ReplaySubject.java
/*
* Copyright (c) 2016-present, RxJava Contributors.
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is
* distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
* the License for the specific language governing permissions and limitations under the License.
*/
package io.reactivex.rxjava3.subjects;
import java.lang.reflect.Array;
import java.util.*;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.*;
import io.reactivex.rxjava3.annotations.*;
import io.reactivex.rxjava3.core.Observer;
import io.reactivex.rxjava3.core.Scheduler;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.internal.functions.ObjectHelper;
import io.reactivex.rxjava3.internal.util.*;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
/**
* Replays events (in a configurable bounded or unbounded manner) to current and late {@link Observer}s.
* <p>
* This subject does not have a public constructor by design; a new empty instance of this
* {@code ReplaySubject} can be created via the following {@code create} methods that
* allow specifying the retention policy for items:
* <ul>
* <li>{@link #create()} - creates an empty, unbounded {@code ReplaySubject} that
* caches all items and the terminal event it receives.
* <p>
* <img width="640" height="299" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/ReplaySubject.u.png" alt="">
* <p>
* <img width="640" height="398" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/ReplaySubject.ue.png" alt="">
* </li>
* <li>{@link #create(int)} - creates an empty, unbounded {@code ReplaySubject}
* with a hint about how many <b>total</b> items one expects to retain.
* </li>
* <li>{@link #createWithSize(int)} - creates an empty, size-bound {@code ReplaySubject}
* that retains at most the given number of the latest item it receives.
* <p>
* <img width="640" height="420" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/ReplaySubject.n.png" alt="">
* </li>
* <li>{@link #createWithTime(long, TimeUnit, Scheduler)} - creates an empty, time-bound
* {@code ReplaySubject} that retains items no older than the specified time amount.
* <p>
* <img width="640" height="415" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/ReplaySubject.t.png" alt="">
* </li>
* <li>{@link #createWithTimeAndSize(long, TimeUnit, Scheduler, int)} - creates an empty,
* time- and size-bound {@code ReplaySubject} that retains at most the given number
* items that are also not older than the specified time amount.
* <p>
* <img width="640" height="404" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/ReplaySubject.nt.png" alt="">
* </li>
* </ul>
* <p>
* Since a {@code Subject} is conceptionally derived from the {@code Processor} type in the Reactive Streams specification,
* {@code null}s are not allowed (<a href="https://github.com/reactive-streams/reactive-streams-jvm#2.13">Rule 2.13</a>) as
* parameters to {@link #onNext(Object)} and {@link #onError(Throwable)}. Such calls will result in a
* {@link NullPointerException} being thrown and the subject's state is not changed.
* <p>
* Since a {@code ReplaySubject} is an {@link io.reactivex.rxjava3.core.Observable}, it does not support backpressure.
* <p>
* When this {@code ReplaySubject} is terminated via {@link #onError(Throwable)} or {@link #onComplete()},
* late {@link io.reactivex.rxjava3.core.Observer}s will receive the retained/cached items first (if any) followed by the respective
* terminal event. If the {@code ReplaySubject} has a time-bound, the age of the retained/cached items are still considered
* when replaying and thus it may result in no items being emitted before the terminal event.
* <p>
* Once an {@code Observer} has subscribed, it will receive items continuously from that point on. Bounds only affect how
* many past items a new {@code Observer} will receive before it catches up with the live event feed.
* <p>
* Even though {@code ReplaySubject} implements the {@code Observer} interface, calling
* {@code onSubscribe} is not required (<a href="https://github.com/reactive-streams/reactive-streams-jvm#2.12">Rule 2.12</a>)
* if the subject is used as a standalone source. However, calling {@code onSubscribe}
* after the {@code ReplaySubject} reached its terminal state will result in the
* given {@code Disposable} being disposed immediately.
* <p>
* Calling {@link #onNext(Object)}, {@link #onError(Throwable)} and {@link #onComplete()}
* is required to be serialized (called from the same thread or called non-overlappingly from different threads
* through external means of serialization). The {@link #toSerialized()} method available to all {@code Subject}s
* provides such serialization and also protects against reentrance (i.e., when a downstream {@code Observer}
* consuming this subject also wants to call {@link #onNext(Object)} on this subject recursively).
