--- /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.reports;
+
+import peersim.core.*;
+import peersim.config.Configuration;
+import peersim.graph.*;
+import peersim.cdsim.CDState;
+
+/**
+* Class that provides functionality for observing graphs.
+* It can efficiently create an undirected version of the graph, making sure
+* it is updated only when the simulation has advanced already, and provides
+* some common parameters.
+*/
+public abstract class GraphObserver implements Control {
+
+
+// ===================== fields =======================================
+// ====================================================================
+
+/**
+ * The protocol to operate on.
+ * @config
+ */
+private static final String PAR_PROT = "protocol";
+
+/**
+ * If defined, the undirected version of the graph will be analyzed. Not defined
+ * by default.
+ * @config
+ */
+protected static final String PAR_UNDIR = "undir";
+
+/**
+* Alias for {@value #PAR_UNDIR}.
+* @config
+*/
+private static final String PAR_UNDIR_ALT = "undirected";
+
+/**
+ * If defined, the undirected version of the graph will be stored using much
+ * more memory but observers will be in general a few times faster. As a
+ * consequence, it will not work with large graphs. Not defined by default. It
+ * is a static property, that is, it affects all graph observers that are used
+ * in a simulation. That is, it is not a parameter of any observer, the name
+ * should be specified as a standalone property.
+ * @config
+ */
+private static final String PAR_FAST = "graphobserver.fast";
+
+/** The name of this observer in the configuration */
+protected final String name;
+
+protected final int pid;
+
+protected final boolean undir;
+
+protected final GraphAlgorithms ga = new GraphAlgorithms();
+
+protected Graph g;
+
+// ---------------------------------------------------------------------
+
+private static int lastpid = -1234;
+
+private static long time = -1234;
+
+private static int phase = -1234;
+
+private static int ctime = -1234;
+
+private static Graph dirg;
+
+private static Graph undirg;
+
+private static boolean fast;
+
+/** If any instance of some extending class defines undir we need to
+maintain an undir graph. Note that the graph is stored in a static
+field so it is common to all instances. */
+private static boolean needUndir=false;
+
+// ===================== initialization ================================
+// =====================================================================
+
+
+/**
+ * Standard constructor that reads the configuration parameters.
+ * Invoked by the simulation engine.
+ * @param name the configuration prefix for this class
+ */
+protected GraphObserver(String name) {
+
+ this.name = name;
+ pid = Configuration.getPid(name+"."+PAR_PROT);
+ undir = (Configuration.contains(name + "." + PAR_UNDIR) |
+ Configuration.contains(name + "." + PAR_UNDIR_ALT));
+ GraphObserver.fast = Configuration.contains(PAR_FAST);
+ GraphObserver.needUndir = (GraphObserver.needUndir || undir);
+}
+
+
+// ====================== methods ======================================
+// =====================================================================
+
+/**
+* Sets {@link #g}.
+* It MUST be called by any implementation of {@link #execute()} before
+* doing anything else.
+* Attempts to initialize {@link #g} from a
+* pre-calculated graph stored in a static field, but first it
+* checks whether it needs to be updated.
+* If the simulation time has progressed or it was calculated for a different
+* protocol, then updates this static graph as well.
+* The purpose of this mechanism is to save the time of constructing the
+* graph if many observers are run on the same graph. Time savings can be very
+* significant if the undirected version of the same graph is observed by many
+* observers.
+*/
+protected void updateGraph() {
+
+ if( CommonState.getTime() != GraphObserver.time ||
+ (CDState.isCD() && (CDState.getCycleT() != GraphObserver.ctime)) ||
+ CommonState.getPhase() != GraphObserver.phase ||
+ pid != GraphObserver.lastpid )
+ {
+ // we need to update the graphs
+
+ GraphObserver.lastpid = pid;
+ GraphObserver.time = CommonState.getTime();
+ if( CDState.isCD() ) GraphObserver.ctime = CDState.getCycleT();
+ GraphObserver.phase = CommonState.getPhase();
+
+ GraphObserver.dirg = new OverlayGraph(pid);
+ if( GraphObserver.needUndir )
+ {
+ if( fast )
+ GraphObserver.undirg =
+ new FastUndirGraph(GraphObserver.dirg);
+ else
+ GraphObserver.undirg =
+ new ConstUndirGraph(GraphObserver.dirg);
+ }
+ }
+
+ if( undir ) g = GraphObserver.undirg;
+ else g = GraphObserver.dirg;
+}
+
+}
+
+
+
