/*
* ProtocolLib - Bukkit server library that allows access to the Minecraft protocol.
* Copyright (C) 2012 Kristian S. Stangeland
*
* This program is free software; you can redistribute it and/or modify it under the terms of the
* GNU General Public License as published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with this program;
* if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
* 02111-1307 USA
*/
package com.comphenix.protocol.reflect.compiler;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryPoolMXBean;
import java.lang.management.MemoryUsage;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import com.comphenix.protocol.error.ErrorReporter;
import com.comphenix.protocol.error.Report;
import com.comphenix.protocol.error.ReportType;
import com.comphenix.protocol.reflect.StructureModifier;
import com.comphenix.protocol.reflect.compiler.StructureCompiler.StructureKey;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
/**
* Compiles structure modifiers on a background thread.
* <p>
* This is necessary as we cannot block the main thread.
*
* @author Kristian
*/
public class BackgroundCompiler {
public static final ReportType REPORT_CANNOT_COMPILE_STRUCTURE_MODIFIER = new ReportType("Cannot compile structure. Disabing compiler.");
public static final ReportType REPORT_CANNOT_SCHEDULE_COMPILATION = new ReportType("Unable to schedule compilation task.");
/**
* The default format for the name of new worker threads.
*/
public static final String THREAD_FORMAT = "ProtocolLib-StructureCompiler %s";
// How long to wait for a shutdown
public static final int SHUTDOWN_DELAY_MS = 2000;
/**
* The default fraction of perm gen space after which the background compiler will be disabled.
*/
public static final double DEFAULT_DISABLE_AT_PERM_GEN = 0.65;
// The single background compiler we're using
private static BackgroundCompiler backgroundCompiler;
// Classes we're currently compiling
private Map<StructureKey, List<CompileListener<?>>> listeners = Maps.newHashMap();
private Object listenerLock = new Object();
private StructureCompiler compiler;
private boolean enabled;
private boolean shuttingDown;
private ExecutorService executor;
private ErrorReporter reporter;
private double disablePermGenFraction = DEFAULT_DISABLE_AT_PERM_GEN;
/**
* Retrieves the current background compiler.
* @return Current background compiler.
*/
public static BackgroundCompiler getInstance() {
return backgroundCompiler;
}
/**
* Sets the single background compiler we're using.
* @param backgroundCompiler - current background compiler, or NULL if the library is not loaded.
*/
public static void setInstance(BackgroundCompiler backgroundCompiler) {
BackgroundCompiler.backgroundCompiler = backgroundCompiler;
}
/**
* Initialize a background compiler.
* <p>
* Uses the default {@link #THREAD_FORMAT} to name worker threads.
* @param loader - class loader from Bukkit.
* @param reporter - current error reporter.
*/
public BackgroundCompiler(ClassLoader loader, ErrorReporter reporter) {
ThreadFactory factory = new ThreadFactoryBuilder().
setDaemon(true).
setNameFormat(THREAD_FORMAT).
build();
initializeCompiler(loader, reporter, Executors.newSingleThreadExecutor(factory));
}
/**
* Initialize a background compiler utilizing the given thread pool.
* @param loader - class loader from Bukkit.
* @param reporter - current error reporter.
* @param executor - thread pool we'll use.
*/
public BackgroundCompiler(ClassLoader loader, ErrorReporter reporter, ExecutorService executor) {
initializeCompiler(loader, reporter, executor);
}
// Avoid "Constructor call must be the first statement".
private void initializeCompiler(ClassLoader loader, ErrorReporter reporter, ExecutorService executor) {
if (loader == null)
throw new IllegalArgumentException("loader cannot be NULL");
if (executor == null)
throw new IllegalArgumentException("executor cannot be NULL");
if (reporter == null)
throw new IllegalArgumentException("reporter cannot be NULL.");
this.compiler = new StructureCompiler(loader);
this.reporter = reporter;
this.executor = executor;
this.enabled = true;
}
/**
* Ensure that the indirectly given structure modifier is eventually compiled.
* @param cache - store of structure modifiers.
* @param key - key of the structure modifier to compile.
*/
@SuppressWarnings("rawtypes")
public void scheduleCompilation(final Map<Class, StructureModifier> cache, final Class key) {
@SuppressWarnings("unchecked")
final StructureModifier<Object> uncompiled = cache.get(key);
if (uncompiled != null) {
scheduleCompilation(uncompiled, new CompileListener<Object>() {
@Override
public void onCompiled(StructureModifier<Object> compiledModifier) {
// Update cache
cache.put(key, compiledModifier);
}
});
}
}
/**
* Ensure that the given structure modifier is eventually compiled.
* @param uncompiled - structure modifier to compile.
* @param listener - listener responsible for responding to the compilation.
