Port ConcurrentHashMapV8 again to get the recent upstream fixes

This commit is contained in:
Trustin Lee 2013-07-07 12:22:59 +09:00
parent da5a5af520
commit 378626b31f
7 changed files with 5040 additions and 5736 deletions

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@ -22,20 +22,23 @@
package io.netty.util.internal.chmv8;
import java.util.concurrent.RecursiveAction;
/**
* A {@link ForkJoinTask} with a completion action performed when
* triggered and there are no remaining pending
* actions. CountedCompleters are in general more robust in the
* triggered and there are no remaining pending actions.
* CountedCompleters are in general more robust in the
* presence of subtask stalls and blockage than are other forms of
* ForkJoinTasks, but are less intuitive to program. Uses of
* CountedCompleter are similar to those of other completion based
* components (such as {@link java.nio.channels.CompletionHandler})
* except that multiple <em>pending</em> completions may be necessary
* to trigger the {@link #onCompletion} action, not just one. Unless
* initialized otherwise, the {@link #getPendingCount pending count}
* starts at zero, but may be (atomically) changed using methods
* {@link #setPendingCount}, {@link #addToPendingCount}, and {@link
* #compareAndSetPendingCount}. Upon invocation of {@link
* to trigger the completion action {@link #onCompletion(CountedCompleter)},
* not just one.
* Unless initialized otherwise, the {@linkplain #getPendingCount pending
* count} starts at zero, but may be (atomically) changed using
* methods {@link #setPendingCount}, {@link #addToPendingCount}, and
* {@link #compareAndSetPendingCount}. Upon invocation of {@link
* #tryComplete}, if the pending action count is nonzero, it is
* decremented; otherwise, the completion action is performed, and if
* this completer itself has a completer, the process is continued
@ -56,9 +59,10 @@ package io.netty.util.internal.chmv8;
* <p>A concrete CountedCompleter class must define method {@link
* #compute}, that should in most cases (as illustrated below), invoke
* {@code tryComplete()} once before returning. The class may also
* optionally override method {@link #onCompletion} to perform an
* action upon normal completion, and method {@link
* #onExceptionalCompletion} to perform an action upon any exception.
* optionally override method {@link #onCompletion(CountedCompleter)}
* to perform an action upon normal completion, and method
* {@link #onExceptionalCompletion(Throwable, CountedCompleter)} to
* perform an action upon any exception.
*
* <p>CountedCompleters most often do not bear results, in which case
* they are normally declared as {@code CountedCompleter<Void>}, and
@ -79,13 +83,14 @@ package io.netty.util.internal.chmv8;
* only as an internal helper for other computations, so its own task
* status (as reported in methods such as {@link ForkJoinTask#isDone})
* is arbitrary; this status changes only upon explicit invocations of
* {@link #complete}, {@link ForkJoinTask#cancel}, {@link
* ForkJoinTask#completeExceptionally} or upon exceptional completion
* of method {@code compute}. Upon any exceptional completion, the
* exception may be relayed to a task's completer (and its completer,
* and so on), if one exists and it has not otherwise already
* completed. Similarly, cancelling an internal CountedCompleter has
* only a local effect on that completer, so is not often useful.
* {@link #complete}, {@link ForkJoinTask#cancel},
* {@link ForkJoinTask#completeExceptionally(Throwable)} or upon
* exceptional completion of method {@code compute}. Upon any
* exceptional completion, the exception may be relayed to a task's
* completer (and its completer, and so on), if one exists and it has
* not otherwise already completed. Similarly, cancelling an internal
* CountedCompleter has only a local effect on that completer, so is
* not often useful.
*
* <p><b>Sample Usages.</b>
*
@ -112,8 +117,8 @@ package io.netty.util.internal.chmv8;
* improve load balancing. In the recursive case, the second of each
* pair of subtasks to finish triggers completion of its parent
* (because no result combination is performed, the default no-op
* implementation of method {@code onCompletion} is not overridden). A
* static utility method sets up the base task and invokes it
* implementation of method {@code onCompletion} is not overridden).
* A static utility method sets up the base task and invokes it
* (here, implicitly using the {@link ForkJoinPool#commonPool()}).
