/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*/
package java.util.concurrent;
import java.util.function.Supplier;
import java.util.function.Consumer;
import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.function.BiFunction;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.Executor;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.CancellationException;
import java.util.concurrent.CompletionException;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.locks.LockSupport;
/**
* A {@link Future} that may be explicitly completed (setting its
* value and status), and may be used as a {@link CompletionStage},
* supporting dependent functions and actions that trigger upon its
* completion.
*
* <p>When two or more threads attempt to
* {@link #complete complete},
* {@link #completeExceptionally completeExceptionally}, or
* {@link #cancel cancel}
* a CompletableFuture, only one of them succeeds.
*
* <p>In addition to these and related methods for directly
* manipulating status and results, CompletableFuture implements
* interface {@link CompletionStage} with the following policies: <ul>
*
* <li>Actions supplied for dependent completions of
* <em>non-async</em> methods may be performed by the thread that
* completes the current CompletableFuture, or by any other caller of
* a completion method.</li>
*
* <li>All <em>async</em> methods without an explicit Executor
* argument are performed using the {@link ForkJoinPool#commonPool()}
* (unless it does not support a parallelism level of at least two, in
* which case, a new Thread is created to run each task). To simplify
* monitoring, debugging, and tracking, all generated asynchronous
* tasks are instances of the marker interface {@link
* AsynchronousCompletionTask}. </li>
*
* <li>All CompletionStage methods are implemented independently of
* other public methods, so the behavior of one method is not impacted
* by overrides of others in subclasses. </li> </ul>
*
* <p>CompletableFuture also implements {@link Future} with the following
* policies: <ul>
*
* <li>Since (unlike {@link FutureTask}) this class has no direct
* control over the computation that causes it to be completed,
* cancellation is treated as just another form of exceptional
* completion. Method {@link #cancel cancel} has the same effect as
* {@code completeExceptionally(new CancellationException())}. Method
* {@link #isCompletedExceptionally} can be used to determine if a
* CompletableFuture completed in any exceptional fashion.</li>
*
* <li>In case of exceptional completion with a CompletionException,
* methods {@link #get()} and {@link #get(long, TimeUnit)} throw an
* {@link ExecutionException} with the same cause as held in the
* corresponding CompletionException. To simplify usage in most
* contexts, this class also defines methods {@link #join()} and
* {@link #getNow} that instead throw the CompletionException directly
* in these cases.</li> </ul>
*
* @author Doug Lea
* @since 1.8
*/
public class CompletableFuture<T> implements Future<T>, CompletionStage<T> {
/*
* Overview:
*
* A CompletableFuture may have dependent completion actions,
* collected in a linked stack. It atomically completes by CASing
* a result field, and then pops off and runs those actions. This
* applies across normal vs exceptional outcomes, sync vs async
* actions, binary triggers, and various forms of completions.
*
* Non-nullness of field result (set via CAS) indicates done. An
* AltResult is used to box null as a result, as well as to hold
* exceptions. Using a single field makes completion simple to
* detect and trigger. Encoding and decoding is straightforward
* but adds to the sprawl of trapping and associating exceptions
* with targets. Minor simplifications rely on (static) NIL (to
* box null results) being the only AltResult with a null
* exception field, so we don't usually need explicit comparisons.
* Even though some of the generics casts are unchecked (see
* SuppressWarnings annotations), they are placed to be
* appropriate even if checked.
*
* Dependent actions are represented by Completion objects linked
* as Treiber stacks headed by field "stack". There are Completion
* classes for each kind of action, grouped into single-input
* (UniCompletion), two-input (BiCompletion), projected
* (BiCompletions using either (not both) of two inputs), shared
* (CoCompletion, used by the second of two sources), zero-input
* source actions, and Signallers that unblock waiters. Class
* Completion extends ForkJoinTask to enable async execution
* (adding no space overhead because we exploit its "tag" methods
* to maintain claims). It is also declared as Runnable to allow
* usage with arbitrary executors.
*
* Support for each kind of CompletionStage relies on a separate
* class, along with two CompletableFuture methods:
*
* * A Completion class with name X corresponding to function,
* prefaced with "Uni", "Bi", or "Or". Each class contains
* fields for source(s), actions, and dependent. They are
* boringly similar, differing from others only with respect to
* underlying functional forms. We do this so that users don't
* encounter layers of adaptors in common usages. We also
* include "Relay" classes/methods that don't correspond to user
* methods; they copy results from one stage to another.
*
* * Boolean CompletableFuture method x(...) (for example
* uniApply) takes all of the arguments needed to check that an
* action is triggerable, and then either runs the action or
* arranges its async execution by executing its Completion
* argument, if present. The method returns true if known to be
* complete.
*
* * Completion method tryFire(int mode) invokes the associated x
* method with its held arguments, and on success cleans up.
* The mode argument allows tryFire to be called twice (SYNC,
* then ASYNC); the first to screen and trap exceptions while
* arranging to execute, and the second when called from a
* task. (A few classes are not used async so take slightly
* different forms.) The claim() callback suppresses function
* invocation if already claimed by another thread.
*
* * CompletableFuture method xStage(...) is called from a public
* stage method of CompletableFuture x. It screens user
* arguments and invokes and/or creates the stage object. If
* not async and x is already complete, the action is run
* immediately. Otherwise a Completion c is created, pushed to
* x's stack (unless done), and started or triggered via
* c.tryFire. This also covers races possible if x completes
* while pushing. Classes with two inputs (for example BiApply)
* deal with races across both while pushing actions. The
* second completion is a CoCompletion pointing to the first,
* shared so that at most one performs the action. The
* multiple-arity methods allOf and anyOf do this pairwise to
* form trees of completions.
*
* Note that the generic type parameters of methods vary according
* to whether "this" is a source, dependent, or completion.
*
* Method postComplete is called upon completion unless the target
* is guaranteed not to be observable (i.e., not yet returned or
* linked). Multiple threads can call postComplete, which
* atomically pops each dependent action, and tries to trigger it
* via method tryFire, in NESTED mode. Triggering can propagate
* recursively, so NESTED mode returns its completed dependent (if
* one exists) for further processing by its caller (see method
* postFire).
*
* Blocking methods get() and join() rely on Signaller Completions
* that wake up waiting threads. The mechanics are similar to
* Treiber stack wait-nodes used in FutureTask, Phaser, and
* SynchronousQueue. See their internal documentation for
* algorithmic details.
*
* Without precautions, CompletableFutures would be prone to
* garbage accumulation as chains of Completions build up, each
* pointing back to its sources. So we null out fields as soon as
* possible (see especially method Completion.detach). The
* screening checks needed anyway harmlessly ignore null arguments
* that may have been obtained during races with threads nulling
* out fields. We also try to unlink fired Completions from
* stacks that might never be popped (see method postFire).
* Completion fields need not be declared as final or volatile
* because they are only visible to other threads upon safe
* publication.
*/
volatile Object result; // Either the result or boxed AltResult
volatile Completion stack; // Top of Treiber stack of dependent actions
final boolean internalComplete(Object r) { // CAS from null to r
return UNSAFE.compareAndSwapObject(this, RESULT, null, r);
}
final boolean casStack(Completion cmp, Completion val) {
return UNSAFE.compareAndSwapObject(this, STACK, cmp, val);
}
/** Returns true if successfully pushed c onto stack. */
final boolean tryPushStack(Completion c) {
Completion h = stack;
lazySetNext(c, h);
return UNSAFE.compareAndSwapObject(this, STACK, h, c);
}
/** Unconditionally pushes c onto stack, retrying if necessary. */
final void pushStack(Completion c) {
do {} while (!tryPushStack(c));
}
/* ------------- Encoding and decoding outcomes -------------- */
static final class AltResult { // See above
final Throwable ex; // null only for NIL
AltResult(Throwable x) { this.ex = x; }
}
/** The encoding of the null value. */
static final AltResult NIL = new AltResult(null);
/** Completes with the null value, unless already completed. */
final boolean completeNull() {
return UNSAFE.compareAndSwapObject(this, RESULT, null,
NIL);
}
/** Returns the encoding of the given non-exceptional value. */
final Object encodeValue(T t) {
return (t == null) ? NIL : t;
}
/** Completes with a non-exceptional result, unless already completed. */
final boolean completeValue(T t) {
return UNSAFE.compareAndSwapObject(this, RESULT, null,
(t == null) ? NIL : t);
}
/**
* Returns the encoding of the given (non-null) exception as a
* wrapped CompletionException unless it is one already.
