/*
* Copyright 2013 The Netty Project
*
* The Netty Project 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.netty.util;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.SystemPropertyUtil;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import java.lang.ref.PhantomReference;
import java.lang.ref.ReferenceQueue;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.EnumSet;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicBoolean;
import static io.netty.util.internal.StringUtil.*;
public final class ResourceLeakDetector<T> {
private static final String PROP_LEVEL = "io.netty.leakDetectionLevel";
private static final Level DEFAULT_LEVEL = Level.SIMPLE;
/**
* Represents the level of resource leak detection.
*/
public enum Level {
/**
* Disables resource leak detection.
*/
DISABLED,
/**
* Enables simplistic sampling resource leak detection which reports there is a leak or not,
* at the cost of small overhead (default).
*/
SIMPLE,
/**
* Enables advanced sampling resource leak detection which reports where the leaked object was accessed
* recently at the cost of high overhead.
*/
ADVANCED,
/**
* Enables paranoid resource leak detection which reports where the leaked object was accessed recently,
* at the cost of the highest possible overhead (for testing purposes only).
*/
PARANOID
}
private static Level level;
private static final InternalLogger logger = InternalLoggerFactory.getInstance(ResourceLeakDetector.class);
static {
final boolean disabled;
if (SystemPropertyUtil.get("io.netty.noResourceLeakDetection") != null) {
disabled = SystemPropertyUtil.getBoolean("io.netty.noResourceLeakDetection", false);
logger.debug("-Dio.netty.noResourceLeakDetection: {}", disabled);
logger.warn(
"-Dio.netty.noResourceLeakDetection is deprecated. Use '-D{}={}' instead.",
PROP_LEVEL, DEFAULT_LEVEL.name().toLowerCase());
} else {
disabled = false;
}
Level defaultLevel = disabled? Level.DISABLED : DEFAULT_LEVEL;
String levelStr = SystemPropertyUtil.get(PROP_LEVEL, defaultLevel.name()).trim().toUpperCase();
Level level = DEFAULT_LEVEL;
for (Level l: EnumSet.allOf(Level.class)) {
if (levelStr.equals(l.name()) || levelStr.equals(String.valueOf(l.ordinal()))) {
level = l;
}
}
ResourceLeakDetector.level = level;
if (logger.isDebugEnabled()) {
logger.debug("-D{}: {}", PROP_LEVEL, level.name().toLowerCase());
}
}
private static final int DEFAULT_SAMPLING_INTERVAL = 113;
/**
* @deprecated Use {@link #setLevel(Level)} instead.
*/
@Deprecated
public static void setEnabled(boolean enabled) {
setLevel(enabled? Level.SIMPLE : Level.DISABLED);
}
/**
* Returns {@code true} if resource leak detection is enabled.
*/
public static boolean isEnabled() {
return getLevel().ordinal() > Level.DISABLED.ordinal();
}
/**
* Sets the resource leak detection level.
*/
public static void setLevel(Level level) {
if (level == null) {
throw new NullPointerException("level");
}
ResourceLeakDetector.level = level;
}
/**
* Returns the current resource leak detection level.
*/
public static Level getLevel() {
return level;
}
/** the linked list of active resources */
private final DefaultResourceLeak head = new DefaultResourceLeak(null);
private final DefaultResourceLeak tail = new DefaultResourceLeak(null);
private final ReferenceQueue<Object> refQueue = new ReferenceQueue<Object>();
private final ConcurrentMap<String, Boolean> reportedLeaks = PlatformDependent.newConcurrentHashMap();
private final String resourceType;
private final int samplingInterval;
private final long maxActive;
private long active;
private final AtomicBoolean loggedTooManyActive = new AtomicBoolean();
private long leakCheckCnt;
public ResourceLeakDetector(Class<?> resourceType) {
this(simpleClassName(resourceType));
}
public ResourceLeakDetector(String resourceType) {
this(resourceType, DEFAULT_SAMPLING_INTERVAL, Long.MAX_VALUE);
}
public ResourceLeakDetector(Class<?> resourceType, int samplingInterval, long maxActive) {
this(simpleClassName(resourceType), samplingInterval, maxActive);
}
public ResourceLeakDetector(String resourceType, int samplingInterval, long maxActive) {
if (resourceType == null) {
throw new NullPointerException("resourceType");
}
if (samplingInterval <= 0) {
throw new IllegalArgumentException("samplingInterval: " + samplingInterval + " (expected: 1+)");
}
if (maxActive <= 0) {
throw new IllegalArgumentException("maxActive: " + maxActive + " (expected: 1+)");
}
this.resourceType = resourceType;
this.samplingInterval = samplingInterval;
this.maxActive = maxActive;
head.next = tail;
tail.prev = head;
}
/**
* Creates a new {@link ResourceLeak} which is expected to be closed via {@link ResourceLeak#close()} when the
* related resource is deallocated.
