org.cache2k.config.ToggleFeature Maven / Gradle / Ivy
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package org.cache2k.config;
/*-
* #%L
* cache2k API
* %%
* Copyright (C) 2000 - 2022 headissue GmbH, Munich
* %%
* 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.
* #L%
*/
import org.cache2k.Cache2kBuilder;
import org.cache2k.annotation.Nullable;
import java.util.Set;
/**
* Base class for a cache feature that can be enabled or disables and
* appears only once in the feature set. A feature can be disabled in
* two ways: Either by setting enabled to {@code false} or by removing
* it from the feature set.
*
* This allows enablement of features based on the users' preference:
* A feature can be enabled by default and then disabled per individual
* cache or just enabled at the individual cache level.
*
* @author Jens Wilke
*/
public abstract class ToggleFeature implements SingleFeature {
/**
* Enable the feature in the main configuration. If the feature is
* already existing it is replaced by a newly created one.
*
* @return the created feature to set additional parameters
*/
public static T enable(Cache2kBuilder builder,
Class featureType) {
try {
T feature = featureType.getConstructor().newInstance();
Set features = builder.config().getFeatures();
features.remove(feature);
features.add(feature);
return feature;
} catch (Exception e) {
throw new LinkageError("Instantiation failed", e);
}
}
/**
* Disable the feature by removing it from the configuration.
*/
public static void disable(Cache2kBuilder builder,
Class featureType) {
builder.config().getFeatures().removeIf(feature -> feature.getClass().equals(featureType));
}
/**
* Returns the feature instance, if present.
*/
@SuppressWarnings("unchecked")
public static @Nullable T extract(Cache2kBuilder builder,
Class featureType) {
for (Feature feature : builder.config().getFeatures()) {
if (feature.getClass().equals(featureType)) {
return (T) feature;
}
}
return null;
}
/**
* Returns true if the feature is enabled. Meaning, the feature instance is present
* and enabled.
*/
public static boolean isEnabled(Cache2kBuilder builder,
Class featureType) {
ToggleFeature f = extract(builder, featureType);
return f != null && f.isEnabled();
}
/**
* Feature is enabled by default. The enabled field is intended for
* usage with an external configuration, to disable a feature
* which was enabled globally e.g. {@code false}
*/
private boolean enabled = true;
/**
* Checks whether enabled and call implementations doEnlist method.
*/
@Override
public final void enlist(CacheBuildContext ctx) {
if (enabled) {
doEnlist(ctx);
}
}
protected abstract void doEnlist(CacheBuildContext ctx);
public final boolean isEnabled() {
return enabled;
}
public final void setEnabled(boolean v) {
this.enabled = v;
}
/**
* Alternate setter for spelling flexibility in XML configuration.
*/
public final void setEnable(boolean v) {
this.enabled = v;
}
/**
* Identical if it is the same implementation class. Relevant for
* keeping only one feature within the configuration.
*/
@Override
public final boolean equals(@Nullable Object o) {
if (o == null) { return false; }
return getClass().equals(o.getClass());
}
/**
* Hashcode from the implementation class.
*/
@Override
public final int hashCode() {
return getClass().hashCode();
}
/**
* Override if this takes additional parameters.
*/
@Override
public String toString() {
return getClass().getSimpleName() + '{' + (enabled ? "enabled" : "disabled") + '}';
}
}