*
* <pre> {@code
@ -168,12 +173,11 @@ package io.netty.util.internal.chmv8;
* }
* }</pre>
*
* As a further improvement, notice that the left task need not even
* exist. Instead of creating a new one, we can iterate using the
* original task, and add a pending count for each fork. Additionally,
* because no task in this tree implements an {@link #onCompletion}
* method, {@code tryComplete()} can be replaced with {@link
* #propagateCompletion}.
* As a further improvement, notice that the left task need not even exist.
* Instead of creating a new one, we can iterate using the original task,
* and add a pending count for each fork. Additionally, because no task
* in this tree implements an {@link #onCompletion(CountedCompleter)} method,
* {@code tryComplete()} can be replaced with {@link #propagateCompletion}.
*
* <pre> {@code
* class ForEach<E> ...
@ -251,7 +255,7 @@ package io.netty.util.internal.chmv8;
*
* <p><b>Recording subtasks.</b> CountedCompleter tasks that combine
* results of multiple subtasks usually need to access these results
* in method {@link #onCompletion}. As illustrated in the following
* in method {@link #onCompletion(CountedCompleter)}. As illustrated in the following
* class (that performs a simplified form of map-reduce where mappings
* and reductions are all of type {@code E}), one way to do this in
* divide and conquer designs is to have each subtask record its
@ -352,7 +356,7 @@ package io.netty.util.internal.chmv8;
* while (h - l >= 2) {
* int mid = (l + h) >>> 1;
* addToPendingCount(1);
* (forks = new MapReducer(this, array, mapper, reducer, mid, h, forks)).fork;
* (forks = new MapReducer(this, array, mapper, reducer, mid, h, forks)).fork();
* h = mid;
* }
* if (h > l)
@ -373,7 +377,7 @@ package io.netty.util.internal.chmv8;
*
* <p><b>Triggers.</b> Some CountedCompleters are themselves never
* forked, but instead serve as bits of plumbing in other designs;
* including those in which the completion of one of more async tasks
* including those in which the completion of one or more async tasks
* triggers another async task. For example:
*
* <pre> {@code
@ -394,7 +398,7 @@ package io.netty.util.internal.chmv8;
* @author Doug Lea
*/
@SuppressWarnings("all")
abstract class CountedCompleter<T> extends ForkJoinTask<T> {
public abstract class CountedCompleter<T> extends ForkJoinTask<T> {
private static final long serialVersionUID = 5232453752276485070L;
/** This task's completer, or null if none */
@ -454,20 +458,21 @@ abstract class CountedCompleter<T> extends ForkJoinTask<T> {
}
/**
* Performs an action when method {@link #completeExceptionally}
* is invoked or method {@link #compute} throws an exception, and
* this task has not otherwise already completed normally. On
* entry to this method, this task {@link
* ForkJoinTask#isCompletedAbnormally}. The return value of this
* method controls further propagation: If {@code true} and this
* task has a completer, then this completer is also completed
* exceptionally. The default implementation of this method does
* nothing except return {@code true}.
* Performs an action when method {@link
* #completeExceptionally(Throwable)} is invoked or method {@link
* #compute} throws an exception, and this task has not already
* otherwise completed normally. On entry to this method, this task
* {@link ForkJoinTask#isCompletedAbnormally}. The return value
* of this method controls further propagation: If {@code true}
* and this task has a completer that has not completed, then that
* completer is also completed exceptionally, with the same
* exception as this completer. The default implementation of
* this method does nothing except return {@code true}.
*
* @param ex the exception
* @param caller the task invoking this method (which may
* be this task itself)
* @return true if this exception should be propagated to this
* @return {@code true} if this exception should be propagated to this
* task's completer, if one exists
*/
public boolean onExceptionalCompletion(Throwable ex, CountedCompleter<?> caller) {
@ -508,7 +513,7 @@ abstract class CountedCompleter<T> extends ForkJoinTask<T> {
* @param delta the value to add
*/
public final void addToPendingCount(int delta) {
int c; // note: can replace with intrinsic in jdk8
int c;
do {} while (!U.compareAndSwapInt(this, PENDING, c = pending, c+delta));
}
@ -518,7 +523,7 @@ abstract class CountedCompleter<T> extends ForkJoinTask<T> {
*
* @param expected the expected value
* @param count the new value
* @return true if successful
* @return {@code true} if successful
*/
public final boolean compareAndSetPendingCount(int expected, int count) {
return U.compareAndSwapInt(this, PENDING, expected, count);
@ -552,9 +557,9 @@ abstract class CountedCompleter<T> extends ForkJoinTask<T> {
/**
* If the pending count is nonzero, decrements the count;
* otherwise invokes {@link #onCompletion} and then similarly
* tries to complete this task's completer, if one exists,
* else marks this task as complete.