*
* @return the {@link ResourceLeak} or {@code null}
*/
public ResourceLeak open(T obj) {
Level level = ResourceLeakDetector.level;
if (level == Level.DISABLED) {
return null;
}
if (level.ordinal() < Level.PARANOID.ordinal()) {
if (leakCheckCnt ++ % samplingInterval == 0) {
reportLeak(level);
return new DefaultResourceLeak(obj);
} else {
return null;
}
} else {
reportLeak(level);
return new DefaultResourceLeak(obj);
}
}
private void reportLeak(Level level) {
if (!logger.isErrorEnabled()) {
for (;;) {
@SuppressWarnings("unchecked")
DefaultResourceLeak ref = (DefaultResourceLeak) refQueue.poll();
if (ref == null) {
break;
}
ref.close();
}
return;
}
// Report too many instances.
int samplingInterval = level == Level.PARANOID? 1 : this.samplingInterval;
if (active * samplingInterval > maxActive && loggedTooManyActive.compareAndSet(false, true)) {
logger.error("LEAK: You are creating too many " + resourceType + " instances. " +
resourceType + " is a shared resource that must be reused across the JVM," +
"so that only a few instances are created.");
}
// Detect and report previous leaks.
for (;;) {
@SuppressWarnings("unchecked")
DefaultResourceLeak ref = (DefaultResourceLeak) refQueue.poll();
if (ref == null) {
break;
}
ref.clear();
if (!ref.close()) {
continue;
}
String records = ref.toString();
if (reportedLeaks.putIfAbsent(records, Boolean.TRUE) == null) {
if (records.isEmpty()) {
logger.error("LEAK: {}.release() was not called before it's garbage-collected. " +
"Enable advanced leak reporting to find out where the leak occurred. " +
"To enable advanced leak reporting, " +
"specify the JVM option '-D{}={}' or call {}.setLevel() " +
"See http://netty.io/wiki/reference-counted-objects.html for more information.",
resourceType, PROP_LEVEL, Level.ADVANCED.name().toLowerCase(), simpleClassName(this));
} else {
logger.error(
"LEAK: {}.release() was not called before it's garbage-collected. " +
"See http://netty.io/wiki/reference-counted-objects.html for more information.{}",
resourceType, records);
}
}
}
}
private final class DefaultResourceLeak extends PhantomReference<Object> implements ResourceLeak {
private static final int MAX_RECORDS = 4;
private final String creationRecord;
private final Deque<String> lastRecords = new ArrayDeque<String>();
private final AtomicBoolean freed;
private DefaultResourceLeak prev;
private DefaultResourceLeak next;
DefaultResourceLeak(Object referent) {
super(referent, referent != null? refQueue : null);
if (referent != null) {
Level level = getLevel();
if (level.ordinal() >= Level.ADVANCED.ordinal()) {
creationRecord = newRecord(3);
} else {
creationRecord = null;
}
// TODO: Use CAS to update the list.
synchronized (head) {
prev = head;
next = head.next;
head.next.prev = this;
head.next = this;
active ++;
}
freed = new AtomicBoolean();
} else {
creationRecord = null;
freed = new AtomicBoolean(true);
}
}
@Override
public void record() {
if (creationRecord != null) {
String value = newRecord(2);
synchronized (lastRecords) {
int size = lastRecords.size();
if (size == 0 || !lastRecords.getLast().equals(value)) {
lastRecords.add(value);
}
if (size > MAX_RECORDS) {
lastRecords.removeFirst();
}
}
}
}
@Override
public boolean close() {
if (freed.compareAndSet(false, true)) {
synchronized (head) {
active --;
prev.next = next;
next.prev = prev;
prev = null;
next = null;
}
return true;
}
return false;
}
@Override
public String toString() {
if (creationRecord == null) {
return "";
}
Object[] array;
synchronized (lastRecords) {
array = lastRecords.toArray();
}
StringBuilder buf = new StringBuilder(16384)
.append(NEWLINE)
.append("Recent access records: ")
.append(array.length)
.append(NEWLINE);
if (array.length > 0) {
for (int i = array.length - 1; i >= 0; i --) {
buf.append('#')
.append(i + 1)
.append(':')
.append(NEWLINE)
.append(array[i]);
}
}
buf.append("Created at:")
.append(NEWLINE)
.append(creationRecord);
buf.setLength(buf.length() - NEWLINE.length());
return buf.toString();
}
}
private static final String[] STACK_TRACE_ELEMENT_EXCLUSIONS = {
"io.netty.buffer.AbstractByteBufAllocator.toLeakAwareBuffer(",
};
static String newRecord(int recordsToSkip) {
StringBuilder buf = new StringBuilder(4096);
StackTraceElement[] array = new Throwable().getStackTrace();
for (StackTraceElement e: array) {
if (recordsToSkip > 0) {
recordsToSkip --;
} else {
String estr = e.toString();
// Strip the noisy stack trace elements.
boolean excluded = false;
for (String exclusion: STACK_TRACE_ELEMENT_EXCLUSIONS) {
if (estr.startsWith(exclusion)) {
excluded = true;
break;
}
}
if (!excluded) {
buf.append('\t');
buf.append(estr);
buf.append(NEWLINE);
}
}
}
return buf.toString();
}
}