global.namespace.neuron.di.internal.RealCachingStrategy Maven / Gradle / Ivy
/*
* Copyright © 2016 - 2019 Schlichtherle IT Services
*
* 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
*
* https://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 global.namespace.neuron.di.internal;
import global.namespace.neuron.di.java.CachingStrategy;
import global.namespace.neuron.di.java.DependencyProvider;
/**
* Mirrors {@link CachingStrategy}.
*/
enum RealCachingStrategy {
/**
* @see #valueOf(CachingStrategy)
*/
@SuppressWarnings("unused")
DISABLED {
@Override
DependencyProvider decorate(DependencyProvider provider) {
return provider;
}
},
/**
* @see #valueOf(CachingStrategy)
*/
@SuppressWarnings("unused")
NOT_THREAD_SAFE {
@Override
DependencyProvider decorate(final DependencyProvider provider) {
return new DependencyProvider() {
D returnValue;
@Override
public D get() throws Throwable {
final D value = returnValue;
return null != value ? value : (returnValue = provider.get());
}
};
}
},
/**
* @see #valueOf(CachingStrategy)
*/
@SuppressWarnings("unused")
THREAD_SAFE {
@Override
DependencyProvider decorate(final DependencyProvider provider) {
return new DependencyProvider() {
volatile D returnValue;
@Override
public D get() throws Throwable {
D value;
if (null == (value = returnValue)) {
synchronized (this) {
if (null == (value = returnValue)) {
returnValue = value = provider.get();
}
}
}
return value;
}
};
}
},
/**
* @see #valueOf(CachingStrategy)
*/
@SuppressWarnings("unused")
THREAD_LOCAL {
@Override
DependencyProvider decorate(final DependencyProvider provider) {
return new DependencyProvider() {
final ThreadLocal results = new ThreadLocal<>();
@Override
public D get() throws Throwable {
D result = results.get();
if (null == result) {
results.set(result = provider.get());
}
return result;
}
};
}
};
static RealCachingStrategy valueOf(CachingStrategy strategy) {
return valueOf(strategy.name());
}
abstract DependencyProvider decorate(DependencyProvider provider);
}