* <p>
* This {@code ReplaySubject} supports the standard state-peeking methods {@link #hasComplete()}, {@link #hasThrowable()},
* {@link #getThrowable()} and {@link #hasObservers()} as well as means to read the retained/cached items
* in a non-blocking and thread-safe manner via {@link #hasValue()}, {@link #getValue()},
* {@link #getValues()} or {@link #getValues(Object[])}.
* <p>
* Note that due to concurrency requirements, a size- and time-bounded {@code ReplaySubject} may hold strong references to more
* source emissions than specified while it isn't terminated yet. Use the {@link #cleanupBuffer()} to allow
* such inaccessible items to be cleaned up by GC once no consumer references it anymore.
* <dl>
* <dt><b>Scheduler:</b></dt>
* <dd>{@code ReplaySubject} does not operate by default on a particular {@link io.reactivex.rxjava3.core.Scheduler} and
* the {@code Observer}s get notified on the thread the respective {@code onXXX} methods were invoked.
* Time-bound {@code ReplaySubject}s use the given {@code Scheduler} in their {@code create} methods
* as time source to timestamp of items received for the age checks.</dd>
* <dt><b>Error handling:</b></dt>
* <dd>When the {@link #onError(Throwable)} is called, the {@code ReplaySubject} enters into a terminal state
* and emits the same {@code Throwable} instance to the last set of {@code Observer}s. During this emission,
* if one or more {@code Observer}s dispose their respective {@code Disposable}s, the
* {@code Throwable} is delivered to the global error handler via
* {@link io.reactivex.rxjava3.plugins.RxJavaPlugins#onError(Throwable)} (multiple times if multiple {@code Observer}s
* cancel at once).
* If there were no {@code Observer}s subscribed to this {@code ReplaySubject} when the {@code onError()}
* was called, the global error handler is not invoked.
* </dd>
* </dl>
* <p>
* Example usage:
* <pre> {@code
ReplaySubject<Object> subject = ReplaySubject.create();
subject.onNext("one");
subject.onNext("two");
subject.onNext("three");
subject.onComplete();
// both of the following will get the onNext/onComplete calls from above
subject.subscribe(observer1);
subject.subscribe(observer2);
} </pre>
*
* @param <T> the value type
*/
public final class ReplaySubject<T> extends Subject<T> {
final ReplayBuffer<T> buffer;
final AtomicReference<ReplayDisposable<T>[]> observers;
@SuppressWarnings("rawtypes")
static final ReplayDisposable[] EMPTY = new ReplayDisposable[0];
@SuppressWarnings("rawtypes")
static final ReplayDisposable[] TERMINATED = new ReplayDisposable[0];
boolean done;
/**
* Creates an unbounded replay subject.
* <p>
* The internal buffer is backed by an {@link ArrayList} and starts with an initial capacity of 16. Once the
* number of items reaches this capacity, it will grow as necessary (usually by 50%). However, as the
* number of items grows, this causes frequent array reallocation and copying, and may hurt performance
* and latency. This can be avoided with the {@link #create(int)} overload which takes an initial capacity
* parameter and can be tuned to reduce the array reallocation frequency as needed.
*
* @param <T>
* the type of items observed and emitted by the Subject
* @return the created subject
*/
@CheckReturnValue
@NonNull
public static <T> ReplaySubject<T> create() {
return new ReplaySubject<>(new UnboundedReplayBuffer<>(16));
}
/**
* Creates an unbounded replay subject with the specified initial buffer capacity.
* <p>
* Use this method to avoid excessive array reallocation while the internal buffer grows to accommodate new
* items. For example, if you know that the buffer will hold 32k items, you can ask the
* {@code ReplaySubject} to preallocate its internal array with a capacity to hold that many items. Once
* the items start to arrive, the internal array won't need to grow, creating less garbage and no overhead
* due to frequent array-copying.
*
* @param <T>
* the type of items observed and emitted by the Subject
* @param capacityHint
* the initial buffer capacity
* @return the created subject
* @throws IllegalArgumentException if {@code capacityHint} is non-positive
*/
@CheckReturnValue
@NonNull
public static <T> ReplaySubject<T> create(int capacityHint) {
ObjectHelper.verifyPositive(capacityHint, "capacityHint");
return new ReplaySubject<>(new UnboundedReplayBuffer<>(capacityHint));
}
/**
* Creates a size-bounded replay subject.
