--- /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.core;
+
+import peersim.config.*;
+
+// XXX a quite primitive scheduler, should be able to be configured
+// much more flexibly using a simple syntax for time ranges.
+/**
+* A binary function over the time points. That is,
+* for each time point returns a boolean value.
+*
+* The concept of time depends on the simulation model. Current time
+* has to be set by the simulation engine, irrespective of the model,
+* and can be read using {@link CommonState#getTime()}. This scheduler
+* is interpreted over those time points.
+*
+* <p>In this simple implementation the valid times will be
+* <tt>from, from+step, from+2*step, etc,</tt>
+* where the last element is strictly less than <tt>until</tt>.
+* Alternatively, if <tt>at</tt> is defined, then the schedule will be a single
+* time point. If FINAL is
+* defined, it is also added to the set of active time points.
+* It refers to the time after the simulation has finished (see
+* {@link CommonState#getPhase}).
+*/
+public class Scheduler {
+
+
+// ========================= fields =================================
+// ==================================================================
+
+
+/**
+* Defaults to 1.
+* @config
+*/
+private static final String PAR_STEP = "step";
+
+/**
+* Defaults to -1. That is, defaults to be ineffective.
+* @config
+*/
+private static final String PAR_AT = "at";
+
+
+/**
+* Defaults to 0.
+* @config
+*/
+private static final String PAR_FROM = "from";
+
+/**
+* Defaults to <tt>Long.MAX_VALUE</tt>.
+* @config
+*/
+private static final String PAR_UNTIL = "until";
+
+/**
+* Defines if component is active after the simulation has finished.
+* Note that the exact time the simulation finishes is not know in advance
+* because other components can stop the simulation at any time.
+* By default not set.
+* @see CommonState#getPhase
+* @config
+*/
+private static final String PAR_FINAL = "FINAL";
+
+public final long step;
+
+public final long from;
+
+public final long until;
+
+public final boolean fin;
+
+/** The next scheduled time point.*/
+protected long next = -1;
+
+// ==================== initialization ==============================
+// ==================================================================
+
+
+/** Reads configuration parameters from the component defined by
+* <code>prefix</code>. {@value #PAR_STEP} defaults to 1.
+*/
+public Scheduler(String prefix) {
+
+ this(prefix, true);
+}
+
+// ------------------------------------------------------------------
+
+/** Reads configuration parameters from the component defined by
+* <code>prefix</code>. If useDefault is false, then at least parameter
+* {@value #PAR_STEP} must be explicitly defined. Otherwise {@value #PAR_STEP}
+* defaults to 1.
+*/
+public Scheduler(String prefix, boolean useDefault)
+{
+ if (Configuration.contains(prefix+"."+PAR_AT)) {
+ // FROM, UNTIL, and STEP should *not* be defined
+ if (Configuration.contains(prefix+"."+PAR_FROM) ||
+ Configuration.contains(prefix+"."+PAR_UNTIL) ||
+ Configuration.contains(prefix+"."+PAR_STEP))
+ throw new IllegalParameterException(prefix,
+ "Cannot use \""+PAR_AT+"\" together with \""
+ +PAR_FROM+"\", \""+PAR_UNTIL+"\", or \""+
+ PAR_STEP+"\"");
+
+ from = Configuration.getLong(prefix+"."+PAR_AT);
+ until = from+1;
+ step = 1;
+ } else {
+ if (useDefault)
+ step = Configuration.getLong(prefix+"."+PAR_STEP,1);
+ else
+ step = Configuration.getLong(prefix+"."+PAR_STEP);
+ if( step < 1 )
+ throw new IllegalParameterException(prefix,
+ "\""+PAR_STEP+"\" must be >= 1");
+
+ from = Configuration.getLong(prefix+"."+PAR_FROM,0);
+ until = Configuration.getLong(prefix+"."+PAR_UNTIL,Long.MAX_VALUE);
+ }
+
+ if( from < until ) next = from;
+ else next = -1;
+
+ fin = Configuration.contains(prefix+"."+PAR_FINAL);
+}
+
+
+// ===================== public methods ==============================
+// ===================================================================
+
+/** true if given time point is covered by this scheduler */
+public boolean active(long time) {
+
+ if( time < from || time >= until ) return false;
+ return (time - from)%step == 0;
+}
+
+// -------------------------------------------------------------------
+
+/** true if current time point is covered by this scheduler */
+public boolean active() {
+
+ return active( CommonState.getTime() );
+}
+
+//-------------------------------------------------------------------
+
+/**
+* Returns the next time point. If the returned value is negative, there are
+* no more time points. As a side effect, it also updates the next time point,
+* so repeated calls to this method return the scheduled times.
+*/
+public long getNext()
+{
+ long ret = next;
+ // check like this to prevent integer overflow of "next"
+ if( until-next > step ) next += step;
+ else next = -1;
+ return ret;
+}
+
+}
+
+
