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Ripped out the guts of IntervalManager and replaced them with Java 1.4's

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java.util.Timer. We might as well use the standard stuff, and why not:
it's got a snazzy priority heap for scheduling.
However, we still like the flexibility of IntervalManager's static methods
and the Interval interface (Timer's helper, TimerTask, is a class. Boo.).
Note: I ripped out so many guts that we no longer have the ability to
use a pool of helper threads for expiring Intervals. We never used it
anyway. If we desire it in the future, it'd be easy enough to put back in.


git-svn-id: https://samskivert.googlecode.com/svn/trunk@757 6335cc39-0255-0410-8fd6-9bcaacd3b74c
This commit is contained in:
ray
2002-05-23 23:37:50 +00:00
parent fd6775b3d9
commit 404ac11173
1 changed files with 93 additions and 301 deletions
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projects/samskivert/src/java/com/samskivert/util/IntervalManager.java
+93 -301
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@@ -1,5 +1,5 @@
//
// $Id: IntervalManager.java,v 1.5 2002/02/19 03:39:41 mdb Exp $
// $Id: IntervalManager.java,v 1.6 2002/05/23 23:37:50 ray Exp $
//
// samskivert library - useful routines for java programs
// Copyright (C) 2001 Michael Bayne
@@ -20,58 +20,22 @@
package com.samskivert.util;
import java.util.Timer;
import java.util.TimerTask;
import com.samskivert.Log;
/**
* Interval: can be used to register an object that is to be called once
* or repeatedly after an interval has expired.
*
* <p> A caveat: be careful about deadlocks kids. The number of helper
* threads should exceed the number of times you nest calls to Interval
* stuff from inside the intervalExpired method of an Interval. Normally,
* if all you're using this for is interrupting other threads or calling
* repaint you can get by with 0 helpers. If you want to do some more
* complicated stuff in intervalExpired() then you probably want a few
* threads in the pool. If you're doing extensive processing and setting
* up other timeouts on that thread then you want to make sure you've got
* plenty of threads.
* This now uses java.util.Timer to do all the actual scheduling, but we
* keep this front end because it is static (accessable anywhere)
* and because Interval is an interface, unlike TimerTask, which is an
* abstract class.
*/
public class IntervalManager extends Thread
public class IntervalManager
{
/**
* Sets the maximum number of helper threads to run methods in
* Intervals. Defaults to 0, meaning that the main thread does all
* the work. Setting this to a nonzero value makes it such that a
* pool of helper threads is created to do all the actual work.
*/
public static synchronized void setMaxHelperThreads (int newmax)
{
newmax = Math.max(newmax, 0);
// if we are moving down, we need to kill some threads.
if (_helpers > newmax) {
for (int ii=0; ii < _helpers - newmax; ii++) {
_queue.append(KILLHELPER);
}
_helpers = newmax;
}
// finally, set the new maximum thread pool size.
_maxhelpers = newmax;
}
/**
* Increment the number of maximum helper threads. This is useful if
* you may have many packages which use the IntervalMgr as a
* threadpool to do work, each package can statically initialize the
* number of threads they want to be available by calling this method
* and they'll all be added together.
*/
public static synchronized void incrementHelperThreads (int amt)
{
setMaxHelperThreads(_maxhelpers + amt);
}
/**
* Schedule the intervaled object to get called after an interval.
*
@@ -87,16 +51,33 @@ public class IntervalManager extends Thread
public static int register (Interval i, long delay, Object arg,
boolean recur)
{
synchronized (_mgr) {
IntervalItem item = new IntervalItem(i, delay, arg, recur);
_hash.put(item.id, item);
_schedule.add(item);
_schedule.sort();
if (item.endtime < _nextwake) {
_mgr.notify();
}
return item.id;
}
IntervalTask task = new IntervalTask(i, arg, recur);
_hash.put(task.id, task);
if (recur) {
_timer.scheduleAtFixedRate(task, delay, delay);
} else {
_timer.schedule(task, delay);
}
return task.id;
}
/**
* Schedule the interval to be called repeatedly, but at a fixed delay
* instead of fixed rate.
* This means that the delay between executions will be the
* delay specified below plus the actual execution time it takes
* to run the interval's expire method.
*/
public static int registerAtFixedDelay (Interval i, long delay, Object arg)
{
IntervalTask task = new IntervalTask(i, arg, true);
_hash.put(task.id, task);
_timer.schedule(task, delay, delay);
return task.id;
}
/**
@@ -107,256 +88,67 @@ public class IntervalManager extends Thread
*/
public static void remove (int id)
{
synchronized (_mgr) {
IntervalItem item = (IntervalItem) _hash.remove(id);
if (item != null) {
_schedule.remove(item);
return;
}
}
Log.warning("remove() called on non-registered " +
"interval [id=" + id + "].");
Thread.dumpStack();
IntervalTask task = (IntervalTask) _hash.remove(id);
if (task != null) {
task.cancel();
} else {
Log.warning("remove() called on non-registered " +
"interval [id=" + id + "].");
}
}
/**
* Do our interval thing.
*/
public void run ()
{
while (_mgr == Thread.currentThread()) {
// check to see if an interval has expired, if so call
// expired from an unsynchronized position.
// TrackedThread.setState("Checking intervals");
IntervalItem item = checkInterval();
if (item != null) {
if (_maxhelpers > 0) {
helperHandle(item);
} else {
item.expired(); // we have no helpers, do it ourselves.
}
}
// now attempt to sleep
// TrackedThread.setState("Waiting for Interval event...");
doWait();
}
}
/**
* Have a helper thread handle the expiration of this interval.
*/
protected static synchronized void helperHandle (IntervalItem item)
{
// put the item on the queue...
