/*
* 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.
Iterator;
import java.util.
Objects;
import java.util.
Queue;
import java.util.concurrent.
Callable;
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 org.reactivestreams.
Subscriber;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Exceptions;
import reactor.core.
Fuseable;
import reactor.util.annotation.
Nullable;
import reactor.util.context.
Context;
/**
* Concatenates values from Iterable sequences generated via a mapper function.
*
* @param <T> the input value type
* @param <R> the value type of the iterables and the result type
*
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxFlattenIterable<T, R> extends
FluxOperator<T, R> implements
Fuseable {
final
Function<? super T, ? extends
Iterable<? extends R>>
mapper;
final int
prefetch;
final
Supplier<
Queue<T>>
queueSupplier;
FluxFlattenIterable(
Flux<? extends T>
source,
Function<? super T, ? extends
Iterable<? extends R>>
mapper,
int
prefetch,
Supplier<
Queue<T>>
queueSupplier) {
super(
source);
if (
prefetch <= 0) {
throw new
IllegalArgumentException("prefetch > 0 required but it was " +
prefetch);
}
this.
mapper =
Objects.
requireNonNull(
mapper, "mapper");
this.
prefetch =
prefetch;
this.
queueSupplier =
Objects.
requireNonNull(
queueSupplier, "queueSupplier");
}
@
Override
public int
getPrefetch() {
return
prefetch;
}
@
SuppressWarnings("unchecked")
@
Override
public void
subscribe(
CoreSubscriber<? super R>
actual) {
if (
source instanceof
Callable) {
T
v;
try {
v = ((
Callable<T>)
source).
call();
}
catch (
Throwable ex) {
Operators.
error(
actual,
Operators.
onOperatorError(
ex,
actual.
currentContext()));
return;
}
if (
v == null) {
Operators.
complete(
actual);
return;
}
Iterator<? extends R>
it;
try {
Iterable<? extends R>
iter =
mapper.
apply(
v);
it =
iter.
iterator();
}
catch (
Throwable ex) {
Context ctx =
actual.
currentContext();
Operators.
error(
actual,
Operators.
onOperatorError(
ex,
ctx));
Operators.
onDiscard(
v,
ctx);
return;
}
FluxIterable.
subscribe(
actual,
it);
return;
}
source.
subscribe(new
FlattenIterableSubscriber<>(
actual,
mapper,
prefetch,
queueSupplier));
}
static final class
FlattenIterableSubscriber<T, R>
implements
InnerOperator<T, R>,
QueueSubscription<R> {
final
CoreSubscriber<? super R>
actual;
final
Function<? super T, ? extends
Iterable<? extends R>>
mapper;
final int
prefetch;
final int
limit;
final
Supplier<
Queue<T>>
queueSupplier;
volatile int
wip;
@
SuppressWarnings("rawtypes")
static final
AtomicIntegerFieldUpdater<
FlattenIterableSubscriber>
WIP =
AtomicIntegerFieldUpdater.
newUpdater(
FlattenIterableSubscriber.class,
"wip");
volatile long
requested;
@
SuppressWarnings("rawtypes")
static final
AtomicLongFieldUpdater<
FlattenIterableSubscriber>
REQUESTED =
AtomicLongFieldUpdater.
newUpdater(
FlattenIterableSubscriber.class,
"requested");
Subscription s;
Queue<T>
queue;
volatile boolean
done;
volatile boolean
cancelled;
volatile
Throwable error;
@
SuppressWarnings("rawtypes")
static final
AtomicReferenceFieldUpdater<
FlattenIterableSubscriber,
Throwable>
ERROR =
AtomicReferenceFieldUpdater.
newUpdater(
FlattenIterableSubscriber.class,
Throwable.class,
"error");
Iterator<? extends R>
current;
int
consumed;
int
fusionMode;
FlattenIterableSubscriber(
CoreSubscriber<? super R>
actual,
Function<? super T, ? extends
Iterable<? extends R>>
mapper,
int
prefetch,
Supplier<
Queue<T>>
queueSupplier) {
this.
actual =
actual;
this.
mapper =
mapper;
this.
prefetch =
prefetch;
this.
queueSupplier =
queueSupplier;
this.
limit =
Operators.
unboundedOrLimit(
prefetch);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
TERMINATED) return
done;
if (
key ==
Attr.
ERROR) return
error;
if (
key ==
Attr.
REQUESTED_FROM_DOWNSTREAM) return
requested;
if (
key ==
Attr.
CANCELLED) return
cancelled;
if (
key ==
Attr.
PREFETCH) return
prefetch;
if (
key ==
Attr.
