spark BlockManagerManagedBuffer 源码
spark BlockManagerManagedBuffer 代码
文件路径：/core/src/main/scala/org/apache/spark/storage/BlockManagerManagedBuffer.scala
/*
* 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.spark.storage
import java.io.InputStream
import java.nio.ByteBuffer
import java.util.concurrent.atomic.AtomicInteger
import org.apache.spark.network.buffer.ManagedBuffer
/**
* This [[ManagedBuffer]] wraps a [[BlockData]] instance retrieved from the [[BlockManager]]
* so that the corresponding block's read lock can be released once this buffer's references
* are released.
*
* If `dispose` is set to true, the [[BlockData]]will be disposed when the buffer's reference
* count drops to zero.
*
* This is effectively a wrapper / bridge to connect the BlockManager's notion of read locks
* to the network layer's notion of retain / release counts.
*/
private[storage] class BlockManagerManagedBuffer(
blockInfoManager: BlockInfoManager,
blockId: BlockId,
data: BlockData,
dispose: Boolean,
unlockOnDeallocate: Boolean = true) extends ManagedBuffer {
private val refCount = new AtomicInteger(1)
override def size(): Long = data.size
override def nioByteBuffer(): ByteBuffer = data.toByteBuffer()
override def createInputStream(): InputStream = data.toInputStream()
override def convertToNetty(): Object = data.toNetty()
override def retain(): ManagedBuffer = {
refCount.incrementAndGet()
val locked = blockInfoManager.lockForReading(blockId, blocking = false)
assert(locked.isDefined)
this
}
override def release(): ManagedBuffer = {
if (unlockOnDeallocate) {
blockInfoManager.unlock(blockId)
}
if (refCount.decrementAndGet() == 0 && dispose) {
data.dispose()
}
this
}
}
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