/*
* Copyright (c) 2011-2017 Pivotal Software Inc, 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
*
* 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 reactor.core.publisher;
import java.util.
Objects;
import java.util.
Queue;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.
AtomicLongFieldUpdater;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import java.util.function.
Function;
import java.util.function.
Supplier;
import java.util.stream.
Stream;
import org.reactivestreams.
Publisher;
import org.reactivestreams.
Subscriber;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Exceptions;
import reactor.core.
Fuseable;
import reactor.core.
Fuseable.
QueueSubscription;
import reactor.core.
Scannable;
import reactor.core.publisher.
FluxConcatMap.
ErrorMode;
import reactor.util.annotation.
Nullable;
import reactor.util.concurrent.
Queues;
import reactor.util.context.
Context;
/**
* Maps each upstream value into a Publisher and concatenates them into one
* sequence of items.
*
* @param <T> the source value type
* @param <R> the output value type
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxMergeSequential<T, R> extends
FluxOperator<T, R> {
final
ErrorMode errorMode;
final
Function<? super T, ? extends
Publisher<? extends R>>
mapper;
final int
maxConcurrency;
final int
prefetch;
final
Supplier<
Queue<
MergeSequentialInner<R>>>
queueSupplier;
FluxMergeSequential(
Flux<? extends T>
source,
Function<? super T, ? extends
Publisher<? extends R>>
mapper,
int
maxConcurrency, int
prefetch,
ErrorMode errorMode) {
this(
source,
mapper,
maxConcurrency,
prefetch,
errorMode,
Queues.
get(
Math.
max(
prefetch,
maxConcurrency)));
}
//for testing purpose
FluxMergeSequential(
Flux<? extends T>
source,
Function<? super T, ? extends
Publisher<? extends R>>
mapper,
int
maxConcurrency, int
prefetch,
ErrorMode errorMode,
Supplier<
Queue<
MergeSequentialInner<R>>>
queueSupplier) {
super(
source);
if (
prefetch <= 0) {
throw new
IllegalArgumentException("prefetch > 0 required but it was " +
prefetch);
}
if (
maxConcurrency <= 0) {
throw new
IllegalArgumentException("maxConcurrency > 0 required but it was " +
maxConcurrency);
}
this.
mapper =
Objects.
requireNonNull(
mapper, "mapper");
this.
maxConcurrency =
maxConcurrency;
this.
prefetch =
prefetch;
this.
errorMode =
errorMode;
this.
queueSupplier =
queueSupplier;
}
@
Override
public void
subscribe(
CoreSubscriber<? super R>
actual) {
if (
FluxFlatMap.
trySubscribeScalarMap(
source,
actual,
mapper, false)) {
return;
}
Subscriber<T>
parent = new
MergeSequentialMain<T, R>(
actual,
mapper,
maxConcurrency,
prefetch,
errorMode,
queueSupplier);
source.
subscribe(
parent);
}
static final class
MergeSequentialMain<T, R> implements
InnerOperator<T, R> {
/** the mapper giving the inner publisher for each source value */
final
Function<? super T, ? extends
Publisher<? extends R>>
mapper;
/** how many eagerly subscribed inner stream at a time, at most */
final int
maxConcurrency;
/** request size for inner subscribers (size of the inner queues) */
final int
prefetch;
final
Queue<
MergeSequentialInner<R>>
subscribers;
/** whether or not errors should be delayed until the very end of all inner
* publishers or just until the completion of the currently merged inner publisher
*/
final
ErrorMode errorMode;
final
CoreSubscriber<? super R>
actual;
Subscription s;
volatile boolean
done;
volatile boolean
cancelled;
volatile
Throwable error;
static final
AtomicReferenceFieldUpdater<
MergeSequentialMain,
Throwable>
ERROR =
AtomicReferenceFieldUpdater.
newUpdater(
MergeSequentialMain.class,
Throwable.class, "error");
MergeSequentialInner<R>
current;
/** guard against multiple threads entering the drain loop. allows thread
* stealing by continuing the loop if wip has been incremented externally by
* a separate thread. */
volatile int
wip;
static final
AtomicIntegerFieldUpdater<
MergeSequentialMain>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
MergeSequentialMain.class, "wip");
volatile long
requested;
static final
AtomicLongFieldUpdater<
MergeSequentialMain>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
MergeSequentialMain.class, "requested");
MergeSequentialMain(
CoreSubscriber<? super R>
actual,
Function<? super T, ? extends
Publisher<? extends R>>
mapper,
int
maxConcurrency, int
prefetch,
ErrorMode errorMode,
Supplier<
Queue<
MergeSequentialInner<R>>>
queueSupplier) {
this.
actual =
actual;
this.
mapper =
mapper;
this.
maxConcurrency =
maxConcurrency;
this.
prefetch =
prefetch;
this.
errorMode =
errorMode;
this.
subscribers =
queueSupplier.
get();
}
@
Override
public final
CoreSubscriber<? super R>
actual() {
return
actual;
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
subscribers.
peek());
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
ERROR) return
error;
if (
key ==
Attr.
