Please wait. This can take some minutes ...
Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $
You can buy this project and download/modify it how often you want.
reactor.core.publisher.MonoCacheInvalidateIf Maven / Gradle / Ivy
Go to download
Easy Redis Java client and Real-Time Data Platform. Valkey compatible. Sync/Async/RxJava3/Reactive API. Client side caching. Over 50 Redis based Java objects and services: JCache API, Apache Tomcat, Hibernate, Spring, Set, Multimap, SortedSet, Map, List, Queue, Deque, Semaphore, Lock, AtomicLong, Map Reduce, Bloom filter, Scheduler, RPC
/*
* Copyright (c) 2021 VMware Inc. or its affiliates, All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package reactor.core.publisher;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.function.Predicate;
import org.reactivestreams.Subscription;
import reactor.core.CoreSubscriber;
import reactor.util.Logger;
import reactor.util.Loggers;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;
/**
* A caching operator that uses a {@link Predicate} to potentially invalidate the cached value whenever a late subscriber arrives.
* Subscribers accumulated between the upstream susbscription is triggered and the actual value is received and stored
* don't trigger the predicate, as the operator assumes that values are not invalid at reception.
*
* @author Simon Baslé
*/
final class MonoCacheInvalidateIf extends InternalMonoOperator {
/**
* A state-holding interface for {@link MonoCacheInvalidateIf} and {@link MonoCacheInvalidateWhen},
* leaner than a {@link Signal} to represent valued state, and allowing specific subclasses for pending
* state and disconnected state.
*
* @param the type of data cached by the parent operator
*/
static interface State {
@Nullable
T get();
void clear();
}
/**
* Common implementation of {@link State} for storing the cached value.
*
* @param the type of data cached by the parent operator
*/
static final class ValueState implements State {
@Nullable
T value;
ValueState(T value) {
this.value = value;
}
@Nullable
@Override
public T get() {
return value;
}
@Override
public void clear() {
this.value = null;
}
}
/**
* Singleton implementation of an empty {@link State}, to represent initial state
* pre-subscription, when no caching has been requested.
*/
static final State> EMPTY_STATE = new State() {
@Nullable
@Override
public Object get() {
return null;
}
@Override
public void clear() {
//NO-OP
}
};
final Predicate super T> shouldInvalidatePredicate;
volatile State state;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater STATE =
AtomicReferenceFieldUpdater.newUpdater(MonoCacheInvalidateIf.class, State.class, "state");
MonoCacheInvalidateIf(Mono source, Predicate super T> invalidationPredicate) {
super(source);
this.shouldInvalidatePredicate = Objects.requireNonNull(invalidationPredicate, "invalidationPredicate");
@SuppressWarnings("unchecked")
State state = (State) EMPTY_STATE;
this.state = state;
}
@Override
public CoreSubscriber super T> subscribeOrReturn(CoreSubscriber super T> actual) {
CacheMonoSubscriber inner = new CacheMonoSubscriber<>(actual);
//important: onSubscribe should be deferred until we're sure we're in the Coordinator case OR the cached value passes the predicate
for(;;) {
State state = this.state;
if (state == EMPTY_STATE || state instanceof CoordinatorSubscriber) {
boolean connectToUpstream = false;
CoordinatorSubscriber coordinator;
if (state == EMPTY_STATE) {
coordinator = new CoordinatorSubscriber<>(this, this.source);
if (!STATE.compareAndSet(this, EMPTY_STATE, coordinator)) {
continue;
}
connectToUpstream = true;
}
else {
coordinator = (CoordinatorSubscriber) state;
}
if (coordinator.add(inner)) {
if (inner.isCancelled()) {
coordinator.remove(inner);
}
else {
inner.coordinator = coordinator;
actual.onSubscribe(inner);
}
if (connectToUpstream) {
coordinator.delayedSubscribe();
}
return null;
}
}
else {
//state is an actual signal, cached
T cached = state.get();
try {
boolean invalidated = this.shouldInvalidatePredicate.test(cached);
if (invalidated) {
if (STATE.compareAndSet(this, state, EMPTY_STATE)) {
Operators.onDiscard(cached, actual.currentContext());
}
//we CAS but even if it fails we want to loop back
continue;
}
}
catch (Throwable error) {
if (STATE.compareAndSet(this, state, EMPTY_STATE)) {
Operators.onDiscard(cached, actual.currentContext());
Operators.error(actual, error);
return null;
}
}
actual.onSubscribe(inner);
inner.complete(state.get());
return null;
}
}
}
@Override
public Object scanUnsafe(Attr key) {
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
static final class CoordinatorSubscriber implements InnerConsumer, State {
final MonoCacheInvalidateIf main;
final Mono extends T> source;
//no need for volatile: only used in onNext/onError/onComplete
boolean done = false;
volatile Subscription upstream;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater UPSTREAM =
AtomicReferenceFieldUpdater.newUpdater(CoordinatorSubscriber.class, Subscription.class, "upstream");
volatile CacheMonoSubscriber[] subscribers;
@SuppressWarnings("rawtypes")
static final AtomicReferenceFieldUpdater SUBSCRIBERS =
AtomicReferenceFieldUpdater.newUpdater(CoordinatorSubscriber.class, CacheMonoSubscriber[].class, "subscribers");
@SuppressWarnings("rawtypes")
private static final CacheMonoSubscriber[] COORDINATOR_DONE = new CacheMonoSubscriber[0];
@SuppressWarnings("rawtypes")
private static final CacheMonoSubscriber[] COORDINATOR_INIT = new CacheMonoSubscriber[0];
@SuppressWarnings("unchecked")
CoordinatorSubscriber(MonoCacheInvalidateIf main, Mono extends T> source) {
this.main = main;
this.source = source;
this.subscribers = COORDINATOR_INIT;
}
/**
* unused in this context as the {@link State} interface is only
* implemented for use in the main's STATE compareAndSet.