_busyhelpers++;
_queue.append(item);
// possibly create a new thread in the pool to do this work.
if ((_busyhelpers > _helpers) && (_helpers < _maxhelpers)) {
IntervalExpirer helper = new IntervalExpirer(_queue);
_helpers++;
helper.start();
}
}
/**
* A helper thread lets us know when it has finished its work.
*/
protected static synchronized void helperFinished ()
{
_busyhelpers--;
}
/**
* Check to see if anything needs calling.
*/
private synchronized IntervalItem checkInterval ()
{
// TrackedThread.setState("Checking intervals");
if (_schedule.size() > 0) {
IntervalItem item = (IntervalItem) _schedule.get(0);
// it's totally valid for us to wake up early..
// so make sure we really want to run the first item on the queue.
if (item.endtime <= System.currentTimeMillis()) {
// we gotta deal with this monster!
// first, remove it.
_schedule.remove(0);
if (item.checkRecur()) {
// since we're definitionally not sleeping, we can just
// insert into the queue without checking wait times..
_schedule.add(item);
_schedule.sort();
} else {
// otherwise, get rid of this interval altogether
_hash.remove(item.id);
}
return item;
}
}
return null;
}
/**
* Sleep until the next Interval needs to be attended to.
*/
private synchronized void doWait ()
{
// TrackedThread.setState("Waiting for Interval event...");
if (_schedule.size() == 0) {
_nextwake = Long.MAX_VALUE;
} else {
IntervalItem item = (IntervalItem) _schedule.get(0);
_nextwake = item.endtime;
}
long waittime = _nextwake - System.currentTimeMillis();
if (waittime > 0L) {
try {
wait(waittime);
} catch (InterruptedException e) {
}
}
}
private IntervalManager ()
{
super("IntervalManager");
setDaemon(true);
start();
}
// there can be only one!
protected static IntervalManager _mgr = new IntervalManager();
// We just use a sorted list for now since we aren't likely to have
// too many monitorables at any time. Insertions are O(log n),
// removals are O(n) since we search then entire queue to find the
// intervaleds to remove.
//
// If we someday find that we have a lot of intervaleds, we may want
// to rewrite this such that we can add and remove intervaleds much
// faster.
protected static SortableArrayList _schedule = new SortableArrayList();
/** The timer we use to schedule everything. */
protected static Timer _timer = new Timer(true);
/** Our registered intervals, indexed by id. */
protected static HashIntMap _hash = new HashIntMap();
protected static long _nextwake = Long.MAX_VALUE;
protected static int _helpers = 0; // # of created helpers
protected static int _maxhelpers = 0; // max # of helpers we can create
protected static int _busyhelpers = 0; // # of outstanding requests
protected static Queue _queue = new Queue();
/**
* A class to adapt TimerTask to the smooth action of Interval.
*/
static class IntervalTask extends TimerTask
{
public int id;
protected Interval _i;
protected Object _arg;
protected boolean _onetime;
protected static final Object KILLHELPER = new Object();
}
class IntervalItem implements Comparable
{
public long endtime;
public int id;
protected long _timeout;
protected boolean _recur;
protected Interval _i;
protected Object _arg;
public IntervalItem (Interval i, long timeout, Object arg, boolean recur)
{
_i = i;
_timeout = Math.max(timeout, 0);
_arg = arg;
_recur = recur;
id = nextID();
endtime = System.currentTimeMillis() + timeout;
}
public int compareTo (Object other)
{
return (int) (endtime - ((IntervalItem) other).endtime);
}
/**
* Test-n-set recurring stuff. If we do recur, increment the time we
* are to next wake.
*/
public boolean checkRecur ()
{
if (_recur) {
endtime += _timeout;
}
return _recur;
}
/**
* Run the interval. It's synchronized so that if we someday have
* multiple threads, the same interval won't be called multiple times.
*/
public synchronized void expired ()
{
// protect our ass.
try {
_i.intervalExpired(id, _arg);
} catch (Exception e) {
Log.warning("Exception while expiring interval: " + e);
Log.logStackTrace(e);
}
}
/**
* For debugging.
*/
public String toString()
{
return "Interval: " + _i + " (wakes in " +
(endtime - System.currentTimeMillis()) + "ms)" +
(_recur ? (" [recurring every " + _timeout + "ms]") : "");
}
/**
* Unique ids for each interval item.
*/
private static synchronized int nextID ()
{
return _idseq++;
}
private static int _idseq = 0;
}
/**
* These are the helper threads for the IntervalManager.
*/
class IntervalExpirer extends Thread
{
public IntervalExpirer (Queue queue)
{
super("IntervalExpirer");
setDaemon(true);
_queue = queue;
}
public void run ()
{
while (true) {
// TrackedThread.setState("Waiting for Interval to run...");
Object o = _queue.get();
if (o == IntervalManager.KILLHELPER) {
break; //exit
}
// otherwise run the bashtard!
((IntervalItem) o).expired();
IntervalManager.helperFinished();
}
}
protected Queue _queue;
public IntervalTask (Interval i, Object arg, boolean recur)
{
_i = i;
_arg = arg;
_onetime = !recur;
id = nextID();
}
/**
* Run the interval. It's synchronized so that if we someday have
* multiple threads, the same interval won't be called multiple times.
*/
public void run ()
{
// protect our ass.
try {
_i.intervalExpired(id, _arg);
} catch (Exception e) {
Log.warning("Exception while expiring interval: " + e);
Log.logStackTrace(e);
}
// if we're not recurring, be sure to remove from the mgr's hash
if (_onetime) {
_hash.remove(id);
}
}
/**
* Unique ids for each interval item.
*/
private static synchronized int nextID ()
{
return _idseq++;
}
private static int _idseq = 0;
}
}