/**
* Copyright 2016 Netflix, Inc.
*
* 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 rx.internal.operators;
import java.util.*;
import java.util.concurrent.atomic.*;
import rx.*;
import rx.
Observable;
import rx.
Observable.
OnSubscribe;
import rx.exceptions.*;
import rx.functions.
Func1;
import rx.internal.util.*;
import rx.internal.util.atomic.*;
import rx.internal.util.unsafe.*;
import rx.plugins.
RxJavaHooks;
/**
* Flattens a sequence if Iterable sources, generated via a function, into a single sequence.
*
* @param <T> the input value type
* @param <R> the output value type
*/
public final class
OnSubscribeFlattenIterable<T, R> implements
OnSubscribe<R> {
final
Observable<? extends T>
source;
final
Func1<? super T, ? extends
Iterable<? extends R>>
mapper;
final int
prefetch;
/** Protected: use createFrom to handle source-dependent optimizations. */
protected
OnSubscribeFlattenIterable(
Observable<? extends T>
source,
Func1<? super T, ? extends
Iterable<? extends R>>
mapper, int
prefetch) {
this.
source =
source;
this.
mapper =
mapper;
this.
prefetch =
prefetch;
}
@
Override
public void
call(
Subscriber<? super R>
t) {
final
FlattenIterableSubscriber<T, R>
parent = new
FlattenIterableSubscriber<T, R>(
t,
mapper,
prefetch);
t.
add(
parent);
t.
setProducer(new
Producer() {
@
Override
public void
request(long
n) {
parent.
requestMore(
n);
}
});
source.
unsafeSubscribe(
parent);
}
public static <T, R>
Observable<R>
createFrom(
Observable<? extends T>
source,
Func1<? super T, ? extends
Iterable<? extends R>>
mapper, int
prefetch) {
if (
source instanceof
ScalarSynchronousObservable) {
T
scalar = ((
ScalarSynchronousObservable<? extends T>)
source).
get();
return
Observable.
unsafeCreate(new
OnSubscribeScalarFlattenIterable<T, R>(
scalar,
mapper));
}
return
Observable.
unsafeCreate(new
OnSubscribeFlattenIterable<T, R>(
source,
mapper,
prefetch));
}
static final class
FlattenIterableSubscriber<T, R> extends
Subscriber<T> {
final
Subscriber<? super R>
actual;
final
Func1<? super T, ? extends
Iterable<? extends R>>
mapper;
final long
limit;
final
Queue<
Object>
queue;
final
AtomicReference<
Throwable>
error;
final
AtomicLong requested;
final
AtomicInteger wip;
volatile boolean
done;
long
produced;
Iterator<? extends R>
active;
public
FlattenIterableSubscriber(
Subscriber<? super R>
actual,
Func1<? super T, ? extends
Iterable<? extends R>>
mapper, int
prefetch) {
this.
actual =
actual;
this.
mapper =
mapper;
this.
error = new
AtomicReference<
Throwable>();
this.
wip = new
AtomicInteger();
this.
requested = new
AtomicLong();
if (
prefetch ==
Integer.
MAX_VALUE) {
this.
limit =
Long.
MAX_VALUE;
this.
queue = new
SpscLinkedArrayQueue<
Object>(
RxRingBuffer.
SIZE);
} else {
// limit = prefetch * 75% rounded up
this.
limit =
prefetch - (
prefetch >> 2);
if (
UnsafeAccess.
isUnsafeAvailable()) {
this.
queue = new
SpscArrayQueue<
Object>(
prefetch);
} else {
this.
queue = new
SpscAtomicArrayQueue<
Object>(
prefetch);
}
}
request(
prefetch);
}
@
Override
public void
onNext(T
t) {
if (!
queue.
offer(
NotificationLite.
next(
t))) {
unsubscribe();
onError(new
MissingBackpressureException());
return;
}
drain();
}
@
Override
public void
onError(
Throwable e) {
if (
ExceptionsUtils.
addThrowable(
error,
e)) {
done = true;
drain();
} else {
RxJavaHooks.
