+//---------------------------------------------------------------------
+
+/**
+ * Returns the latency associated to the specified (sender, receiver)
+ * pair. Routers are indexed from 0.
+ *
+ * @param sender the index of the sender
+ * @param receiver the index of the receiver
+ * @return the latency associated to the specified (sender, receiver)
+ * pair.
+ */
+public static int getLatency(int sender, int receiver)
+{
+ if (sender == receiver)
+ return 0;
+ // XXX There should be the possibility to fix the delay.
+ if (symm) {
+ // Symmetric network
+ if (sender < receiver) {
+ int tmp = sender;
+ sender = receiver;
+ receiver = tmp;
+ }
+ }
+ return array[sender][receiver];
+}
+
+//---------------------------------------------------------------------
+
+/**
+ * Sets the latency associated to the specified (sender, receiver)
+ * pair. Routers are indexed from 0.
+ *
+ * @param sender the index of the sender
+ * @param receiver the index of the receiver
+ * @param latency the latency to be set
+ */
+public static void setLatency(int sender, int receiver, int latency)
+{
+ if (symm) {
+ // Symmetric network
+ if (sender < receiver) {
+ int tmp = sender;
+ sender = receiver;
+ receiver = tmp;
+ }
+ }
+ array[sender][receiver] = latency;
+}
+
+//---------------------------------------------------------------------
+
+/**
+ * Returns the current size of the underlying network (i.e., the number of
+ * routers).
+ */
+public static int getSize()
+{
+ return size;
+}
+
+}