* otherwise invokes {@link #onCompletion(CountedCompleter)}
* and then similarly tries to complete this task's completer,
* if one exists, else marks this task as complete.
*/
public final void tryComplete() {
CountedCompleter<?> a = this, s = a;
@ -573,12 +578,12 @@ abstract class CountedCompleter<T> extends ForkJoinTask<T> {
/**
* Equivalent to {@link #tryComplete} but does not invoke {@link
* #onCompletion} along the completion path: If the pending count
* is nonzero, decrements the count; otherwise, similarly tries to
* complete this task's completer, if one exists, else marks this
* task as complete. This method may be useful in cases where
* {@code onCompletion} should not, or need not, be invoked for
* each completer in a computation.
* #onCompletion(CountedCompleter)} along the completion path:
* If the pending count is nonzero, decrements the count;
* otherwise, similarly tries to complete this task's completer, if
* one exists, else marks this task as complete. This method may be
* useful in cases where {@code onCompletion} should not, or need
* not, be invoked for each completer in a computation.
*/
public final void propagateCompletion() {
CountedCompleter<?> a = this, s = a;
@ -595,13 +600,15 @@ abstract class CountedCompleter<T> extends ForkJoinTask<T> {
}
/**
* Regardless of pending count, invokes {@link #onCompletion},
* marks this task as complete and further triggers {@link
* #tryComplete} on this task's completer, if one exists. The
* given rawResult is used as an argument to {@link #setRawResult}
* before invoking {@link #onCompletion} or marking this task as
* complete; its value is meaningful only for classes overriding
* {@code setRawResult}.
* Regardless of pending count, invokes
* {@link #onCompletion(CountedCompleter)}, marks this task as
* complete and further triggers {@link #tryComplete} on this
* task's completer, if one exists. The given rawResult is
* used as an argument to {@link #setRawResult} before invoking
* {@link #onCompletion(CountedCompleter)} or marking this task
* as complete; its value is meaningful only for classes
* overriding {@code setRawResult}. This method does not modify
* the pending count.
*
* <p>This method may be useful when forcing completion as soon as
* any one (versus all) of several subtask results are obtained.
@ -641,8 +648,8 @@ abstract class CountedCompleter<T> extends ForkJoinTask<T> {
/**
* If this task does not have a completer, invokes {@link
* ForkJoinTask#quietlyComplete} and returns {@code null}. Or, if
* this task's pending count is non-zero, decrements its pending
* count and returns {@code null}. Otherwise, returns the
* the completer's pending count is non-zero, decrements that
* pending count and returns {@code null}. Otherwise, returns the
* completer. This method can be used as part of a completion
* traversal loop for homogeneous task hierarchies:
*
@ -684,8 +691,9 @@ abstract class CountedCompleter<T> extends ForkJoinTask<T> {
void internalPropagateException(Throwable ex) {
CountedCompleter<?> a = this, s = a;
while (a.onExceptionalCompletion(ex, s) &&
(a = (s = a).completer) != null && a.status >= 0)
a.recordExceptionalCompletion(ex);
(a = (s = a).completer) != null && a.status >= 0 &&
a.recordExceptionalCompletion(ex) == EXCEPTIONAL)
;
}
/**

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@ -33,6 +33,10 @@ import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.Phaser;
import java.util.concurrent.RecursiveAction;
import java.util.concurrent.RecursiveTask;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.RunnableFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
@ -53,12 +57,12 @@ import java.util.concurrent.locks.ReentrantLock;
* subtasks. As indicated by the name of this class, many programs
* using {@code ForkJoinTask} employ only methods {@link #fork} and
* {@link #join}, or derivatives such as {@link
* #invokeAll(io.netty.util.internal.chmv8.ForkJoinTask...) invokeAll}. However, this class also
* #invokeAll(ForkJoinTask...) invokeAll}. However, this class also
* provides a number of other methods that can come into play in
* advanced usages, as well as extension mechanics that allow support
* of new forms of fork/join processing.
