uk.co.codera.lang.concurrent.Tasks Maven / Gradle / Ivy
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package uk.co.codera.lang.concurrent;
/**
* Responsible for constructing the different kind of tasks used by the
* {@link PriorityTaskExecutor}.
*
* @author andystewart
*/
public class Tasks {
private Tasks() {
super();
}
public static SimpleTask.Builder aTask() {
return SimpleTask.aTask();
}
public static CancellableTask.Builder aCancellableTask() {
return CancellableTask.aTask();
}
public static CancellingTask.Builder aCancellingTask() {
return CancellingTask.aTask();
}
public abstract static class AbstractTask implements Task, CommandExecutor {
private final Command command;
private AbstractTask(Builder builder) {
this.command = builder.command;
}
@Override
public void execute() {
this.command.execute();
}
@Override
public Command getCommand() {
return this.command;
}
public abstract static class Builder {
private Command command;
@SuppressWarnings("unchecked")
public T with(Command command) {
this.command = command;
return (T) this;
}
public abstract Task build();
}
}
public abstract static class AbstractCorrelatedTask extends AbstractTask {
private final Object correlationId;
private final Comparable sequence;
private AbstractCorrelatedTask(Builder builder) {
super(builder);
this.correlationId = builder.correlationId;
this.sequence = builder.sequence;
}
public Object getCorrelationId() {
return this.correlationId;
}
@SuppressWarnings("squid:S1452")
public Comparable getSequence() {
return this.sequence;
}
public abstract static class Builder extends AbstractTask.Builder {
private Object correlationId;
private Comparable sequence;
@SuppressWarnings("unchecked")
public T correlationId(Object correlationId) {
this.correlationId = correlationId;
return (T) this;
}
@SuppressWarnings("unchecked")
public T sequence(Comparable sequence) {
this.sequence = sequence;
return (T) this;
}
}
}
/**
*
* This is the default kind of task. It has no affect on any tasks it may
* overtake (if it does indeed overtake them) nor can it be affected by any
* tasks that may overtake it. The executor will attempt to invoke the
* command whatever.
*
*
* @author andystewart
*/
public static class SimpleTask extends AbstractTask {
private SimpleTask(Builder builder) {
super(builder);
}
private static Builder aTask() {
return new Builder();
}
public static class Builder extends AbstractTask.Builder {
@Override
public Task build() {
return new SimpleTask(this);
}
}
}
/**
*
* This kind of task can be cancelled by a {@link CancellingTask} that has
* the same correlationId and a sequence that is considered later than that
* on this task.
*
*
* @author andystewart
*/
public static class CancellableTask extends AbstractCorrelatedTask {
private CancellableTask(Builder builder) {
super(builder);
}
private static Builder aTask() {
return new Builder();
}
public static class Builder extends AbstractCorrelatedTask.Builder {
@Override
public Task build() {
return new CancellableTask(this);
}
}
}
/**
*
* This kind of task will cancel any {@link CancellableTask} that has the
* same correlationId and an earlier sequence to this task.
*
*
* @author andystewart
*/
public static class CancellingTask extends AbstractCorrelatedTask {
private CancellingTask(Builder builder) {
super(builder);
}
private static Builder aTask() {
return new Builder();
}
public static class Builder extends AbstractCorrelatedTask.Builder {
@Override
public Task build() {
return new CancellingTask(this);
}
}
}
}