Author: toad
Date: 2007-08-11 13:49:20 +0000 (Sat, 11 Aug 2007)
New Revision: 14600
Added:
trunk/freenet/src/freenet/support/Executor.java
trunk/freenet/src/freenet/support/PooledExecutor.java
Log:
Add Executor interface (clone of java.util.concurrent) and homegrown
PooledExecutor impl (we create a thread when we need one, they die after 5
minutes of inactivity)
Added: trunk/freenet/src/freenet/support/Executor.java
===================================================================
--- trunk/freenet/src/freenet/support/Executor.java
(rev 0)
+++ trunk/freenet/src/freenet/support/Executor.java 2007-08-11 13:49:20 UTC
(rev 14600)
@@ -0,0 +1,14 @@
+/**
+ * @author toad
+ * To the extent that this is copyrightable, it's part of Freenet and licensed
+ * under GPL2 or later. However, it's a trivial interface taken from Sun JDK
1.5,
+ * and we will use that when we migrate to 1.5.
+ */
+package freenet.support;
+
+public interface Executor {
+
+ /** Execute a job. */
+ public void execute(Runnable job);
+
+}
Added: trunk/freenet/src/freenet/support/PooledExecutor.java
===================================================================
--- trunk/freenet/src/freenet/support/PooledExecutor.java
(rev 0)
+++ trunk/freenet/src/freenet/support/PooledExecutor.java 2007-08-11
13:49:20 UTC (rev 14600)
@@ -0,0 +1,101 @@
+package freenet.support;
+
+import java.util.ArrayList;
+
+public class PooledExecutor implements Executor {
+
+ private final ArrayList runningThreads /* <MyThread> */ = new
ArrayList();
+ private final ArrayList waitingThreads /* <MyThread> */ = new
ArrayList();
+ long threadCounter = 0;
+
+ /** Maximum time a thread will wait for a job */
+ static final int TIMEOUT = 5*60*1000;
+
+ public void execute(Runnable job) {
+ while(true) {
+ MyThread t;
+ boolean mustStart = false;
+ synchronized(this) {
+ if(!waitingThreads.isEmpty()) {
+ t = (MyThread)
waitingThreads.remove(waitingThreads.size()-1);
+ } else {
+ t = new MyThread("Pooled thread
"+(threadCounter++));
+ t.setDaemon(true);
+ mustStart = true;
+ }
+ }
+ synchronized(t) {
+ if(!t.alive) continue;
+ if(t.nextJob != null) continue;
+ t.nextJob = job;
+ if(!mustStart)
+ t.notify();
+ }
+ if(mustStart) {
+ t.start();
+ synchronized(this) {
+ runningThreads.add(t);
+ }
+ }
+ return;
+ }
+ }
+
+ class MyThread extends Thread {
+
+ boolean alive = true;
+ Runnable nextJob;
+
+ public MyThread(String string) {
+ super(string);
+ }
+
+ public void run() {
+ while(true) {
+ Runnable job;
+
+ synchronized(this) {
+ job = nextJob;
+ nextJob = null;
+ }
+
+ if(job == null) {
+ synchronized(PooledExecutor.this) {
+ waitingThreads.add(this);
+ }
+ synchronized(this) {
+ if(nextJob == null) {
+ try {
+ wait(TIMEOUT);
+ } catch
(InterruptedException e) {
+ // Ignore
+ }
+ }
+ job = nextJob;
+ nextJob = null;
+ if(job == null) {
+ alive = false;
+ // execute() won't give
us another one if alive = false
+ }
+ }
+ synchronized(PooledExecutor.this) {
+ waitingThreads.remove(this);
+ if(!alive) {
+
runningThreads.remove(this);
+ return;
+ }
+ }
+ }
+
+ // Run the job
+ try {
+ job.run();
+ } catch (Throwable t) {
+ Logger.error(this, "Caught "+t+"
running job "+job, t);
+ }
+ }
+ }
+
+ }
+
+}
