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Fibers, Channels and Actors for the JVM
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/*
* Quasar: lightweight threads and actors for the JVM.
* Copyright (c) 2013-2014, Parallel Universe Software Co. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 3.0
* as published by the Free Software Foundation.
*/
package co.paralleluniverse.strands;
import co.paralleluniverse.fibers.Fiber;
import co.paralleluniverse.fibers.FiberFactory;
import co.paralleluniverse.fibers.FiberScheduler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicLong;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
/**
* Easily creates {@code StrandFactory}s.
* You can construct a new instance of this builder and use the builder pattern
* (call the setter methods followed by {@link #build() build()}) to create a new {@code StrandFactory},
* or use one of the static {@code from} methods to convert a {@link ThreadFactory} or {@link FiberFactory} into a {@code StrandFactory}.
* When using the builder pattern, either {@link #setFiber(FiberScheduler) setFiber} or {@link #setThread(boolean) setThread} must be called
* prior to calling {@link #build() build()}.
*
* @author pron
*/
public class StrandFactoryBuilder {
/**
* Converts a {@link ThreadFactory} into a {@link StrandFactory}.
*/
public static StrandFactory from(final ThreadFactory tf) {
checkNotNull(tf);
return new StrandFactory() {
@Override
public Strand newStrand(SuspendableCallable target) {
return Strand.of(tf.newThread(Strand.toRunnable(target)));
}
};
}
/**
* Converts a {@link FiberFactory} into a {@link StrandFactory}.
*/
public static StrandFactory from(final FiberFactory ff) {
checkNotNull(ff);
return new StrandFactory() {
@Override
public Strand newStrand(SuspendableCallable target) {
return ff.newFiber(target);
}
};
}
private Boolean fiber;
private boolean daemon;
private FiberScheduler fs;
private String nameFormat;
private Integer stackSize;
private Integer priority;
private Strand.UncaughtExceptionHandler ueh;
/**
* Makes the resulting {@link StrandFactory} produce threads.
*
* @param daemon whether or not the new threads are daemon threads.
* @return {@code this}
*/
public StrandFactoryBuilder setThread(boolean daemon) {
this.fiber = false;
this.fs = null;
this.daemon = daemon;
return this;
}
/**
* Makes the resulting {@link StrandFactory} produce fibers.
*
* @param fs the {@link FiberScheduler} to use for the new fibers, or {@code null} for the default scheduler.
* @return {@code this}
*/
public StrandFactoryBuilder setFiber(FiberScheduler fs) {
this.fiber = true;
this.fs = fs;
return this;
}
/**
* Sets the naming format to use when naming strands ({@link Strand#setName}) which are created with this StrandFactory.
*
* @param nameFormat a {@link String#format(String, Object...)}-compatible
* format String, to which a unique integer (0, 1, etc.) will be supplied
* as the single parameter. This integer will be unique to the built
* instance of the StrandFactory and will be assigned sequentially. For
* example, {@code "rpc-pool-%d"} will generate strand names like
* {@code "rpc-pool-0"}, {@code "rpc-pool-1"}, {@code "rpc-pool-2"}, etc.
* @return {@code this}
*/
public StrandFactoryBuilder setNameFormat(String nameFormat) {
String ignore = String.format(nameFormat, 0); // fail fast if the format is bad or null
this.nameFormat = nameFormat;
return this;
}
/**
* Suggests a stack size of strands created by the resulting StrandFactory.
* The stack size used might be an approximation of the given value, or even ignore the passed value completely.
*
* @param stackSize the stack size, in bytes
* @return {@code this}
*/
public StrandFactoryBuilder setStackSize(int stackSize) {
this.stackSize = stackSize;
return this;
}
/**
* Sets the priority for strands created by the {@code StrandFactory}.
* Priority currently applies only to thread, and even then the JVM and the OS are free to ignore it.
*
* @param priority the priority
* @return {@code this}
*/
public StrandFactoryBuilder setPriority(int priority) {
checkArgument(priority >= Thread.MIN_PRIORITY, "Strand priority (%s) must be >= %s", priority, Thread.MIN_PRIORITY);
checkArgument(priority <= Thread.MAX_PRIORITY, "Strand priority (%s) must be <= %s", priority, Thread.MAX_PRIORITY);
this.priority = priority;
return this;
}
/**
* Sets the {@link Strand.UncaughtExceptionHandler} for new threads created with this
* ThreadFactory.
*
* @param ueh the uncaught exception handler
* @return {@code this}
*/
public StrandFactoryBuilder setUncaughtExceptionHandler(Strand.UncaughtExceptionHandler ueh) {
this.ueh = ueh;
return this;
}
/**
* Creates and returns the {@link StrandFactory} that will create new strands based on this builder's settings.
*
* @return a new {@link StrandFactory}.
*/
public StrandFactory build() {
if (fiber == null)
throw new IllegalStateException("setFiber or setThread must be called before calling build");
final boolean _fiber = fiber;
final boolean _daemon = daemon;
final FiberScheduler _fs = fs;
final String _nameFormat = nameFormat;
final Strand.UncaughtExceptionHandler _ueh = ueh;
final int _stackSize = stackSize != null ? stackSize : 0;
final Integer _priority = priority;
final AtomicLong _count = (nameFormat != null) ? new AtomicLong(0) : null;
return new StrandFactory() {
@Override
public Strand newStrand(SuspendableCallable target) {
final String name = _nameFormat != null ? String.format(_nameFormat, _count.getAndIncrement()) : null;
final Strand s;
if (_fiber) {
s = _fs != null ? new Fiber(name, _fs, _stackSize, target) : new Fiber(name, _stackSize, target);
} else {
final Thread t = new Thread(null, Strand.toRunnable(target),
name != null ? name : "Thread-" + nextThreadNum(),
_stackSize);
if (name != null)
t.setName(name);
t.setDaemon(_daemon);
if (_priority != null)
t.setPriority(_priority);
s = Strand.of(t);
}
if (_ueh != null)
s.setUncaughtExceptionHandler(_ueh);
return s;
}
};
}
private static final Method nextThreadNum;
static {
try {
nextThreadNum = Thread.class.getDeclaredMethod("nextThreadNum");
nextThreadNum.setAccessible(true);
} catch (ReflectiveOperationException e) {
throw new AssertionError(e);
}
}
private static int nextThreadNum() {
try {
return (Integer) nextThreadNum.invoke(null);
} catch (IllegalAccessException ex) {
throw new AssertionError(ex);
} catch (InvocationTargetException ex) {
throw new RuntimeException(ex.getCause());
}
}
}