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/**
* 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.ambari.metrics.adservice.db
trait MetadataDatasource {
type Key = Array[Byte]
type Value = Array[Byte]
/**
* Idempotent call at the start of the application to initialize db
*/
def initialize(): Unit
/**
* This function obtains the associated value to a key. It requires the (key-value) pair to be in the DataSource
*
* @param key
* @return the value associated with the passed key.
*/
def apply(key: Key): Value = get(key).get
/**
* This function obtains the associated value to a key, if there exists one.
*
* @param key
* @return the value associated with the passed key.
*/
def get(key: Key): Option[Value]
/**
* This function associates a key to a value, overwriting if necessary
*/
def put(key: Key, value: Value): Unit
/**
* Delete key from the db
*/
def delete(key: Key): Unit
/**
* This function updates the DataSource by deleting, updating and inserting new (key-value) pairs.
*
* @param toRemove which includes all the keys to be removed from the DataSource.
* @param toUpsert which includes all the (key-value) pairs to be inserted into the DataSource.
* If a key is already in the DataSource its value will be updated.
* @return the new DataSource after the removals and insertions were done.
*/
def update(toRemove: Seq[Key], toUpsert: Seq[(Key, Value)]): Unit
/**
* This function closes the DataSource, without deleting the files used by it.
*/
def close(): Unit
}