*/
@SuppressWarnings({"rawtypes", "unchecked"})
public <TKey> void scheduleCompilation(final StructureModifier<TKey> uncompiled, final CompileListener<TKey> listener) {
// Only schedule if we're enabled
if (enabled && !shuttingDown) {
// Check perm gen
if (getPermGenUsage() > disablePermGenFraction)
return;
// Don't try to schedule anything
if (executor == null || executor.isShutdown())
return;
// Use to look up structure modifiers
final StructureKey key = new StructureKey(uncompiled);
// Allow others to listen in too
synchronized (listenerLock) {
List list = listeners.get(key);
if (!listeners.containsKey(key)) {
listeners.put(key, (List) Lists.newArrayList(listener));
} else {
// We're currently compiling
list.add(listener);
return;
}
}
// Create the worker that will compile our modifier
Callable<?> worker = new Callable<Object>() {
@Override
public Object call() throws Exception {
StructureModifier<TKey> modifier = uncompiled;
List list = null;
// Do our compilation
try {
modifier = compiler.compile(modifier);
synchronized (listenerLock) {
list = listeners.get(key);
// Prevent ConcurrentModificationExceptions
if (list != null) {
list = Lists.newArrayList(list);
}
}
// Only execute the listeners if there is a list
if (list != null) {
for (Object compileListener : list) {
((CompileListener<TKey>) compileListener).onCompiled(modifier);
}
// Remove it when we're done
synchronized (listenerLock) {
list = listeners.remove(key);
}
}
} catch (OutOfMemoryError e) {
setEnabled(false);
throw e;
} catch (ThreadDeath e) {
setEnabled(false);
throw e;
} catch (Throwable e) {
// Disable future compilations!
setEnabled(false);
// Inform about this error as best as we can
reporter.reportDetailed(BackgroundCompiler.this,
Report.newBuilder(REPORT_CANNOT_COMPILE_STRUCTURE_MODIFIER).callerParam(uncompiled).error(e)
);
}
// We'll also return the new structure modifier
return modifier;
}
};
try {
// Lookup the previous class name on the main thread.
// This is necessary as the Bukkit class loaders are not thread safe
if (compiler.lookupClassLoader(uncompiled)) {
try {
worker.call();
} catch (Exception e) {
// Impossible!
e.printStackTrace();
}
} else {
// Perform the compilation on a seperate thread
executor.submit(worker);
}
} catch (RejectedExecutionException e) {
// Occures when the underlying queue is overflowing. Since the compilation
// is only an optmization and not really essential we'll just log this failure
// and move on.
reporter.reportWarning(this, Report.newBuilder(REPORT_CANNOT_SCHEDULE_COMPILATION).error(e));
}
}
}
/**
* Add a compile listener if we are still waiting for the structure modifier to be compiled.
* @param uncompiled - the structure modifier that may get compiled.
* @param listener - the listener to invoke in that case.
*/
@SuppressWarnings("unchecked")
public <TKey> void addListener(final StructureModifier<TKey> uncompiled, final CompileListener<TKey> listener) {
synchronized (listenerLock) {
StructureKey key = new StructureKey(uncompiled);
@SuppressWarnings("rawtypes")
List list = listeners.get(key);
if (list != null) {
list.add(listener);
}
}
}
/**
* Retrieve the current usage of the Perm Gen space in percentage.
* @return Usage of the perm gen space.
*/
private double getPermGenUsage() {
for (MemoryPoolMXBean item : ManagementFactory.getMemoryPoolMXBeans()) {
if (item.getName().contains("Perm Gen")) {
MemoryUsage usage = item.getUsage();
return usage.getUsed() / (double) usage.getCommitted();
}
}
// Unknown
return 0;
}
/**
* Clean up after ourselves using the default timeout.
*/
public void shutdownAll() {
shutdownAll(SHUTDOWN_DELAY_MS, TimeUnit.MILLISECONDS);
}
/**
* Clean up after ourselves.
* @param timeout - the maximum time to wait.
* @param unit - the time unit of the timeout argument.
*/
public void shutdownAll(long timeout, TimeUnit unit) {
setEnabled(false);
shuttingDown = true;
executor.shutdown();
try {
executor.awaitTermination(timeout, unit);
} catch (InterruptedException e) {
// Unlikely to ever occur - it's the main thread
e.printStackTrace();
}
}
/**
* Retrieve whether or not the background compiler is enabled.
* @return TRUE if it is enabled, FALSE otherwise.
*/
public boolean isEnabled() {
return enabled;
}
/**
* Sets whether or not the background compiler is enabled.
* @param enabled - TRUE to enable it, FALSE otherwise.
*/
public void setEnabled(boolean enabled) {
this.enabled = enabled;
}
/**
* Retrieve the fraction of perm gen space used after which the background compiler will be disabled.
* @return The fraction after which the background compiler is disabled.
*/
public double getDisablePermGenFraction() {
return disablePermGenFraction;
}
/**
* Set the fraction of perm gen space used after which the background compiler will be disabled.
* @param fraction - the maximum use of perm gen space.
*/
public void setDisablePermGenFraction(double fraction) {
this.disablePermGenFraction = fraction;
}
/**
* Retrieve the current structure compiler.
* @return Current structure compiler.
*/
public StructureCompiler getCompiler() {
return compiler;
}
}