| /* |
| * 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.hadoop.fs.impl.prefetch; |
| |
| import java.io.Closeable; |
| import java.nio.ByteBuffer; |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.IdentityHashMap; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.concurrent.Future; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import static java.util.Objects.requireNonNull; |
| import static org.apache.hadoop.fs.impl.prefetch.Validate.checkNotNegative; |
| import static org.apache.hadoop.fs.impl.prefetch.Validate.checkState; |
| import static org.apache.hadoop.util.Preconditions.checkArgument; |
| import static org.apache.hadoop.util.Preconditions.checkNotNull; |
| |
| /** |
| * Manages a fixed pool of {@code ByteBuffer} instances. |
| * <p> |
| * Avoids creating a new buffer if a previously created buffer is already available. |
| */ |
| public class BufferPool implements Closeable { |
| |
| private static final Logger LOG = LoggerFactory.getLogger(BufferPool.class); |
| |
| /** |
| * Max number of buffers in this pool. |
| */ |
| private final int size; |
| |
| /** |
| * Size in bytes of each buffer. |
| */ |
| private final int bufferSize; |
| |
| /* |
| Invariants for internal state. |
| -- a buffer is either in this.pool or in this.allocated |
| -- transition between this.pool <==> this.allocated must be atomic |
| -- only one buffer allocated for a given blockNumber |
| */ |
| |
| |
| /** |
| * Underlying bounded resource pool. |
| */ |
| private BoundedResourcePool<ByteBuffer> pool; |
| |
| /** |
| * Allows associating metadata to each buffer in the pool. |
| */ |
| private Map<BufferData, ByteBuffer> allocated; |
| |
| /** |
| * Prefetching stats. |
| */ |
| private PrefetchingStatistics prefetchingStatistics; |
| |
| /** |
| * Initializes a new instance of the {@code BufferPool} class. |
| * @param size number of buffer in this pool. |
| * @param bufferSize size in bytes of each buffer. |
| * @param prefetchingStatistics statistics for this stream. |
| * @throws IllegalArgumentException if size is zero or negative. |
| * @throws IllegalArgumentException if bufferSize is zero or negative. |
| */ |
| public BufferPool(int size, |
| int bufferSize, |
| PrefetchingStatistics prefetchingStatistics) { |
| Validate.checkPositiveInteger(size, "size"); |
| Validate.checkPositiveInteger(bufferSize, "bufferSize"); |
| |
| this.size = size; |
| this.bufferSize = bufferSize; |
| this.allocated = new IdentityHashMap<BufferData, ByteBuffer>(); |
| this.prefetchingStatistics = requireNonNull(prefetchingStatistics); |
| this.pool = new BoundedResourcePool<ByteBuffer>(size) { |
| @Override |
| public ByteBuffer createNew() { |
| ByteBuffer buffer = ByteBuffer.allocate(bufferSize); |
| prefetchingStatistics.memoryAllocated(bufferSize); |
| return buffer; |
| } |
| }; |
| } |
| |
| /** |
| * Gets a list of all blocks in this pool. |
| * @return a list of all blocks in this pool. |
| */ |
| public List<BufferData> getAll() { |
| synchronized (allocated) { |
| return Collections.unmodifiableList(new ArrayList<>(allocated.keySet())); |
| } |
| } |
| |
| /** |
| * Acquires a {@code ByteBuffer}; blocking if necessary until one becomes available. |
| * @param blockNumber the id of the block to acquire. |
| * @return the acquired block's {@code BufferData}. |
| */ |
| public synchronized BufferData acquire(int blockNumber) { |
| BufferData data; |
| final int maxRetryDelayMs = 600 * 1000; |
| final int statusUpdateDelayMs = 120 * 1000; |
| Retryer retryer = new Retryer(10, maxRetryDelayMs, statusUpdateDelayMs); |
| |
| do { |
| if (retryer.updateStatus()) { |
| if (LOG.isDebugEnabled()) { |
| LOG.debug("waiting to acquire block: {}", blockNumber); |
| LOG.debug("state = {}", this); |
| } |
| releaseReadyBlock(blockNumber); |
| } |
| data = tryAcquire(blockNumber); |
| } |
| while ((data == null) && retryer.continueRetry()); |
| |
| if (data != null) { |
| return data; |
| } else { |
| String message = |
| String.format("Wait failed for acquire(%d)", blockNumber); |
| throw new IllegalStateException(message); |
| } |
| } |
| |
| /** |
| * Acquires a buffer if one is immediately available. Otherwise returns null. |
| * @param blockNumber the id of the block to try acquire. |
| * @return the acquired block's {@code BufferData} or null. |
