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Apache Commons Lang, a package of Java utility classes for the
classes that are in java.lang's hierarchy, or are considered to be so
standard as to justify existence in java.lang.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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 org.apache.commons.lang3;
import java.time.Duration;
import java.util.Collection;
import java.util.Collections;
import java.util.Objects;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.apache.commons.lang3.time.DurationUtils;
/**
* Helpers for {@code java.lang.Thread} and {@code java.lang.ThreadGroup}.
*
*
* #ThreadSafe#
*
*
* @see Thread
* @see ThreadGroup
* @since 3.5
*/
public class ThreadUtils {
/**
* A predicate implementation which always returns true.
*
* @deprecated Use a {@link Predicate}.
*/
@Deprecated
private static final class AlwaysTruePredicate implements ThreadPredicate, ThreadGroupPredicate {
private AlwaysTruePredicate() {
}
@Override
public boolean test(final Thread thread) {
return true;
}
@Override
public boolean test(final ThreadGroup threadGroup) {
return true;
}
}
/**
* Used internally, consider private.
*
* A predicate implementation which matches a thread or thread group name.
*
*
* @deprecated Use a {@link Predicate}.
*/
@Deprecated
public static class NamePredicate implements ThreadPredicate, ThreadGroupPredicate {
private final String name;
/**
* Constructs an instance.
*
* @param name thread or thread group name
* @throws NullPointerException if the name is {@code null}
*/
public NamePredicate(final String name) {
Objects.requireNonNull(name, "name");
this.name = name;
}
@Override
public boolean test(final Thread thread) {
return thread != null && thread.getName().equals(name);
}
@Override
public boolean test(final ThreadGroup threadGroup) {
return threadGroup != null && threadGroup.getName().equals(name);
}
}
/**
* A predicate for selecting thread groups.
*
* @deprecated Use a {@link Predicate}.
*/
@Deprecated
// When breaking BC, replace this with Predicate
@FunctionalInterface
public interface ThreadGroupPredicate {
/**
* Evaluates this predicate on the given thread group.
* @param threadGroup the thread group
* @return {@code true} if the threadGroup matches the predicate, otherwise {@code false}
*/
boolean test(ThreadGroup threadGroup);
}
/**
* A predicate implementation which matches a thread id.
*
* @deprecated Use a {@link Predicate}.
*/
@Deprecated
public static class ThreadIdPredicate implements ThreadPredicate {
private final long threadId;
/**
* Predicate constructor
*
* @param threadId the threadId to match
* @throws IllegalArgumentException if the threadId is zero or negative
*/
public ThreadIdPredicate(final long threadId) {
if (threadId <= 0) {
throw new IllegalArgumentException("The thread id must be greater than zero");
}
this.threadId = threadId;
}
@Override
public boolean test(final Thread thread) {
return thread != null && thread.getId() == threadId;
}
}
/**
* A predicate for selecting threads.
*
* @deprecated Use a {@link Predicate}.
*/
@Deprecated
// When breaking BC, replace this with Predicate
@FunctionalInterface
public interface ThreadPredicate {
/**
* Evaluates this predicate on the given thread.
* @param thread the thread
* @return {@code true} if the thread matches the predicate, otherwise {@code false}
*/
boolean test(Thread thread);
}
/**
* Predicate which always returns true.
*
* @deprecated Use a {@link Predicate}.
*/
@Deprecated
public static final AlwaysTruePredicate ALWAYS_TRUE_PREDICATE = new AlwaysTruePredicate();
private static final Predicate ALWAYS_TRUE = t -> true;
@SuppressWarnings("unchecked")
private static Predicate alwaysTruePredicate() {
return (Predicate) ALWAYS_TRUE;
}
/**
* Finds the active thread with the specified id.
*
* @param threadId The thread id
* @return The thread with the specified id or {@code null} if no such thread exists
* @throws IllegalArgumentException if the specified id is zero or negative
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Thread findThreadById(final long threadId) {
if (threadId <= 0) {
throw new IllegalArgumentException("The thread id must be greater than zero");
}
final Collection result = findThreads((Predicate) t -> t != null && t.getId() == threadId);
return result.isEmpty() ? null : result.iterator().next();
}
/**
* Finds the active thread with the specified id if it belongs to a thread group with the specified group name.
