org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/BlockBasedFile.java - sop/jgit - Git at Google

 /*
  * Copyright (C) 2017, Google Inc.
  * and other copyright owners as documented in the project's IP log.
  *
  * This program and the accompanying materials are made available
  * under the terms of the Eclipse Distribution License v1.0 which
  * accompanies this distribution, is reproduced below, and is
  * available at http://www.eclipse.org/org/documents/edl-v10.php
  *
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or
  * without modification, are permitted provided that the following
  * conditions are met:
  *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  *
  * - Redistributions in binary form must reproduce the above
  *   copyright notice, this list of conditions and the following
  *   disclaimer in the documentation and/or other materials provided
  *   with the distribution.
  *
  * - Neither the name of the Eclipse Foundation, Inc. nor the
  *   names of its contributors may be used to endorse or promote
  *   products derived from this software without specific prior
  *   written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 package org.eclipse.jgit.internal.storage.dfs;

 import java.io.EOFException;
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.text.MessageFormat;

 import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.errors.PackInvalidException;
 import org.eclipse.jgit.internal.storage.pack.PackExt;

 /** Block based file stored in {@link DfsBlockCache}. */
 public abstract class BlockBasedFile {
 	/** Cache that owns this file and its data. */
 	final DfsBlockCache cache;

 	/** Unique identity of this file while in-memory. */
 	final DfsStreamKey key;

 	/** Description of the associated pack file's storage. */
 	final DfsPackDescription packDesc;
 	final PackExt ext;

 	/**
 	 * Preferred alignment for loading blocks from the backing file.
 	 * <p>
 	 * It is initialized to 0 and filled in on the first read made from the
 	 * file. Block sizes may be odd, e.g. 4091, caused by the underling DFS
 	 * storing 4091 user bytes and 5 bytes block metadata into a lower level
 	 * 4096 byte block on disk.
 	 */
 	volatile int blockSize;

 	/**
 	 * Total number of bytes in this pack file.
 	 * <p>
 	 * This field initializes to -1 and gets populated when a block is loaded.
 	 */
 	volatile long length;

 	/** True once corruption has been detected that cannot be worked around. */
 	volatile boolean invalid;

 	BlockBasedFile(DfsBlockCache cache, DfsStreamKey key,
 			DfsPackDescription packDesc, PackExt ext) {
 		this.cache = cache;
 		this.key = key;
 		this.packDesc = packDesc;
 		this.ext = ext;
 	}

 	String getFileName() {
 		return packDesc.getFileName(ext);
 	}

 	boolean invalid() {
 		return invalid;
 	}

 	void setInvalid() {
 		invalid = true;
 	}

 	void setBlockSize(int newSize) {
 		blockSize = newSize;
 	}

 	long alignToBlock(long pos) {
 		int size = blockSize;
 		if (size == 0)
 			size = cache.getBlockSize();
 		return (pos / size) * size;
 	}

 	int blockSize(ReadableChannel rc) {
 		// If the block alignment is not yet known, discover it. Prefer the
 		// larger size from either the cache or the file itself.
 		int size = blockSize;
 		if (size == 0) {
 			size = rc.blockSize();
 			if (size <= 0)
 				size = cache.getBlockSize();
 			else if (size < cache.getBlockSize())
 				size = (cache.getBlockSize() / size) * size;
 			blockSize = size;
 		}
 		return size;
 	}

 	DfsBlock readOneBlock(long pos, DfsReader ctx,
 			@Nullable ReadableChannel fileChannel) throws IOException {
 		if (invalid)
 			throw new PackInvalidException(getFileName());

 		ctx.stats.readBlock++;
 		long start = System.nanoTime();
 		ReadableChannel rc = fileChannel != null ? fileChannel
 				: ctx.db.openFile(packDesc, ext);
 		try {
 			int size = blockSize(rc);
 			pos = (pos / size) * size;

 			// If the size of the file is not yet known, try to discover it.
 			// Channels may choose to return -1 to indicate they don't
 			// know the length yet, in this case read up to the size unit
 			// given by the caller, then recheck the length.
 			long len = length;
 			if (len < 0) {
 				len = rc.size();
 				if (0 <= len)
 					length = len;
 			}

 			if (0 <= len && len < pos + size)
 				size = (int) (len - pos);
 			if (size <= 0)
 				throw new EOFException(MessageFormat.format(
 						DfsText.get().shortReadOfBlock, Long.valueOf(pos),
 						getFileName(), Long.valueOf(0), Long.valueOf(0)));

 			byte[] buf = new byte[size];
 			rc.position(pos);
 			int cnt = read(rc, ByteBuffer.wrap(buf, 0, size));
 			ctx.stats.readBlockBytes += cnt;
 			if (cnt != size) {
 				if (0 <= len) {
 					throw new EOFException(MessageFormat.format(
 							DfsText.get().shortReadOfBlock, Long.valueOf(pos),
 							getFileName(), Integer.valueOf(size),
 							Integer.valueOf(cnt)));
 				}