* <p>
* In this setting, the {@code ReplaySubject} holds at most {@code size} items in its internal buffer and
* discards the oldest item.
* <p>
* When observers subscribe to a terminated {@code ReplaySubject}, they are guaranteed to see at most
* {@code size} {@code onNext} events followed by a termination event.
* <p>
* If an observer subscribes while the {@code ReplaySubject} is active, it will observe all items in the
* buffer at that point in time and each item observed afterwards, even if the buffer evicts items due to
* the size constraint in the mean time. In other words, once an Observer subscribes, it will receive items
* without gaps in the sequence.
*
* @param <T>
* the type of items observed and emitted by the Subject
* @param maxSize
* the maximum number of buffered items
* @return the created subject
* @throws IllegalArgumentException if {@code maxSize} is non-positive
*/
@CheckReturnValue
@NonNull
public static <T> ReplaySubject<T> createWithSize(int maxSize) {
ObjectHelper.verifyPositive(maxSize, "maxSize");
return new ReplaySubject<>(new SizeBoundReplayBuffer<>(maxSize));
}
/**
* Creates an unbounded replay subject with the bounded-implementation for testing purposes.
* <p>
* This variant behaves like the regular unbounded {@code ReplaySubject} created via {@link #create()} but
* uses the structures of the bounded-implementation. This is by no means intended for the replacement of
* the original, array-backed and unbounded {@code ReplaySubject} due to the additional overhead of the
* linked-list based internal buffer. The sole purpose is to allow testing and reasoning about the behavior
* of the bounded implementations without the interference of the eviction policies.
*
* @param <T>
* the type of items observed and emitted by the Subject
* @return the created subject
*/
/* test */ static <T> ReplaySubject<T> createUnbounded() {
return new ReplaySubject<>(new SizeBoundReplayBuffer<>(Integer.MAX_VALUE));
}
/**
* Creates a time-bounded replay subject.
* <p>
* In this setting, the {@code ReplaySubject} internally tags each observed item with a timestamp value
* supplied by the {@link Scheduler} and keeps only those whose age is less than the supplied time value
* converted to milliseconds. For example, an item arrives at T=0 and the max age is set to 5; at T>=5
* this first item is then evicted by any subsequent item or termination event, leaving the buffer empty.
* <p>
* Once the subject is terminated, observers subscribing to it will receive items that remained in the
* buffer after the terminal event, regardless of their age.
* <p>
* If an observer subscribes while the {@code ReplaySubject} is active, it will observe only those items
* from within the buffer that have an age less than the specified time, and each item observed thereafter,
* even if the buffer evicts items due to the time constraint in the mean time. In other words, once an
* observer subscribes, it observes items without gaps in the sequence except for any outdated items at the
* beginning of the sequence.
* <p>
* Note that terminal notifications ({@code onError} and {@code onComplete}) trigger eviction as well. For
* example, with a max age of 5, the first item is observed at T=0, then an {@code onComplete} notification
* arrives at T=10. If an observer subscribes at T=11, it will find an empty {@code ReplaySubject} with just
* an {@code onComplete} notification.
*
* @param <T>
* the type of items observed and emitted by the Subject
* @param maxAge
* the maximum age of the contained items
* @param unit
* the time unit of {@code time}
* @param scheduler
* the {@link Scheduler} that provides the current time
* @return the created subject
* @throws NullPointerException if {@code unit} or {@code scheduler} is {@code null}
* @throws IllegalArgumentException if {@code maxAge} is non-positive
*/
@CheckReturnValue
@NonNull
public static <T> ReplaySubject<T> createWithTime(long maxAge, @NonNull TimeUnit unit, @NonNull Scheduler scheduler) {
ObjectHelper.verifyPositive(maxAge, "maxAge");
Objects.requireNonNull(unit, "unit is null");
Objects.requireNonNull(scheduler, "scheduler is null");
return new ReplaySubject<>(new SizeAndTimeBoundReplayBuffer<>(Integer.MAX_VALUE, maxAge, unit, scheduler));
}
/**
* Creates a time- and size-bounded replay subject.
* <p>
* In this setting, the {@code ReplaySubject} internally tags each received item with a timestamp value
* supplied by the {@link Scheduler} and holds at most {@code size} items in its internal buffer. It evicts
* items from the start of the buffer if their age becomes less-than or equal to the supplied age in
* milliseconds or the buffer reaches its {@code size} limit.