*
* @param threadId The thread id
* @param threadGroupName The thread group name
* @return The threads which belongs to a thread group with the specified group name and the thread's id match the specified id.
* {@code null} is returned if no such thread exists
* @throws NullPointerException if the group name is null
* @throws IllegalArgumentException if the specified id is zero or negative
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Thread findThreadById(final long threadId, final String threadGroupName) {
Objects.requireNonNull(threadGroupName, "threadGroupName");
final Thread thread = findThreadById(threadId);
if (thread != null && thread.getThreadGroup() != null && thread.getThreadGroup().getName().equals(threadGroupName)) {
return thread;
}
return null;
}
/**
* Finds the active thread with the specified id if it belongs to the specified thread group.
*
* @param threadId The thread id
* @param threadGroup The thread group
* @return The thread which belongs to a specified thread group and the thread's id match the specified id.
* {@code null} is returned if no such thread exists
* @throws NullPointerException if {@code threadGroup == null}
* @throws IllegalArgumentException if the specified id is zero or negative
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Thread findThreadById(final long threadId, final ThreadGroup threadGroup) {
Objects.requireNonNull(threadGroup, "threadGroup");
final Thread thread = findThreadById(threadId);
if (thread != null && threadGroup.equals(thread.getThreadGroup())) {
return thread;
}
return null;
}
/**
* Finds all active thread groups which match the given predicate.
*
* @param predicate the predicate
* @return An unmodifiable {@link Collection} of active thread groups matching the given predicate
* @throws NullPointerException if the predicate is null
* @throws SecurityException
* if the current thread cannot access the system thread group
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
* @since 3.13.0
*/
public static Collection findThreadGroups(final Predicate predicate) {
return findThreadGroups(getSystemThreadGroup(), true, predicate);
}
/**
* Finds all active thread groups which match the given predicate and which is a subgroup of the given thread group (or one of its subgroups).
*
* @param threadGroup the thread group
* @param recurse if {@code true} then evaluate the predicate recursively on all thread groups in all subgroups of the given group
* @param predicate the predicate
* @return An unmodifiable {@link Collection} of active thread groups which match the given predicate and which is a subgroup of the given thread group
* @throws NullPointerException if the given group or predicate is null
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
* @since 3.13.0
*/
public static Collection findThreadGroups(final ThreadGroup threadGroup, final boolean recurse, final Predicate predicate) {
Objects.requireNonNull(threadGroup, "threadGroup");
Objects.requireNonNull(predicate, "predicate");
int count = threadGroup.activeGroupCount();
ThreadGroup[] threadGroups;
do {
threadGroups = new ThreadGroup[count + count / 2 + 1]; //slightly grow the array size
count = threadGroup.enumerate(threadGroups, recurse);
//return value of enumerate() must be strictly less than the array size according to Javadoc
} while (count >= threadGroups.length);
return Collections.unmodifiableCollection(Stream.of(threadGroups).limit(count).filter(predicate).collect(Collectors.toList()));
}
/**
* Finds all active thread groups which match the given predicate and which is a subgroup of the given thread group (or one of its subgroups).
*
* @param threadGroup the thread group
* @param recurse if {@code true} then evaluate the predicate recursively on all thread groups in all subgroups of the given group
* @param predicate the predicate
* @return An unmodifiable {@link Collection} of active thread groups which match the given predicate and which is a subgroup of the given thread group
* @throws NullPointerException if the given group or predicate is null
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
* @deprecated Use {@link #findThreadGroups(ThreadGroup, boolean, Predicate)}.
*/
@Deprecated
public static Collection findThreadGroups(final ThreadGroup threadGroup, final boolean recurse, final ThreadGroupPredicate predicate) {
return findThreadGroups(threadGroup, recurse, (Predicate) predicate::test);
}
/**
* Finds all active thread groups which match the given predicate.
