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DynamicConfig.java
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DynamicConfig.java
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/*
* Copyright 2021 IBM Corporation
*
* 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.ibm.watson.kvutils;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.Map;
import java.util.Set;
/**
* String {@link Map} backed by remote kv-store.
* <p/>
* It must be {@linkplain #start() started} before use.
*/
public interface DynamicConfig extends Map<String, String>, AutoCloseable {
@FunctionalInterface
interface Listener {
/**
* @param key
* @param value null if parameter has been removed
*/
void configChanged(String key, String value);
}
/**
* Listen for changes to any of the entries.
*
* @param listener
*/
void addListener(Listener listener);
/**
* Listen for changes to some or all of the keys, first producing
* an event for each key with its initial value.
*
* @param listener
* @param forKeys set of keys to recieve events for, or {@code null}
* to recieve events for all keys.
*/
void addAndInvokeListener(Listener listener, Set<String> forKeys);
/**
* Start this DynamicConfig, blocking until complete.
*
* @throws Exception
*/
default void start() throws Exception {}
/**
* Start this DynamicConfig asynchronously if possible.
*
* @throws Exception
*/
default ListenableFuture<Boolean> startAsync() {
try {
start();
return Futures.immediateFuture(Boolean.TRUE);
} catch (Exception e) {
return Futures.immediateFailedFuture(e);
}
}
/**
* Convenience - same as {@link #get(Object)} but with default
*
* @param key
* @param defaultValue
* @return
*/
@Override
default String getOrDefault(Object key, String defaultValue) {
String v = get(key);
return v != null? v : defaultValue;
}
}