org.apache.flink.table.runtime.functions.ThreadLocalCache.scala Maven / Gradle / Ivy
/*
* 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.flink.table.runtime.functions
import java.util.{LinkedHashMap => JLinkedHashMap}
import java.util.{Map => JMap}
/**
* Provides a ThreadLocal cache with a maximum cache size per thread.
* Values must not be null.
*/
abstract class ThreadLocalCache[K, V](val maxSizePerThread: Int) {
private val cache = new ThreadLocal[BoundedMap[K, V]]
protected def getNewInstance(key: K): V
def get(key: K): V = {
var m = cache.get
if (m == null) {
m = new BoundedMap(maxSizePerThread)
cache.set(m)
}
var v = m.get(key)
if (v == null) {
v = getNewInstance(key)
m.put(key, v)
}
v
}
}
private class BoundedMap[K, V](val maxSize: Int) extends JLinkedHashMap[K,V] {
override protected def removeEldestEntry(eldest: JMap.Entry[K, V]): Boolean = size > maxSize
}