/**
* Copyright 2005-2016 Red Hat, Inc.
*
* Red Hat licenses this file to you under the Apache License, version
* 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package io.fabric8.apmagent.strategy.sampling;
import io.fabric8.apmagent.ApmConfiguration;
import io.fabric8.apmagent.Strategy;
import io.fabric8.apmagent.metrics.ApmAgentContext;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
public class SamplingStrategy implements Strategy, Runnable {
private static final long CLEANUP_INTERVAL = 1000;
private ApmAgentContext context;
private ApmConfiguration configuration;
private AtomicBoolean initialized = new AtomicBoolean();
private AtomicBoolean started = new AtomicBoolean();
private Thread samplingThread;
private final Map<Long, String> currentMethods = new HashMap<>();
public SamplingStrategy(ApmAgentContext context) {
this.context = context;
this.configuration = context.getConfiguration();
}
@Override
public void initialize() throws Exception {
if (initialized.compareAndSet(false, true)) {
samplingThread = new Thread(this, "Fabric8-ApmAgent-SamplingStrategy");
samplingThread.setDaemon(true);
configuration.addChangeListener(this);
}
}
@Override
public void start() throws Exception {
if (started.compareAndSet(false, true)) {
initialize();
samplingThread.start();
}
}
@Override
public void stop() throws Exception {
if (started.compareAndSet(true, false)) {
}
}
@Override
public void shutDown() throws Exception {
if (initialized.compareAndSet(true, false)) {
configuration.removeChangeListener(this);
samplingThread = null;
}
}
@Override
public void configurationChanged() {
}
@Override
public void run() {
long lastTime = 0;
while (started.get()) {
try {
for (Map.Entry<Thread, StackTraceElement[]> threadEntry : Thread.getAllStackTraces().entrySet()) {
if (threadEntry.getKey() != Thread.currentThread()) {
addMeasurement(threadEntry.getKey(), threadEntry.getValue());
}
}
long currentTime = System.currentTimeMillis();
if ((currentTime - lastTime) > CLEANUP_INTERVAL) {
cleanup();
lastTime = currentTime;
}
Thread.sleep(configuration.getSamplingInterval());
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
private void cleanup() {
List<ThreadInfo> removeList = null;
ThreadMXBean threadMXBean = ManagementFactory.getThreadMXBean();
for (Long id : currentMethods.keySet()) {
ThreadInfo threadInfo = threadMXBean.getThreadInfo(id);
if (threadInfo != null) {
if (threadInfo.getThreadState() == Thread.State.TERMINATED) {
if (removeList == null) {
removeList = new ArrayList<>();
}
removeList.add(threadInfo);
}
}
}
if (removeList != null) {
for (ThreadInfo threadInfo : removeList) {
currentMethods.remove(threadInfo.getThreadId());
}
}
}
private void addMeasurement(Thread thread, StackTraceElement[] stackTraceElements) {
if (thread != null && thread.isAlive() &&
stackTraceElements != null && stackTraceElements.length > 0) {
StackTraceElement topOfStack = stackTraceElements[0];
String currentMethod = getCurrentMethod(topOfStack);
if (configuration.isAudit(topOfStack.getClassName(), topOfStack.getMethodName())) {
String lastMethod = currentMethods.put(thread.getId(), currentMethod);
if (lastMethod == null) {
context.enterMethod(thread, currentMethod, true);
} else if (!lastMethod.equals(currentMethod)) {
context.exitMethod(thread, lastMethod, true);
} else {
//we are still in the currentMethod
}
}
}
}
private String getCurrentMethod(StackTraceElement topOfStack) {
StringBuilder stringBuilder = new StringBuilder(topOfStack.getClassName().length() + topOfStack.getMethodName().length() + 1);
stringBuilder.append(topOfStack.getClassName()).append(".").append(topOfStack.getMethodName());
return stringBuilder.toString();
}
}