*/
static AltResult encodeThrowable(Throwable x) {
return new AltResult((x instanceof CompletionException) ? x :
new CompletionException(x));
}
/** Completes with an exceptional result, unless already completed. */
final boolean completeThrowable(Throwable x) {
return UNSAFE.compareAndSwapObject(this, RESULT, null,
encodeThrowable(x));
}
/**
* Returns the encoding of the given (non-null) exception as a
* wrapped CompletionException unless it is one already. May
* return the given Object r (which must have been the result of a
* source future) if it is equivalent, i.e. if this is a simple
* relay of an existing CompletionException.
*/
static Object encodeThrowable(Throwable x, Object r) {
if (!(x instanceof CompletionException))
x = new CompletionException(x);
else if (r instanceof AltResult && x == ((AltResult)r).ex)
return r;
return new AltResult(x);
}
/**
* Completes with the given (non-null) exceptional result as a
* wrapped CompletionException unless it is one already, unless
* already completed. May complete with the given Object r
* (which must have been the result of a source future) if it is
* equivalent, i.e. if this is a simple propagation of an
* existing CompletionException.
*/
final boolean completeThrowable(Throwable x, Object r) {
return UNSAFE.compareAndSwapObject(this, RESULT, null,
encodeThrowable(x, r));
}
/**
* Returns the encoding of the given arguments: if the exception
* is non-null, encodes as AltResult. Otherwise uses the given
* value, boxed as NIL if null.
*/
Object encodeOutcome(T t, Throwable x) {
return (x == null) ? (t == null) ? NIL : t : encodeThrowable(x);
}
/**
* Returns the encoding of a copied outcome; if exceptional,
* rewraps as a CompletionException, else returns argument.
*/
static Object encodeRelay(Object r) {
Throwable x;
return (((r instanceof AltResult) &&
(x = ((AltResult)r).ex) != null &&
!(x instanceof CompletionException)) ?
new AltResult(new CompletionException(x)) : r);
}
/**
* Completes with r or a copy of r, unless already completed.
* If exceptional, r is first coerced to a CompletionException.
*/
final boolean completeRelay(Object r) {
return UNSAFE.compareAndSwapObject(this, RESULT, null,
encodeRelay(r));
}
/**
* Reports result using Future.get conventions.
*/
private static <T> T reportGet(Object r)
throws InterruptedException, ExecutionException {
if (r == null) // by convention below, null means interrupted
throw new InterruptedException();
if (r instanceof AltResult) {
Throwable x, cause;
if ((x = ((AltResult)r).ex) == null)
return null;
if (x instanceof CancellationException)
throw (CancellationException)x;
if ((x instanceof CompletionException) &&
(cause = x.getCause()) != null)
x = cause;
throw new ExecutionException(x);
}
@SuppressWarnings("unchecked") T t = (T) r;
return t;
}
/**
* Decodes outcome to return result or throw unchecked exception.
*/
private static <T> T reportJoin(Object r) {
if (r instanceof AltResult) {
Throwable x;
if ((x = ((AltResult)r).ex) == null)
return null;
if (x instanceof CancellationException)
throw (CancellationException)x;
if (x instanceof CompletionException)
throw (CompletionException)x;
throw new CompletionException(x);
}
@SuppressWarnings("unchecked") T t = (T) r;
return t;
}
/* ------------- Async task preliminaries -------------- */
/**
* A marker interface identifying asynchronous tasks produced by
* {@code async} methods. This may be useful for monitoring,
* debugging, and tracking asynchronous activities.
*
* @since 1.8
*/
public static interface AsynchronousCompletionTask {
}
private static final boolean useCommonPool =
(ForkJoinPool.getCommonPoolParallelism() > 1);
/**
* Default executor -- ForkJoinPool.commonPool() unless it cannot
* support parallelism.
*/
private static final Executor asyncPool = useCommonPool ?
ForkJoinPool.commonPool() : new ThreadPerTaskExecutor();
/** Fallback if ForkJoinPool.commonPool() cannot support parallelism */
static final class ThreadPerTaskExecutor implements Executor {
public void execute(Runnable r) { new Thread(r).start(); }
}
/**
* Null-checks user executor argument, and translates uses of
* commonPool to asyncPool in case parallelism disabled.
*/
static Executor screenExecutor(Executor e) {
if (!useCommonPool && e == ForkJoinPool.commonPool())
return asyncPool;
if (e == null) throw new NullPointerException();
return e;
}
// Modes for Completion.tryFire. Signedness matters.
static final int SYNC = 0;
static final int ASYNC = 1;
static final int NESTED = -1;
/* ------------- Base Completion classes and operations -------------- */
@SuppressWarnings("serial")
abstract static class Completion extends ForkJoinTask<Void>
implements Runnable, AsynchronousCompletionTask {
volatile Completion next; // Treiber stack link
/**
* Performs completion action if triggered, returning a
* dependent that may need propagation, if one exists.
*
* @param mode SYNC, ASYNC, or NESTED
*/
abstract CompletableFuture<?> tryFire(int mode);
/** Returns true if possibly still triggerable. Used by cleanStack. */
abstract boolean isLive();
public final void run() { tryFire(ASYNC); }
public final boolean exec() { tryFire(ASYNC); return true; }
public final Void getRawResult() { return null; }
public final void setRawResult(Void v) {}
}
static void lazySetNext(Completion c, Completion next) {
UNSAFE.putOrderedObject(c, NEXT, next);
}
/**
* Pops and tries to trigger all reachable dependents. Call only
* when known to be done.
*/
final void postComplete() {
/*
* On each step, variable f holds current dependents to pop
* and run. It is extended along only one path at a time,
* pushing others to avoid unbounded recursion.
*/
CompletableFuture<?> f = this; Completion h;
while ((h = f.stack) != null ||
(f != this && (h = (f = this).stack) != null)) {
CompletableFuture<?> d; Completion t;
if (f.casStack(h, t = h.next)) {
if (t != null) {
if (f != this) {
pushStack(h);
continue;
}
h.next = null; // detach
}
f = (d = h.tryFire(NESTED)) == null ? this : d;
}
}
}
/** Traverses stack and unlinks dead Completions. */
final void cleanStack() {
for (Completion p = null, q = stack; q != null;) {
Completion s = q.next;
if (q.isLive()) {
p = q;
q = s;
}
else if (p == null) {
casStack(q, s);
q = stack;
}
else {
p.next = s;
if (p.isLive())
q = s;
else {
p = null; // restart
q = stack;
}
}
}
}
/* ------------- One-input Completions -------------- */
/** A Completion with a source, dependent, and executor. */
@SuppressWarnings("serial")
abstract static class UniCompletion<T,V> extends Completion {
Executor executor; // executor to use (null if none)
CompletableFuture<V> dep; // the dependent to complete
CompletableFuture<T> src; // source for action
UniCompletion(Executor executor, CompletableFuture<V> dep,
CompletableFuture<T> src) {
this.executor = executor; this.dep = dep; this.src = src;
}
/**
* Returns true if action can be run. Call only when known to
* be triggerable. Uses FJ tag bit to ensure that only one
* thread claims ownership. If async, starts as task -- a
* later call to tryFire will run action.
*/
final boolean claim() {
Executor e = executor;
if (compareAndSetForkJoinTaskTag((short)0, (short)1)) {
if (e == null)
return true;
executor = null; // disable
e.execute(this);
}
return false;
}
final boolean isLive() { return dep != null; }
}
/** Pushes the given completion (if it exists) unless done. */
final void push(UniCompletion<?,?> c) {
if (c != null) {
while (result == null && !tryPushStack(c))
lazySetNext(c, null); // clear on failure
}
}
/**
* Post-processing by dependent after successful UniCompletion
* tryFire. Tries to clean stack of source a, and then either runs
* postComplete or returns this to caller, depending on mode.