TERMINATED) return
done &&
subscribers.
isEmpty();
if (
key ==
Attr.
DELAY_ERROR) return
errorMode !=
ErrorMode.
IMMEDIATE;
if (
key ==
Attr.
PREFETCH) return
maxConcurrency;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
if (
key ==
Attr.
BUFFERED) return
subscribers.
size();
return
InnerOperator.super.scanUnsafe(
key);
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
s,
s)) {
this.
s =
s;
actual.
onSubscribe(this);
s.
request(
maxConcurrency ==
Integer.
MAX_VALUE ?
Long.
MAX_VALUE :
maxConcurrency);
}
}
@
Override
public void
onNext(T
t) {
Publisher<? extends R>
publisher;
try {
publisher =
Objects.
requireNonNull(
mapper.
apply(
t), "publisher");
}
catch (
Throwable ex) {
onError(
Operators.
onOperatorError(
s,
ex,
t,
actual.
currentContext()));
return;
}
MergeSequentialInner<R>
inner = new
MergeSequentialInner<>(this,
prefetch);
if (
cancelled) {
return;
}
if (!
subscribers.
offer(
inner)) {
int
badSize =
subscribers.
size();
inner.
cancel();
drainAndCancel();
onError(
Operators.
onOperatorError(
s,
new
IllegalStateException("Too many subscribers for " +
"fluxMergeSequential on item: " +
t +
"; subscribers: " +
badSize),
t,
actual.
currentContext()));
return;
}
if (
cancelled) {
return;
}
publisher.
subscribe(
inner);
if (
cancelled) {
inner.
cancel();
drainAndCancel();
}
}
@
Override
public void
onError(
Throwable t) {
if (
Exceptions.
addThrowable(
ERROR, this,
t)) {
done = true;
drain();
}
else {
Operators.
onErrorDropped(
t,
actual.
currentContext());
}
}
@
Override
public void
onComplete() {
done = true;
drain();
}
@
Override
public void
cancel() {
if (
cancelled) {
return;
}
cancelled = true;
s.
cancel();
drainAndCancel();
}
void
drainAndCancel() {
if (
WIP.
getAndIncrement(this) == 0) {
do {
cancelAll();
}
while (
WIP.
decrementAndGet(this) != 0);
}
}
void
cancelAll() {
MergeSequentialInner<R>
inner;
while ((
inner =
subscribers.
poll()) != null) {
inner.
cancel();
}
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
Operators.
addCap(
REQUESTED, this,
n);
drain();
}
}
void
innerNext(
MergeSequentialInner<R>
inner, R
value) {
if (
inner.
queue().
offer(
value)) {
drain();
}
else {
inner.
cancel();
onError(
Operators.
onOperatorError(null,
Exceptions.
failWithOverflow(
Exceptions.
BACKPRESSURE_ERROR_QUEUE_FULL),
value,
actual.
currentContext()));
}
}
void
innerError(
MergeSequentialInner<R>
inner,
Throwable e) {
if (
Exceptions.
addThrowable(
ERROR, this,
e)) {
inner.
setDone();
if (
errorMode !=
ErrorMode.
END) {
s.
cancel();
}
drain();
}
else {
Operators.
onErrorDropped(
e,
actual.
currentContext());
}
}
void
innerComplete(
MergeSequentialInner<R>
inner) {
inner.
setDone();
drain();
}
void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
int
missed = 1;
MergeSequentialInner<R>
inner =
current;
Subscriber<? super R>
a =
actual;
ErrorMode em =
errorMode;
for (; ; ) {
long
r =
requested;
long
e = 0L;
if (
inner == null) {
if (
em !=
ErrorMode.
END) {
Throwable ex =
error;
if (
ex != null) {
cancelAll();
a.
onError(
ex);
return;
}
}
boolean
outerDone =
done;
inner =
subscribers.
poll();
if (
outerDone &&
inner == null) {
Throwable ex =
error;
if (
ex != null) {
a.
onError(
ex);
}
else {
a.
onComplete();
}
return;
}
if (
inner != null) {
current =
inner;
}
}
boolean
continueNextSource = false;
if (
inner != null) {
Queue<R>
q =
inner.
queue();
//noinspection ConstantConditions
if (
q != null) {
while (
e !=
r) {
if (
cancelled) {
cancelAll();
return;
}
if (
em ==
ErrorMode.