* <p>
* When observers subscribe to a terminated {@code ReplaySubject}, they observe the items that remained in
* the buffer after the terminal notification, regardless of their age, but at most {@code size} items.
* <p>
* If an observer subscribes while the {@code ReplaySubject} is active, it will observe only those items
* from within the buffer that have age less than the specified time and each subsequent item, even if the
* buffer evicts items due to the time constraint in the mean time. In other words, once an observer
* subscribes, it observes items without gaps in the sequence except for the outdated items at the beginning
* of the sequence.
* <p>
* Note that terminal notifications ({@code onError} and {@code onComplete}) trigger eviction as well. For
* example, with a max age of 5, the first item is observed at T=0, then an {@code onComplete} notification
* arrives at T=10. If an observer subscribes at T=11, it will find an empty {@code ReplaySubject} with just
* an {@code onComplete} notification.
*
* @param <T>
* the type of items observed and emitted by the Subject
* @param maxAge
* the maximum age of the contained items
* @param unit
* the time unit of {@code time}
* @param maxSize
* the maximum number of buffered items
* @param scheduler
* the {@link Scheduler} that provides the current time
* @return the created subject
* @throws NullPointerException if {@code unit} or {@code scheduler} is {@code null}
* @throws IllegalArgumentException if {@code maxAge} or {@code maxSize} is non-positive
*/
@CheckReturnValue
@NonNull
public static <T> ReplaySubject<T> createWithTimeAndSize(long maxAge, @NonNull TimeUnit unit, @NonNull Scheduler scheduler, int maxSize) {
ObjectHelper.verifyPositive(maxSize, "maxSize");
ObjectHelper.verifyPositive(maxAge, "maxAge");
Objects.requireNonNull(unit, "unit is null");
Objects.requireNonNull(scheduler, "scheduler is null");
return new ReplaySubject<>(new SizeAndTimeBoundReplayBuffer<>(maxSize, maxAge, unit, scheduler));
}
/**
* Constructs a ReplayProcessor with the given custom ReplayBuffer instance.
* @param buffer the ReplayBuffer instance, not null (not verified)
*/
@SuppressWarnings("unchecked")
ReplaySubject(ReplayBuffer<T> buffer) {
this.buffer = buffer;
this.observers = new AtomicReference<>(EMPTY);
}
@Override
protected void subscribeActual(Observer<? super T> observer) {
ReplayDisposable<T> rs = new ReplayDisposable<>(observer, this);
observer.onSubscribe(rs);
if (add(rs)) {
if (rs.cancelled) {
remove(rs);
return;
}
}
buffer.replay(rs);
}
@Override
public void onSubscribe(Disposable d) {
if (done) {
d.dispose();
}
}
@Override
public void onNext(T t) {
ExceptionHelper.nullCheck(t, "onNext called with a null value.");
if (done) {
return;
}
ReplayBuffer<T> b = buffer;
b.add(t);
for (ReplayDisposable<T> rs : observers.get()) {
b.replay(rs);
}
}
@Override
public void onError(Throwable t) {
ExceptionHelper.nullCheck(t, "onError called with a null Throwable.");
if (done) {
RxJavaPlugins.onError(t);
return;
}
done = true;
Object o = NotificationLite.error(t);
ReplayBuffer<T> b = buffer;
b.addFinal(o);
for (ReplayDisposable<T> rs : terminate(o)) {
b.replay(rs);
}
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
Object o = NotificationLite.complete();
ReplayBuffer<T> b = buffer;
b.addFinal(o);
for (ReplayDisposable<T> rs : terminate(o)) {
b.replay(rs);
}
}
@Override
@CheckReturnValue
public boolean hasObservers() {
return observers.get().length != 0;
}
@CheckReturnValue
/* test */ int observerCount() {
return observers.get().length;
}
@Override
@Nullable
@CheckReturnValue
public Throwable getThrowable() {
Object o = buffer.get();
if (NotificationLite.isError(o)) {
return NotificationLite.getError(o);
}
return null;
}
/**
* Returns a single value the Subject currently has or null if no such value exists.
* <p>The method is thread-safe.
