/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Eclipse Public License (EPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/eclipse-1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.jikesrvm.adaptive.util;
import org.jikesrvm.classloader.MethodReference;
/**
* A collection of weighted call targets. In some case we can't resolve a
* class too early in the process. So we recorded it as unresolved and
* resolve the method when the method is being compiled.
*/
public abstract class UnResolvedWeightedCallTargets {
/**
* Iterate over all of the targets, evaluating the argument function on each edge.
* NOTE: We guarentee that the targets will be iterated in monotonically decrasing
* edge weight. This simplifies the coding of the inlining clients that consume
* this information.
* @param func the function to evaluate on each target
*/
public abstract void visitTargets(Visitor func);
/**
* Augment the weight associated with the argument method by 1.
* NOTE: This method may change the representation of the target
* method. The caller must be sure to update their backing store of
* UnResolvedWeightedCallTargets accordingly to avoid losing the update.
*/
public final UnResolvedWeightedCallTargets incrementCount(MethodReference target) {
return augmentCount(target, 1);
}
/**
* Augment the weight associated with the argument method by the argument amount.
* NOTE: This method may change the representation of the target
* method. The caller must be sure to update their backing store of
* UnResolvedWeightedCallTargets accordingly to avoid losing the update.
*/
public abstract UnResolvedWeightedCallTargets augmentCount(MethodReference target, double amount);
/**
* Decay the weights of all call targets by the specified amount
* @param rate the value to decay by
*/
public abstract void decay(double rate);
/**
* totalWeight of all call targets
*/
public abstract double totalWeight();
/**
* @param goal MethodReference that is the only statically possible target
* @return the filtered call targets or null if no such target exisits
*/
public abstract UnResolvedWeightedCallTargets filter(MethodReference goal);
public static UnResolvedWeightedCallTargets create(MethodReference target, double weight) {
return new UnResolvedSingleTarget(target, weight);
}
/**
* Used by visitTargets
*/
public interface Visitor {
void visit(MethodReference target, double weight);
}
/**
* An implementation for storing a call site distribution that has a single target.
*/
private static final class UnResolvedSingleTarget extends UnResolvedWeightedCallTargets {
private final MethodReference target;
private float weight;
UnResolvedSingleTarget(MethodReference t, double w) {
target = t;
weight = (float) w;
}
public void visitTargets(Visitor func) {
func.visit(target, weight);
}
public UnResolvedWeightedCallTargets augmentCount(MethodReference t, double v) {
if (target.equals(t)) {
weight += v;
return this;
} else {
UnResolvedMultiTarget ms = new UnResolvedMultiTarget();
ms.augmentCount(target, weight);
ms.augmentCount(t, v);
return ms;
}
}
public void decay(double rate) {
weight /= rate;
}
public double totalWeight() { return weight; }
public UnResolvedWeightedCallTargets filter(MethodReference goal) {
return (goal.equals(target)) ? this : null;
}
}
/**
* An implementation for storing a call site distribution that has multiple targets.
*/
private static final class UnResolvedMultiTarget extends UnResolvedWeightedCallTargets {
MethodReference[] methods = new MethodReference[5];
float[] weights = new float[5];
public synchronized void visitTargets(Visitor func) {
// Typically expect elements to be "almost" sorted due to previous sorting operations.
// When this is true, expected time for insertion sort is O(n).
for (int i = 1; i < methods.length; i++) {
MethodReference m = methods[i];
if (m != null) {
float w = weights[i];
int j = i;
while (j > 0 && weights[j - 1] < w) {
methods[j] = methods[j - 1];
weights[j] = weights[j - 1];
j--;
}
methods[j] = m;
weights[j] = w;
}
}
for (int i = 0; i < methods.length; i++) {
if (methods[i] != null) {
func.visit(methods[i], weights[i]);
}
}
}
public synchronized UnResolvedWeightedCallTargets augmentCount(MethodReference t, double v) {
int empty = -1;
for (int i = 0; i < methods.length; i++) {
if (methods[i] != null) {
if (methods[i].equals(t)) {
weights[i] += v;
return this;
}
} else {
if (empty == -1) { empty = i; }
}
}
// New target must be added
if (empty == -1) {
// must grow arrays
empty = methods.length;
MethodReference[] newM = new MethodReference[methods.length * 2];
System.arraycopy(methods, 0, newM, 0, methods.length);
methods = newM;
float[] newW = new float[weights.length * 2];
System.arraycopy(weights, 0, newW, 0, weights.length);
weights = newW;
}
methods[empty] = t;
weights[empty] = (float) v;
return this;
}
public synchronized void decay(double rate) {
for (int i = 0; i < weights.length; i++) {
weights[i] /= rate;
}
}
public synchronized double totalWeight() {
double sum = 0;
for (float weight : weights) {
sum += weight;
}
return sum;
}
public synchronized UnResolvedWeightedCallTargets filter(MethodReference goal) {
for (int i = 0; i < methods.length; i++) {
if (goal.equals(methods[i])) {
return UnResolvedWeightedCallTargets.create(methods[i], weights[i]);
}
}
return null;
}
}
}