*
* <p>A {@code ForkJoinTask} is a lightweight form of {@link java.util.concurrent.Future}.
* <p>A {@code ForkJoinTask} is a lightweight form of {@link Future}.
* The efficiency of {@code ForkJoinTask}s stems from a set of
* restrictions (that are only partially statically enforceable)
* reflecting their main use as computational tasks calculating pure
@ -77,7 +81,7 @@ import java.util.concurrent.locks.ReentrantLock;
* thrown. However, computations may still encounter unchecked
* exceptions, that are rethrown to callers attempting to join
* them. These exceptions may additionally include {@link
* java.util.concurrent.RejectedExecutionException} stemming from internal resource
* RejectedExecutionException} stemming from internal resource
* exhaustion, such as failure to allocate internal task
* queues. Rethrown exceptions behave in the same way as regular
* exceptions, but, when possible, contain stack traces (as displayed
@ -101,7 +105,7 @@ import java.util.concurrent.locks.ReentrantLock;
*
* <p>The primary method for awaiting completion and extracting
* results of a task is {@link #join}, but there are several variants:
* The {@link java.util.concurrent.Future#get} methods support interruptible and/or timed
* The {@link Future#get} methods support interruptible and/or timed
* waits for completion and report results using {@code Future}
* conventions. Method {@link #invoke} is semantically
* equivalent to {@code fork(); join()} but always attempts to begin
@ -149,10 +153,9 @@ import java.util.concurrent.locks.ReentrantLock;
* (DAG). Otherwise, executions may encounter a form of deadlock as
* tasks cyclically wait for each other. However, this framework
* supports other methods and techniques (for example the use of
* {@link java.util.concurrent.Phaser}, {@link #helpQuiesce}, and
* {@link #complete}) that
* {@link Phaser}, {@link #helpQuiesce}, and {@link #complete}) that
* may be of use in constructing custom subclasses for problems that
* are not statically structured as DAGs. To support such usages a
* are not statically structured as DAGs. To support such usages, a
* ForkJoinTask may be atomically <em>tagged</em> with a {@code short}
* value using {@link #setForkJoinTaskTag} or {@link
* #compareAndSetForkJoinTaskTag} and checked using {@link
@ -184,7 +187,7 @@ import java.util.concurrent.locks.ReentrantLock;
* overwhelm processing.
*
* <p>This class provides {@code adapt} methods for {@link Runnable}
* and {@link java.util.concurrent.Callable}, that may be of use when mixing execution of
* and {@link Callable}, that may be of use when mixing execution of
* {@code ForkJoinTasks} with other kinds of tasks. When all tasks are
* of this form, consider using a pool constructed in <em>asyncMode</em>.