*
* @param predicate the predicate
* @return An unmodifiable {@link Collection} of active thread groups matching the given predicate
* @throws NullPointerException if the predicate is null
* @throws SecurityException
* if the current thread cannot access the system thread group
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
* @deprecated Use {@link #findThreadGroups(Predicate)}.
*/
@Deprecated
public static Collection findThreadGroups(final ThreadGroupPredicate predicate) {
return findThreadGroups(getSystemThreadGroup(), true, predicate);
}
/**
* Finds active thread groups with the specified group name.
*
* @param threadGroupName The thread group name
* @return the thread groups with the specified group name or an empty collection if no such thread group exists. The collection returned is always unmodifiable.
* @throws NullPointerException if group name is null
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Collection findThreadGroupsByName(final String threadGroupName) {
return findThreadGroups(predicateThreadGroup(threadGroupName));
}
/**
* Finds all active threads which match the given predicate.
*
* @param predicate the predicate
* @return An unmodifiable {@link Collection} of active threads matching the given predicate
*
* @throws NullPointerException if the predicate is null
* @throws SecurityException
* if the current thread cannot access the system thread group
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
* @since 3.13.0
*/
public static Collection findThreads(final Predicate predicate) {
return findThreads(getSystemThreadGroup(), true, predicate);
}
/**
* Finds all active threads which match the given predicate and which belongs to the given thread group (or one of its subgroups).
*
* @param threadGroup the thread group
* @param recurse if {@code true} then evaluate the predicate recursively on all threads in all subgroups of the given group
* @param predicate the predicate
* @return An unmodifiable {@link Collection} of active threads which match the given predicate and which belongs to the given thread group
* @throws NullPointerException if the given group or predicate is null
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
* @since 3.13.0
*/
public static Collection findThreads(final ThreadGroup threadGroup, final boolean recurse, final Predicate predicate) {
Objects.requireNonNull(threadGroup, "The group must not be null");
Objects.requireNonNull(predicate, "The predicate must not be null");
int count = threadGroup.activeCount();
Thread[] threads;
do {
threads = new Thread[count + count / 2 + 1]; //slightly grow the array size
count = threadGroup.enumerate(threads, recurse);
//return value of enumerate() must be strictly less than the array size according to javadoc
} while (count >= threads.length);
return Collections.unmodifiableCollection(Stream.of(threads).limit(count).filter(predicate).collect(Collectors.toList()));
}
/**
* Finds all active threads which match the given predicate and which belongs to the given thread group (or one of its subgroups).
*
* @param threadGroup the thread group
* @param recurse if {@code true} then evaluate the predicate recursively on all threads in all subgroups of the given group
* @param predicate the predicate
* @return An unmodifiable {@link Collection} of active threads which match the given predicate and which belongs to the given thread group
* @throws NullPointerException if the given group or predicate is null
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
* @deprecated Use {@link #findThreads(ThreadGroup, boolean, Predicate)}.
*/
@Deprecated
public static Collection findThreads(final ThreadGroup threadGroup, final boolean recurse, final ThreadPredicate predicate) {
return findThreads(threadGroup, recurse, (Predicate) predicate::test);
}
/**
* Finds all active threads which match the given predicate.
*
* @param predicate the predicate
* @return An unmodifiable {@link Collection} of active threads matching the given predicate
*
* @throws NullPointerException if the predicate is null
* @throws SecurityException
* if the current thread cannot access the system thread group
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
* @deprecated Use {@link #findThreads(Predicate)}.
*/
@Deprecated
public static Collection findThreads(final ThreadPredicate predicate) {
return findThreads(getSystemThreadGroup(), true, predicate);
}
/**
* Finds active threads with the specified name.
*
* @param threadName The thread name
* @return The threads with the specified name or an empty collection if no such thread exists. The collection returned is always unmodifiable.
* @throws NullPointerException if the specified name is null
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Collection findThreadsByName(final String threadName) {
return findThreads(predicateThread(threadName));
}
/**
* Finds active threads with the specified name if they belong to a thread group with the specified group name.
*
* @param threadName The thread name
* @param threadGroupName The thread group name
* @return The threads which belongs to a thread group with the specified group name and the thread's name match the specified name,
* An empty collection is returned if no such thread exists. The collection returned is always unmodifiable.