| */ |
| public synchronized BufferData tryAcquire(int blockNumber) { |
| return acquireHelper(blockNumber, false); |
| } |
| |
| private synchronized BufferData acquireHelper(int blockNumber, |
| boolean canBlock) { |
| checkNotNegative(blockNumber, "blockNumber"); |
| |
| releaseDoneBlocks(); |
| |
| BufferData data = find(blockNumber); |
| if (data != null) { |
| return data; |
| } |
| |
| ByteBuffer buffer = canBlock ? pool.acquire() : pool.tryAcquire(); |
| if (buffer == null) { |
| return null; |
| } |
| |
| buffer.clear(); |
| data = new BufferData(blockNumber, buffer.duplicate()); |
| |
| synchronized (allocated) { |
| checkState(find(blockNumber) == null, "buffer data already exists"); |
| |
| allocated.put(data, buffer); |
| } |
| |
| return data; |
| } |
| |
| /** |
| * Releases resources for any blocks marked as 'done'. |
| */ |
| private synchronized void releaseDoneBlocks() { |
| for (BufferData data : getAll()) { |
| if (data.stateEqualsOneOf(BufferData.State.DONE)) { |
| release(data); |
| } |
| } |
| } |
| |
| /** |
| * If no blocks were released after calling releaseDoneBlocks() a few times, |
| * we may end up waiting forever. To avoid that situation, we try releasing |
| * a 'ready' block farthest away from the given block. |
| */ |
| private synchronized void releaseReadyBlock(int blockNumber) { |
| BufferData releaseTarget = null; |
| for (BufferData data : getAll()) { |
| if (data.stateEqualsOneOf(BufferData.State.READY)) { |
| if (releaseTarget == null) { |
| releaseTarget = data; |
| } else { |
| if (distance(data, blockNumber) > distance(releaseTarget, |
| blockNumber)) { |
| releaseTarget = data; |
| } |
| } |
| } |
| } |
| |
| if (releaseTarget != null) { |
| LOG.warn("releasing 'ready' block: {}", releaseTarget); |
| releaseTarget.setDone(); |
| } |
| } |
| |
| private int distance(BufferData data, int blockNumber) { |
| return Math.abs(data.getBlockNumber() - blockNumber); |
| } |
| |
| /** |
| * Releases a previously acquired resource. |
| * @param data the {@code BufferData} instance to release. |
| * @throws IllegalArgumentException if data is null. |
| * @throws IllegalArgumentException if data cannot be released due to its state. |
| */ |
| public synchronized void release(BufferData data) { |
| checkNotNull(data, "data"); |
| |
| synchronized (data) { |
| checkArgument( |
| canRelease(data), |
| String.format("Unable to release buffer: %s", data)); |
| |
| ByteBuffer buffer = allocated.get(data); |
| if (buffer == null) { |
| // Likely released earlier. |
| return; |
| } |
| buffer.clear(); |
| pool.release(buffer); |
| allocated.remove(data); |
| } |
| |
| releaseDoneBlocks(); |
| } |
| |
| @Override |
| public synchronized void close() { |
| for (BufferData data : getAll()) { |
| Future<Void> actionFuture = data.getActionFuture(); |
| if (actionFuture != null) { |
| actionFuture.cancel(true); |
| } |
| } |
| |
| int currentPoolSize = pool.numCreated(); |
| |
| pool.close(); |
| pool = null; |
| |
| allocated.clear(); |
| allocated = null; |
| |
| prefetchingStatistics.memoryFreed(currentPoolSize * bufferSize); |
| } |
| |
| // For debugging purposes. |
| @Override |
| public String toString() { |
| StringBuilder sb = new StringBuilder(); |
| sb.append(pool.toString()); |
| sb.append("\n"); |
| List<BufferData> allData = new ArrayList<>(getAll()); |
| Collections.sort(allData, |
| (d1, d2) -> d1.getBlockNumber() - d2.getBlockNumber()); |
| for (BufferData data : allData) { |
| sb.append(data.toString()); |
| sb.append("\n"); |
| } |
| |
| return sb.toString(); |
| } |
| |
| // Number of ByteBuffers created so far. |
| public synchronized int numCreated() { |
| return pool.numCreated(); |
| } |
| |
| // Number of ByteBuffers available to be acquired. |
| public synchronized int numAvailable() { |
| releaseDoneBlocks(); |
| return pool.numAvailable(); |
| } |
| |
| private BufferData find(int blockNumber) { |
| synchronized (allocated) { |
| for (BufferData data : allocated.keySet()) { |
| if ((data.getBlockNumber() == blockNumber) |
| && !data.stateEqualsOneOf(BufferData.State.DONE)) { |
| return data; |
| } |
| } |
| } |
| |
| return null; |
| } |
| |
| private boolean canRelease(BufferData data) { |
| return data.stateEqualsOneOf( |
| BufferData.State.DONE, |
| BufferData.State.READY); |
| } |
| } |