*
@ -197,7 +200,7 @@ import java.util.concurrent.locks.ReentrantLock;
* @author Doug Lea
*/
@SuppressWarnings("all")
abstract class ForkJoinTask<V> implements Future<V>, Serializable {
public abstract class ForkJoinTask<V> implements Future<V>, Serializable {
/*
* See the internal documentation of class ForkJoinPool for a
@ -302,9 +305,17 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
*/
private int externalAwaitDone() {
int s;
ForkJoinPool.externalHelpJoin(this);
ForkJoinPool cp = ForkJoinPool.common;
if ((s = status) >= 0) {
if (cp != null) {
if (this instanceof CountedCompleter)
s = cp.externalHelpComplete((CountedCompleter<?>)this);
else if (cp.tryExternalUnpush(this))
s = doExec();
}
if (s >= 0 && (s = status) >= 0) {
boolean interrupted = false;
while ((s = status) >= 0) {
do {
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
synchronized (this) {
if (status >= 0) {
@ -318,9 +329,11 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
notifyAll();
}
}
}
} while ((s = status) >= 0);
if (interrupted)
Thread.currentThread().interrupt();
}
}
return s;
}
@ -329,9 +342,15 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
*/
private int externalInterruptibleAwaitDone() throws InterruptedException {
int s;
ForkJoinPool cp = ForkJoinPool.common;
if (Thread.interrupted())
throw new InterruptedException();
ForkJoinPool.externalHelpJoin(this);
if ((s = status) >= 0 && cp != null) {
if (this instanceof CountedCompleter)
cp.externalHelpComplete((CountedCompleter<?>)this);
else if (cp.tryExternalUnpush(this))
doExec();
}
while ((s = status) >= 0) {
if (U.compareAndSwapInt(this, STATUS, s, s | SIGNAL)) {
synchronized (this) {
@ -617,15 +636,10 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
/**
* A version of "sneaky throw" to relay exceptions
*/
static void rethrow(final Throwable ex) {
if (ex != null) {
if (ex instanceof Error)
throw (Error)ex;
if (ex instanceof RuntimeException)
throw (RuntimeException)ex;
static void rethrow(Throwable ex) {
if (ex != null)
ForkJoinTask.<RuntimeException>uncheckedThrow(ex);
}
}
/**
* The sneaky part of sneaky throw, relying on generics
@ -634,7 +648,6 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
*/
@SuppressWarnings("unchecked") static <T extends Throwable>
void uncheckedThrow(Throwable t) throws T {
if (t != null)
throw (T)t; // rely on vacuous cast
}
@ -846,7 +859,7 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
* <p>This method is designed to be invoked by <em>other</em>
* tasks. To terminate the current task, you can just return or
* throw an unchecked exception from its computation method, or
* invoke {@link #completeExceptionally}.
* invoke {@link #completeExceptionally(Throwable)}.
*
* @param mayInterruptIfRunning this value has no effect in the
* default implementation because interrupts are not used to
@ -960,8 +973,8 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
* retrieves its result.
*
* @return the computed result
* @throws java.util.concurrent.CancellationException if the computation was cancelled
* @throws java.util.concurrent.ExecutionException if the computation threw an
* @throws CancellationException if the computation was cancelled
* @throws ExecutionException if the computation threw an
* exception
* @throws InterruptedException if the current thread is not a
* member of a ForkJoinPool and was interrupted while waiting
@ -984,12 +997,12 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
* @param timeout the maximum time to wait
* @param unit the time unit of the timeout argument
* @return the computed result
* @throws java.util.concurrent.CancellationException if the computation was cancelled
* @throws java.util.concurrent.ExecutionException if the computation threw an
* @throws CancellationException if the computation was cancelled
* @throws ExecutionException if the computation threw an
* exception
* @throws InterruptedException if the current thread is not a
* member of a ForkJoinPool and was interrupted while waiting
* @throws java.util.concurrent.TimeoutException if the wait timed out
* @throws TimeoutException if the wait timed out
*/
public final V get(long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException {
@ -998,6 +1011,7 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
// Messy in part because we measure in nanosecs, but wait in millisecs
int s; long ms;
long ns = unit.toNanos(timeout);
ForkJoinPool cp;
if ((s = status) >= 0 && ns > 0L) {
long deadline = System.nanoTime() + ns;
ForkJoinPool p = null;
@ -1009,8 +1023,12 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
w = wt.workQueue;
p.helpJoinOnce(w, this); // no retries on failure
}
else
ForkJoinPool.externalHelpJoin(this);
else if ((cp = ForkJoinPool.common) != null) {
if (this instanceof CountedCompleter)
cp.externalHelpComplete((CountedCompleter<?>)this);
else if (cp.tryExternalUnpush(this))
doExec();
}
boolean canBlock = false;
boolean interrupted = false;
try {
@ -1018,7 +1036,7 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
if (w != null && w.qlock < 0)
cancelIgnoringExceptions(this);
else if (!canBlock) {
if (p == null || p.tryCompensate())
if (p == null || p.tryCompensate(p.ctl))
canBlock = true;
}
else {
@ -1159,7 +1177,7 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
Thread t;
return (((t = Thread.currentThread()) instanceof ForkJoinWorkerThread) ?
