- * All {@link CDProtocol} specifications in the configuration need to contain a - * {@link Scheduler} specification at least for the step size (see config - * parameter {@value peersim.core.Scheduler#PAR_STEP} of {@link Scheduler}). - * This value is used as the cycle length for the corresponding protocol. - * - * @see NextCycleEvent - */ -public class CDScheduler implements Control, NodeInitializer { - - // ============================== fields ============================== - // ==================================================================== - - /** - * Parameter that is used to define the class that is used to schedule the - * next cycle. Its type is (or extends) {@link NextCycleEvent}. Defaults to - * {@link NextCycleEvent}. - * - * @config - */ - private static final String PAR_NEXTC = "nextcycle"; - - /** - * The protocols that this scheduler schedules for the first execution. It - * might contain several protocol names, separated by whitespace. All - * protocols will be scheduled based on the common parameter set for this - * scheduler and the parameters of the protocol (cycle length). Protocols - * are scheduled independently of each other. - * - * @config - */ - private static final String PAR_PROTOCOL = "protocol"; - - /** - * If set, it means that the initial execution of the given protocol is - * scheduled for a different random time for all nodes. The random time is a - * sample between the current time (inclusive) and the cycle length - * (exclusive), the latter being specified by the step parameter (see - * {@link Scheduler}) of the assigned protocol. - * - * @see #execute - * @config - */ - private static final String PAR_RNDSTART = "randstart"; - - /** - * Contains the scheduler objects for all {@link CDProtocol}s defined in the - * configuration. The length of the array is the number of protocols - * defined, but those entries that belong to protocols that are not - * {@link CDProtocol}s are null. - */ - public static final Scheduler[] sch; - - private final NextCycleEvent[] nce; - - private final int[] pid; - - private final boolean randstart; - - // =============================== initialization ====================== - // ===================================================================== - - /** - * Loads protocol schedulers for all protocols. - */ - static { - - String[] names = Configuration.getNames(Node.PAR_PROT); - sch = new Scheduler[names.length]; - for (int i = 0; i < names.length; ++i) { - if (Network.prototype.getProtocol(i) instanceof CDProtocol) - // with no default values for step to avoid - // "overscheduling" due to lack of step option. - sch[i] = new Scheduler(names[i], false); - } - } - - // -------------------------------------------------------------------- - - /** - * Initialization based on configuration parameters. - */ - public CDScheduler(String n) { - String[] prots = Configuration.getString(n + "." + PAR_PROTOCOL).split("\\s"); - pid = new int[prots.length]; - nce = new NextCycleEvent[prots.length]; - for (int i = 0; i < prots.length; ++i) { - pid[i] = Configuration.lookupPid(prots[i]); - if (!(Network.prototype.getProtocol(pid[i]) instanceof CDProtocol)) { - throw new IllegalParameterException(n + "." + PAR_PROTOCOL, - "Only CDProtocols are accepted here"); - } - nce[i] = (NextCycleEvent) Configuration.getInstance(n + "." - + PAR_NEXTC, new NextCycleEvent(null)); - } - randstart = Configuration.contains(n + "." + PAR_RNDSTART); - } - - // ========================== methods ================================== - // ===================================================================== - - /** - * Schedules the protocol at all nodes for the first execution adding it to - * the priority queue of the event driven simulation. The time of the first - * execution is determined by {@link #firstDelay}. The implementation calls - * {@link #initialize} for all nodes. - * - * @see #initialize - */ - public boolean execute() { - - for (int i = 0; i < Network.size(); ++i) { - initialize(Network.get(i)); - } - - return false; - } - - // -------------------------------------------------------------------- - - /** - * Schedules the protocol at given node for the first execution adding it to - * the priority queue of the event driven simulation. The time of the first - * execution is determined by a reference point in time and - * {@link #firstDelay}, which defines the delay from the reference point. - * The reference point is the maximum of the current time, and the value of - * parameter {@value peersim.core.Scheduler#PAR_FROM} of the protocol being - * scheduled. If the calculated time of the first execution is not valid - * according to the schedule of the protocol then no execution is scheduled - * for that protocol. - *
- * A final note: for performance reasons, the recommended practice is not to - * use parameter {@value peersim.core.Scheduler#PAR_FROM} in protocols, but - * to schedule {@link CDScheduler} itself for the desired time, whenever - * possible (e.g., it is not possible if {@link CDScheduler} is used as a - * {@link NodeInitializer}). - */ - public void initialize(Node n) { - /* - * XXX If "from" is not the current time and this is used as a control - * (not node initializer) then we dump _lots_ of events in the queue - * that are just stored there until "from" comes. This reduces - * performance, and should be fixed. When fixed, the final comment can - * be removed from the docs. - */ - - final long time = CommonState.getTime(); - for (int i = 0; i < pid.length; ++i) { - Object nceclone = null; - try { - nceclone = nce[i].clone(); - } catch (CloneNotSupportedException e) { - } // cannot possibly happen - - final long delay = firstDelay(sch[pid[i]].step); - final long nexttime = Math.max(time, sch[pid[i]].from) + delay; - if (nexttime < sch[pid[i]].until) - EDSimulator.add(nexttime - time, nceclone, n, pid[i]); - } - } - - // -------------------------------------------------------------------- - - /** - * Returns the time (through giving the delay from the current time) when - * this even is first executed. If {@value #PAR_RNDSTART} is not set, it - * returns zero, otherwise a random value between 0, inclusive, and - * cyclelength, exclusive. - * - * @param cyclelength - * The cycle length of the cycle based protocol for which this - * method is called - */ - protected long firstDelay(long cyclelength) { - - if (randstart) - return CommonState.r.nextLong(cyclelength); - else - return 0; - } -}