com.devexperts.qd.util

Class SubscriptionProcessor

java.lang.Object

com.devexperts.qd.util.SubscriptionProcessor

public abstract class SubscriptionProcessor
extends Object

This class is base class for listening QD for subscription availability and rescheduling its processing using Executor. Classes which extends SubscriptionProcessor listen for subscription coming from QD and process incoming subscription in separate thread or threads. Executor may be single thread or thread pool executor. One Executor may be shared by different subscription processors. It is guaranteed that new subscription processing handler will not be called until previous has completed its work. SubscriptionProcessor registers RecordListener in all RecordProvider instances when startProcessing(com.devexperts.qd.QDDistributor) method is called. Class client is responsible to call stopProcessing() when processing is not required any more. This class is thread-safe and lock-free. Change carefully.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SubscriptionProcessor(Executor executor, QDContract contract) Constructs new subscription processor for the specified executor.

Method Summary

Modifier and Type	Method and Description
boolean	hasMoreToProcess() Returns true when this SubscriptionProcessor has more subscription available to process or its task is scheduled for processing.
protected abstract void	processAddedSubscription(RecordSource source) Method for processing incoming added subscription from QD.
protected abstract void	processRemovedSubscription(RecordSource source) Method for processing incoming removed subscription from QD.
protected void	signalNoMoreToProcess() This method is called immediately before hasMoreToProcess() becomes false.
void	startProcessing(QDDistributor distributor) Starts subscription processing for the specified QDDistributor.
void	startProcessing(RecordProvider addedSubscriptionProvider, RecordProvider removedSubscriptionProvider) Starts subscription processing for the specified added and removed RecordProvider instances.
void	stopProcessing() Stop subscription processing.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SubscriptionProcessor

protected SubscriptionProcessor(Executor executor,
                                QDContract contract)

Constructs new subscription processor for the specified executor.

Parameters:

executor - the executor.

contract - the contract for which subscription shall be processed.

Throws:

NullPointerException - if executor is null.

Method Detail

processAddedSubscription

protected abstract void processAddedSubscription(RecordSource source)

Method for processing incoming added subscription from QD. When added subscription is received, SubscriptionProcessor calls this method in Executor thread.

processRemovedSubscription

protected abstract void processRemovedSubscription(RecordSource source)

Method for processing incoming removed subscription from QD. When removed subscription is received, SubscriptionProcessor calls this method in Executor thread.

startProcessing

public void startProcessing(QDDistributor distributor)

Starts subscription processing for the specified QDDistributor. This method is equivalent to the following code: startProcessing(distributor.getAddedRecordProvider(), distributor.getRemovedRecordProvider()). This method or startProcessing(RecordProvider, RecordProvider) may be called at most once after construction.

Throws:

NullPointerException - if distributor is null.

IllegalStateException - if called multiple times. It is checked weakly to ensure fail-fast error detection behaviour. There is no strict thread-safe guarantee for this exception to be thrown if this method is called concurrently from multiple threads.

startProcessing

public void startProcessing(RecordProvider addedSubscriptionProvider,
                            RecordProvider removedSubscriptionProvider)

Starts subscription processing for the specified added and removed RecordProvider instances. This method accepts null for one of the providers. This method or startProcessing(QDDistributor) may be called at most once after construction.

Throws:

NullPointerException - if both RecordProvider arguments are null.

IllegalStateException - if called multiple times. It is checked weakly to ensure fail-fast error detection behaviour. There is no strict thread-safe guarantee for this exception to be thrown if this method is called concurrently from multiple threads.

stopProcessing

public void stopProcessing()

Stop subscription processing. Unregisters RecordProvider instances from RecordProvider instances. Note: client code is responsible for disposing SubscriptionProviders originally passed to SubscriptionProcessor.

Throws:

IllegalStateException - if called before startProcessing(QDDistributor) or startProcessing(RecordProvider, RecordProvider).

hasMoreToProcess

public boolean hasMoreToProcess()

Returns true when this SubscriptionProcessor has more subscription available to process or its task is scheduled for processing.

signalNoMoreToProcess

protected void signalNoMoreToProcess()

This method is called immediately before hasMoreToProcess() becomes false.