((ForkJoinWorkerThread)t).workQueue.tryUnpush(this) :
ForkJoinPool.tryExternalUnpush(this));
ForkJoinPool.common.tryExternalUnpush(this));
}
/**
@ -1328,7 +1346,7 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
*
* @param e the expected tag value
* @param tag the new tag value
* @return true if successful; i.e., the current value was
* @return {@code true} if successful; i.e., the current value was
* equal to e and is now tag.
* @since 1.8
*/
@ -1380,6 +1398,24 @@ abstract class ForkJoinTask<V> implements Future<V>, Serializable {
private static final long serialVersionUID = 5232453952276885070L;
}
/**
* Adaptor for Runnables in which failure forces worker exception
*/
static final class RunnableExecuteAction extends ForkJoinTask<Void> {
final Runnable runnable;
RunnableExecuteAction(Runnable runnable) {
if (runnable == null) throw new NullPointerException();
this.runnable = runnable;
}
public final Void getRawResult() { return null; }
public final void setRawResult(Void v) { }
public final boolean exec() { runnable.run(); return true; }
void internalPropagateException(Throwable ex) {
rethrow(ex); // rethrow outside exec() catches.
}
private static final long serialVersionUID = 5232453952276885070L;
}
/**
* Adaptor for Callables
*/

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@ -22,6 +22,7 @@
package io.netty.util.internal.chmv8;
/**
* A thread managed by a {@link ForkJoinPool}, which executes
* {@link ForkJoinTask}s.
@ -30,14 +31,14 @@ package io.netty.util.internal.chmv8;
* scheduling or execution. However, you can override initialization
* and termination methods surrounding the main task processing loop.
* If you do create such a subclass, you will also need to supply a
* custom {@link ForkJoinPool.ForkJoinWorkerThreadFactory} to use it
* in a {@code ForkJoinPool}.
* custom {@link ForkJoinPool.ForkJoinWorkerThreadFactory} to
* {@linkplain ForkJoinPool#ForkJoinPool use it} in a {@code ForkJoinPool}.
*
* @since 1.7
* @author Doug Lea
*/
@SuppressWarnings("all")
final class ForkJoinWorkerThread extends Thread {
public class ForkJoinWorkerThread extends Thread {
/*
* ForkJoinWorkerThreads are managed by ForkJoinPools and perform
* ForkJoinTasks. For explanation, see the internal documentation
@ -77,16 +78,17 @@ final class ForkJoinWorkerThread extends Thread {
}
/**
* Returns the index number of this thread in its pool. The
* returned value ranges from zero to the maximum number of
* threads (minus one) that have ever been created in the pool.
* This method may be useful for applications that track status or
* collect results per-worker rather than per-task.
* Returns the unique index number of this thread in its pool.
* The returned value ranges from zero to the maximum number of
* threads (minus one) that may exist in the pool, and does not
* change during the lifetime of the thread. This method may be
* useful for applications that track status or collect results
* per-worker-thread rather than per-task.
*
* @return the index number
*/
public int getPoolIndex() {
return workQueue.poolIndex;
return workQueue.poolIndex >>> 1; // ignore odd/even tag bit
}
/**

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@ -21,7 +21,9 @@
*/
package io.netty.util.internal.chmv8;
import java.io.Serializable;
import java.util.concurrent.atomic.AtomicLong;
/**
* One or more variables that together maintain an initially zero
@ -31,7 +33,7 @@ import java.io.Serializable;
* #longValue}) returns the current total combined across the
* variables maintaining the sum.
*
* <p>This class is usually preferable to {@link java.util.concurrent.atomic.AtomicLong} when
* <p>This class is usually preferable to {@link AtomicLong} when
* multiple threads update a common sum that is used for purposes such
* as collecting statistics, not for fine-grained synchronization
* control. Under low update contention, the two classes have similar
@ -51,7 +53,7 @@ import java.io.Serializable;
* @author Doug Lea
*/
@SuppressWarnings("all")
final class LongAdder extends Striped64 implements Serializable {
public class LongAdder extends Striped64 implements Serializable {
private static final long serialVersionUID = 7249069246863182397L;
/**

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@ -21,6 +21,7 @@
*/
package io.netty.util.internal.chmv8;
import java.util.Random;
/**