com.couchbase.client.core.state.AbstractStateZipper Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of core-io Show documentation
Show all versions of core-io Show documentation
The official Couchbase JVM Core IO Library
/**
* Copyright (c) 2015 Couchbase, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALING
* IN THE SOFTWARE.
*/
package com.couchbase.client.core.state;
import rx.Subscriber;
import rx.Subscription;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* The default implementation of a {@link StateZipper}.
*
* The implementing class only needs to provide the zip function, as well as a initial state that is always used
* when no source stream is registered.
*
* @author Michael Nitschinger
* @since 1.1.0
*/
public abstract class AbstractStateZipper
extends AbstractStateMachine
implements StateZipper {
private final Map subscriptions;
private final Map states;
private final S initialState;
protected AbstractStateZipper(S initialState) {
super(initialState);
this.initialState = initialState;
this.subscriptions = new ConcurrentHashMap();
this.states = new ConcurrentHashMap();
}
/**
* The zip function to map from N states to one that represents the state of the zipper.
*
* @param states all subscribed states.
* @return the zipped state which represents the zipper state.
*/
protected abstract S zipWith(Collection states);
@Override
public void register(final T identifier, final Stateful upstream) {
Subscription subscription = upstream.states().subscribe(new Subscriber() {
@Override
public void onCompleted() {
deregister(identifier);
}
@Override
public void onError(Throwable error) {
deregister(identifier);
}
@Override
public void onNext(S state) {
states.put(identifier, state);
transitionStateThroughZipper();
}
});
subscriptions.put(identifier, subscription);
}
@Override
public void deregister(final T identifier) {
if (identifier == null) {
return;
}
Subscription subscription = subscriptions.get(identifier);
if (subscription != null && !subscription.isUnsubscribed()) {
subscription.unsubscribe();
subscriptions.remove(identifier);
states.remove(identifier);
transitionStateThroughZipper();
}
}
@Override
public void terminate() {
Iterator iterator = subscriptions.keySet().iterator();
while (iterator.hasNext()) {
T identifier = iterator.next();
Subscription subscription = subscriptions.get(identifier);
if (subscription != null && !subscription.isUnsubscribed()) {
subscription.unsubscribe();
iterator.remove();
states.remove(identifier);
}
}
transitionStateThroughZipper();
}
/**
* Ask the zip function to compute the states and then transition the state of the zipper.
*
* When no registrations are available, the zipper immediately transitions into the initial state
* without asking the zip function for a computation.
*/
private void transitionStateThroughZipper() {
Collection currentStates = states.values();
if (currentStates.isEmpty()) {
transitionState(initialState);
} else {
transitionState(zipWith(currentStates));
}
}
/**
* Helper method to export the current internal subscriptions.
*
* @return the internally stored subscriptions.
*/
protected Map currentSubscriptions() {
return subscriptions;
}
/**
* Helper method to export the current internal states.
*
* Should only be used for testing.
* @return the internally stored states.
*/
protected Map currentStates() {
return states;
}
}