osd-contiki/tools/cooja/java/se/sics/cooja/EventQueue.java
fros4943 64293abe03 major update to cooja's event scheduler:
* all events must now be scheduled from the simulation thread
* added new methods for requesting simulation thread execution

this patch solves some race conditions introduced by the new mspsim execution scheduling, but affects many existing plugins and interfaces
2009-10-27 10:06:59 +00:00

160 lines
4.2 KiB
Java

/*
* Copyright (c) 2008, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: EventQueue.java,v 1.9 2009/10/27 10:06:59 fros4943 Exp $
*/
package se.sics.cooja;
/**
* @author Joakim Eriksson (ported to COOJA by Fredrik Osterlind)
*/
public class EventQueue {
private TimeEvent first;
private int eventCount = 0;
/**
* Should only be called from simulation thread!
*
* @param event Event
* @param time Time
*/
public void addEvent(TimeEvent event, long time) {
event.time = time;
addEvent(event);
}
private void addEvent(TimeEvent event) {
if (event.removed && event.queue != null) {
removeFromQueue(event);
}
if (event.queue != null) {
throw new IllegalStateException("Event was already scheduled in the past: " + event);
}
if (first == null) {
first = event;
} else {
TimeEvent pos = first;
TimeEvent lastPos = first;
while (pos != null && pos.time <= event.time) {
lastPos = pos;
pos = pos.nextEvent;
}
// Here pos will be the first TE after event
// and lastPos the first before
if (pos == first) {
// Before all other
event.nextEvent = pos;
first = event;
} else {
event.nextEvent = pos;
lastPos.nextEvent = event;
}
}
event.removed = false;
event.queue = this;
eventCount++;
}
/**
* Should only be called from simulation thread!
*
* @param event Event
* @return True if event was removed
*/
private boolean removeFromQueue(TimeEvent event) {
TimeEvent pos = first;
TimeEvent lastPos = first;
while (pos != null && pos != event) {
lastPos = pos;
pos = pos.nextEvent;
}
if (pos == null) {
return false;
}
// pos == event!
if (pos == first) {
// remove it from first pos.
first = pos.nextEvent;
} else {
// else link prev to next...
lastPos.nextEvent = pos.nextEvent;
}
// unlink
pos.nextEvent = null;
event.queue = null;
eventCount--;
return true;
}
public void removeAll() {
TimeEvent event = popFirst();
while (event != null) {
event = popFirst();
}
}
/**
* Should only be called from simulation thread!
*
* @return Event
*/
public TimeEvent popFirst() {
TimeEvent tmp = first;
if (tmp == null) {
return null;
}
first = tmp.nextEvent;
// Unlink.
tmp.nextEvent = null;
// No longer scheduled!
tmp.queue = null;
eventCount--;
if (tmp.removed) {
/* pop and return another event instead */
return popFirst();
}
return tmp;
}
public TimeEvent peekFirst() {
return first;
}
public String toString() {
return "EventQueue with " + eventCount + " events";
}
}