/*
* 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.concurrent.ConcurrentMap;
import static io.netty.util.internal.StringUtil.EMPTY_STRING;
import static io.netty.util.internal.StringUtil.NEWLINE;
import static io.netty.util.internal.StringUtil.simpleClassName;
public class ResourceLeakDetector<T> {
private static final String PROP_LEVEL_OLD = "io.netty.leakDetectionLevel";
private static final String PROP_LEVEL = "io.netty.leakDetection.level";
private static final Level DEFAULT_LEVEL = Level.SIMPLE;
private static final String PROP_MAX_RECORDS = "io.netty.leakDetection.maxRecords";
private static final int DEFAULT_MAX_RECORDS = 4;
private static final int MAX_RECORDS;
/**
* 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;
/**
* Returns level based on string value. Accepts also string that represents ordinal number of enum.
*
* @param levelStr - level string : DISABLED, SIMPLE, ADVANCED, PARANOID. Ignores case.
* @return corresponding level or SIMPLE level in case of no match.
*/
static Level parseLevel(String levelStr) {
String trimmedLevelStr = levelStr.trim();
for (Level l : values()) {
if (trimmedLevelStr.equalsIgnoreCase(l.name()) || trimmedLevelStr.equals(String.valueOf(l.ordinal()))) {
return l;
}
}
return DEFAULT_LEVEL;
}
}
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;
// First read old property name
String levelStr = SystemPropertyUtil.get(PROP_LEVEL_OLD, defaultLevel.name());
// If new property name is present, use it
levelStr = SystemPropertyUtil.get(PROP_LEVEL, levelStr);
Level level = Level.parseLevel(levelStr);
MAX_RECORDS = SystemPropertyUtil.getInt(PROP_MAX_RECORDS, DEFAULT_MAX_RECORDS);
ResourceLeakDetector.level = level;
if (logger.isDebugEnabled()) {
logger.debug("-D{}: {}", PROP_LEVEL, level.name().toLowerCase());
logger.debug("-D{}: {}", PROP_MAX_RECORDS, MAX_RECORDS);
}
}
// Should be power of two.
static final int DEFAULT_SAMPLING_INTERVAL = 128;
/**
* @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 collection of active resources */
private final ConcurrentMap<DefaultResourceLeak, LeakEntry> allLeaks = PlatformDependent.newConcurrentHashMap();
private final ReferenceQueue<Object> refQueue = new ReferenceQueue<Object>();
private final ConcurrentMap<String, Boolean> reportedLeaks = PlatformDependent.newConcurrentHashMap();
private final String resourceType;
private final int samplingInterval;
/**
* @deprecated use {@link ResourceLeakDetectorFactory#newResourceLeakDetector(Class, int, long)}.
*/
@Deprecated
public ResourceLeakDetector(Class<?> resourceType) {
this(simpleClassName(resourceType));
}
/**
* @deprecated use {@link ResourceLeakDetectorFactory#newResourceLeakDetector(Class, int, long)}.
*/
@Deprecated
public ResourceLeakDetector(String resourceType) {
this(resourceType, DEFAULT_SAMPLING_INTERVAL, Long.MAX_VALUE);
}
/**
* @deprecated Use {@link ResourceLeakDetector#ResourceLeakDetector(Class, int)}.
* <p>
* This should not be used directly by users of {@link ResourceLeakDetector}.
* Please use {@link ResourceLeakDetectorFactory#newResourceLeakDetector(Class)}
* or {@link ResourceLeakDetectorFactory#newResourceLeakDetector(Class, int, long)}
*
* @param maxActive This is deprecated and will be ignored.
*/
@Deprecated
public ResourceLeakDetector(Class<?> resourceType, int samplingInterval, long maxActive) {
this(resourceType, samplingInterval);
}
/**
* This should not be used directly by users of {@link ResourceLeakDetector}.
* Please use {@link ResourceLeakDetectorFactory#newResourceLeakDetector(Class)}
* or {@link ResourceLeakDetectorFactory#newResourceLeakDetector(Class, int, long)}
*/
@SuppressWarnings("deprecation")
public ResourceLeakDetector(Class<?> resourceType, int samplingInterval) {
this(simpleClassName(resourceType), samplingInterval, Long.MAX_VALUE);
}
/**
* @deprecated use {@link ResourceLeakDetectorFactory#newResourceLeakDetector(Class, int, long)}.
* <p>
* @param maxActive This is deprecated and will be ignored.
*/
@Deprecated
public ResourceLeakDetector(String resourceType, int samplingInterval, long maxActive) {
if (resourceType == null) {
throw new NullPointerException("resourceType");
}
this.resourceType = resourceType;
this.samplingInterval = samplingInterval;
}
/**
* 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}
* @deprecated use {@link #track(Object)}
*/
@Deprecated
public final ResourceLeak open(T obj) {
return track0(obj);
}
/**
* Creates a new {@link ResourceLeakTracker} which is expected to be closed via
* {@link ResourceLeakTracker#close(Object)} when the related resource is deallocated.
