/*
* 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.
Queue;
import java.util.concurrent.atomic.
AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.
AtomicLongArray;
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.
Scannable;
import reactor.util.annotation.
Nullable;
import reactor.util.context.
Context;
/**
* Dispatches the values from upstream in a round robin fashion to subscribers which are
* ready to consume elements. A value from upstream is sent to only one of the subscribers.
*
* @param <T> the value type
*/
final class
ParallelSource<T> extends
ParallelFlux<T> implements
Scannable {
final
Publisher<? extends T>
source;
final int
parallelism;
final int
prefetch;
final
Supplier<
Queue<T>>
queueSupplier;
ParallelSource(
Publisher<? extends T>
source, int
parallelism, int
prefetch,
Supplier<
Queue<T>>
queueSupplier) {
if (
parallelism <= 0) {
throw new
IllegalArgumentException("parallelism > 0 required but it was " +
parallelism);
}
if (
prefetch <= 0) {
throw new
IllegalArgumentException("prefetch > 0 required but it was " +
prefetch);
}
this.
source =
source;
this.
parallelism =
parallelism;
this.
prefetch =
prefetch;
this.
queueSupplier =
queueSupplier;
}
@
Override
public int
getPrefetch() {
return
prefetch;
}
@
Override
public int
parallelism() {
return
parallelism;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Scannable.
Attr key) {
if (
key ==
Attr.
PARENT) return
source;
if (
key ==
Attr.
PREFETCH) return
getPrefetch();
return null;
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>[]
subscribers) {
if (!
validate(
subscribers)) {
return;
}
source.
subscribe(new
ParallelSourceMain<>(
subscribers,
prefetch,
queueSupplier));
}
static final class
ParallelSourceMain<T> implements
InnerConsumer<T> {
final
CoreSubscriber<? super T>[]
subscribers;
final
AtomicLongArray requests;
final long[]
emissions;
final int
prefetch;
final int
limit;
final
Supplier<
Queue<T>>
queueSupplier;
Subscription s;
Queue<T>
queue;
Throwable error;
volatile boolean
done;
int
index;
volatile boolean
cancelled;
volatile int
wip;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
ParallelSourceMain>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
ParallelSourceMain.class, "wip");
/**
* Counts how many subscribers were setup to delay triggering the
* drain of upstream until all of them have been setup.
*/
volatile int
subscriberCount;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
ParallelSourceMain>
SUBSCRIBER_COUNT =
AtomicIntegerFieldUpdater.
newUpdater(
ParallelSourceMain.class, "subscriberCount");
int
produced;
int
sourceMode;
ParallelSourceMain(
CoreSubscriber<? super T>[]
subscribers, int
prefetch,
Supplier<
Queue<T>>
queueSupplier) {
this.
subscribers =
subscribers;
this.
prefetch =
prefetch;
this.
queueSupplier =
queueSupplier;
this.
limit =
Operators.
unboundedOrLimit(
prefetch);
this.
requests = new
AtomicLongArray(
subscribers.length);
this.
emissions = new long[
subscribers.length];
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
PREFETCH) return
prefetch;
if (
key ==
Attr.
TERMINATED) return
done;
if (
key ==
Attr.
CANCELLED) return
cancelled;
if (
key ==
Attr.
ERROR) return
error;
if (
key ==
Attr.
BUFFERED) return
queue != null ?
queue.
size() : 0;
return null;
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
subscribers).
map(
Scannable::from);
}
@
Override
public
Context currentContext() {
return
subscribers[0].
currentContext();
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
s,
s)) {
this.
s =
s;
if (
s instanceof
Fuseable.
QueueSubscription) {
@
SuppressWarnings("unchecked")
Fuseable.
QueueSubscription<T>
qs = (
Fuseable.
QueueSubscription<T>)
s;
int
m =
qs.
requestFusion(
Fuseable.
ANY |
Fuseable.
THREAD_BARRIER);
if (
m ==
Fuseable.
SYNC) {
sourceMode =
m;
queue =
qs;
done = true;
setupSubscribers();
drain();
return;
} else
if (
m ==
Fuseable.
ASYNC) {
sourceMode =
m;
queue =
qs;
setupSubscribers();
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
return;
}
}
queue =
queueSupplier.
get();
setupSubscribers();
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
}
}
void
setupSubscribers() {
int
m =
subscribers.length;
for (int
i = 0;
i <
m;
i++) {
if (
cancelled) {
return;
}
int
j =
i;
SUBSCRIBER_COUNT.
lazySet(this,
i + 1);
subscribers[
i].
onSubscribe(new
ParallelSourceInner<>(this,
j,
m));
}
}
@
Override
public void
onNext(T
t) {
if (
done) {
Operators.
onNextDropped(
t,
currentContext());
return;
}
if (
sourceMode ==
Fuseable.