* @return a single value the Subject currently has or null if no such value exists
*/
@Nullable
@CheckReturnValue
public T getValue() {
return buffer.getValue();
}
/**
* Makes sure the item cached by the head node in a bounded
* ReplaySubject is released (as it is never part of a replay).
* <p>
* By default, live bounded buffers will remember one item before
* the currently receivable one to ensure subscribers can always
* receive a continuous sequence of items. A terminated ReplaySubject
* automatically releases this inaccessible item.
* <p>
* The method must be called sequentially, similar to the standard
* {@code onXXX} methods.
* <p>History: 2.1.11 - experimental
* @since 2.2
*/
public void cleanupBuffer() {
buffer.trimHead();
}
/** An empty array to avoid allocation in getValues(). */
private static final Object[] EMPTY_ARRAY = new Object[0];
/**
* Returns an Object array containing snapshot all values of the Subject.
* <p>The method is thread-safe.
* @return the array containing the snapshot of all values of the Subject
*/
@CheckReturnValue
public Object[] getValues() {
@SuppressWarnings("unchecked")
T[] a = (T[])EMPTY_ARRAY;
T[] b = getValues(a);
if (b == EMPTY_ARRAY) {
return new Object[0];
}
return b;
}
/**
* Returns a typed array containing a snapshot of all values of the Subject.
* <p>The method follows the conventions of Collection.toArray by setting the array element
* after the last value to null (if the capacity permits).
* <p>The method is thread-safe.
* @param array the target array to copy values into if it fits
* @return the given array if the values fit into it or a new array containing all values
*/
@CheckReturnValue
public T[] getValues(T[] array) {
return buffer.getValues(array);
}
@Override
@CheckReturnValue
public boolean hasComplete() {
Object o = buffer.get();
return NotificationLite.isComplete(o);
}
@Override
@CheckReturnValue
public boolean hasThrowable() {
Object o = buffer.get();
return NotificationLite.isError(o);
}
/**
* Returns true if the subject has any value.
* <p>The method is thread-safe.
* @return true if the subject has any value
*/
@CheckReturnValue
public boolean hasValue() {
return buffer.size() != 0; // NOPMD
}
@CheckReturnValue
/* test*/ int size() {
return buffer.size();
}
boolean add(ReplayDisposable<T> rs) {
for (;;) {
ReplayDisposable<T>[] a = observers.get();
if (a == TERMINATED) {
return false;
}
int len = a.length;
@SuppressWarnings("unchecked")
ReplayDisposable<T>[] b = new ReplayDisposable[len + 1];
System.arraycopy(a, 0, b, 0, len);
b[len] = rs;
if (observers.compareAndSet(a, b)) {
return true;
}
}
}
@SuppressWarnings("unchecked")
void remove(ReplayDisposable<T> rs) {
for (;;) {
ReplayDisposable<T>[] a = observers.get();
if (a == TERMINATED || a == EMPTY) {
return;
}
int len = a.length;
int j = -1;
for (int i = 0; i < len; i++) {
if (a[i] == rs) {
j = i;
break;
}
}
if (j < 0) {
return;
}
ReplayDisposable<T>[] b;
if (len == 1) {
b = EMPTY;
} else {
b = new ReplayDisposable[len - 1];
System.arraycopy(a, 0, b, 0, j);
System.arraycopy(a, j + 1, b, j, len - j - 1);
}
if (observers.compareAndSet(a, b)) {
return;
}
}
}
@SuppressWarnings("unchecked")
ReplayDisposable<T>[] terminate(Object terminalValue) {
buffer.compareAndSet(null, terminalValue);
return observers.getAndSet(TERMINATED);
}
/**
* Abstraction over a buffer that receives events and replays them to
* individual Observers.
*
* @param <T> the value type
*/
interface ReplayBuffer<T> {
void add(T value);
void addFinal(Object notificationLite);
void replay(ReplayDisposable<T> rs);
int size();
@Nullable
T getValue();
T[] getValues(T[] array);
/**
* Returns the terminal NotificationLite object or null if not yet terminated.
* @return the terminal NotificationLite object or null if not yet terminated
*/
Object get();
/**
* Atomically compares and sets the next terminal NotificationLite object if the
* current equals to the expected NotificationLite object.
* @param expected the expected NotificationLite object
* @param next the next NotificationLite object
* @return true if successful
*/
boolean compareAndSet(Object expected, Object next);
/**
* Make sure an old inaccessible head value is released
* in a bounded buffer.
