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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;
/**
* Transactional Map data structure.
* <p>
* A TransactionalMap is created by invoking {@link TransactionContext#getTransactionalMap getTransactionalMap}
* method. All operations performed on this map within a transaction boundary are invisible externally
* until the point when the transaction commits. A commit usually succeeds in the absence of conflicts.
*
* @param <K> type of key.
* @param <V> type of value.
*/
public interface TransactionalMap<K, V> {
/**
* Returns the value 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 is to be returned
* @return the value to which the specified key is mapped, or null if
* this map contains no mapping for the key
*/
V get(K key);
/**
* 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 associated with key, or null if there was
* no mapping for key.
*/
V put(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 to which this map previously associated the key,
* or null if the map contained no mapping for the key.
*/
V remove(K key);
/**
* 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.
*/
V 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);
/**
* 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);
}
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