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/* *******************************************************************
* Copyright (c) 2004 IBM Corporation
*
* All rights reserved.
* This program and the accompanying materials are made available
* under the terms of the Eclipse Public License v 2.0
* which accompanies this distribution and is available at
* https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
*
* Contributors:
* Andy Clement initial implementation
* Copied from bits of original CFlowStack
* ******************************************************************/
package org.aspectj.runtime.internal.cflowstack;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Stack;
public class ThreadStackImpl11 implements ThreadStack {
private Hashtable stacks = new Hashtable<>();
private Thread cached_thread;
private Stack cached_stack;
private int change_count = 0;
private static final int COLLECT_AT = 20000;
private static final int MIN_COLLECT_AT = 100;
public synchronized Stack getThreadStack() {
if (Thread.currentThread() != cached_thread) {
cached_thread = Thread.currentThread();
cached_stack = (Stack)stacks.get(cached_thread);
if (cached_stack == null) {
cached_stack = new Stack<>();
stacks.put(cached_thread, cached_stack);
}
change_count++;
// Collect more often if there are many threads, but not *too* often
int size = Math.max(1, stacks.size()); // should be >1 b/c always live threads, but...
if (change_count > Math.max(MIN_COLLECT_AT, COLLECT_AT/size)) {
Stack dead_stacks = new Stack<>();
for (Enumeration e = stacks.keys(); e.hasMoreElements(); ) {
Thread t = e.nextElement();
if (!t.isAlive()) dead_stacks.push(t);
}
for (Enumeration e = dead_stacks.elements(); e.hasMoreElements(); ) {
Thread t = e.nextElement();
stacks.remove(t);
}
change_count = 0;
}
}
return cached_stack;
}
public void removeThreadStack() {
// TODO
}
}