*/
@Nullable
@Override
public T get() {
throw new UnsupportedOperationException("coordinator State#get shouldn't be used");
}
/**
* unused in this context as the {@link State} interface is only
* implemented for use in the main's STATE compareAndSet.
*/
@Override
public void clear() {
//NO-OP
}
final boolean add(CacheMonoSubscriber toAdd) {
for (; ; ) {
CacheMonoSubscriber[] a = subscribers;
if (a == COORDINATOR_DONE) {
return false;
}
int n = a.length;
@SuppressWarnings("unchecked")
CacheMonoSubscriber[] b = new CacheMonoSubscriber[n + 1];
System.arraycopy(a, 0, b, 0, n);
b[n] = toAdd;
if (SUBSCRIBERS.compareAndSet(this, a, b)) {
return true;
}
}
}
final void remove(CacheMonoSubscriber toRemove) {
for (; ; ) {
CacheMonoSubscriber[] a = subscribers;
if (a == COORDINATOR_DONE || a == COORDINATOR_INIT) {
return;
}
int n = a.length;
int j = -1;
for (int i = 0; i < n; i++) {
if (a[i] == toRemove) {
j = i;
break;
}
}
if (j < 0) {
return;
}
if (n == 1) {
if (SUBSCRIBERS.compareAndSet(this, a, COORDINATOR_DONE)) {
//cancel the subscription no matter what, at this point coordinator is done and cannot accept new subscribers
this.upstream.cancel();
//only switch to EMPTY_STATE if the current state is this coordinator
STATE.compareAndSet(this.main, this, EMPTY_STATE);
return;
}
//else loop back
}
else {
CacheMonoSubscriber>[] b = new CacheMonoSubscriber>[n - 1];
System.arraycopy(a, 0, b, 0, j);
System.arraycopy(a, j + 1, b, j, n - j - 1);
if (SUBSCRIBERS.compareAndSet(this, a, b)) {
return;
}
//else loop back
}
}
}
void delayedSubscribe() {
Subscription old = UPSTREAM.getAndSet(this, null);
if (old != null && old != Operators.cancelledSubscription()) {
old.cancel();
}
source.subscribe(this);
}
@Override
public void onSubscribe(Subscription s) {
//this only happens if there was at least one incoming subscriber
if (UPSTREAM.compareAndSet(this, null, s)) {
s.request(Long.MAX_VALUE);
}
}
@Override
public void onNext(T t) {
if (main.state != this || done) {
Operators.onNextDropped(t, currentContext());
return;
}
done = true;
//note the predicate is not applied upon reception of the value to be cached. only late subscribers will trigger revalidation.
State valueState = new ValueState<>(t);
if (STATE.compareAndSet(main, this, valueState)) {
for (@SuppressWarnings("unchecked") CacheMonoSubscriber inner : SUBSCRIBERS.getAndSet(this, COORDINATOR_DONE)) {
inner.complete(t);
}
}
}
@Override
public void onError(Throwable t) {
if (main.state != this || done) {
Operators.onErrorDropped(t, currentContext());
return;
}
if (STATE.compareAndSet(main, this, EMPTY_STATE)) {
for (@SuppressWarnings("unchecked") CacheMonoSubscriber inner : SUBSCRIBERS.getAndSet(this, COORDINATOR_DONE)) {
inner.onError(t);
}
}
}
@Override
public void onComplete() {
if (done) {
done = false;
return;
}
if (STATE.compareAndSet(main, this, EMPTY_STATE)) {
for (@SuppressWarnings("unchecked") CacheMonoSubscriber inner : SUBSCRIBERS.getAndSet(this, COORDINATOR_DONE)) {
inner.onError(new NoSuchElementException("cacheInvalidateWhen expects a value, source completed empty"));
}
}
}
@Override
public Context currentContext() {
return Operators.multiSubscribersContext(subscribers);
}
@Nullable
@Override
public Object scanUnsafe(Attr key) {
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return null;
}
}
static final class CacheMonoSubscriber extends Operators.MonoSubscriber {
CoordinatorSubscriber coordinator;
CacheMonoSubscriber(CoreSubscriber super T> actual) {
super(actual);
}
@Override
public void cancel() {
super.cancel();
CoordinatorSubscriber coordinator = this.coordinator;
if (coordinator != null) {
coordinator.remove(this);
}
}
@Override
public Object scanUnsafe(Attr key) {
if (key == Attr.PARENT) return coordinator.main;
if (key == Attr.RUN_STYLE) return Attr.RunStyle.SYNC;
return super.scanUnsafe(key);
}
}
}