BUFFERED) return
queue != null ?
queue.
size() : 0;
return
InnerOperator.super.scanUnsafe(
key);
}
@
Override
public
CoreSubscriber<? super R>
actual() {
return
actual;
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
s,
s)) {
this.
s =
s;
if (
s instanceof
QueueSubscription) {
@
SuppressWarnings("unchecked")
QueueSubscription<T>
qs =
(
QueueSubscription<T>)
s;
int
m =
qs.
requestFusion(
Fuseable.
ANY);
if (
m ==
Fuseable.
SYNC) {
fusionMode =
m;
this.
queue =
qs;
done = true;
actual.
onSubscribe(this);
return;
}
else if (
m ==
Fuseable.
ASYNC) {
fusionMode =
m;
this.
queue =
qs;
actual.
onSubscribe(this);
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
return;
}
}
queue =
queueSupplier.
get();
actual.
onSubscribe(this);
s.
request(
Operators.
unboundedOrPrefetch(
prefetch));
}
}
@
Override
public void
onNext(T
t) {
if (
fusionMode !=
Fuseable.
ASYNC) {
if (!
queue.
offer(
t)) {
Context ctx =
actual.
currentContext();
onError(
Operators.
onOperatorError(
s,
Exceptions.
failWithOverflow(
Exceptions.
BACKPRESSURE_ERROR_QUEUE_FULL),
ctx));
Operators.
onDiscard(
t,
ctx);
return;
}
}
drain();
}
@
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
request(long
n) {
if (
Operators.
validate(
n)) {
Operators.
addCap(
REQUESTED, this,
n);
drain();
}
}
@
Override
public void
cancel() {
if (!
cancelled) {
cancelled = true;
s.
cancel();
if (
WIP.
getAndIncrement(this) == 0) {
Operators.
onDiscardQueueWithClear(
queue,
actual.
currentContext(), null);
}
}
}
void
drainAsync() {
final
Subscriber<? super R>
a =
actual;
final
Queue<T>
q =
queue;
int
missed = 1;
Context ctx =
actual.
currentContext();
Iterator<? extends R>
it =
current;
for (; ; ) {
if (
it == null) {
if (
cancelled) {
Operators.
onDiscardQueueWithClear(
q,
ctx, null);
return;
}
Throwable ex =
error;
if (
ex != null) {
ex =
Exceptions.
terminate(
ERROR, this);
current = null;
Operators.
onDiscardQueueWithClear(
q,
ctx, null);
a.
onError(
ex);
return;
}
boolean
d =
done;
T
t;
try {
t =
q.
poll();
} catch (
Throwable pollEx) {
current = null;
Operators.
onDiscardQueueWithClear(
q,
ctx, null);
a.
onError(
pollEx);
return;
}
boolean
empty =
t == null;
if (
d &&
empty) {
a.
onComplete();
return;
}
if (!
empty) {
Iterable<? extends R>
iterable;
boolean
b;
try {
iterable =
mapper.
apply(
t);
it =
iterable.
iterator();
b =
it.
hasNext();
}
catch (
Throwable exc) {
it = null;
onError(
Operators.
onOperatorError(
s,
exc,
t,
ctx));
Operators.
onDiscard(
t,
ctx);
continue;
}
if (!
b) {
it = null;
int
c =
consumed + 1;
if (
c ==
limit) {
consumed = 0;
s.
request(
c);
}
else {
consumed =
c;
}
continue;
}
}
}
if (
it != null) {
long
r =
requested;
long
e = 0L;
while (
e !=
r) {
if (
cancelled) {
current = null;
Operators.
onDiscardQueueWithClear(
q,
ctx, null);
return;
}
Throwable ex =
error;
if (
ex != null) {
ex =
Exceptions.
terminate(
ERROR, this);
current = null;
Operators.
onDiscardQueueWithClear(
q,
ctx, null);
a.
onError(
ex);
return;
}
R
v;
try {
v =
Objects.
requireNonNull(
it.
next(),
"iterator returned null");
}
catch (
Throwable exc) {
onError(
Operators.
onOperatorError(
s,
exc,
actual.
currentContext()));
continue;
}
a.
onNext(
v);
if (
cancelled) {
current = null;
Operators.
onDiscardQueueWithClear(
q,
actual.
currentContext(), null);
return;
}
e++;
boolean
b;
try {
b =
it.
hasNext();
}
catch (
Throwable exc) {
onError(
Operators.
onOperatorError(
s,
exc,
actual.
currentContext()));
continue;
}
if (!
b) {
int
c =
consumed + 1;
if (
c ==
limit) {
consumed = 0;
s.
request(
c);
}
else {
consumed =
c;
}
it = null;
current = null;
break;
}
}
if (
e ==
r) {
if (
cancelled) {
current = null;
Operators.
onDiscardQueueWithClear(
q,
actual.
currentContext(), null);
return;
}
Throwable ex =
error;
if (
ex != null) {
ex =
Exceptions.
terminate(
ERROR, this);
current = null;
Operators.
onDiscardQueueWithClear(
q,
actual.
currentContext(), null);
a.
onError(
ex);
return;
}
boolean
d =
done;
boolean
empty =
q.
isEmpty() &&
it == null;
if (
d &&
empty) {
current = null;
a.
onComplete();
return;
}
}
if (
e != 0L) {
if (
r !=
Long.