* @throws NullPointerException if the specified thread name or group name is null
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Collection findThreadsByName(final String threadName, final String threadGroupName) {
Objects.requireNonNull(threadName, "threadName");
Objects.requireNonNull(threadGroupName, "threadGroupName");
return Collections.unmodifiableCollection(findThreadGroups(predicateThreadGroup(threadGroupName)).stream()
.flatMap(group -> findThreads(group, false, predicateThread(threadName)).stream()).collect(Collectors.toList()));
}
/**
* Finds active threads with the specified name if they belong to a specified thread group.
*
* @param threadName The thread name
* @param threadGroup The thread group
* @return The threads which belongs to a thread group and the thread's name match the specified name,
* An empty collection is returned if no such thread exists. The collection returned is always unmodifiable.
* @throws NullPointerException if the specified thread name or group is null
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Collection findThreadsByName(final String threadName, final ThreadGroup threadGroup) {
return findThreads(threadGroup, false, predicateThread(threadName));
}
/**
* Gets all active thread groups excluding the system thread group (A thread group is active if it has been not destroyed).
*
* @return all thread groups excluding the system thread group. The collection returned is always unmodifiable.
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Collection getAllThreadGroups() {
return findThreadGroups(alwaysTruePredicate());
}
/**
* Gets all active threads (A thread is active if it has been started and has not yet died).
*
* @return all active threads. The collection returned is always unmodifiable.
* @throws SecurityException
* if the current thread cannot access the system thread group
*
* @throws SecurityException if the current thread cannot modify
* thread groups from this thread's thread group up to the system thread group
*/
public static Collection getAllThreads() {
return findThreads(alwaysTruePredicate());
}
/**
* Gets the system thread group (sometimes also referred as "root thread group").
*
* This method returns null if this thread has died (been stopped).
*
*
* @return the system thread group
* @throws SecurityException if the current thread cannot modify thread groups from this thread's thread group up to the
* system thread group
*/
public static ThreadGroup getSystemThreadGroup() {
ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
while (threadGroup != null && threadGroup.getParent() != null) {
threadGroup = threadGroup.getParent();
}
return threadGroup;
}
/**
* Waits for the given thread to die for the given duration. Implemented using {@link Thread#join(long, int)}.
*
* @param thread The thread to join.
* @param duration How long to wait.
* @throws InterruptedException if any thread has interrupted the current thread.
* @see Thread#join(long, int)
* @since 3.12.0
*/
public static void join(final Thread thread, final Duration duration) throws InterruptedException {
DurationUtils.accept(thread::join, duration);
}
private static Predicate namePredicate(final String name, final Function nameGetter) {
return (Predicate) t -> t != null && Objects.equals(nameGetter.apply(t), Objects.requireNonNull(name));
}
private static Predicate predicateThread(final String threadName) {
return namePredicate(threadName, Thread::getName);
}
private static Predicate predicateThreadGroup(final String threadGroupName) {
return namePredicate(threadGroupName, ThreadGroup::getName);
}
/**
* Sleeps the current thread for the given duration. Implemented using {@link Thread#sleep(long, int)}.
*
* @param duration How long to sleep.
* @throws InterruptedException if any thread has interrupted the current thread.
* @see Thread#sleep(long, int)
* @since 3.12.0
*/
public static void sleep(final Duration duration) throws InterruptedException {
DurationUtils.accept(Thread::sleep, duration);
}
/**
* Sleeps for the given duration while ignoring {@link InterruptedException}.
*
* The sleep duration may be shorter than duration if we catch a {@link InterruptedException}.
*
*
* @param duration the length of time to sleep.
* @since 3.13.0
*/
public static void sleepQuietly(final Duration duration) {
try {
sleep(duration);
} catch (final InterruptedException e) {
// be quiet.
}
}
/**
* ThreadUtils instances should NOT be constructed in standard programming. Instead, the class should be used as
* {@code ThreadUtils.getAllThreads()}
*
*
* This constructor is public to permit tools that require a JavaBean instance to operate.
*
*/
public ThreadUtils() {
}
}