*/
final CompletableFuture<T> postFire(CompletableFuture<?> a, int mode) {
if (a != null && a.stack != null) {
if (mode < 0 || a.result == null)
a.cleanStack();
else
a.postComplete();
}
if (result != null && stack != null) {
if (mode < 0)
return this;
else
postComplete();
}
return null;
}
@SuppressWarnings("serial")
static final class UniApply<T,V> extends UniCompletion<T,V> {
Function<? super T,? extends V> fn;
UniApply(Executor executor, CompletableFuture<V> dep,
CompletableFuture<T> src,
Function<? super T,? extends V> fn) {
super(executor, dep, src); this.fn = fn;
}
final CompletableFuture<V> tryFire(int mode) {
CompletableFuture<V> d; CompletableFuture<T> a;
if ((d = dep) == null ||
!d.uniApply(a = src, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; fn = null;
return d.postFire(a, mode);
}
}
final <S> boolean uniApply(CompletableFuture<S> a,
Function<? super S,? extends T> f,
UniApply<S,T> c) {
Object r; Throwable x;
if (a == null || (r = a.result) == null || f == null)
return false;
tryComplete: if (result == null) {
if (r instanceof AltResult) {
if ((x = ((AltResult)r).ex) != null) {
completeThrowable(x, r);
break tryComplete;
}
r = null;
}
try {
if (c != null && !c.claim())
return false;
@SuppressWarnings("unchecked") S s = (S) r;
completeValue(f.apply(s));
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private <V> CompletableFuture<V> uniApplyStage(
Executor e, Function<? super T,? extends V> f) {
if (f == null) throw new NullPointerException();
CompletableFuture<V> d = new CompletableFuture<V>();
if (e != null || !d.uniApply(this, f, null)) {
UniApply<T,V> c = new UniApply<T,V>(e, d, this, f);
push(c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class UniAccept<T> extends UniCompletion<T,Void> {
Consumer<? super T> fn;
UniAccept(Executor executor, CompletableFuture<Void> dep,
CompletableFuture<T> src, Consumer<? super T> fn) {
super(executor, dep, src); this.fn = fn;
}
final CompletableFuture<Void> tryFire(int mode) {
CompletableFuture<Void> d; CompletableFuture<T> a;
if ((d = dep) == null ||
!d.uniAccept(a = src, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; fn = null;
return d.postFire(a, mode);
}
}
final <S> boolean uniAccept(CompletableFuture<S> a,
Consumer<? super S> f, UniAccept<S> c) {
Object r; Throwable x;
if (a == null || (r = a.result) == null || f == null)
return false;
tryComplete: if (result == null) {
if (r instanceof AltResult) {
if ((x = ((AltResult)r).ex) != null) {
completeThrowable(x, r);
break tryComplete;
}
r = null;
}
try {
if (c != null && !c.claim())
return false;
@SuppressWarnings("unchecked") S s = (S) r;
f.accept(s);
completeNull();
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private CompletableFuture<Void> uniAcceptStage(Executor e,
Consumer<? super T> f) {
if (f == null) throw new NullPointerException();
CompletableFuture<Void> d = new CompletableFuture<Void>();
if (e != null || !d.uniAccept(this, f, null)) {
UniAccept<T> c = new UniAccept<T>(e, d, this, f);
push(c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class UniRun<T> extends UniCompletion<T,Void> {
Runnable fn;
UniRun(Executor executor, CompletableFuture<Void> dep,
CompletableFuture<T> src, Runnable fn) {
super(executor, dep, src); this.fn = fn;
}
final CompletableFuture<Void> tryFire(int mode) {
CompletableFuture<Void> d; CompletableFuture<T> a;
if ((d = dep) == null ||
!d.uniRun(a = src, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; fn = null;
return d.postFire(a, mode);
}
}
final boolean uniRun(CompletableFuture<?> a, Runnable f, UniRun<?> c) {
Object r; Throwable x;
if (a == null || (r = a.result) == null || f == null)
return false;
if (result == null) {
if (r instanceof AltResult && (x = ((AltResult)r).ex) != null)
completeThrowable(x, r);
else
try {
if (c != null && !c.claim())
return false;
f.run();
completeNull();
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private CompletableFuture<Void> uniRunStage(Executor e, Runnable f) {
if (f == null) throw new NullPointerException();
CompletableFuture<Void> d = new CompletableFuture<Void>();
if (e != null || !d.uniRun(this, f, null)) {
UniRun<T> c = new UniRun<T>(e, d, this, f);
push(c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class UniWhenComplete<T> extends UniCompletion<T,T> {
BiConsumer<? super T, ? super Throwable> fn;
UniWhenComplete(Executor executor, CompletableFuture<T> dep,
CompletableFuture<T> src,
BiConsumer<? super T, ? super Throwable> fn) {
super(executor, dep, src); this.fn = fn;
}
final CompletableFuture<T> tryFire(int mode) {
CompletableFuture<T> d; CompletableFuture<T> a;
if ((d = dep) == null ||
!d.uniWhenComplete(a = src, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; fn = null;
return d.postFire(a, mode);
}
}
final boolean uniWhenComplete(CompletableFuture<T> a,
BiConsumer<? super T,? super Throwable> f,
UniWhenComplete<T> c) {
Object r; T t; Throwable x = null;
if (a == null || (r = a.result) == null || f == null)
return false;
if (result == null) {
try {
if (c != null && !c.claim())
return false;
if (r instanceof AltResult) {
x = ((AltResult)r).ex;
t = null;
} else {
@SuppressWarnings("unchecked") T tr = (T) r;
t = tr;
}
f.accept(t, x);
if (x == null) {
internalComplete(r);
return true;
}
} catch (Throwable ex) {
if (x == null)
x = ex;
}
completeThrowable(x, r);
}
return true;
}
private CompletableFuture<T> uniWhenCompleteStage(
Executor e, BiConsumer<? super T, ? super Throwable> f) {
if (f == null) throw new NullPointerException();
CompletableFuture<T> d = new CompletableFuture<T>();
if (e != null || !d.uniWhenComplete(this, f, null)) {
UniWhenComplete<T> c = new UniWhenComplete<T>(e, d, this, f);
push(c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class UniHandle<T,V> extends UniCompletion<T,V> {
BiFunction<? super T, Throwable, ? extends V> fn;
UniHandle(Executor executor, CompletableFuture<V> dep,
CompletableFuture<T> src,
BiFunction<? super T, Throwable, ? extends V> fn) {
super(executor, dep, src); this.fn = fn;
}
final CompletableFuture<V> tryFire(int mode) {
CompletableFuture<V> d; CompletableFuture<T> a;
if ((d = dep) == null ||
!d.uniHandle(a = src, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; fn = null;
return d.postFire(a, mode);
}
}
final <S> boolean uniHandle(CompletableFuture<S> a,
BiFunction<? super S, Throwable, ? extends T> f,
UniHandle<S,T> c) {
Object r; S s; Throwable x;
if (a == null || (r = a.result) == null || f == null)
return false;
if (result == null) {
try {
if (c != null && !c.claim())
return false;
if (r instanceof AltResult) {
x = ((AltResult)r).ex;
s = null;
} else {
x = null;
@SuppressWarnings("unchecked") S ss = (S) r;
s = ss;
}
completeValue(f.apply(s, x));
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private <V> CompletableFuture<V> uniHandleStage(
Executor e, BiFunction<? super T, Throwable, ? extends V> f) {
if (f == null) throw new NullPointerException();
CompletableFuture<V> d = new CompletableFuture<V>();
if (e != null || !d.uniHandle(this, f, null)) {
UniHandle<T,V> c = new UniHandle<T,V>(e, d, this, f);
push(c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class UniExceptionally<T> extends UniCompletion<T,T> {
Function<? super Throwable, ? extends T> fn;
UniExceptionally(CompletableFuture<T> dep, CompletableFuture<T> src,
Function<? super Throwable, ? extends T> fn) {
super(null, dep, src); this.fn = fn;
}
final CompletableFuture<T> tryFire(int mode) { // never ASYNC
// assert mode != ASYNC;
CompletableFuture<T> d; CompletableFuture<T> a;
if ((d = dep) == null || !d.uniExceptionally(a = src, fn, this))
return null;
dep = null; src = null; fn = null;
return d.postFire(a, mode);
}
}
final boolean uniExceptionally(CompletableFuture<T> a,
Function<? super Throwable, ? extends T> f,
UniExceptionally<T> c) {
Object r; Throwable x;
if (a == null || (r = a.result) == null || f == null)
return false;
if (result == null) {
try {
if (r instanceof AltResult && (x = ((AltResult)r).ex) != null) {
if (c != null && !c.claim())
return false;
completeValue(f.apply(x));
} else
internalComplete(r);
