nifi-nar-bundles/nifi-standard-services/nifi-distributed-cache-client-service-api/src/main/java/org/apache/nifi/distributed/cache/client/DistributedMapCacheClient.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.nifi.distributed.cache.client;

import org.apache.nifi.annotation.documentation.CapabilityDescription;
import org.apache.nifi.annotation.documentation.Tags;
import org.apache.nifi.controller.ControllerService;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * This interface defines an API that can be used for interacting with a
 * Distributed Cache that functions similarly to a {@link java.util.Map Map}.
 *
 */
@Tags({"distributed", "client", "cluster", "map", "cache"})
@CapabilityDescription("Provides the ability to communicate with a DistributedMapCacheServer. This allows "
        + "multiple nodes to coordinate state with a single remote entity.")
public interface DistributedMapCacheClient extends ControllerService {

    /**
     * Adds the specified key and value to the cache, if they are not already
     * present, serializing the key and value with the given
     * {@link Serializer}s.
     *
     * @param <K> type of key
     * @param <V> type of value
     * @param key the key for into the map
     * @param value the value to add to the map if and only if the key is absent
     * @param keySerializer key serializer
     * @param valueSerializer value serializer
     * @return true if the value was added to the cache, false if the value
     * already existed in the cache
     *
     * @throws IOException if unable to communicate with the remote instance
     */
    <K, V> boolean putIfAbsent(K key, V value, Serializer<K> keySerializer, Serializer<V> valueSerializer) throws IOException;

    /**
     * Adds the specified key and value to the cache, if they are not already
     * present, serializing the key and value with the given
     * {@link Serializer}s. If a value already exists in the cache for the given
     * key, the value associated with the key is returned, after being
     * deserialized with the given valueDeserializer.
     *
     * @param <K> type of key
     * @param <V> type of value
     * @param key key
     * @param value value
     * @param keySerializer key serializer
     * @param valueSerializer key serializer
     * @param valueDeserializer value deserializer
     * @return If a value already exists in the cache for the given
     * key, the value associated with the key is returned, after being
     * deserialized with the given {@code valueDeserializer}. If the key does not
     * exist, the key and its value will be added to the cache.
     * @throws IOException ex
     */
    <K, V> V getAndPutIfAbsent(K key, V value, Serializer<K> keySerializer, Serializer<V> valueSerializer, Deserializer<V> valueDeserializer) throws IOException;

    /**
     * Determines if the given value is present in the cache and if so returns
     * <code>true</code>, else returns <code>false</code>
     *
     * @param <K> type of key
     * @param key key
     * @param keySerializer key serializer
     * @return Determines if the given value is present in the cache and if so returns
     * <code>true</code>, else returns <code>false</code>
     *
     * @throws IOException if unable to communicate with the remote instance
     */
    <K> boolean containsKey(K key, Serializer<K> keySerializer) throws IOException;

    /**
     * Adds the specified key and value to the cache, overwriting any value that is
     * currently set.
     *
     * @param <K> the key type
     * @param <V> the value type
     * @param key The key to set
     * @param value The value to associate with the given Key
     * @param keySerializer the Serializer that will be used to serialize the key into bytes
     * @param valueSerializer the Serializer that will be used to serialize the value into bytes
     *
     * @throws IOException if unable to communicate with the remote instance
     * @throws NullPointerException if the key or either serializer is null
     */
    <K, V> void put(K key, V value, Serializer<K> keySerializer, Serializer<V> valueSerializer) throws IOException;

    /**
     * Performs a bulk put operation. This should be used when needed to send a large batch of updates to a cache
     * in a single update operation.
     *
     * @param keysAndValues   A java.util.Map that contains an association between keys and values to be bulk inserted into the cache.
     * @param keySerializer   The Serializer that will be used to serialize the key into bytes
     * @param valueSerializer The Serializer that will be used to serialize the value into bytes
     * @param <K>             The key type
     * @param <V>             The value type
     * @throws IOException if unable to communicate with the remote instance
     */
    default <K, V> void putAll(Map<K, V> keysAndValues, Serializer<K> keySerializer, Serializer<V> valueSerializer) throws IOException {
        for (Map.Entry<K, V> entry : keysAndValues.entrySet()) {
            put(entry.getKey(), entry.getValue(), keySerializer, valueSerializer);
        }
    }