*/
void trimHead();
}
static final class ReplayDisposable<T> extends AtomicInteger implements Disposable {
private static final long serialVersionUID = 466549804534799122L;
final Observer<? super T> downstream;
final ReplaySubject<T> state;
Object index;
volatile boolean cancelled;
ReplayDisposable(Observer<? super T> actual, ReplaySubject<T> state) {
this.downstream = actual;
this.state = state;
}
@Override
public void dispose() {
if (!cancelled) {
cancelled = true;
state.remove(this);
}
}
@Override
public boolean isDisposed() {
return cancelled;
}
}
static final class UnboundedReplayBuffer<T>
extends AtomicReference<Object>
implements ReplayBuffer<T> {
private static final long serialVersionUID = -733876083048047795L;
final List<Object> buffer;
volatile boolean done;
volatile int size;
UnboundedReplayBuffer(int capacityHint) {
this.buffer = new ArrayList<>(capacityHint);
}
@Override
public void add(T value) {
buffer.add(value);
size++;
}
@Override
public void addFinal(Object notificationLite) {
buffer.add(notificationLite);
trimHead();
size++;
done = true;
}
@Override
public void trimHead() {
// no-op in this type of buffer
}
@Override
@Nullable
@SuppressWarnings("unchecked")
public T getValue() {
int s = size;
if (s != 0) {
List<Object> b = buffer;
Object o = b.get(s - 1);
if (NotificationLite.isComplete(o) || NotificationLite.isError(o)) {
if (s == 1) {
return null;
}
return (T)b.get(s - 2);
}
return (T)o;
}
return null;
}
@Override
@SuppressWarnings("unchecked")
public T[] getValues(T[] array) {
int s = size;
if (s == 0) {
if (array.length != 0) {
array[0] = null;
}
return array;
}
List<Object> b = buffer;
Object o = b.get(s - 1);
if (NotificationLite.isComplete(o) || NotificationLite.isError(o)) {
s--;
if (s == 0) {
if (array.length != 0) {
array[0] = null;
}
return array;
}
}
if (array.length < s) {
array = (T[])Array.newInstance(array.getClass().getComponentType(), s);
}
for (int i = 0; i < s; i++) {
array[i] = (T)b.get(i);
}
if (array.length > s) {
array[s] = null;
}
return array;
}
@Override
@SuppressWarnings("unchecked")
public void replay(ReplayDisposable<T> rs) {
if (rs.getAndIncrement() != 0) {
return;
}
int missed = 1;
final List<Object> b = buffer;
final Observer<? super T> a = rs.downstream;
Integer indexObject = (Integer)rs.index;
int index;
if (indexObject != null) {
index = indexObject;
} else {
index = 0;
rs.index = 0;
}
for (;;) {
if (rs.cancelled) {
rs.index = null;
return;
}
int s = size;
while (s != index) {
if (rs.cancelled) {
rs.index = null;
return;
}
Object o = b.get(index);
if (done) {
if (index + 1 == s) {
s = size;
if (index + 1 == s) {
if (NotificationLite.isComplete(o)) {
a.onComplete();
} else {
a.onError(NotificationLite.getError(o));
}
rs.index = null;
rs.cancelled = true;
return;
}
}
}
a.onNext((T)o);
index++;
}
if (index != size) {
continue;
}
rs.index = index;
missed = rs.addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
@Override
public int size() {
int s = size;
if (s != 0) {
Object o = buffer.get(s - 1);
if (NotificationLite.isComplete(o) || NotificationLite.isError(o)) {
return s - 1;
}
return s;
}
return 0;
}
}
static final class Node<T> extends AtomicReference<Node<T>> {
private static final long serialVersionUID = 6404226426336033100L;
final T value;
Node(T value) {
this.value = value;
}
}
static final class TimedNode<T> extends AtomicReference<TimedNode<T>> {
private static final long serialVersionUID = 6404226426336033100L;
final T value;
final long time;
TimedNode(T value, long time) {
this.value = value;
this.time = time;
}
}
static final class SizeBoundReplayBuffer<T>
extends AtomicReference<Object>
implements ReplayBuffer<T> {
private static final long serialVersionUID = 1107649250281456395L;
final int maxSize;
int size;
volatile Node<Object> head;
Node<Object> tail;
volatile boolean done;
SizeBoundReplayBuffer(int maxSize) {
this.maxSize = maxSize;
Node<Object> h = new Node<>(null);
this.tail = h;
this.head = h;
}
void trim() {
if (size > maxSize) {
size--;
Node<Object> h = head;
head = h.get();
}
}
@Override
public void add(T value) {
Node<Object> n = new Node<>(value);
Node<Object> t = tail;
tail = n;
size++;
t.set(n); // releases both the tail and size
trim();
}
@Override
public void addFinal(Object notificationLite) {
Node<Object> n = new Node<>(notificationLite);
Node<Object> t = tail;
tail = n;
size++;
t.lazySet(n); // releases both the tail and size
trimHead();
done = true;
}
/**
* Replace a non-empty head node with an empty one to
* allow the GC of the inaccessible old value.