MAX_VALUE) {
REQUESTED.
addAndGet(this, -
e);
}
}
if (
it == null) {
continue;
}
}
current =
it;
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
void
drainSync() {
final
Subscriber<? super R>
a =
actual;
int
missed = 1;
Context ctx =
actual.
currentContext();
Iterator<? extends R>
it =
current;
for (; ; ) {
if (
it == null) {
if (
cancelled) {
Operators.
onDiscardQueueWithClear(
queue,
ctx, null);
return;
}
boolean
d =
done;
T
t;
Queue<T>
q =
queue;
try {
t =
q.
poll();
} catch (
Throwable pollEx) {
current = null;
Operators.
onDiscardQueueWithClear(
q,
ctx, null);
a.
onError(
pollEx);
return;
}
boolean
empty =
t == null;
if (
d &&
empty) {
a.
onComplete();
return;
}
if (!
empty) {
Iterable<? extends R>
iterable;
boolean
b;
try {
iterable =
mapper.
apply(
t);
it =
iterable.
iterator();
b =
it.
hasNext();
}
catch (
Throwable exc) {
current = null;
a.
onError(
Operators.
onOperatorError(
s,
exc,
t,
ctx));
Operators.
onDiscard(
t,
ctx);
return;
}
if (!
b) {
it = null;
continue;
}
}
}
if (
it != null) {
long
r =
requested;
long
e = 0L;
while (
e !=
r) {
if (
cancelled) {
current = null;
Operators.
onDiscardQueueWithClear(
queue,
ctx, null);
return;
}
R
v;
try {
v =
Objects.
requireNonNull(
it.
next(),
"iterator returned null");
}
catch (
Throwable exc) {
current = null;
a.
onError(
Operators.
onOperatorError(
s,
exc,
ctx));
return;
}
a.
onNext(
v);
if (
cancelled) {
current = null;
Operators.
onDiscardQueueWithClear(
queue,
ctx, null);
return;
}
e++;
boolean
b;
try {
b =
it.
hasNext();
}
catch (
Throwable exc) {
current = null;
a.
onError(
Operators.
onOperatorError(
s,
exc,
ctx));
return;
}
if (!
b) {
it = null;
current = null;
break;
}
}
if (
e ==
r) {
if (
cancelled) {
current = null;
Operators.
onDiscardQueueWithClear(
queue,
ctx, null);
return;
}
boolean
d =
done;
boolean
empty =
queue.
isEmpty() &&
it == null;
if (
d &&
empty) {
current = null;
a.
onComplete();
return;
}
}
if (
e != 0L) {
if (
r !=
Long.
MAX_VALUE) {
REQUESTED.
addAndGet(this, -
e);
}
}
if (
it == null) {
continue;
}
}
current =
it;
missed =
WIP.
addAndGet(this, -
missed);
if (
missed == 0) {
break;
}
}
}
void
drain() {
if (
WIP.
getAndIncrement(this) != 0) {
return;
}
if (
fusionMode ==
SYNC) {
drainSync();
}
else {
drainAsync();
}
}
@
Override
public void
clear() {
current = null;
Operators.
onDiscardQueueWithClear(
queue,
actual.
currentContext(), null);
}
@
Override
public boolean
isEmpty() {
Iterator<? extends R>
it =
current;
if (
it != null) {
return !
it.
hasNext();
}
return
queue.
isEmpty(); // estimate
}
@
Override
@
Nullable
public R
poll() {
Iterator<? extends R>
it =
current;
Context ctx =
actual.
currentContext();
for (; ; ) {
if (
it == null) {
T
v =
queue.
poll();
if (
v == null) {
return null;
}
try {
it =
mapper.
apply(
v)
.
iterator();
}
catch (
Throwable error) {
Operators.
onDiscard(
v,
ctx);
throw
error;
}
if (!
it.
hasNext()) {
continue;
}
current =
it;
}
else if (!
it.
hasNext()) {
it = null;
continue;
}
R
r =
Objects.
requireNonNull(
it.
next(), "iterator returned null");
if (!
it.
hasNext()) {
current = null;
}
return
r;
}
}
@
Override
public int
requestFusion(int
requestedMode) {
if ((
requestedMode &
SYNC) != 0 &&
fusionMode ==
SYNC) {
return
SYNC;
}
return
NONE;
}
@
Override
public int
size() {
return
queue.
size(); // estimate
}
}
}