IMMEDIATE) {
Throwable ex =
error;
if (
ex != null) {
current = null;
inner.
cancel();
cancelAll();
a.
onError(
ex);
return;
}
}
boolean
d =
inner.
isDone();
R
v;
try {
v =
q.
poll();
}
catch (
Throwable ex) {
current = null;
inner.
cancel();
ex =
Operators.
onOperatorError(
ex,
actual.
currentContext());
cancelAll();
a.
onError(
ex);
return;
}
boolean
empty =
v == null;
if (
d &&
empty) {
inner = null;
current = null;
s.
request(1);
continueNextSource = true;
break;
}
if (
empty) {
break;
}
a.
onNext(
v);
e++;
inner.
requestOne();
}
if (
e ==
r) {
if (
cancelled) {
cancelAll();
return;
}
if (
em ==
ErrorMode.
IMMEDIATE) {
Throwable ex =
error;
if (
ex != null) {
current = null;
inner.
cancel();
cancelAll();
a.
onError(
ex);
return;
}
}
boolean
d =
inner.
isDone();
boolean
empty =
q.
isEmpty();
if (
d &&
empty) {
inner = null;
current = null;
s.
request(1);
continueNextSource = true;
}
}
}
}
if (
e != 0L &&
r !=
Long.
MAX_VALUE) {
REQUESTED.
addAndGet(this, -
e);
}
if (
continueNextSource) {
continue;
}
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
}
/**
* Represents the inner flux in a mergeSequential, that has an internal queue to
* hold items while they arrive out of order. The queue is drained as soon as correct
* order can be restored.
* @param <R> the type of objects emitted by the inner flux
*/
static final class
MergeSequentialInner<R> implements
InnerConsumer<R>{
final
MergeSequentialMain<?, R>
parent;
final int
prefetch;
final int
limit;
volatile
Queue<R>
queue;
volatile
Subscription subscription;
static final
AtomicReferenceFieldUpdater<
MergeSequentialInner,
Subscription>
SUBSCRIPTION =
AtomicReferenceFieldUpdater.
newUpdater(
MergeSequentialInner.class,
Subscription.class, "subscription");
volatile boolean
done;
long
produced;
int
fusionMode;
MergeSequentialInner(
MergeSequentialMain<?, R>
parent, int
prefetch) {
this.
parent =
parent;
this.
prefetch =
prefetch;
this.
limit =
Operators.
unboundedOrLimit(
prefetch);
}
@
Override
public
Context currentContext() {
return
parent.
currentContext();
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
subscription;
if (
key ==
Attr.
ACTUAL) return
parent;
if (
key ==
Attr.
TERMINATED) return
done && (
queue == null ||
queue.
isEmpty());
if (
key ==
Attr.
CANCELLED) return
subscription ==
Operators.
cancelledSubscription();
if (
key ==
Attr.
BUFFERED) return
queue == null ? 0 :
queue.
size();
if (
key ==
Attr.
PREFETCH) return
prefetch;
return null;
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
setOnce(
SUBSCRIPTION, this,
s)) {
if (
s instanceof
QueueSubscription) {
@
SuppressWarnings("unchecked")
QueueSubscription<R>
qs = (
QueueSubscription<R>)
s;
int
m =
qs.
requestFusion(
Fuseable.
ANY |
Fuseable.
THREAD_BARRIER);
if (
m ==
Fuseable.
SYNC) {
fusionMode =
m;
queue =
qs;
done = true;
parent.
innerComplete(this);
return;
}
if (
m ==
Fuseable.
ASYNC) {
fusionMode =
m;
queue =
qs;
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
return;
}
}
queue =
Queues.<R>
get(
prefetch).
get();
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
}
}
@
Override
public void
onNext(R
t) {
if (
fusionMode ==
Fuseable.
NONE) {
parent.
innerNext(this,
t);
} else {
parent.
drain();
}
}
@
Override
public void
onError(
Throwable t) {
parent.
innerError(this,
t);
}
@
Override
public void
onComplete() {
parent.
innerComplete(this);
}
void
requestOne() {
if (
fusionMode !=
Fuseable.
SYNC) {
long
p =
produced + 1;
if (
p ==
limit) {
produced = 0L;
subscription.
request(
p);
} else {
produced =
p;
}
}
}
void
cancel() {
Operators.
set(
SUBSCRIPTION, this,
Operators.
cancelledSubscription());
}
boolean
isDone() {
return
done;
}
void
setDone() {
this.
done = true;
}
Queue<R>
queue() {
return
queue;
}
}
}