Class ResourceSubscriber<T>
- Type Parameters:
T
- the value type
- All Implemented Interfaces:
FlowableSubscriber<T>
,Disposable
,org.reactivestreams.Subscriber<T>
All pre-implemented final methods are thread-safe.
To release the associated resources, one has to call dispose()
in onError()
and onComplete()
explicitly.
Use add(Disposable)
to associate resources (as Disposable
s)
with this ResourceSubscriber
that will be cleaned up when dispose()
is called.
Removing previously associated resources is not possible but one can create a
CompositeDisposable
, associate it with this
ResourceSubscriber
and then add/remove resources to/from the CompositeDisposable
freely.
The default onStart()
requests Long.MAX_VALUE
by default. Override
the method to request a custom positive amount. Use the protected request(long)
to request more items and dispose()
to cancel the sequence from within an
onNext
implementation.
Note that calling request(long)
from onStart()
may trigger
an immediate, asynchronous emission of data to Subscriber.onNext(Object)
. Make sure
all initialization happens before the call to request()
in onStart()
.
Calling request(long)
inside Subscriber.onNext(Object)
can happen at any time
because by design, onNext
calls from upstream are non-reentrant and non-overlapping.
Like all other consumers, ResourceSubscriber
can be subscribed only once.
Any subsequent attempt to subscribe it to a new source will yield an
IllegalStateException
with message "It is not allowed to subscribe with a(n) <class name> multiple times."
.
Implementation of onStart()
, Subscriber.onNext(Object)
, Subscriber.onError(Throwable)
and Subscriber.onComplete()
are not allowed to throw any unchecked exceptions.
If for some reason this can't be avoided, use Flowable.safeSubscribe(org.reactivestreams.Subscriber)
instead of the standard subscribe()
method.
Example
Disposable d =
Flowable.range(1, 5)
.subscribeWith(new ResourceSubscriber<Integer>() {
@Override public void onStart() {
add(Schedulers.single()
.scheduleDirect(() -> System.out.println("Time!"),
2, TimeUnit.SECONDS));
request(1);
}
@Override public void onNext(Integer t) {
if (t == 3) {
dispose();
}
System.out.println(t);
request(1);
}
@Override public void onError(Throwable t) {
t.printStackTrace();
dispose();
}
@Override public void onComplete() {
System.out.println("Done!");
dispose();
}
});
// ...
d.dispose();
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate final AtomicLong
Remembers the request(n) counts until a subscription arrives.private final ListCompositeDisposable
The resource composite, can never be null.private final AtomicReference
<org.reactivestreams.Subscription> The active subscription. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionfinal void
add
(Disposable resource) Adds a resource to thisResourceSubscriber
.final void
dispose()
Cancels the subscription (if any) and disposes the resources associated with thisResourceSubscriber
(if any).final boolean
Returns true if thisResourceSubscriber
has been disposed/cancelled.protected void
onStart()
Called once the upstream sets aSubscription
on thisResourceSubscriber
.final void
onSubscribe
(org.reactivestreams.Subscription s) Implementors of this method should make sure everything that needs to be visible inSubscriber.onNext(Object)
is established before callingSubscription.request(long)
.protected final void
request
(long n) Request the specified amount of elements from upstream.Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface org.reactivestreams.Subscriber
onComplete, onError, onNext
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Field Details
-
upstream
The active subscription. -
resources
The resource composite, can never be null. -
missedRequested
Remembers the request(n) counts until a subscription arrives.
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Constructor Details
-
ResourceSubscriber
public ResourceSubscriber()
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Method Details
-
add
Adds a resource to thisResourceSubscriber
.- Parameters:
resource
- the resource to add- Throws:
NullPointerException
- ifresource
isnull
-
onSubscribe
public final void onSubscribe(org.reactivestreams.Subscription s) Description copied from interface:FlowableSubscriber
Implementors of this method should make sure everything that needs to be visible inSubscriber.onNext(Object)
is established before callingSubscription.request(long)
. In practice this means no initialization should happen after therequest()
call and additional behavior is thread safe in respect toonNext
.- Specified by:
onSubscribe
in interfaceFlowableSubscriber<T>
- Specified by:
onSubscribe
in interfaceorg.reactivestreams.Subscriber<T>
-
onStart
protected void onStart()Called once the upstream sets aSubscription
on thisResourceSubscriber
.You can perform initialization at this moment. The default implementation requests
Long.MAX_VALUE
from upstream. -
request
protected final void request(long n) Request the specified amount of elements from upstream.This method can be called before the upstream calls
onSubscribe(Subscription)
. When the subscription happens, all missed requests are requested.- Parameters:
n
- the request amount, must be positive
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dispose
public final void dispose()Cancels the subscription (if any) and disposes the resources associated with thisResourceSubscriber
(if any).This method can be called before the upstream calls
onSubscribe(Subscription)
at which case theSubscription
will be immediately cancelled.- Specified by:
dispose
in interfaceDisposable
-
isDisposed
public final boolean isDisposed()Returns true if thisResourceSubscriber
has been disposed/cancelled.- Specified by:
isDisposed
in interfaceDisposable
- Returns:
- true if this
ResourceSubscriber
has been disposed/cancelled
-