/*
* 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.
AtomicLongFieldUpdater;
import java.util.concurrent.atomic.
AtomicReferenceFieldUpdater;
import java.util.function.
Supplier;
import java.util.stream.
Stream;
import org.reactivestreams.
Subscriber;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Exceptions;
import reactor.core.
Scannable;
import reactor.util.annotation.
Nullable;
import reactor.util.context.
Context;
/**
* Merges the individual 'rails' of the source ParallelFlux, unordered,
* into a single regular Publisher sequence (exposed as reactor.core.publisher.Flux).
*
* @param <T> the value type
*/
final class
ParallelMergeSequential<T> extends
Flux<T> implements
Scannable {
final
ParallelFlux<? extends T>
source;
final int
prefetch;
final
Supplier<
Queue<T>>
queueSupplier;
ParallelMergeSequential(
ParallelFlux<? extends T>
source, int
prefetch,
Supplier<
Queue<T>>
queueSupplier) {
if (
prefetch <= 0) {
throw new
IllegalArgumentException("prefetch > 0 required but it was " +
prefetch);
}
this.
source =
source;
this.
prefetch =
prefetch;
this.
queueSupplier =
queueSupplier;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
source;
if (
key ==
Attr.
PREFETCH) return
getPrefetch();
return null;
}
@
Override
public int
getPrefetch() {
return
prefetch;
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
MergeSequentialMain<T>
parent = new
MergeSequentialMain<>(
actual,
source
.
parallelism(),
prefetch,
queueSupplier);
actual.
onSubscribe(
parent);
source.
subscribe(
parent.
subscribers);
}
static final class
MergeSequentialMain<T> implements
InnerProducer<T> {
final
MergeSequentialInner<T>[]
subscribers;
final
Supplier<
Queue<T>>
queueSupplier;
final
CoreSubscriber<? super T>
actual;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
MergeSequentialMain,
Throwable>
ERROR =
AtomicReferenceFieldUpdater.
newUpdater(
MergeSequentialMain.class,
Throwable.class, "error");
volatile int
wip;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
MergeSequentialMain>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
MergeSequentialMain.class, "wip");
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
MergeSequentialMain>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
MergeSequentialMain.class, "requested");
volatile boolean
cancelled;
volatile int
done;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
MergeSequentialMain>
DONE =
AtomicIntegerFieldUpdater.
newUpdater(
MergeSequentialMain.class, "done");
volatile
Throwable error;
MergeSequentialMain(
CoreSubscriber<? super T>
actual, int
n, int
prefetch,
Supplier<
Queue<T>>
queueSupplier) {
this.
actual =
actual;
this.
queueSupplier =
queueSupplier;
@
SuppressWarnings("unchecked")
MergeSequentialInner<T>[]
a = new
MergeSequentialInner[
n];
for (int
i = 0;
i <
n;
i++) {
a[
i] = new
MergeSequentialInner<>(this,
prefetch);
}
this.
subscribers =
a;
DONE.
lazySet(this,
n);
}
@
Override
public final
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
CANCELLED) return
cancelled;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
if (
key ==
Attr.
TERMINATED) return
done == 0 ;
if (
key ==
Attr.
ERROR) return
error;
return
InnerProducer.super.scanUnsafe(
key);
}
@
Override
public
Stream<? extends
Scannable>
inners() {
return
Stream.
of(
subscribers);
}
@
Override
public void
request(long
n) {
if (
Operators.
validate(
n)) {
Operators.
addCap(
REQUESTED, this,
n);
drain();
}
}
@
Override
public void
cancel() {
if (!
cancelled) {
cancelled = true;
cancelAll();
if (
WIP.
getAndIncrement(this) == 0) {
cleanup();
}
}
}
void
cancelAll() {
for (
MergeSequentialInner<T>
s :
subscribers) {
s.
cancel();
}
}
void
cleanup() {
for (
MergeSequentialInner<T>
s :
subscribers) {
s.
queue = null;
}
}
void
onNext(
MergeSequentialInner<T>
inner, T
value) {
if (
wip == 0 &&
WIP.
compareAndSet(this, 0, 1)) {
if (
requested != 0) {
actual.
onNext(
value);
if (
requested !=
Long.
MAX_VALUE) {
REQUESTED.
decrementAndGet(this);
}
inner.
requestOne();
} else {
Queue<T>
q =
inner.
getQueue(
queueSupplier);
if(!
q.
offer(
value)){
onError(
Operators.
onOperatorError(this,
Exceptions.
failWithOverflow(
Exceptions.