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private CompletableFuture<T> uniExceptionallyStage(
Function<Throwable, ? extends T> f) {
if (f == null) throw new NullPointerException();
CompletableFuture<T> d = new CompletableFuture<T>();
if (!d.uniExceptionally(this, f, null)) {
UniExceptionally<T> c = new UniExceptionally<T>(d, this, f);
push(c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class UniRelay<T> extends UniCompletion<T,T> { // for Compose
UniRelay(CompletableFuture<T> dep, CompletableFuture<T> src) {
super(null, dep, src);
}
final CompletableFuture<T> tryFire(int mode) {
CompletableFuture<T> d; CompletableFuture<T> a;
if ((d = dep) == null || !d.uniRelay(a = src))
return null;
src = null; dep = null;
return d.postFire(a, mode);
}
}
final boolean uniRelay(CompletableFuture<T> a) {
Object r;
if (a == null || (r = a.result) == null)
return false;
if (result == null) // no need to claim
completeRelay(r);
return true;
}
@SuppressWarnings("serial")
static final class UniCompose<T,V> extends UniCompletion<T,V> {
Function<? super T, ? extends CompletionStage<V>> fn;
UniCompose(Executor executor, CompletableFuture<V> dep,
CompletableFuture<T> src,
Function<? super T, ? extends CompletionStage<V>> fn) {
super(executor, dep, src); this.fn = fn;
}
final CompletableFuture<V> tryFire(int mode) {
CompletableFuture<V> d; CompletableFuture<T> a;
if ((d = dep) == null ||
!d.uniCompose(a = src, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; fn = null;
return d.postFire(a, mode);
}
}
final <S> boolean uniCompose(
CompletableFuture<S> a,
Function<? super S, ? extends CompletionStage<T>> f,
UniCompose<S,T> c) {
Object r; Throwable x;
if (a == null || (r = a.result) == null || f == null)
return false;
tryComplete: if (result == null) {
if (r instanceof AltResult) {
if ((x = ((AltResult)r).ex) != null) {
completeThrowable(x, r);
break tryComplete;
}
r = null;
}
try {
if (c != null && !c.claim())
return false;
@SuppressWarnings("unchecked") S s = (S) r;
CompletableFuture<T> g = f.apply(s).toCompletableFuture();
if (g.result == null || !uniRelay(g)) {
UniRelay<T> copy = new UniRelay<T>(this, g);
g.push(copy);
copy.tryFire(SYNC);
if (result == null)
return false;
}
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private <V> CompletableFuture<V> uniComposeStage(
Executor e, Function<? super T, ? extends CompletionStage<V>> f) {
if (f == null) throw new NullPointerException();
Object r; Throwable x;
if (e == null && (r = result) != null) {
// try to return function result directly
if (r instanceof AltResult) {
if ((x = ((AltResult)r).ex) != null) {
return new CompletableFuture<V>(encodeThrowable(x, r));
}
r = null;
}
try {
@SuppressWarnings("unchecked") T t = (T) r;
CompletableFuture<V> g = f.apply(t).toCompletableFuture();
Object s = g.result;
if (s != null)
return new CompletableFuture<V>(encodeRelay(s));
CompletableFuture<V> d = new CompletableFuture<V>();
UniRelay<V> copy = new UniRelay<V>(d, g);
g.push(copy);
copy.tryFire(SYNC);
return d;
} catch (Throwable ex) {
return new CompletableFuture<V>(encodeThrowable(ex));
}
}
CompletableFuture<V> d = new CompletableFuture<V>();
UniCompose<T,V> c = new UniCompose<T,V>(e, d, this, f);
push(c);
c.tryFire(SYNC);
return d;
}
/* ------------- Two-input Completions -------------- */
/** A Completion for an action with two sources */
@SuppressWarnings("serial")
abstract static class BiCompletion<T,U,V> extends UniCompletion<T,V> {
CompletableFuture<U> snd; // second source for action
BiCompletion(Executor executor, CompletableFuture<V> dep,
CompletableFuture<T> src, CompletableFuture<U> snd) {
super(executor, dep, src); this.snd = snd;
}
}
/** A Completion delegating to a BiCompletion */
@SuppressWarnings("serial")
static final class CoCompletion extends Completion {
BiCompletion<?,?,?> base;
CoCompletion(BiCompletion<?,?,?> base) { this.base = base; }
final CompletableFuture<?> tryFire(int mode) {
BiCompletion<?,?,?> c; CompletableFuture<?> d;
if ((c = base) == null || (d = c.tryFire(mode)) == null)
return null;
base = null; // detach
return d;
}
final boolean isLive() {
BiCompletion<?,?,?> c;
return (c = base) != null && c.dep != null;
}
}
/** Pushes completion to this and b unless both done. */
final void bipush(CompletableFuture<?> b, BiCompletion<?,?,?> c) {
if (c != null) {
Object r;
while ((r = result) == null && !tryPushStack(c))
lazySetNext(c, null); // clear on failure
if (b != null && b != this && b.result == null) {
Completion q = (r != null) ? c : new CoCompletion(c);
while (b.result == null && !b.tryPushStack(q))
lazySetNext(q, null); // clear on failure
}
}
}
/** Post-processing after successful BiCompletion tryFire. */
final CompletableFuture<T> postFire(CompletableFuture<?> a,
CompletableFuture<?> b, int mode) {
if (b != null && b.stack != null) { // clean second source
if (mode < 0 || b.result == null)
b.cleanStack();
else
b.postComplete();
}
return postFire(a, mode);
}
@SuppressWarnings("serial")
static final class BiApply<T,U,V> extends BiCompletion<T,U,V> {
BiFunction<? super T,? super U,? extends V> fn;
BiApply(Executor executor, CompletableFuture<V> dep,
CompletableFuture<T> src, CompletableFuture<U> snd,
BiFunction<? super T,? super U,? extends V> fn) {
super(executor, dep, src, snd); this.fn = fn;
}
final CompletableFuture<V> tryFire(int mode) {
CompletableFuture<V> d;
CompletableFuture<T> a;
CompletableFuture<U> b;
if ((d = dep) == null ||
!d.biApply(a = src, b = snd, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; snd = null; fn = null;
return d.postFire(a, b, mode);
}
}
final <R,S> boolean biApply(CompletableFuture<R> a,
CompletableFuture<S> b,
BiFunction<? super R,? super S,? extends T> f,
BiApply<R,S,T> c) {
Object r, s; Throwable x;
if (a == null || (r = a.result) == null ||
b == null || (s = b.result) == null || f == null)
return false;
tryComplete: if (result == null) {
if (r instanceof AltResult) {
if ((x = ((AltResult)r).ex) != null) {
completeThrowable(x, r);
break tryComplete;
}
r = null;
}
if (s instanceof AltResult) {
if ((x = ((AltResult)s).ex) != null) {
completeThrowable(x, s);
break tryComplete;
}
s = null;
}
try {
if (c != null && !c.claim())
return false;
@SuppressWarnings("unchecked") R rr = (R) r;
@SuppressWarnings("unchecked") S ss = (S) s;
completeValue(f.apply(rr, ss));
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private <U,V> CompletableFuture<V> biApplyStage(
Executor e, CompletionStage<U> o,
BiFunction<? super T,? super U,? extends V> f) {
CompletableFuture<U> b;
if (f == null || (b = o.toCompletableFuture()) == null)
throw new NullPointerException();
CompletableFuture<V> d = new CompletableFuture<V>();
if (e != null || !d.biApply(this, b, f, null)) {
BiApply<T,U,V> c = new BiApply<T,U,V>(e, d, this, b, f);
bipush(b, c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class BiAccept<T,U> extends BiCompletion<T,U,Void> {
BiConsumer<? super T,? super U> fn;
BiAccept(Executor executor, CompletableFuture<Void> dep,
CompletableFuture<T> src, CompletableFuture<U> snd,
BiConsumer<? super T,? super U> fn) {
super(executor, dep, src, snd); this.fn = fn;
}
final CompletableFuture<Void> tryFire(int mode) {
CompletableFuture<Void> d;
CompletableFuture<T> a;
CompletableFuture<U> b;
if ((d = dep) == null ||
!d.biAccept(a = src, b = snd, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; snd = null; fn = null;
return d.postFire(a, b, mode);
}
}
final <R,S> boolean biAccept(CompletableFuture<R> a,
CompletableFuture<S> b,
BiConsumer<? super R,? super S> f,
BiAccept<R,S> c) {
Object r, s; Throwable x;
if (a == null || (r = a.result) == null ||
b == null || (s = b.result) == null || f == null)
return false;
tryComplete: if (result == null) {
if (r instanceof AltResult) {
if ((x = ((AltResult)r).ex) != null) {
completeThrowable(x, r);
break tryComplete;
}
r = null;
}
if (s instanceof AltResult) {
if ((x = ((AltResult)s).ex) != null) {
completeThrowable(x, s);
break tryComplete;
}
s = null;
}
try {
if (c != null && !c.claim())
return false;
@SuppressWarnings("unchecked") R rr = (R) r;
@SuppressWarnings("unchecked") S ss = (S) s;
f.accept(rr, ss);
completeNull();