*
* @return the {@link ResourceLeakTracker} or {@code null}
*/
public final ResourceLeakTracker<T> track(T obj) {
return track0(obj);
}
private DefaultResourceLeak track0(T obj) {
Level level = ResourceLeakDetector.level;
if (level == Level.DISABLED) {
return null;
}
if (level.ordinal() < Level.PARANOID.ordinal()) {
if ((PlatformDependent.threadLocalRandom().nextInt(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;
}
// 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()) {
reportUntracedLeak(resourceType);
} else {
reportTracedLeak(resourceType, records);
}
}
}
}
/**
* This method is called when a traced leak is detected. It can be overridden for tracking how many times leaks
* have been detected.
*/
protected void reportTracedLeak(String resourceType, String records) {
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);
}
/**
* This method is called when an untraced leak is detected. It can be overridden for tracking how many times leaks
* have been detected.
*/
protected void reportUntracedLeak(String resourceType) {
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));
}
/**
* @deprecated This method will no longer be invoked by {@link ResourceLeakDetector}.
*/
@Deprecated
protected void reportInstancesLeak(String resourceType) {
}
@SuppressWarnings("deprecation")
private final class DefaultResourceLeak extends PhantomReference<Object> implements ResourceLeakTracker<T>,
ResourceLeak {
private final String creationRecord;
private final Deque<String> lastRecords = new ArrayDeque<String>();
private final int trackedHash;
private int removedRecords;
DefaultResourceLeak(Object referent) {
super(referent, refQueue);
assert referent != null;
// Store the hash of the tracked object to later assert it in the close(...) method.
// It's important that we not store a reference to the referent as this would disallow it from
// be collected via the PhantomReference.
trackedHash = System.identityHashCode(referent);
Level level = getLevel();
if (level.ordinal() >= Level.ADVANCED.ordinal()) {
creationRecord = newRecord(null, 3);
} else {
creationRecord = null;
}
allLeaks.put(this, LeakEntry.INSTANCE);
}
@Override
public void record() {
record0(null, 3);
}
@Override
public void record(Object hint) {
record0(hint, 3);
}
private void record0(Object hint, int recordsToSkip) {
if (creationRecord != null) {
String value = newRecord(hint, recordsToSkip);
synchronized (lastRecords) {
int size = lastRecords.size();
if (size == 0 || !lastRecords.getLast().equals(value)) {
lastRecords.add(value);
}
if (size > MAX_RECORDS) {
lastRecords.removeFirst();
++removedRecords;
}
}
}
}
@Override
public boolean close() {
// Use the ConcurrentMap remove method, which avoids allocating an iterator.
return allLeaks.remove(this, LeakEntry.INSTANCE);
}
@Override
public boolean close(T trackedObject) {
// Ensure that the object that was tracked is the same as the one that was passed to close(...).
assert trackedHash == System.identityHashCode(trackedObject);
// We need to actually do the null check of the trackedObject after we close the leak because otherwise
// we may get false-positives reported by the ResourceLeakDetector. This can happen as the JIT / GC may
// be able to figure out that we do not need the trackedObject anymore and so already enqueue it for
// collection before we actually get a chance to close the enclosing ResourceLeak.
return close() && trackedObject != null;
}
@Override
public String toString() {
if (creationRecord == null) {
return EMPTY_STRING;
}
final Object[] array;
final int removedRecords;
synchronized (lastRecords) {
array = lastRecords.toArray();
removedRecords = this.removedRecords;
}
StringBuilder buf = new StringBuilder(16384).append(NEWLINE);
if (removedRecords > 0) {
buf.append("WARNING: ")
.append(removedRecords)
.append(" leak records were discarded because the leak record count is limited to ")
.append(MAX_RECORDS)
.append(". Use system property ")
.append(PROP_MAX_RECORDS)
.append(" to increase the limit.")
.append(NEWLINE);
}
buf.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.util.ReferenceCountUtil.touch(",
"io.netty.buffer.AdvancedLeakAwareByteBuf.touch(",
"io.netty.buffer.AbstractByteBufAllocator.toLeakAwareBuffer(",
"io.netty.buffer.AdvancedLeakAwareByteBuf.recordLeakNonRefCountingOperation("
};
static String newRecord(Object hint, int recordsToSkip) {
StringBuilder buf = new StringBuilder(4096);
// Append the hint first if available.
if (hint != null) {
buf.append("\tHint: ");
// Prefer a hint string to a simple string form.
if (hint instanceof ResourceLeakHint) {
buf.append(((ResourceLeakHint) hint).toHintString());
} else {
buf.append(hint);
}
buf.append(NEWLINE);
}
// Append the stack trace.
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();
}
private static final class LeakEntry {
static final LeakEntry INSTANCE = new LeakEntry();
private static final int HASH = System.identityHashCode(INSTANCE);
private LeakEntry() {
}
@Override
public int hashCode() {
return HASH;
}
@Override
public boolean equals(Object obj) {
return obj == this;
}
}
}