BACKPRESSURE_ERROR_QUEUE_FULL),
value,
actual.
currentContext()));
return;
}
}
if (
WIP.
decrementAndGet(this) == 0) {
return;
}
} else {
Queue<T>
q =
inner.
getQueue(
queueSupplier);
if(!
q.
offer(
value)){
onError(
Operators.
onOperatorError(this,
Exceptions.
failWithOverflow(
Exceptions.
BACKPRESSURE_ERROR_QUEUE_FULL),
value,
actual.
currentContext()));
return;
}
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
}
drainLoop();
}
void
onError(
Throwable ex) {
if(
ERROR.
compareAndSet(this, null,
ex)){
cancelAll();
drain();
}
else if(
error !=
ex) {
Operators.
onErrorDropped(
ex,
actual.
currentContext());
}
}
void
onComplete() {
if(
DONE.
decrementAndGet(this) < 0){
return;
}
drain();
}
void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
drainLoop();
}
void
drainLoop() {
int
missed = 1;
MergeSequentialInner<T>[]
s = this.
subscribers;
int
n =
s.length;
Subscriber<? super T>
a = this.
actual;
for (;;) {
long
r =
requested;
long
e = 0;
middle:
while (
e !=
r) {
if (
cancelled) {
cleanup();
return;
}
Throwable ex =
error;
if (
ex != null) {
cleanup();
a.
onError(
ex);
return;
}
boolean
d =
done == 0;
boolean
empty = true;
for (int
i = 0;
i <
n;
i++) {
MergeSequentialInner<T>
inner =
s[
i];
Queue<T>
q =
inner.
queue;
if (
q != null) {
T
v =
q.
poll();
if (
v != null) {
empty = false;
a.
onNext(
v);
inner.
requestOne();
if (++
e ==
r) {
break
middle;
}
}
}
}
if (
d &&
empty) {
a.
onComplete();
return;
}
if (
empty) {
break;
}
}
if (
e ==
r) {
if (
cancelled) {
cleanup();
return;
}
Throwable ex =
error;
if (
ex != null) {
cleanup();
a.
onError(
ex);
return;
}
boolean
d =
done == 0;
boolean
empty = true;
for (int
i = 0;
i <
n;
i++) {
MergeSequentialInner<T>
inner =
s[
i];
Queue<T>
q =
inner.
queue;
if (
q != null && !
q.
isEmpty()) {
empty = false;
break;
}
}
if (
d &&
empty) {
a.
onComplete();
return;
}
}
if (
e != 0 &&
r !=
Long.
MAX_VALUE) {
REQUESTED.
addAndGet(this, -
e);
}
int
w =
wip;
if (
w ==
missed) {
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
} else {
missed =
w;
}
}
}
}
static final class
MergeSequentialInner<T> implements
InnerConsumer<T> {
final
MergeSequentialMain<T>
parent;
final int
prefetch;
final int
limit;
long
produced;
volatile
Subscription s;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
MergeSequentialInner,
Subscription>
S =
AtomicReferenceFieldUpdater.
newUpdater(
MergeSequentialInner.class,
Subscription.class, "s");
volatile
Queue<T>
queue;
volatile boolean
done;
MergeSequentialInner(
MergeSequentialMain<T>
parent, int
prefetch) {
this.
parent =
parent;
this.
prefetch =
prefetch ;
this.
limit =
Operators.
unboundedOrLimit(
prefetch);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
CANCELLED) return
s ==
Operators.
cancelledSubscription();
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
ACTUAL) return
parent;
if (
key ==
Attr.
PREFETCH) return
prefetch;
if (
key ==
Attr.
BUFFERED) return
queue != null ?
queue.
size() : 0;
if (
key ==
Attr.
TERMINATED) return
done;
return null;
}
@
Override
public
Context currentContext() {
return
parent.
actual.
currentContext();
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
setOnce(
S, this,
s)) {
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
}
}
@
Override
public void
onNext(T
t) {
parent.
onNext(this,
t);
}
@
Override
public void
onError(
Throwable t) {
parent.
onError(
t);
}
@
Override
public void
onComplete() {
parent.
onComplete();
}
void
requestOne() {
long
p =
produced + 1;
if (
p ==
limit) {
produced = 0;
s.
request(
p);
} else {
produced =
p;
}
}
public void
cancel() {
Operators.
terminate(
S, this);
}
Queue<T>
getQueue(
Supplier<
Queue<T>>
queueSupplier) {
Queue<T>
q =
queue;
if (
q == null) {
q =
queueSupplier.
get();
this.
queue =
q;
}
return
q;
}
}
}