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private <U> CompletableFuture<Void> biAcceptStage(
Executor e, CompletionStage<U> o,
BiConsumer<? super T,? super U> f) {
CompletableFuture<U> b;
if (f == null || (b = o.toCompletableFuture()) == null)
throw new NullPointerException();
CompletableFuture<Void> d = new CompletableFuture<Void>();
if (e != null || !d.biAccept(this, b, f, null)) {
BiAccept<T,U> c = new BiAccept<T,U>(e, d, this, b, f);
bipush(b, c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class BiRun<T,U> extends BiCompletion<T,U,Void> {
Runnable fn;
BiRun(Executor executor, CompletableFuture<Void> dep,
CompletableFuture<T> src,
CompletableFuture<U> snd,
Runnable fn) {
super(executor, dep, src, snd); this.fn = fn;
}
final CompletableFuture<Void> tryFire(int mode) {
CompletableFuture<Void> d;
CompletableFuture<T> a;
CompletableFuture<U> b;
if ((d = dep) == null ||
!d.biRun(a = src, b = snd, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; snd = null; fn = null;
return d.postFire(a, b, mode);
}
}
final boolean biRun(CompletableFuture<?> a, CompletableFuture<?> b,
Runnable f, BiRun<?,?> c) {
Object r, s; Throwable x;
if (a == null || (r = a.result) == null ||
b == null || (s = b.result) == null || f == null)
return false;
if (result == null) {
if (r instanceof AltResult && (x = ((AltResult)r).ex) != null)
completeThrowable(x, r);
else if (s instanceof AltResult && (x = ((AltResult)s).ex) != null)
completeThrowable(x, s);
else
try {
if (c != null && !c.claim())
return false;
f.run();
completeNull();
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private CompletableFuture<Void> biRunStage(Executor e, CompletionStage<?> o,
Runnable f) {
CompletableFuture<?> b;
if (f == null || (b = o.toCompletableFuture()) == null)
throw new NullPointerException();
CompletableFuture<Void> d = new CompletableFuture<Void>();
if (e != null || !d.biRun(this, b, f, null)) {
BiRun<T,?> c = new BiRun<>(e, d, this, b, f);
bipush(b, c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class BiRelay<T,U> extends BiCompletion<T,U,Void> { // for And
BiRelay(CompletableFuture<Void> dep,
CompletableFuture<T> src,
CompletableFuture<U> snd) {
super(null, dep, src, snd);
}
final CompletableFuture<Void> tryFire(int mode) {
CompletableFuture<Void> d;
CompletableFuture<T> a;
CompletableFuture<U> b;
if ((d = dep) == null || !d.biRelay(a = src, b = snd))
return null;
src = null; snd = null; dep = null;
return d.postFire(a, b, mode);
}
}
boolean biRelay(CompletableFuture<?> a, CompletableFuture<?> b) {
Object r, s; Throwable x;
if (a == null || (r = a.result) == null ||
b == null || (s = b.result) == null)
return false;
if (result == null) {
if (r instanceof AltResult && (x = ((AltResult)r).ex) != null)
completeThrowable(x, r);
else if (s instanceof AltResult && (x = ((AltResult)s).ex) != null)
completeThrowable(x, s);
else
completeNull();
}
return true;
}
/** Recursively constructs a tree of completions. */
static CompletableFuture<Void> andTree(CompletableFuture<?>[] cfs,
int lo, int hi) {
CompletableFuture<Void> d = new CompletableFuture<Void>();
if (lo > hi) // empty
d.result = NIL;
else {
CompletableFuture<?> a, b;
int mid = (lo + hi) >>> 1;
if ((a = (lo == mid ? cfs[lo] :
andTree(cfs, lo, mid))) == null ||
(b = (lo == hi ? a : (hi == mid+1) ? cfs[hi] :
andTree(cfs, mid+1, hi))) == null)
throw new NullPointerException();
if (!d.biRelay(a, b)) {
BiRelay<?,?> c = new BiRelay<>(d, a, b);
a.bipush(b, c);
c.tryFire(SYNC);
}
}
return d;
}
/* ------------- Projected (Ored) BiCompletions -------------- */
/** Pushes completion to this and b unless either done. */
final void orpush(CompletableFuture<?> b, BiCompletion<?,?,?> c) {
if (c != null) {
while ((b == null || b.result == null) && result == null) {
if (tryPushStack(c)) {
if (b != null && b != this && b.result == null) {
Completion q = new CoCompletion(c);
while (result == null && b.result == null &&
!b.tryPushStack(q))
lazySetNext(q, null); // clear on failure
}
break;
}
lazySetNext(c, null); // clear on failure
}
}
}
@SuppressWarnings("serial")
static final class OrApply<T,U extends T,V> extends BiCompletion<T,U,V> {
Function<? super T,? extends V> fn;
OrApply(Executor executor, CompletableFuture<V> dep,
CompletableFuture<T> src,
CompletableFuture<U> snd,
Function<? super T,? extends V> fn) {
super(executor, dep, src, snd); this.fn = fn;
}
final CompletableFuture<V> tryFire(int mode) {
CompletableFuture<V> d;
CompletableFuture<T> a;
CompletableFuture<U> b;
if ((d = dep) == null ||
!d.orApply(a = src, b = snd, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; snd = null; fn = null;
return d.postFire(a, b, mode);
}
}
final <R,S extends R> boolean orApply(CompletableFuture<R> a,
CompletableFuture<S> b,
Function<? super R, ? extends T> f,
OrApply<R,S,T> c) {
Object r; Throwable x;
if (a == null || b == null ||
((r = a.result) == null && (r = b.result) == null) || f == null)
return false;
tryComplete: if (result == null) {
try {
if (c != null && !c.claim())
return false;
if (r instanceof AltResult) {
if ((x = ((AltResult)r).ex) != null) {
completeThrowable(x, r);
break tryComplete;
}
r = null;
}
@SuppressWarnings("unchecked") R rr = (R) r;
completeValue(f.apply(rr));
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private <U extends T,V> CompletableFuture<V> orApplyStage(
Executor e, CompletionStage<U> o,
Function<? super T, ? extends V> f) {
CompletableFuture<U> b;
if (f == null || (b = o.toCompletableFuture()) == null)
throw new NullPointerException();
CompletableFuture<V> d = new CompletableFuture<V>();
if (e != null || !d.orApply(this, b, f, null)) {
OrApply<T,U,V> c = new OrApply<T,U,V>(e, d, this, b, f);
orpush(b, c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class OrAccept<T,U extends T> extends BiCompletion<T,U,Void> {
Consumer<? super T> fn;
OrAccept(Executor executor, CompletableFuture<Void> dep,
CompletableFuture<T> src,
CompletableFuture<U> snd,
Consumer<? super T> fn) {
super(executor, dep, src, snd); this.fn = fn;
}
final CompletableFuture<Void> tryFire(int mode) {
CompletableFuture<Void> d;
CompletableFuture<T> a;
CompletableFuture<U> b;
if ((d = dep) == null ||
!d.orAccept(a = src, b = snd, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; snd = null; fn = null;
return d.postFire(a, b, mode);
}
}
final <R,S extends R> boolean orAccept(CompletableFuture<R> a,
CompletableFuture<S> b,
Consumer<? super R> f,
OrAccept<R,S> c) {
Object r; Throwable x;
if (a == null || b == null ||
((r = a.result) == null && (r = b.result) == null) || f == null)
return false;
tryComplete: if (result == null) {
try {
if (c != null && !c.claim())
return false;
if (r instanceof AltResult) {
if ((x = ((AltResult)r).ex) != null) {
completeThrowable(x, r);
break tryComplete;
}
r = null;
}
@SuppressWarnings("unchecked") R rr = (R) r;
f.accept(rr);
completeNull();
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private <U extends T> CompletableFuture<Void> orAcceptStage(
Executor e, CompletionStage<U> o, Consumer<? super T> f) {
CompletableFuture<U> b;
if (f == null || (b = o.toCompletableFuture()) == null)
throw new NullPointerException();
CompletableFuture<Void> d = new CompletableFuture<Void>();
if (e != null || !d.orAccept(this, b, f, null)) {
OrAccept<T,U> c = new OrAccept<T,U>(e, d, this, b, f);
orpush(b, c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class OrRun<T,U> extends BiCompletion<T,U,Void> {
Runnable fn;
OrRun(Executor executor, CompletableFuture<Void> dep,
CompletableFuture<T> src,
CompletableFuture<U> snd,
Runnable fn) {
super(executor, dep, src, snd); this.fn = fn;
}
final CompletableFuture<Void> tryFire(int mode) {
CompletableFuture<Void> d;
CompletableFuture<T> a;
CompletableFuture<U> b;
if ((d = dep) == null ||
!d.orRun(a = src, b = snd, fn, mode > 0 ? null : this))
return null;
dep = null; src = null; snd = null; fn = null;
return d.postFire(a, b, mode);
}
}
final boolean orRun(CompletableFuture<?> a, CompletableFuture<?> b,
Runnable f, OrRun<?,?> c) {
Object r; Throwable x;
if (a == null || b == null ||
((r = a.result) == null && (r = b.result) == null) || f == null)