*/
@Override
public void trimHead() {
Node<Object> h = head;
if (h.value != null) {
Node<Object> n = new Node<>(null);
n.lazySet(h.get());
head = n;
}
}
@Override
@Nullable
@SuppressWarnings("unchecked")
public T getValue() {
Node<Object> prev = null;
Node<Object> h = head;
for (;;) {
Node<Object> next = h.get();
if (next == null) {
break;
}
prev = h;
h = next;
}
Object v = h.value;
if (v == null) {
return null;
}
if (NotificationLite.isComplete(v) || NotificationLite.isError(v)) {
return (T)prev.value;
}
return (T)v;
}
@Override
@SuppressWarnings("unchecked")
public T[] getValues(T[] array) {
Node<Object> h = head;
int s = size();
if (s == 0) {
if (array.length != 0) {
array[0] = null;
}
} else {
if (array.length < s) {
array = (T[])Array.newInstance(array.getClass().getComponentType(), s);
}
int i = 0;
while (i != s) {
Node<Object> next = h.get();
array[i] = (T)next.value;
i++;
h = next;
}
if (array.length > s) {
array[s] = null;
}
}
return array;
}
@Override
@SuppressWarnings("unchecked")
public void replay(ReplayDisposable<T> rs) {
if (rs.getAndIncrement() != 0) {
return;
}
int missed = 1;
final Observer<? super T> a = rs.downstream;
Node<Object> index = (Node<Object>)rs.index;
if (index == null) {
index = head;
}
for (;;) {
for (;;) {
if (rs.cancelled) {
rs.index = null;
return;
}
Node<Object> n = index.get();
if (n == null) {
break;
}
Object o = n.value;
if (done) {
if (n.get() == null) {
if (NotificationLite.isComplete(o)) {
a.onComplete();
} else {
a.onError(NotificationLite.getError(o));
}
rs.index = null;
rs.cancelled = true;
return;
}
}
a.onNext((T)o);
index = n;
}
if (index.get() != null) {
continue;
}
rs.index = index;
missed = rs.addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
@Override
public int size() {
int s = 0;
Node<Object> h = head;
while (s != Integer.MAX_VALUE) {
Node<Object> next = h.get();
if (next == null) {
Object o = h.value;
if (NotificationLite.isComplete(o) || NotificationLite.isError(o)) {
s--;
}
break;
}
s++;
h = next;
}
return s;
}
}
static final class SizeAndTimeBoundReplayBuffer<T>
extends AtomicReference<Object>
implements ReplayBuffer<T> {
private static final long serialVersionUID = -8056260896137901749L;
final int maxSize;
final long maxAge;
final TimeUnit unit;
final Scheduler scheduler;
int size;
volatile TimedNode<Object> head;
TimedNode<Object> tail;
volatile boolean done;
SizeAndTimeBoundReplayBuffer(int maxSize, long maxAge, TimeUnit unit, Scheduler scheduler) {
this.maxSize = maxSize;
this.maxAge = maxAge;
this.unit = unit;
this.scheduler = scheduler;
TimedNode<Object> h = new TimedNode<>(null, 0L);
this.tail = h;
this.head = h;
}
void trim() {
if (size > maxSize) {
size--;
TimedNode<Object> h = head;
head = h.get();
}
long limit = scheduler.now(unit) - maxAge;
TimedNode<Object> h = head;
for (;;) {
if (size <= 1) {
head = h;
break;
}
TimedNode<Object> next = h.get();
if (next.time > limit) {
head = h;
break;
}
h = next;
size--;
}
}
void trimFinal() {
long limit = scheduler.now(unit) - maxAge;
TimedNode<Object> h = head;
for (;;) {
TimedNode<Object> next = h.get();
if (next.get() == null) {
if (h.value != null) {
TimedNode<Object> lasth = new TimedNode<>(null, 0L);
lasth.lazySet(h.get());
head = lasth;