NONE) {
if (!
queue.
offer(
t)) {
onError(
Operators.
onOperatorError(
s,
Exceptions.
failWithOverflow(
Exceptions.
BACKPRESSURE_ERROR_QUEUE_FULL),
t,
currentContext()));
return;
}
}
drain();
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
Operators.
onErrorDropped(
t,
currentContext());
return;
}
error =
t;
done = true;
drain();
}
@
Override
public void
onComplete() {
if(
done){
return;
}
done = true;
drain();
}
void
cancel() {
if (!
cancelled) {
cancelled = true;
this.
s.
cancel();
if (
WIP.
getAndIncrement(this) == 0) {
queue.
clear();
}
}
}
void
drainAsync() {
int
missed = 1;
Queue<T>
q =
queue;
CoreSubscriber<? super T>[]
a = this.
subscribers;
AtomicLongArray r = this.
requests;
long[]
e = this.
emissions;
int
n =
e.length;
int
idx =
index;
int
consumed =
produced;
for (;;) {
int
notReady = 0;
for (;;) {
if (
cancelled) {
q.
clear();
return;
}
boolean
d =
done;
if (
d) {
Throwable ex =
error;
if (
ex != null) {
q.
clear();
for (
Subscriber<? super T>
s :
a) {
s.
onError(
ex);
}
return;
}
}
boolean
empty =
q.
isEmpty();
if (
d &&
empty) {
for (
Subscriber<? super T>
s :
a) {
s.
onComplete();
}
return;
}
if (
empty) {
break;
}
long
ridx =
r.
get(
idx);
long
eidx =
e[
idx];
if (
ridx !=
eidx) {
T
v;
try {
v =
q.
poll();
} catch (
Throwable ex) {
ex =
Operators.
onOperatorError(
s,
ex,
a[
idx].
currentContext());
for (
Subscriber<? super T>
s :
a) {
s.
onError(
ex);
}
return;
}
if (
v == null) {
break;
}
a[
idx].
onNext(
v);
e[
idx] =
eidx + 1;
int
c = ++
consumed;
if (
c ==
limit) {
consumed = 0;
s.
request(
c);
}
notReady = 0;
} else {
notReady++;
}
idx++;
if (
idx ==
n) {
idx = 0;
}
if (
notReady ==
n) {
break;
}
}
int
w =
wip;
if (
w ==
missed) {
index =
idx;
produced =
consumed;
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
} else {
missed =
w;
}
}
}
void
drainSync() {
int
missed = 1;
Queue<T>
q =
queue;
CoreSubscriber<? super T>[]
a = this.
subscribers;
AtomicLongArray r = this.
requests;
long[]
e = this.
emissions;
int
n =
e.length;
int
idx =
index;
for (;;) {
int
notReady = 0;
for (;;) {
if (
cancelled) {
q.
clear();
return;
}
if (
q.
isEmpty()) {
for (
Subscriber<? super T>
s :
a) {
s.
onComplete();
}
return;
}
long
ridx =
r.
get(
idx);
long
eidx =
e[
idx];
if (
ridx !=
eidx) {
T
v;
try {
v =
q.
poll();
} catch (
Throwable ex) {
ex =
Operators.
onOperatorError(
s,
ex,
a[
idx].
currentContext());
for (
Subscriber<? super T>
s :
a) {
s.
onError(
ex);
}
return;
}
if (
v == null) {
for (
Subscriber<? super T>
s :
a) {
s.
onComplete();
}
return;
}
a[
idx].
onNext(
v);
e[
idx] =
eidx + 1;
notReady = 0;
} else {
notReady++;
}
idx++;
if (
idx ==
n) {
idx = 0;
}
if (
notReady ==
n) {
break;
}
}
int
w =
wip;
if (
w ==
missed) {
index =
idx;
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
} else {
missed =
w;
}
}
}
void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
if (
sourceMode ==
Fuseable.
SYNC) {
drainSync();
} else {
drainAsync();
}
}
static final class
ParallelSourceInner<T> implements
InnerProducer<T> {
final
ParallelSourceMain<T>
parent;
final int
index;
final int
length;
ParallelSourceInner(
ParallelSourceMain<T>
parent, int
index, int
length) {
this.
index =
index;
this.
length =
length;
this.
parent =
parent;
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
parent.
subscribers[
index];
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
parent;
return
InnerProducer.super.scanUnsafe(
key);
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
AtomicLongArray ra =
parent.
requests;
for (;;) {
long
r =
ra.
get(
index);
if (
r ==
Long.
MAX_VALUE) {
return;
}
long
u =
Operators.
addCap(
r,
n);
if (
ra.
compareAndSet(
index,
r,
u)) {
break;
}
}
if (
parent.
subscriberCount ==
length) {
parent.
drain();
}
}
}
@
Override
public void
cancel() {
parent.
cancel();
}
}
}
}