return false;
if (result == null) {
try {
if (c != null && !c.claim())
return false;
if (r instanceof AltResult && (x = ((AltResult)r).ex) != null)
completeThrowable(x, r);
else {
f.run();
completeNull();
}
} catch (Throwable ex) {
completeThrowable(ex);
}
}
return true;
}
private CompletableFuture<Void> orRunStage(Executor e, CompletionStage<?> o,
Runnable f) {
CompletableFuture<?> b;
if (f == null || (b = o.toCompletableFuture()) == null)
throw new NullPointerException();
CompletableFuture<Void> d = new CompletableFuture<Void>();
if (e != null || !d.orRun(this, b, f, null)) {
OrRun<T,?> c = new OrRun<>(e, d, this, b, f);
orpush(b, c);
c.tryFire(SYNC);
}
return d;
}
@SuppressWarnings("serial")
static final class OrRelay<T,U> extends BiCompletion<T,U,Object> { // for Or
OrRelay(CompletableFuture<Object> dep, CompletableFuture<T> src,
CompletableFuture<U> snd) {
super(null, dep, src, snd);
}
final CompletableFuture<Object> tryFire(int mode) {
CompletableFuture<Object> d;
CompletableFuture<T> a;
CompletableFuture<U> b;
if ((d = dep) == null || !d.orRelay(a = src, b = snd))
return null;
src = null; snd = null; dep = null;
return d.postFire(a, b, mode);
}
}
final boolean orRelay(CompletableFuture<?> a, CompletableFuture<?> b) {
Object r;
if (a == null || b == null ||
((r = a.result) == null && (r = b.result) == null))
return false;
if (result == null)
completeRelay(r);
return true;
}
/** Recursively constructs a tree of completions. */
static CompletableFuture<Object> orTree(CompletableFuture<?>[] cfs,
int lo, int hi) {
CompletableFuture<Object> d = new CompletableFuture<Object>();
if (lo <= hi) {
CompletableFuture<?> a, b;
int mid = (lo + hi) >>> 1;
if ((a = (lo == mid ? cfs[lo] :
orTree(cfs, lo, mid))) == null ||
(b = (lo == hi ? a : (hi == mid+1) ? cfs[hi] :
orTree(cfs, mid+1, hi))) == null)
throw new NullPointerException();
if (!d.orRelay(a, b)) {
OrRelay<?,?> c = new OrRelay<>(d, a, b);
a.orpush(b, c);
c.tryFire(SYNC);
}
}
return d;
}
/* ------------- Zero-input Async forms -------------- */
@SuppressWarnings("serial")
static final class AsyncSupply<T> extends ForkJoinTask<Void>
implements Runnable, AsynchronousCompletionTask {
CompletableFuture<T> dep; Supplier<T> fn;
AsyncSupply(CompletableFuture<T> dep, Supplier<T> fn) {
this.dep = dep; this.fn = fn;
}
public final Void getRawResult() { return null; }
public final void setRawResult(Void v) {}
public final boolean exec() { run(); return true; }
public void run() {
CompletableFuture<T> d; Supplier<T> f;
if ((d = dep) != null && (f = fn) != null) {
dep = null; fn = null;
if (d.result == null) {
try {
d.completeValue(f.get());
} catch (Throwable ex) {
d.completeThrowable(ex);
}
}
d.postComplete();
}
}
}
static <U> CompletableFuture<U> asyncSupplyStage(Executor e,
Supplier<U> f) {
if (f == null) throw new NullPointerException();
CompletableFuture<U> d = new CompletableFuture<U>();
e.execute(new AsyncSupply<U>(d, f));
return d;
}
@SuppressWarnings("serial")
static final class AsyncRun extends ForkJoinTask<Void>
implements Runnable, AsynchronousCompletionTask {
CompletableFuture<Void> dep; Runnable fn;
AsyncRun(CompletableFuture<Void> dep, Runnable fn) {
this.dep = dep; this.fn = fn;
}
public final Void getRawResult() { return null; }
public final void setRawResult(Void v) {}
public final boolean exec() { run(); return true; }
public void run() {
CompletableFuture<Void> d; Runnable f;
if ((d = dep) != null && (f = fn) != null) {
dep = null; fn = null;
if (d.result == null) {
try {
f.run();
d.completeNull();
} catch (Throwable ex) {
d.completeThrowable(ex);
}
}
d.postComplete();
}
}
}
static CompletableFuture<Void> asyncRunStage(Executor e, Runnable f) {
if (f == null) throw new NullPointerException();
CompletableFuture<Void> d = new CompletableFuture<Void>();
e.execute(new AsyncRun(d, f));
return d;
}
/* ------------- Signallers -------------- */
/**
* Completion for recording and releasing a waiting thread. This
* class implements ManagedBlocker to avoid starvation when
* blocking actions pile up in ForkJoinPools.
*/
@SuppressWarnings("serial")
static final class Signaller extends Completion
implements ForkJoinPool.ManagedBlocker {
long nanos; // wait time if timed
final long deadline; // non-zero if timed
volatile int interruptControl; // > 0: interruptible, < 0: interrupted
volatile Thread thread;
Signaller(boolean interruptible, long nanos, long deadline) {
this.thread = Thread.currentThread();
this.interruptControl = interruptible ? 1 : 0;
this.nanos = nanos;
this.deadline = deadline;
}
final CompletableFuture<?> tryFire(int ignore) {
Thread w; // no need to atomically claim
if ((w = thread) != null) {
thread = null;
LockSupport.unpark(w);
}
return null;
}
public boolean isReleasable() {
if (thread == null)
return true;
if (Thread.interrupted()) {
int i = interruptControl;
interruptControl = -1;
if (i > 0)
return true;
}
if (deadline != 0L &&
(nanos <= 0L || (nanos = deadline - System.nanoTime()) <= 0L)) {
thread = null;
return true;
}
return false;
}
public boolean block() {
if (isReleasable())
return true;
else if (deadline == 0L)
LockSupport.park(this);
else if (nanos > 0L)
LockSupport.parkNanos(this, nanos);
return isReleasable();
}
final boolean isLive() { return thread != null; }
}
/**
* Returns raw result after waiting, or null if interruptible and
* interrupted.
*/
private Object waitingGet(boolean interruptible) {
Signaller q = null;
boolean queued = false;
int spins = -1;
Object r;
while ((r = result) == null) {
if (spins < 0)
spins = (Runtime.getRuntime().availableProcessors() > 1) ?
1 << 8 : 0; // Use brief spin-wait on multiprocessors
else if (spins > 0) {
if (ThreadLocalRandom.nextSecondarySeed() >= 0)
--spins;
}
else if (q == null)
q = new Signaller(interruptible, 0L, 0L);
else if (!queued)
queued = tryPushStack(q);
else if (interruptible && q.interruptControl < 0) {
q.thread = null;
cleanStack();
return null;
}
else if (q.thread != null && result == null) {
try {
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
if (q != null) {
q.thread = null;
if (q.interruptControl < 0) {
if (interruptible)
r = null; // report interruption
else
Thread.currentThread().interrupt();
}
}
postComplete();
return r;
}
/**
* Returns raw result after waiting, or null if interrupted, or
* throws TimeoutException on timeout.
*/
private Object timedGet(long nanos) throws TimeoutException {
if (Thread.interrupted())
return null;
if (nanos <= 0L)
throw new TimeoutException();
long d = System.nanoTime() + nanos;
Signaller q = new Signaller(true, nanos, d == 0L ? 1L : d); // avoid 0
boolean queued = false;
Object r;
// We intentionally don't spin here (as waitingGet does) because
// the call to nanoTime() above acts much like a spin.
while ((r = result) == null) {
if (!queued)
queued = tryPushStack(q);
else if (q.interruptControl < 0 || q.nanos <= 0L) {
q.thread = null;
cleanStack();
if (q.interruptControl < 0)
return null;
throw new TimeoutException();
}
else if (q.thread != null && result == null) {
try {
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
if (q.interruptControl < 0)
r = null;
q.thread = null;
postComplete();
return r;
}
/* ------------- public methods -------------- */
/**
* Creates a new incomplete CompletableFuture.
*/
public CompletableFuture() {
}
/**
* Creates a new complete CompletableFuture with given encoded result.
*/
private CompletableFuture(Object r) {
this.result = r;
}
/**
* Returns a new CompletableFuture that is asynchronously completed
* by a task running in the {@link ForkJoinPool#commonPool()} with
* the value obtained by calling the given Supplier.
*
* @param supplier a function returning the value to be used
* to complete the returned CompletableFuture
* @param <U> the function's return type
* @return the new CompletableFuture
*/
public static <U> CompletableFuture<U> supplyAsync(Supplier<U> supplier) {
return asyncSupplyStage(asyncPool, supplier);
}
/**
* Returns a new CompletableFuture that is asynchronously completed
* by a task running in the given executor with the value obtained
* by calling the given Supplier.
