/**
* Copyright 2012 Netflix, Inc.
*
* 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.netflix.hystrix.strategy.properties;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.netflix.config.PropertyWrapper;
/**
* Chained property allowing a chain of defaults using Archaius (https://github.com/Netflix/archaius) properties which is used by the default properties implementations.
* <p>
* Instead of just a single dynamic property with a default this allows a sequence of properties that fallback to the farthest down the chain with a value.
*
* TODO This should be replaced by a version in the Archaius library once available.
*
* @ExcludeFromJavadoc
*/
public abstract class HystrixPropertiesChainedArchaiusProperty {
private static final Logger logger = LoggerFactory.getLogger(HystrixPropertiesChainedArchaiusProperty.class);
/**
* @ExcludeFromJavadoc
*/
public static abstract class ChainLink<T> {
private final AtomicReference<ChainLink<T>> pReference;
private final ChainLink<T> next;
private final List<Runnable> callbacks;
/**
* @return String
*/
public abstract String getName();
/**
* @return T
*/
protected abstract T getValue();
/**
* @return Boolean
*/
public abstract boolean isValueAcceptable();
/**
* No arg constructor - used for end node
*/
public ChainLink() {
next = null;
pReference = new AtomicReference<ChainLink<T>>(this);
callbacks = new ArrayList<Runnable>();
}
/**
* @param nextProperty next property in the chain
*/
public ChainLink(ChainLink<T> nextProperty) {
next = nextProperty;
pReference = new AtomicReference<ChainLink<T>>(next);
callbacks = new ArrayList<Runnable>();
}
protected void checkAndFlip() {
// in case this is the end node
if (next == null) {
pReference.set(this);
return;
}
if (this.isValueAcceptable()) {
logger.debug("Flipping property: {} to use its current value: {}", getName(), getValue());
pReference.set(this);
} else {
logger.debug("Flipping property: {} to use NEXT property: {}", getName(), next);
pReference.set(next);
}
for (Runnable r : callbacks) {
r.run();
}
}
/**
* @return T
*/
public T get() {
if (pReference.get() == this) {
return this.getValue();
} else {
return pReference.get().get();
}
}
/**
* @param r callback to execut
*/
public void addCallback(Runnable r) {
callbacks.add(r);
}
/**
* @return String
*/
public String toString() {
return getName() + " = " + get();
}
}
/**
* @ExcludeFromJavadoc
*/
public static class StringProperty extends ChainLink<String> {
private final DynamicStringProperty sProp;
public StringProperty(DynamicStringProperty sProperty) {
super();
sProp = sProperty;
}
public StringProperty(String name, DynamicStringProperty sProperty) {
this(name, new StringProperty(sProperty));
}
public StringProperty(String name, StringProperty next) {
this(new DynamicStringProperty(name, null), next);
}
public StringProperty(DynamicStringProperty sProperty, DynamicStringProperty next) {
this(sProperty, new StringProperty(next));
}
public StringProperty(DynamicStringProperty sProperty, StringProperty next) {
super(next); // setup next pointer
sProp = sProperty;
sProp.addCallback(new Runnable() {
@Override
public void run() {
logger.debug("Property changed: '{} = {}'", getName(), getValue());
checkAndFlip();
}
});
checkAndFlip();
}
@Override
public boolean isValueAcceptable() {
return (sProp.get() != null);
}
@Override
protected String getValue() {
return sProp.get();
}
@Override
public String getName() {
return sProp.getName();
}
}
/**
* @ExcludeFromJavadoc
*/
public static class IntegerProperty extends ChainLink<Integer> {
private final DynamicIntegerProperty sProp;
public IntegerProperty(DynamicIntegerProperty sProperty) {
super();
sProp = sProperty;
}
public IntegerProperty(String name, DynamicIntegerProperty sProperty) {
this(name, new IntegerProperty(sProperty));
}
public IntegerProperty(String name, IntegerProperty next) {
this(new DynamicIntegerProperty(name, null), next);
}
public IntegerProperty(DynamicIntegerProperty sProperty, DynamicIntegerProperty next) {
this(sProperty, new IntegerProperty(next));
}
public IntegerProperty(DynamicIntegerProperty sProperty, IntegerProperty next) {
super(next); // setup next pointer
sProp = sProperty;
sProp.addCallback(new Runnable() {
@Override
public void run() {
logger.debug("Property changed: '{} = {}'", getName(), getValue());
checkAndFlip();
}
});
checkAndFlip();
}
@Override
public boolean isValueAcceptable() {
return (sProp.get() != null);
}
@Override
public Integer getValue() {
return sProp.get();
}
@Override
public String getName() {
return sProp.getName();
}
}
/**
* @ExcludeFromJavadoc
*/
public static class BooleanProperty extends ChainLink<Boolean> {
private final DynamicBooleanProperty sProp;
public BooleanProperty(DynamicBooleanProperty sProperty) {
super();
sProp = sProperty;
}
public BooleanProperty(String name, DynamicBooleanProperty sProperty) {
this(name, new BooleanProperty(sProperty));
}
public BooleanProperty(String name, BooleanProperty next) {
this(new DynamicBooleanProperty(name, null), next);
}
public BooleanProperty(DynamicBooleanProperty sProperty, DynamicBooleanProperty next) {
this(sProperty, new BooleanProperty(next));
}
public BooleanProperty(DynamicBooleanProperty sProperty, BooleanProperty next) {
super(next); // setup next pointer
sProp = sProperty;
sProp.addCallback(new Runnable() {
@Override
public void run() {
logger.debug("Property changed: '{} = {}'", getName(), getValue());
checkAndFlip();
}
});
checkAndFlip();
}
@Override
public boolean isValueAcceptable() {
return (sProp.getValue() != null);
}
@Override
public Boolean getValue() {
return sProp.get();
}
@Override
public String getName() {
return sProp.getName();
}
}
/**
* @ExcludeFromJavadoc
*/
public static class DynamicBooleanProperty extends PropertyWrapper<Boolean> {
public DynamicBooleanProperty(String propName, Boolean defaultValue) {
super(propName, defaultValue);
}
/**
* Get the current value from the underlying DynamicProperty
*/
public Boolean get() {
return prop.getBoolean(defaultValue);
}
@Override
public Boolean getValue() {
return get();
}
}
/**
* @ExcludeFromJavadoc
*/
public static class DynamicIntegerProperty extends PropertyWrapper<Integer> {
public DynamicIntegerProperty(String propName, Integer defaultValue) {
super(propName, defaultValue);
}
/**
* Get the current value from the underlying DynamicProperty
*/
public Integer get() {
return prop.getInteger(defaultValue);
}
@Override
public Integer getValue() {
return get();
}
}
/**
* @ExcludeFromJavadoc
*/
public static class DynamicLongProperty extends PropertyWrapper<Long> {
public DynamicLongProperty(String propName, Long defaultValue) {
super(propName, defaultValue);
}
/**
* Get the current value from the underlying DynamicProperty
*/
public Long get() {
return prop.getLong(defaultValue);
}
@Override
public Long getValue() {
return get();
}
}
/**
* @ExcludeFromJavadoc
*/
public static class DynamicStringProperty extends PropertyWrapper<String> {
public DynamicStringProperty(String propName, String defaultValue) {
super(propName, defaultValue);
}
/**
* Get the current value from the underlying DynamicProperty
*/
public String get() {
return prop.getString(defaultValue);
}
@Override
public String getValue() {
return get();
}
}
}