onError(
e);
}
}
@
Override
public void
onCompleted() {
done = true;
drain();
}
void
requestMore(long
n) {
if (
n > 0) {
BackpressureUtils.
getAndAddRequest(
requested,
n);
drain();
} else if (
n < 0) {
throw new
IllegalStateException("n >= 0 required but it was " +
n);
}
}
void
drain() {
if (
wip.
getAndIncrement() != 0) {
return;
}
final
Subscriber<? super R>
actual = this.
actual;
final
Queue<
Object>
queue = this.
queue;
int
missed = 1;
for (;;) {
Iterator<? extends R>
it =
active;
if (
it == null) {
boolean
d =
done;
Object v =
queue.
poll();
boolean
empty =
v == null;
if (
checkTerminated(
d,
empty,
actual,
queue)) {
return;
}
if (!
empty) {
long
p =
produced + 1;
if (
p ==
limit) {
produced = 0L;
request(
p);
} else {
produced =
p;
}
boolean
b;
try {
Iterable<? extends R>
iterable =
mapper.
call(
NotificationLite.<T>
getValue(
v));
it =
iterable.
iterator();
b =
it.
hasNext();
} catch (
Throwable ex) {
Exceptions.
throwIfFatal(
ex);
onError(
ex);
continue;
}
if (!
b) {
continue;
}
active =
it;
}
}
if (
it != null) {
long
r =
requested.
get();
long
e = 0L;
while (
e !=
r) {
if (
checkTerminated(
done, false,
actual,
queue)) {
return;
}
R
v;
try {
v =
it.
next();
} catch (
Throwable ex) {
Exceptions.
throwIfFatal(
ex);
it = null;
active = null;
onError(
ex);
break;
}
actual.
onNext(
v);
if (
checkTerminated(
done, false,
actual,
queue)) {
return;
}
e++;
boolean
b;
try {
b =
it.
hasNext();
} catch (
Throwable ex) {
Exceptions.
throwIfFatal(
ex);
it = null;
active = null;
onError(
ex);
break;
}
if (!
b) {
it = null;
active = null;
break;
}
}
if (
e ==
r) {
if (
checkTerminated(
done,
queue.
isEmpty() &&
it == null,
actual,
queue)) {
return;
}
}
if (
e != 0L) {
BackpressureUtils.
produced(
requested,
e);
}
if (
it == null) {
continue;
}
}
missed =
wip.
addAndGet(-
missed);
if (
missed == 0) {
break;
}
}
}
boolean
checkTerminated(boolean
d, boolean
empty,
Subscriber<?>
a,
Queue<?>
q) {
if (
a.
isUnsubscribed()) {
q.
clear();
active = null;
return true;
}
if (
d) {
Throwable ex =
error.
get();
if (
ex != null) {
ex =
ExceptionsUtils.
terminate(
error);
unsubscribe();
q.
clear();
active = null;
a.
onError(
ex);
return true;
} else
if (
empty) {
a.
onCompleted();
return true;
}
}
return false;
}
}
/**
* A custom flattening operator that works from a scalar value and computes the iterable
* during subscription time.
*
* @param <T> the scalar's value type
* @param <R> the result value type
*/
static final class
OnSubscribeScalarFlattenIterable<T, R> implements
OnSubscribe<R> {
final T
value;
final
Func1<? super T, ? extends
Iterable<? extends R>>
mapper;
public
OnSubscribeScalarFlattenIterable(T
value,
Func1<? super T, ? extends
Iterable<? extends R>>
mapper) {
this.
value =
value;
this.
mapper =
mapper;
}
@
Override
public void
call(
Subscriber<? super R>
t) {
Iterator<? extends R>
iterator;
boolean
b;
try {
Iterable<? extends R>
it =
mapper.
call(
value);
iterator =
it.
iterator();
b =
iterator.
hasNext();
} catch (
Throwable ex) {
Exceptions.
throwOrReport(
ex,
t,
value);
return;
}
if (!
b) {
t.
onCompleted();
return;
}
t.
setProducer(new
OnSubscribeFromIterable.
IterableProducer<R>(
t,
iterator));
}
}
}