*
* @param supplier a function returning the value to be used
* to complete the returned CompletableFuture
* @param executor the executor to use for asynchronous execution
* @param <U> the function's return type
* @return the new CompletableFuture
*/
public static <U> CompletableFuture<U> supplyAsync(Supplier<U> supplier,
Executor executor) {
return asyncSupplyStage(screenExecutor(executor), supplier);
}
/**
* Returns a new CompletableFuture that is asynchronously completed
* by a task running in the {@link ForkJoinPool#commonPool()} after
* it runs the given action.
*
* @param runnable the action to run before completing the
* returned CompletableFuture
* @return the new CompletableFuture
*/
public static CompletableFuture<Void> runAsync(Runnable runnable) {
return asyncRunStage(asyncPool, runnable);
}
/**
* Returns a new CompletableFuture that is asynchronously completed
* by a task running in the given executor after it runs the given
* action.
*
* @param runnable the action to run before completing the
* returned CompletableFuture
* @param executor the executor to use for asynchronous execution
* @return the new CompletableFuture
*/
public static CompletableFuture<Void> runAsync(Runnable runnable,
Executor executor) {
return asyncRunStage(screenExecutor(executor), runnable);
}
/**
* Returns a new CompletableFuture that is already completed with
* the given value.
*
* @param value the value
* @param <U> the type of the value
* @return the completed CompletableFuture
*/
public static <U> CompletableFuture<U> completedFuture(U value) {
return new CompletableFuture<U>((value == null) ? NIL : value);
}
/**
* Returns {@code true} if completed in any fashion: normally,
* exceptionally, or via cancellation.
*
* @return {@code true} if completed
*/
public boolean isDone() {
return result != null;
}
/**
* Waits if necessary for this future to complete, and then
* returns its result.
*
* @return the result value
* @throws CancellationException if this future was cancelled
* @throws ExecutionException if this future completed exceptionally
* @throws InterruptedException if the current thread was interrupted
* while waiting
*/
public T get() throws InterruptedException, ExecutionException {
Object r;
return reportGet((r = result) == null ? waitingGet(true) : r);
}
/**
* Waits if necessary for at most the given time for this future
* to complete, and then returns its result, if available.
*
* @param timeout the maximum time to wait
* @param unit the time unit of the timeout argument
* @return the result value
* @throws CancellationException if this future was cancelled
* @throws ExecutionException if this future completed exceptionally
* @throws InterruptedException if the current thread was interrupted
* while waiting
* @throws TimeoutException if the wait timed out
*/
public T get(long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException {
Object r;
long nanos = unit.toNanos(timeout);
return reportGet((r = result) == null ? timedGet(nanos) : r);
}
/**
* Returns the result value when complete, or throws an
* (unchecked) exception if completed exceptionally. To better
* conform with the use of common functional forms, if a
* computation involved in the completion of this
* CompletableFuture threw an exception, this method throws an
* (unchecked) {@link CompletionException} with the underlying
* exception as its cause.
*
* @return the result value
* @throws CancellationException if the computation was cancelled
* @throws CompletionException if this future completed
* exceptionally or a completion computation threw an exception
*/
public T join() {
Object r;
return reportJoin((r = result) == null ? waitingGet(false) : r);
}
/**
* Returns the result value (or throws any encountered exception)
* if completed, else returns the given valueIfAbsent.
*
* @param valueIfAbsent the value to return if not completed
* @return the result value, if completed, else the given valueIfAbsent
* @throws CancellationException if the computation was cancelled
* @throws CompletionException if this future completed
* exceptionally or a completion computation threw an exception
*/
public T getNow(T valueIfAbsent) {
Object r;
return ((r = result) == null) ? valueIfAbsent : reportJoin(r);
}
/**
* If not already completed, sets the value returned by {@link
* #get()} and related methods to the given value.
*
* @param value the result value
* @return {@code true} if this invocation caused this CompletableFuture
* to transition to a completed state, else {@code false}
*/
public boolean complete(T value) {
boolean triggered = completeValue(value);
postComplete();
return triggered;
}
/**
* If not already completed, causes invocations of {@link #get()}
* and related methods to throw the given exception.
*
* @param ex the exception
* @return {@code true} if this invocation caused this CompletableFuture
* to transition to a completed state, else {@code false}
*/
public boolean completeExceptionally(Throwable ex) {
if (ex == null) throw new NullPointerException();
boolean triggered = internalComplete(new AltResult(ex));
postComplete();
return triggered;
}
public <U> CompletableFuture<U> thenApply(
Function<? super T,? extends U> fn) {
return uniApplyStage(null, fn);
}
public <U> CompletableFuture<U> thenApplyAsync(
Function<? super T,? extends U> fn) {
return uniApplyStage(asyncPool, fn);
}
public <U> CompletableFuture<U> thenApplyAsync(
Function<? super T,? extends U> fn, Executor executor) {
return uniApplyStage(screenExecutor(executor), fn);
}
public CompletableFuture<Void> thenAccept(Consumer<? super T> action) {
return uniAcceptStage(null, action);
}
public CompletableFuture<Void> thenAcceptAsync(Consumer<? super T> action) {
return uniAcceptStage(asyncPool, action);
}
public CompletableFuture<Void> thenAcceptAsync(Consumer<? super T> action,
Executor executor) {
return uniAcceptStage(screenExecutor(executor), action);
}
public CompletableFuture<Void> thenRun(Runnable action) {
return uniRunStage(null, action);
}
public CompletableFuture<Void> thenRunAsync(Runnable action) {
return uniRunStage(asyncPool, action);
}
public CompletableFuture<Void> thenRunAsync(Runnable action,
Executor executor) {
return uniRunStage(screenExecutor(executor), action);
}
public <U,V> CompletableFuture<V> thenCombine(
CompletionStage<? extends U> other,
BiFunction<? super T,? super U,? extends V> fn) {
return biApplyStage(null, other, fn);
}
public <U,V> CompletableFuture<V> thenCombineAsync(
CompletionStage<? extends U> other,
BiFunction<? super T,? super U,? extends V> fn) {
return biApplyStage(asyncPool, other, fn);
}
public <U,V> CompletableFuture<V> thenCombineAsync(
CompletionStage<? extends U> other,
BiFunction<? super T,? super U,? extends V> fn, Executor executor) {
return biApplyStage(screenExecutor(executor), other, fn);
}
public <U> CompletableFuture<Void> thenAcceptBoth(
CompletionStage<? extends U> other,
BiConsumer<? super T, ? super U> action) {
return biAcceptStage(null, other, action);
}
public <U> CompletableFuture<Void> thenAcceptBothAsync(
CompletionStage<? extends U> other,
BiConsumer<? super T, ? super U> action) {
return biAcceptStage(asyncPool, other, action);
}
public <U> CompletableFuture<Void> thenAcceptBothAsync(
CompletionStage<? extends U> other,
BiConsumer<? super T, ? super U> action, Executor executor) {
return biAcceptStage(screenExecutor(executor), other, action);
}
public CompletableFuture<Void> runAfterBoth(CompletionStage<?> other,
Runnable action) {
return biRunStage(null, other, action);
}
public CompletableFuture<Void> runAfterBothAsync(CompletionStage<?> other,
Runnable action) {
return biRunStage(asyncPool, other, action);
}
public CompletableFuture<Void> runAfterBothAsync(CompletionStage<?> other,
Runnable action,
Executor executor) {
return biRunStage(screenExecutor(executor), other, action);
}
public <U> CompletableFuture<U> applyToEither(
CompletionStage<? extends T> other, Function<? super T, U> fn) {
return orApplyStage(null, other, fn);
}
public <U> CompletableFuture<U> applyToEitherAsync(
CompletionStage<? extends T> other, Function<? super T, U> fn) {
return orApplyStage(asyncPool, other, fn);
}
public <U> CompletableFuture<U> applyToEitherAsync(
CompletionStage<? extends T> other, Function<? super T, U> fn,
Executor executor) {
return orApplyStage(screenExecutor(executor), other, fn);
}
public CompletableFuture<Void> acceptEither(
CompletionStage<? extends T> other, Consumer<? super T> action) {
return orAcceptStage(null, other, action);
}
public CompletableFuture<Void> acceptEitherAsync(
CompletionStage<? extends T> other, Consumer<? super T> action) {
return orAcceptStage(asyncPool, other, action);
}
public CompletableFuture<Void> acceptEitherAsync(
CompletionStage<? extends T> other, Consumer<? super T> action,
Executor executor) {
return orAcceptStage(screenExecutor(executor), other, action);
}
public CompletableFuture<Void> runAfterEither(CompletionStage<?> other,
Runnable action) {
return orRunStage(null, other, action);
}
public CompletableFuture<Void> runAfterEitherAsync(CompletionStage<?> other,
Runnable action) {
return orRunStage(asyncPool, other, action);
}
public CompletableFuture<Void> runAfterEitherAsync(CompletionStage<?> other,
Runnable action,
Executor executor) {
return orRunStage(screenExecutor(executor), other, action);
}
public <U> CompletableFuture<U> thenCompose(
Function<? super T, ? extends CompletionStage<U>> fn) {
return uniComposeStage(null, fn);
}
public <U> CompletableFuture<U> thenComposeAsync(
Function<? super T, ? extends CompletionStage<U>> fn) {
return uniComposeStage(asyncPool, fn);
}
public <U> CompletableFuture<U> thenComposeAsync(
Function<? super T, ? extends CompletionStage<U>> fn,
Executor executor) {
return uniComposeStage(screenExecutor(executor), fn);
}
public CompletableFuture<T> whenComplete(
BiConsumer<? super T, ? super Throwable> action) {
return uniWhenCompleteStage(null, action);
}
public CompletableFuture<T> whenCompleteAsync(
BiConsumer<? super T, ? super Throwable> action) {
return uniWhenCompleteStage(asyncPool, action);
}
public CompletableFuture<T> whenCompleteAsync(
BiConsumer<? super T, ? super Throwable> action, Executor executor) {
return uniWhenCompleteStage(screenExecutor(executor), action);
}
public <U> CompletableFuture<U> handle(
BiFunction<? super T, Throwable, ? extends U> fn) {
return uniHandleStage(null, fn);
}
public <U> CompletableFuture<U> handleAsync(
BiFunction<? super T, Throwable, ? extends U> fn) {
return uniHandleStage(asyncPool, fn);
}
public <U> CompletableFuture<U> handleAsync(
BiFunction<? super T, Throwable, ? extends U> fn, Executor executor) {
return uniHandleStage(screenExecutor(executor), fn);
}
/**
* Returns this CompletableFuture.
