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/*
 * Copyright 2015 Open Networking Laboratory
 *
 * 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 org.onosproject.store.service;

import java.util.Collection;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Predicate;

/**
 * A distributed, strongly consistent key-value map.
 * 

* This map offers strong read-after-update (where update == create/update/delete) * consistency. All operations to the map are serialized and applied in a consistent * manner. *

* The stronger consistency comes at the expense of availability in * the event of a network partition. A network partition can be either due to * a temporary disruption in network connectivity between participating nodes * or due to a node being temporarily down. *

* All values stored in this map are versioned and the API supports optimistic * concurrency by allowing conditional updates that take into consideration * the version or value that was previously read. *

* This map does not allow null values. All methods can throw a ConsistentMapException * (which extends RuntimeException) to indicate failures. * */ public interface ConsistentMap { /** * Returns the number of entries in the map. * * @return map size. */ int size(); /** * Returns true if the map is empty. * * @return true if map has no entries, false otherwise */ boolean isEmpty(); /** * Returns true if this map contains a mapping for the specified key. * * @param key key * @return true if map contains key, false otherwise */ boolean containsKey(K key); /** * Returns true if this map contains the specified value. * * @param value value * @return true if map contains value, false otherwise. */ boolean containsValue(V value); /** * Returns the value (and version) to which the specified key is mapped, or null if this * map contains no mapping for the key. * * @param key the key whose associated value (and version) is to be returned * @return the value (and version) to which the specified key is mapped, or null if * this map contains no mapping for the key */ Versioned get(K key); /** * If the specified key is not already associated with a value (or is mapped to null), * attempts to compute its value using the given mapping function and enters it into * this map unless null. * * @param key key with which the specified value is to be associated * @param mappingFunction the function to compute a value * @return the current (existing or computed) value associated with the specified key, * or null if the computed value is null. Method throws {@code ConsistentMapException.ConcurrentModification} * if a concurrent modification of map is detected */ Versioned computeIfAbsent(K key, Function mappingFunction); /** * Attempts to compute a mapping for the specified key and its current mapped value (or * null if there is no current mapping). * If the computed value is null, the current mapping will be removed from the map. * * @param key key with which the specified value is to be associated * @param remappingFunction the function to compute a value * @return the new value associated with the specified key, or null if none. * This method throws {@code ConsistentMapException.ConcurrentModification} * if a concurrent modification of map is detected */ Versioned compute(K key, BiFunction remappingFunction); /** * If the value for the specified key is present and non-null, attempts to compute a new * mapping given the key and its current mapped value. * If the computed value is null, the current mapping will be removed from the map. * * @param key key with which the specified value is to be associated * @param remappingFunction the function to compute a value * @return the new value associated with the specified key, or null if none. * This method throws {@code ConsistentMapException.ConcurrentModification} * if a concurrent modification of map is detected */ Versioned computeIfPresent(K key, BiFunction remappingFunction); /** * If the value for the specified key satisfies a condition, attempts to compute a new * mapping given the key and its current mapped value. * If the computed value is null, the current mapping will be removed from the map. * * @param key key with which the specified value is to be associated * @param condition condition that should evaluate to true for the computation to proceed * @param remappingFunction the function to compute a value * @return the new value associated with the specified key, or the old value if condition evaluates to false. * This method throws {@code ConsistentMapException.ConcurrentModification} if a concurrent * modification of map is detected */ Versioned computeIf(K key, Predicate condition, BiFunction remappingFunction); /** * Associates the specified value with the specified key in this map (optional operation). * If the map previously contained a mapping for the key, the old value is replaced by the * specified value. * * @param key key with which the specified value is to be associated * @param value value to be associated with the specified key * @return the previous value (and version) associated with key, or null if there was * no mapping for key. */ Versioned put(K key, V value); /** * Associates the specified value with the specified key in this map (optional operation). * If the map previously contained a mapping for the key, the old value is replaced by the * specified value. * * @param key key with which the specified value is to be associated * @param value value to be associated with the specified key * @return new value. */ Versioned putAndGet(K key, V value); /** * Removes the mapping for a key from this map if it is present (optional operation). * * @param key key whose value is to be removed from the map * @return the value (and version) to which this map previously associated the key, * or null if the map contained no mapping for the key. */ Versioned remove(K key); /** * Removes all of the mappings from this map (optional operation). * The map will be empty after this call returns. */ void clear(); /** * Returns a Set view of the keys contained in this map. * This method differs from the behavior of java.util.Map.keySet() in that * what is returned is a unmodifiable snapshot view of the keys in the ConsistentMap. * Attempts to modify the returned set, whether direct or via its iterator, * result in an UnsupportedOperationException. * * @return a set of the keys contained in this map */ Set keySet(); /** * Returns the collection of values (and associated versions) contained in this map. * This method differs from the behavior of java.util.Map.values() in that * what is returned is a unmodifiable snapshot view of the values in the ConsistentMap. * Attempts to modify the returned collection, whether direct or via its iterator, * result in an UnsupportedOperationException. * * @return a collection of the values (and associated versions) contained in this map */ Collection> values(); /** * Returns the set of entries contained in this map. * This method differs from the behavior of java.util.Map.entrySet() in that * what is returned is a unmodifiable snapshot view of the entries in the ConsistentMap. * Attempts to modify the returned set, whether direct or via its iterator, * result in an UnsupportedOperationException. * * @return set of entries contained in this map. */ Set>> entrySet(); /** * If the specified key is not already associated with a value * associates it with the given value and returns null, else returns the current value. * * @param key key with which the specified value is to be associated * @param value value to be associated with the specified key * @return the previous value associated with the specified key or null * if key does not already mapped to a value. */ Versioned putIfAbsent(K key, V value); /** * Removes the entry for the specified key only if it is currently * mapped to the specified value. * * @param key key with which the specified value is associated * @param value value expected to be associated with the specified key * @return true if the value was removed */ boolean remove(K key, V value); /** * Removes the entry for the specified key only if its current * version in the map is equal to the specified version. * * @param key key with which the specified version is associated * @param version version expected to be associated with the specified key * @return true if the value was removed */ boolean remove(K key, long version); /** * Replaces the entry for the specified key only if currently mapped * to the specified value. * * @param key key with which the specified value is associated * @param oldValue value expected to be associated with the specified key * @param newValue value to be associated with the specified key * @return true if the value was replaced */ boolean replace(K key, V oldValue, V newValue); /** * Replaces the entry for the specified key only if it is currently mapped to the * specified version. * * @param key key key with which the specified value is associated * @param oldVersion version expected to be associated with the specified key * @param newValue value to be associated with the specified key * @return true if the value was replaced */ boolean replace(K key, long oldVersion, V newValue); /** * Registers the specified listener to be notified whenever the map is updated. * * @param listener listener to notify about map events */ void addListener(MapEventListener listener); /** * Unregisters the specified listener such that it will no longer * receive map change notifications. * * @param listener listener to unregister */ void removeListener(MapEventListener listener); /** * Returns a java.util.Map instance backed by this ConsistentMap. * @return java.util.Map */ Map asJavaMap(); }





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