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final promise optimization

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tommyskeff
2025-01-07 14:51:37 +00:00
parent fbeef9833b
commit e10db36a63
1 changed files with 21 additions and 14 deletions
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35
futur-api/src/main/java/dev/tommyjs/futur/promise/AbstractPromise.java
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@@ -11,37 +11,36 @@ import org.slf4j.Logger;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.Objects;
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.AbstractQueuedSynchronizer;
import java.util.function.Consumer;
@SuppressWarnings({"FieldMayBeFinal", "unchecked"})
public abstract class AbstractPromise<T, FS, FA> implements CompletablePromise<T> {
private static final VarHandle COMPLETION_HANDLE;
private static final VarHandle LISTENERS_HANDLE;
static {
try {
MethodHandles.Lookup lookup = MethodHandles.lookup();
COMPLETION_HANDLE = lookup.findVarHandle(AbstractPromise.class, "completion", PromiseCompletion.class);
LISTENERS_HANDLE = lookup.findVarHandle(AbstractPromise.class, "listeners", Collection.class);
} catch (ReflectiveOperationException e) {
throw new ExceptionInInitializerError(e);
}
}
private final AtomicReference<Collection<PromiseListener<T>>> listeners;
private final Sync sync;
@SuppressWarnings("FieldMayBeFinal")
private volatile Collection<PromiseListener<T>> listeners;
private volatile PromiseCompletion<T> completion;
public AbstractPromise() {
this.listeners = new AtomicReference<>(Collections.emptyList());
this.sync = new Sync();
this.listeners = Collections.EMPTY_LIST;
this.completion = null;
}
@@ -400,13 +399,20 @@ public abstract class AbstractPromise<T, FS, FA> implements CompletablePromise<T
}
private @NotNull Promise<T> addAnyListener(PromiseListener<T> listener) {
Collection<PromiseListener<T>> res = listeners.updateAndGet(v -> {
if (v == Collections.EMPTY_LIST) v = new ConcurrentLinkedQueue<>();
if (v != null) v.add(listener);
return v;
});
Collection<PromiseListener<T>> prev = listeners, next = null;
for (boolean haveNext = false;;) {
if (!haveNext) {
next = prev == Collections.EMPTY_LIST ? new ConcurrentLinkedQueue<>() : prev;
if (next != null) next.add(listener);
}
if (res == null) {
if (LISTENERS_HANDLE.weakCompareAndSet(this, prev, next))
break;
haveNext = (prev == (prev = listeners));
}
if (next == null) {
if (listener instanceof AsyncPromiseListener) {
callListenerAsync(listener, Objects.requireNonNull(getCompletion()));
} else {
@@ -492,7 +498,8 @@ public abstract class AbstractPromise<T, FS, FA> implements CompletablePromise<T
if (!COMPLETION_HANDLE.compareAndSet(this, null, cmp)) return;
sync.releaseShared(1);
Iterator<PromiseListener<T>> iter = listeners.getAndSet(null).iterator();
Iterator<PromiseListener<T>> iter = ((Iterable<PromiseListener<T>>) LISTENERS_HANDLE.getAndSet(this, null)).iterator();
try {
while (iter.hasNext()) {
PromiseListener<T> listener = iter.next();