| /* |
| * 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 static org.apache.hadoop.fs.impl.prefetch.Validate.checkNotNegative; |
| import static org.apache.hadoop.fs.impl.prefetch.Validate.checkPositiveInteger; |
| import static org.apache.hadoop.fs.impl.prefetch.Validate.checkWithinRange; |
| |
| /** |
| * Holds information about blocks of data in a file. |
| */ |
| public final class BlockData { |
| |
| // State of each block of data. |
| enum State { |
| |
| /** Data is not yet ready to be read from this block (still being prefetched). */ |
| NOT_READY, |
| |
| /** A read of this block has been enqueued in the prefetch queue. */ |
| QUEUED, |
| |
| /** A read of this block has been enqueued in the prefetch queue. */ |
| READY, |
| |
| /** This block has been cached in the local disk cache. */ |
| CACHED |
| } |
| |
| /** |
| * State of all blocks in a file. |
| */ |
| private State[] state; |
| |
| /** |
| * The size of a file. |
| */ |
| private final long fileSize; |
| |
| /** |
| * The file is divided into blocks of this size. |
| */ |
| private final int blockSize; |
| |
| /** |
| * The file has these many blocks. |
| */ |
| private final int numBlocks; |
| |
| /** |
| * Constructs an instance of {@link BlockData}. |
| * @param fileSize the size of a file. |
| * @param blockSize the file is divided into blocks of this size. |
| * @throws IllegalArgumentException if fileSize is negative. |
| * @throws IllegalArgumentException if blockSize is negative. |
| * @throws IllegalArgumentException if blockSize is zero or negative. |
| */ |
| public BlockData(long fileSize, int blockSize) { |
| checkNotNegative(fileSize, "fileSize"); |
| if (fileSize == 0) { |
| checkNotNegative(blockSize, "blockSize"); |
| } else { |
| checkPositiveInteger(blockSize, "blockSize"); |
| } |
| |
| this.fileSize = fileSize; |
| this.blockSize = blockSize; |
| this.numBlocks = |
| (fileSize == 0) |
| ? 0 |
| : ((int) (fileSize / blockSize)) + (fileSize % blockSize > 0 |
| ? 1 |
| : 0); |
| this.state = new State[this.numBlocks]; |
| for (int b = 0; b < this.numBlocks; b++) { |
| setState(b, State.NOT_READY); |
| } |
| } |
| |
| /** |
| * Gets the size of each block. |
| * @return the size of each block. |
| */ |
| public int getBlockSize() { |
| return blockSize; |
| } |
| |
| /** |
| * Gets the size of the associated file. |
| * @return the size of the associated file. |
| */ |
| public long getFileSize() { |
| return fileSize; |
| } |
| |
| /** |
| * Gets the number of blocks in the associated file. |
| * @return the number of blocks in the associated file. |
| */ |
| public int getNumBlocks() { |
| return numBlocks; |
| } |
| |
| /** |
| * Indicates whether the given block is the last block in the associated file. |
| * @param blockNumber the id of the desired block. |
| * @return true if the given block is the last block in the associated file, false otherwise. |
| * @throws IllegalArgumentException if blockNumber is invalid. |
| */ |
| public boolean isLastBlock(int blockNumber) { |
| if (fileSize == 0) { |
| return false; |
| } |
| |
| throwIfInvalidBlockNumber(blockNumber); |
| |
| return blockNumber == (numBlocks - 1); |
| } |
| |
| /** |
| * Gets the id of the block that contains the given absolute offset. |
| * @param offset the absolute offset to check. |
| * @return the id of the block that contains the given absolute offset. |
| * @throws IllegalArgumentException if offset is invalid. |
| */ |
| public int getBlockNumber(long offset) { |
| throwIfInvalidOffset(offset); |
| |
| return (int) (offset / blockSize); |
| } |
| |
| /** |
| * Gets the size of the given block. |
| * @param blockNumber the id of the desired block. |
| * @return the size of the given block. |
| */ |
| public int getSize(int blockNumber) { |
| if (fileSize == 0) { |
| return 0; |
| } |
| |
| if (isLastBlock(blockNumber)) { |
| return (int) (fileSize - (((long) blockSize) * (numBlocks - 1))); |
| } else { |
| return blockSize; |
| } |
| } |
| |
| /** |
| * Indicates whether the given absolute offset is valid. |
| * @param offset absolute offset in the file.. |
| * @return true if the given absolute offset is valid, false otherwise. |
| */ |
| public boolean isValidOffset(long offset) { |
| return (offset >= 0) && (offset < fileSize); |
| } |
| |
| /** |
| * Gets the start offset of the given block. |
| * @param blockNumber the id of the given block. |
| * @return the start offset of the given block. |
| * @throws IllegalArgumentException if blockNumber is invalid. |
| */ |
| public long getStartOffset(int blockNumber) { |
| throwIfInvalidBlockNumber(blockNumber); |
| |
| return blockNumber * (long) blockSize; |
| } |
| |
| /** |
| * Gets the relative offset corresponding to the given block and the absolute offset. |
| * @param blockNumber the id of the given block. |
| * @param offset absolute offset in the file. |
| * @return the relative offset corresponding to the given block and the absolute offset. |
| * @throws IllegalArgumentException if either blockNumber or offset is invalid. |
| */ |
| public int getRelativeOffset(int blockNumber, long offset) { |
| throwIfInvalidOffset(offset); |
| |
| return (int) (offset - getStartOffset(blockNumber)); |
| } |
| |
| /** |
| * Gets the state of the given block. |
| * @param blockNumber the id of the given block. |
| * @return the state of the given block. |
| * @throws IllegalArgumentException if blockNumber is invalid. |
| */ |
| public State getState(int blockNumber) { |
| throwIfInvalidBlockNumber(blockNumber); |
| |
| return state[blockNumber]; |
| } |
| |
| /** |
| * Sets the state of the given block to the given value. |
| * @param blockNumber the id of the given block. |
| * @param blockState the target state. |
| * @throws IllegalArgumentException if blockNumber is invalid. |
| */ |
| public void setState(int blockNumber, State blockState) { |
| throwIfInvalidBlockNumber(blockNumber); |
| |
| state[blockNumber] = blockState; |
| } |
| |
| // Debug helper. |
| public String getStateString() { |
| StringBuilder sb = new StringBuilder(); |
| int blockNumber = 0; |
| while (blockNumber < numBlocks) { |
| State tstate = getState(blockNumber); |
| int endBlockNumber = blockNumber; |
| while ((endBlockNumber < numBlocks) && (getState(endBlockNumber) |
| == tstate)) { |
| endBlockNumber++; |
| } |
| sb.append( |
| String.format("[%03d ~ %03d] %s%n", blockNumber, endBlockNumber - 1, |
| tstate)); |
| blockNumber = endBlockNumber; |
| } |
| return sb.toString(); |
| } |
| |
| private void throwIfInvalidBlockNumber(int blockNumber) { |
| checkWithinRange(blockNumber, "blockNumber", 0, numBlocks - 1); |
| } |
| |
| private void throwIfInvalidOffset(long offset) { |
| checkWithinRange(offset, "offset", 0, fileSize - 1); |
| } |
| } |