} else {
head = h;
}
break;
}
if (next.time > limit) {
if (h.value != null) {
TimedNode<Object> lasth = new TimedNode<>(null, 0L);
lasth.lazySet(h.get());
head = lasth;
} else {
head = h;
}
break;
}
h = next;
}
}
@Override
public void add(T value) {
TimedNode<Object> n = new TimedNode<>(value, scheduler.now(unit));
TimedNode<Object> t = tail;
tail = n;
size++;
t.set(n); // releases both the tail and size
trim();
}
@Override
public void addFinal(Object notificationLite) {
TimedNode<Object> n = new TimedNode<>(notificationLite, Long.MAX_VALUE);
TimedNode<Object> t = tail;
tail = n;
size++;
t.lazySet(n); // releases both the tail and size
trimFinal();
done = true;
}
/**
* Replace a non-empty head node with an empty one to
* allow the GC of the inaccessible old value.
*/
@Override
public void trimHead() {
TimedNode<Object> h = head;
if (h.value != null) {
TimedNode<Object> n = new TimedNode<>(null, 0);
n.lazySet(h.get());
head = n;
}
}
@Override
@Nullable
@SuppressWarnings("unchecked")
public T getValue() {
TimedNode<Object> prev = null;
TimedNode<Object> h = head;
for (;;) {
TimedNode<Object> next = h.get();
if (next == null) {
break;
}
prev = h;
h = next;
}
long limit = scheduler.now(unit) - maxAge;
if (h.time < limit) {
return null;
}
Object v = h.value;
if (v == null) {
return null;
}
if (NotificationLite.isComplete(v) || NotificationLite.isError(v)) {
return (T)prev.value;
}
return (T)v;
}
TimedNode<Object> getHead() {
TimedNode<Object> index = head;
// skip old entries
long limit = scheduler.now(unit) - maxAge;
TimedNode<Object> next = index.get();
while (next != null) {
long ts = next.time;
if (ts > limit) {
break;
}
index = next;
next = index.get();
}
return index;
}
@Override
@SuppressWarnings("unchecked")
public T[] getValues(T[] array) {
TimedNode<Object> h = getHead();
int s = size(h);
if (s == 0) {
if (array.length != 0) {
array[0] = null;
}
} else {
if (array.length < s) {
array = (T[])Array.newInstance(array.getClass().getComponentType(), s);
}
int i = 0;
while (i != s) {
TimedNode<Object> next = h.get();
array[i] = (T)next.value;
i++;
h = next;
}
if (array.length > s) {
array[s] = null;
}
}
return array;
}
@Override
@SuppressWarnings("unchecked")
public void replay(ReplayDisposable<T> rs) {
if (rs.getAndIncrement() != 0) {
return;
}
int missed = 1;
final Observer<? super T> a = rs.downstream;
TimedNode<Object> index = (TimedNode<Object>)rs.index;
if (index == null) {
index = getHead();
}
for (;;) {
for (;;) {
if (rs.cancelled) {
rs.index = null;
return;
}
TimedNode<Object> n = index.get();
if (n == null) {
break;
}
Object o = n.value;
if (done) {
if (n.get() == null) {
if (NotificationLite.isComplete(o)) {
a.onComplete();
} else {
a.onError(NotificationLite.getError(o));
}
rs.index = null;
rs.cancelled = true;
return;
}
}
a.onNext((T)o);
index = n;
}
rs.index = index;
missed = rs.addAndGet(-missed);
if (missed == 0) {
break;
}
}
}
@Override
public int size() {
return size(getHead());
}
int size(TimedNode<Object> h) {
int s = 0;
while (s != Integer.MAX_VALUE) {
TimedNode<Object> next = h.get();
if (next == null) {
Object o = h.value;
if (NotificationLite.isComplete(o) || NotificationLite.isError(o)) {
s--;
}
break;
}
s++;
h = next;
}
return s;
}
}
}