/*
* Copyright (c) 2008-2017, Hazelcast, Inc. All Rights Reserved.
*
* 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.hazelcast.spi.discovery;
import com.hazelcast.config.properties.PropertyDefinition;
import com.hazelcast.logging.ILogger;
import com.hazelcast.spi.partitiongroup.PartitionGroupStrategy;
import com.hazelcast.util.StringUtil;
import java.util.Collections;
import java.util.Map;
import static java.util.Collections.unmodifiableMap;
/**
* An common abstract superclass for {@link DiscoveryStrategy} implementations,
* offering convenient access to configuration properties (which may be overridden
* on the system's environment or JVM properties), as well as a {@link ILogger} instance.
*
* @since 3.6
*/
public abstract class AbstractDiscoveryStrategy implements DiscoveryStrategy {
private final ILogger logger;
private final Map<String, Comparable> properties;
public AbstractDiscoveryStrategy(ILogger logger, Map<String, Comparable> properties) {
this.logger = logger;
this.properties = unmodifiableMap(properties);
}
@Override
public void destroy() {
}
@Override
public void start() {
}
@Override
public PartitionGroupStrategy getPartitionGroupStrategy() {
return null;
}
@Override
public Map<String, Object> discoverLocalMetadata() {
return Collections.emptyMap();
}
/**
* Returns an immutable copy of the configuration properties.
*
* @return the configuration properties
*/
protected Map<String, Comparable> getProperties() {
return properties;
}
/**
* Returns a {@link ILogger} instance bound to the current class.
*
* @return a ILogger instance
*/
protected ILogger getLogger() {
return logger;
}
/**
* Returns the value of the requested {@link PropertyDefinition} if available in the
* declarative or programmatic configuration (XML or Config API), otherwise it will
* return <tt>null</tt>.
* <p/>
* <b>This method overload won't do environment or JVM property lookup.</b> A call to
* this overload is equivalent to {@link #getOrNull(String, PropertyDefinition)}
* with <tt>null</tt> passed as the first parameter.
*
* @param property the PropertyDefinition to lookup
* @param <T> the type of the property, must be compatible with the conversion
* result of {@link PropertyDefinition#typeConverter()}
* @return the value of the given property if available in the configuration, otherwise null
*/
protected <T extends Comparable> T getOrNull(PropertyDefinition property) {
return getOrDefault(property, null);
}
/**
* Returns the value of the requested {@link PropertyDefinition} if available in the
* declarative or programmatic configuration (XML or Config API), can be found in the
* system's environment, or passed as a JVM property. Otherwise it will return <tt>null</tt>.
* <p/>
* This overload will resolve the requested property in the following order, whereas the
* higher priority is from top to bottom:
* <ul>
* <li>{@link System#getProperty(String)}: JVM properties</li>
* <li>{@link System#getenv(String)}: System environment</li>
* <li>Configuration properties of this {@link DiscoveryStrategy}</li>
* </ul>
* To resolve JVM properties or the system environment the property's key is prefixed with
* given <tt>prefix</tt>, therefore a prefix of <i>com.hazelcast.discovery</i> and a property
* key of <i>hostname</i> will result in a property lookup of <i>com.hazelcast.discovery.hostname</i>
* in the system environment and JVM properties.
*
* @param prefix the property key prefix for environment and JVM properties lookup
* @param property the PropertyDefinition to lookup
* @param <T> the type of the property, must be compatible with the conversion
* result of {@link PropertyDefinition#typeConverter()}
* @return the value of the given property if available in the configuration, system environment
* or JVM properties, otherwise null
*/
protected <T extends Comparable> T getOrNull(String prefix, PropertyDefinition property) {
return getOrDefault(prefix, property, null);
}
/**
* Returns the value of the requested {@link PropertyDefinition} if available in the
* declarative or programmatic configuration (XML or Config API), otherwise it will
* return the given <tt>defaultValue</tt>.
* <p/>
* <b>This method overload won't do environment or JVM property lookup.</b> A call to
* this overload is equivalent to {@link #getOrDefault(String, PropertyDefinition, Comparable)}
* with <tt>null</tt> passed as the first parameter.
*
* @param property the PropertyDefinition to lookup
* @param <T> the type of the property, must be compatible with the conversion
* result of {@link PropertyDefinition#typeConverter()}
* @return the value of the given property if available in the configuration, otherwise the
* given default value
*/
protected <T extends Comparable> T getOrDefault(PropertyDefinition property, T defaultValue) {
return getOrDefault(null, property, defaultValue);
}
/**
* Returns the value of the requested {@link PropertyDefinition} if available in the
* declarative or programmatic configuration (XML or Config API), can be found in the
* system's environment, or passed as a JVM property. otherwise it will return the given
* <tt>defaultValue</tt>.
* <p/>
* This overload will resolve the requested property in the following order, whereas the
* higher priority is from top to bottom:
* <ul>
* <li>{@link System#getProperty(String)}: JVM properties</li>
* <li>{@link System#getenv(String)}: System environment</li>
* <li>Configuration properties of this {@link DiscoveryStrategy}</li>
* </ul>
* To resolve JVM properties or the system environment the property's key is prefixed with
* given <tt>prefix</tt>, therefore a prefix of <i>com.hazelcast.discovery</i> and a property
* key of <i>hostname</i> will result in a property lookup of <i>com.hazelcast.discovery.hostname</i>
* in the system environment and JVM properties.
*
* @param prefix the property key prefix for environment and JVM properties lookup
* @param property the PropertyDefinition to lookup
* @param <T> the type of the property, must be compatible with the conversion
* result of {@link PropertyDefinition#typeConverter()}
* @return the value of the given property if available in the configuration, system environment
* or JVM properties, otherwise the given default value
*/
protected <T extends Comparable> T getOrDefault(String prefix, PropertyDefinition property, T defaultValue) {
if (property == null) {
return defaultValue;
}
Comparable value = readProperty(prefix, property);
if (value == null) {
value = properties.get(property.key());
}
if (value == null) {
return defaultValue;
}
return (T) value;
}
private Comparable readProperty(String prefix, PropertyDefinition property) {
if (prefix != null) {
String p = getProperty(prefix, property);
String v = System.getProperty(p);
if (StringUtil.isNullOrEmpty(v)) {
v = System.getenv(p);
}
if (!StringUtil.isNullOrEmpty(v)) {
return property.typeConverter().convert(v);
}
}
return null;
}
private String getProperty(String prefix, PropertyDefinition property) {
StringBuilder sb = new StringBuilder(prefix);
if (prefix.charAt(prefix.length() - 1) != '.') {
sb.append('.');
}
return sb.append(property.key()).toString();
}
}