    /**
     * Returns the value in the cache for the given key, if one exists;
     * otherwise returns <code>null</code>
     *
     * @param <K> the key type
     * @param <V> the value type
     * @param key the key to lookup in the map
     * @param keySerializer key serializer
     * @param valueDeserializer value serializer
     *
     * @return the value in the cache for the given key, if one exists;
     * otherwise returns <code>null</code>
     * @throws IOException ex
     */
    <K, V> V get(K key, Serializer<K> keySerializer, Deserializer<V> valueDeserializer) throws IOException;

    /**
     * Returns the values in the cache for the given keys, if they exist;
     * otherwise returns <code>null</code>
     *
     * @param <K> the key type
     * @param <V> the value type
     * @param keys a set of keys whose values to lookup in the map
     * @param keySerializer key serializer
     * @param valueDeserializer value serializer
     *
     * @return the value in the cache for the given key, if one exists;
     * otherwise returns <code>null</code>
     * @throws IOException ex
     */
    default <K, V> Map<K, V> subMap(Set<K> keys, Serializer<K> keySerializer, Deserializer<V> valueDeserializer) throws IOException {
        // Default behavior is to iterate over the keys, calling get(key) and putting it into the results map
        if (keys == null) {
            return null;
        }
        Map<K, V> results = new HashMap<>(keys.size());
        for (K key : keys) {
            results.put(key, get(key, keySerializer, valueDeserializer));
        }
        return results;
    }

    /**
     * Attempts to notify the server that we are finished communicating with it
     * and cleans up resources
     *
     * @throws java.io.IOException ex
     */
    void close() throws IOException;

    /**
     * Removes the entry with the given key from the cache, if it is present.
     *
     * @param <K> type of key
     * @param key key
     * @param serializer serializer
     * @return <code>true</code> if the entry is removed, <code>false</code> if
     * the key did not exist in the cache
     * @throws IOException ex
     */
    <K> boolean remove(K key, Serializer<K> serializer) throws IOException;

    /**
     * Removes the entry with the given key from the cache, if it is present,
     * and returns the value that was removed from the map.
     *
     * @param <K> type of key
     * @param <V> type of value
     * @param key key
     * @param keySerializer key serializer
     * @param valueDeserializer value deserializer
     * @return the value previously associated with the key, or null if there was no mapping
     * null can also indicate that the map previously associated null with the key
     * @throws IOException ex
     */
    default <K, V> V removeAndGet(K key, Serializer<K> keySerializer, Deserializer<V> valueDeserializer) throws IOException {
        throw new UnsupportedOperationException();
    }

    /**
     * Removes entries whose keys match the specified pattern
     *
     * @param regex The regular expression / pattern on which to match the keys to be removed
     * @return The number of entries that were removed
     * @throws IOException if any error occurred while removing an entry
     */
    long removeByPattern(String regex) throws IOException;

    /**
     * Removes entries whose keys match the specified pattern, and returns a map of entries that
     * were removed.
     *
     * @param <K> type of key
     * @param <V> type of value
     * @param regex The regular expression / pattern on which to match the keys to be removed
     * @param keyDeserializer key deserializer
     * @param valueDeserializer value deserializer
     * @return A map of key/value entries that were removed from the cache
     * @throws IOException if any error occurred while removing an entry
     */
    default <K, V> Map<K, V> removeByPatternAndGet(String regex, Deserializer<K> keyDeserializer, Deserializer<V> valueDeserializer) throws IOException {
        throw new UnsupportedOperationException();
    }

    /**
     * Returns a set of all keys currently in the cache
     *
     * @param <K> type of key
     * @param keyDeserializer key deserializer
     * @return a Set of all keys currently in the cache
     * @throws IOException ex
     */
    default <K> Set<K> keySet(Deserializer<K> keyDeserializer) throws IOException {
        throw new UnsupportedOperationException();
    }
}