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Parallel programming on the go
/*
* 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 com.github.dm.jrt.core;
import com.github.dm.jrt.builder.IOChannelBuilder;
import com.github.dm.jrt.builder.ObjectRoutineBuilder;
import com.github.dm.jrt.builder.RoutineBuilder;
import com.github.dm.jrt.invocation.InvocationFactory;
import org.jetbrains.annotations.NotNull;
/**
* This utility class represents the entry point to the library by acting as a factory of routine
* builders.
*
* There are mainly two ways to create a routine object:
*
* Routine by invocation customization
* The first approach consists in implementing an invocation object. Invocations mimic the scope of
* a function call. Objects are instantiated when needed and recycled for successive invocations.
*
* Routine by method invocation
* The second approach is based on the asynchronous invocation of a method of an existing class or
* object via reflection.
* It is possible to annotate selected methods to be asynchronously invoked, or to simply select
* a method through its signature. It is also possible to build a proxy object whose methods will
* in turn asynchronously invoke the target object ones.
* Note that a proxy object can be simply defined as an interface implemented by the target, but
* also as a completely unrelated one mirroring the target methods. In this way it is possible to
* apply the library functionality to objects defined by third party libraries which are not under
* direct control.
* A mirror interface adds the possibility to override input and output parameters with output
* channels, so that data are transferred asynchronously, avoiding the need to block execution while
* waiting for them to be available.
* Finally, it also possible to create a wrapper class to enable asynchronous invocation of methods,
* through annotation pre-processing and compile-time code generation. In order to activate the
* processing of annotations, it is simply necessary to include the proxy artifact or module in the
* project dependencies.
*
* This class provides also a way to build I/O channel instances, which can be used to pass data
* without the need to start a routine invocation.
*
* Some usage examples
*
* Example 1: Asynchronously merge the output of two routines.
*
*
*
* final IOChannel<Result, Result> channel = JRoutine.io().buildChannel();
* channel.pass(doSomething1.asyncCall())
* .pass(doSomething2.asyncCall())
* .close();
* .afterMax(seconds(20))
* .allInto(results);
*
*
* Or simply:
*
*
*
* final OutputChannel<Result> output1 = doSomething1.asyncCall();
* final OutputChannel<Result> output2 = doSomething2.asyncCall();
* output1.afterMax(seconds(20)).allInto(results);
* output2.afterMax(seconds(20)).allInto(results);
*
*
* (Note that, the order of the input or the output of the routine is not guaranteed unless properly
* configured)
*
* Example 2: Asynchronously concatenate the output of two routines.
*
*
*
* doSomething2.asyncCall(doSomething1.asyncCall())).afterMax(seconds(20)).allInto(results);
*
*
*
* Example 3: Asynchronously get the output of two routines.
*
*
*
* public interface AsyncCallback {
*
* public void onResults(
* @Input(Result.class) OutputChannel<Result> result1,
* @Input(Result.class) OutputChannel<Result> result2);
* }
*
* final AsyncCallback callback = JRoutine.on(instance(myCallback))
* .buildProxy(AsyncCallback.class);
* callback.onResults(doSomething1.asyncCall(), doSomething2.asyncCall());
*
*
* Where the object myCallback implements a method
* public void onResults(Result result1, Result result2).
*
* Example 4: Asynchronously feed a routine from a different thread.
*
*
*
* final IOChannel<Result, Result> channel = JRoutine.io().buildChannel();
*
* new Thread() {
*
* @Override
* public void run() {
*
* channel.pass(new Result()).close();
* }
*
* }.start();
*
* final Routine<Result, Result> routine =
* JRoutine.<Result>on(PassingInvocation.<Result>factoryOf())
* .buildRoutine();
* routine.asyncCall(channel).afterMax(seconds(20)).allInto(results);
*
*
*
* Created by davide-maestroni on 09/07/2014.
*
* @see Annotations
*/
public class JRoutine {
/**
* Avoid direct instantiation.
*/
protected JRoutine() {
}
/**
* Returns an I/O channel builder.
*
* @return the channel builder instance.
*/
@NotNull
public static IOChannelBuilder io() {
return new DefaultIOChannelBuilder();
}
/**
* Returns a routine builder wrapping the specified target object.
* Note that it is responsibility of the caller to retain a strong reference to the target
* instance to prevent it from being garbage collected.
* Note also that the invocation input data will be cached, and the results will be produced
* only after the invocation channel is closed, so be sure to avoid streaming inputs in
* order to prevent starvation or out of memory errors.
*
* @param target the invocation target.
* @return the routine builder instance.
* @throws java.lang.IllegalArgumentException if the specified object class represents an
* interface.
*/
@NotNull
public static ObjectRoutineBuilder on(@NotNull final InvocationTarget target) {
return new DefaultObjectRoutineBuilder(target);
}
/**
* Returns a routine builder based on the specified invocation factory.
* In order to prevent undesired leaks, the class of the specified factory must have a
* static context.
*
* @param factory the invocation factory.
* @param the input data type.
* @param the output data type.
* @return the routine builder instance.
* @throws java.lang.IllegalArgumentException if the class of the specified factory is not
* static.
*/
@NotNull
public static RoutineBuilder on(
@NotNull final InvocationFactory factory) {
return new DefaultRoutineBuilder(factory);
}
}