*
* @return this CompletableFuture
*/
public CompletableFuture<T> toCompletableFuture() {
return this;
}
// not in interface CompletionStage
/**
* Returns a new CompletableFuture that is completed when this
* CompletableFuture completes, with the result of the given
* function of the exception triggering this CompletableFuture's
* completion when it completes exceptionally; otherwise, if this
* CompletableFuture completes normally, then the returned
* CompletableFuture also completes normally with the same value.
* Note: More flexible versions of this functionality are
* available using methods {@code whenComplete} and {@code handle}.
*
* @param fn the function to use to compute the value of the
* returned CompletableFuture if this CompletableFuture completed
* exceptionally
* @return the new CompletableFuture
*/
public CompletableFuture<T> exceptionally(
Function<Throwable, ? extends T> fn) {
return uniExceptionallyStage(fn);
}
/* ------------- Arbitrary-arity constructions -------------- */
/**
* Returns a new CompletableFuture that is completed when all of
* the given CompletableFutures complete. If any of the given
* CompletableFutures complete exceptionally, then the returned
* CompletableFuture also does so, with a CompletionException
* holding this exception as its cause. Otherwise, the results,
* if any, of the given CompletableFutures are not reflected in
* the returned CompletableFuture, but may be obtained by
* inspecting them individually. If no CompletableFutures are
* provided, returns a CompletableFuture completed with the value
* {@code null}.
*
* <p>Among the applications of this method is to await completion
* of a set of independent CompletableFutures before continuing a
* program, as in: {@code CompletableFuture.allOf(c1, c2,
* c3).join();}.
*
* @param cfs the CompletableFutures
* @return a new CompletableFuture that is completed when all of the
* given CompletableFutures complete
* @throws NullPointerException if the array or any of its elements are
* {@code null}
*/
public static CompletableFuture<Void> allOf(CompletableFuture<?>... cfs) {
return andTree(cfs, 0, cfs.length - 1);
}
/**
* Returns a new CompletableFuture that is completed when any of
* the given CompletableFutures complete, with the same result.
* Otherwise, if it completed exceptionally, the returned
* CompletableFuture also does so, with a CompletionException
* holding this exception as its cause. If no CompletableFutures
* are provided, returns an incomplete CompletableFuture.
*
* @param cfs the CompletableFutures
* @return a new CompletableFuture that is completed with the
* result or exception of any of the given CompletableFutures when
* one completes
* @throws NullPointerException if the array or any of its elements are
* {@code null}
*/
public static CompletableFuture<Object> anyOf(CompletableFuture<?>... cfs) {
return orTree(cfs, 0, cfs.length - 1);
}
/* ------------- Control and status methods -------------- */
/**
* If not already completed, completes this CompletableFuture with
* a {@link CancellationException}. Dependent CompletableFutures
* that have not already completed will also complete
* exceptionally, with a {@link CompletionException} caused by
* this {@code CancellationException}.
*
* @param mayInterruptIfRunning this value has no effect in this
* implementation because interrupts are not used to control
* processing.
*
* @return {@code true} if this task is now cancelled
*/
public boolean cancel(boolean mayInterruptIfRunning) {
boolean cancelled = (result == null) &&
internalComplete(new AltResult(new CancellationException()));
postComplete();
return cancelled || isCancelled();
}
/**
* Returns {@code true} if this CompletableFuture was cancelled
* before it completed normally.
*
* @return {@code true} if this CompletableFuture was cancelled
* before it completed normally
*/
public boolean isCancelled() {
Object r;
return ((r = result) instanceof AltResult) &&
(((AltResult)r).ex instanceof CancellationException);
}
/**
* Returns {@code true} if this CompletableFuture completed
* exceptionally, in any way. Possible causes include
* cancellation, explicit invocation of {@code
* completeExceptionally}, and abrupt termination of a
* CompletionStage action.
*
* @return {@code true} if this CompletableFuture completed
* exceptionally
*/
public boolean isCompletedExceptionally() {
Object r;
return ((r = result) instanceof AltResult) && r != NIL;
}
/**
* Forcibly sets or resets the value subsequently returned by
* method {@link #get()} and related methods, whether or not
* already completed. This method is designed for use only in
* error recovery actions, and even in such situations may result
* in ongoing dependent completions using established versus
* overwritten outcomes.
*
* @param value the completion value
*/
public void obtrudeValue(T value) {
result = (value == null) ? NIL : value;
postComplete();
}
/**
* Forcibly causes subsequent invocations of method {@link #get()}
* and related methods to throw the given exception, whether or
* not already completed. This method is designed for use only in
* error recovery actions, and even in such situations may result
* in ongoing dependent completions using established versus
* overwritten outcomes.
*
* @param ex the exception
* @throws NullPointerException if the exception is null
*/
public void obtrudeException(Throwable ex) {
if (ex == null) throw new NullPointerException();
result = new AltResult(ex);
postComplete();
}
/**
* Returns the estimated number of CompletableFutures whose
* completions are awaiting completion of this CompletableFuture.
* This method is designed for use in monitoring system state, not
* for synchronization control.
*
* @return the number of dependent CompletableFutures
*/
public int getNumberOfDependents() {
int count = 0;
for (Completion p = stack; p != null; p = p.next)
++count;
return count;
}
/**
* Returns a string identifying this CompletableFuture, as well as
* its completion state. The state, in brackets, contains the
* String {@code "Completed Normally"} or the String {@code
* "Completed Exceptionally"}, or the String {@code "Not
* completed"} followed by the number of CompletableFutures
* dependent upon its completion, if any.
*
* @return a string identifying this CompletableFuture, as well as its state
*/
public String toString() {
Object r = result;
int count;
return super.toString() +
((r == null) ?
(((count = getNumberOfDependents()) == 0) ?
"[Not completed]" :
"[Not completed, " + count + " dependents]") :
(((r instanceof AltResult) && ((AltResult)r).ex != null) ?
"[Completed exceptionally]" :
"[Completed normally]"));
}
// Unsafe mechanics
private static final sun.misc.Unsafe UNSAFE;
private static final long RESULT;
private static final long STACK;
private static final long NEXT;
static {
try {
final sun.misc.Unsafe u;
UNSAFE = u = sun.misc.Unsafe.getUnsafe();
Class<?> k = CompletableFuture.class;
RESULT = u.objectFieldOffset(k.getDeclaredField("result"));
STACK = u.objectFieldOffset(k.getDeclaredField("stack"));
NEXT = u.objectFieldOffset
(Completion.class.getDeclaredField("next"));
} catch (Exception x) {
throw new Error(x);
}
}
}