 				// Assume the entire thing was read in a single shot, compact
 				// the buffer to only the space required.
 				byte[] n = new byte[cnt];
 				System.arraycopy(buf, 0, n, 0, n.length);
 				buf = n;
 			} else if (len < 0) {
 				// With no length at the start of the read, the channel should
 				// have the length available at the end.
 				length = len = rc.size();
 			}

 			return new DfsBlock(key, pos, buf);
 		} finally {
 			if (rc != fileChannel) {
 				rc.close();
 			}
 			ctx.stats.readBlockMicros += elapsedMicros(start);
 		}
 	}

 	static int read(ReadableChannel rc, ByteBuffer buf) throws IOException {
 		int n;
 		do {
 			n = rc.read(buf);
 		} while (0 < n && buf.hasRemaining());
 		return buf.position();
 	}

 	static long elapsedMicros(long start) {
 		return (System.nanoTime() - start) / 1000L;
 	}
 }
	/*
	* Copyright (C) 2017, Google Inc.
	* and other copyright owners as documented in the project's IP log.
	*
	* This program and the accompanying materials are made available
	* under the terms of the Eclipse Distribution License v1.0 which
	* accompanies this distribution, is reproduced below, and is
	* available at http://www.eclipse.org/org/documents/edl-v10.php
	*
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or
	* without modification, are permitted provided that the following
	* conditions are met:
	*
	* - Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* - Redistributions in binary form must reproduce the above
	* copyright notice, this list of conditions and the following
	* disclaimer in the documentation and/or other materials provided
	* with the distribution.
	*
	* - Neither the name of the Eclipse Foundation, Inc. nor the
	* names of its contributors may be used to endorse or promote
	* products derived from this software without specific prior
	* written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
	* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
	* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	package org.eclipse.jgit.internal.storage.dfs;

	import java.io.EOFException;
	import java.io.IOException;
	import java.nio.ByteBuffer;
	import java.text.MessageFormat;

	import org.eclipse.jgit.annotations.Nullable;
	import org.eclipse.jgit.errors.PackInvalidException;
	import org.eclipse.jgit.internal.storage.pack.PackExt;

	/** Block based file stored in {@link DfsBlockCache}. */
	public abstract class BlockBasedFile {
	/** Cache that owns this file and its data. */
	final DfsBlockCache cache;

	/** Unique identity of this file while in-memory. */
	final DfsStreamKey key;

	/** Description of the associated pack file's storage. */
	final DfsPackDescription packDesc;
	final PackExt ext;

	/**
	* Preferred alignment for loading blocks from the backing file.
	* <p>
	* It is initialized to 0 and filled in on the first read made from the
	* file. Block sizes may be odd, e.g. 4091, caused by the underling DFS
	* storing 4091 user bytes and 5 bytes block metadata into a lower level
	* 4096 byte block on disk.
	*/
	volatile int blockSize;

	/**
	* Total number of bytes in this pack file.
	* <p>
	* This field initializes to -1 and gets populated when a block is loaded.
	*/
	volatile long length;

	/** True once corruption has been detected that cannot be worked around. */
	volatile boolean invalid;

	BlockBasedFile(DfsBlockCache cache, DfsStreamKey key,
	DfsPackDescription packDesc, PackExt ext) {
	this.cache = cache;
	this.key = key;
	this.packDesc = packDesc;
	this.ext = ext;
	}

	String getFileName() {
	return packDesc.getFileName(ext);
	}

	boolean invalid() {
	return invalid;
	}

	void setInvalid() {
	invalid = true;
	}

	void setBlockSize(int newSize) {
	blockSize = newSize;
	}

	long alignToBlock(long pos) {
	int size = blockSize;
	if (size == 0)
	size = cache.getBlockSize();
	return (pos / size) * size;
	}

	int blockSize(ReadableChannel rc) {
	// If the block alignment is not yet known, discover it. Prefer the
	// larger size from either the cache or the file itself.
	int size = blockSize;
	if (size == 0) {
	size = rc.blockSize();
	if (size <= 0)
	size = cache.getBlockSize();
	else if (size < cache.getBlockSize())
	size = (cache.getBlockSize() / size) * size;
	blockSize = size;
	}
	return size;
	}

	DfsBlock readOneBlock(long pos, DfsReader ctx,
	@Nullable ReadableChannel fileChannel) throws IOException {
	if (invalid)
	throw new PackInvalidException(getFileName());

	ctx.stats.readBlock++;
	long start = System.nanoTime();
	ReadableChannel rc = fileChannel != null ? fileChannel
	: ctx.db.openFile(packDesc, ext);
	try {
	int size = blockSize(rc);
	pos = (pos / size) * size;

	// If the size of the file is not yet known, try to discover it.
	// Channels may choose to return -1 to indicate they don't
	// know the length yet, in this case read up to the size unit
	// given by the caller, then recheck the length.
	long len = length;
	if (len < 0) {
	len = rc.size();
	if (0 <= len)
	length = len;
	}

	if (0 <= len && len < pos + size)
	size = (int) (len - pos);
	if (size <= 0)
	throw new EOFException(MessageFormat.format(
	DfsText.get().shortReadOfBlock, Long.valueOf(pos),
	getFileName(), Long.valueOf(0), Long.valueOf(0)));

	byte[] buf = new byte[size];
	rc.position(pos);
	int cnt = read(rc, ByteBuffer.wrap(buf, 0, size));
	ctx.stats.readBlockBytes += cnt;
	if (cnt != size) {
	if (0 <= len) {
	throw new EOFException(MessageFormat.format(
	DfsText.get().shortReadOfBlock, Long.valueOf(pos),
	getFileName(), Integer.valueOf(size),
	Integer.valueOf(cnt)));
	}

	// Assume the entire thing was read in a single shot, compact
	// the buffer to only the space required.
	byte[] n = new byte[cnt];
	System.arraycopy(buf, 0, n, 0, n.length);
	buf = n;
	} else if (len < 0) {
	// With no length at the start of the read, the channel should
	// have the length available at the end.
	length = len = rc.size();
	}

	return new DfsBlock(key, pos, buf);
	} finally {
	if (rc != fileChannel) {
	rc.close();
	}
	ctx.stats.readBlockMicros += elapsedMicros(start);
	}
	}

	static int read(ReadableChannel rc, ByteBuffer buf) throws IOException {
	int n;
	do {
	n = rc.read(buf);
	} while (0 < n && buf.hasRemaining());
	return buf.position();
	}

	static long elapsedMicros(long start) {
	return (System.nanoTime() - start) / 1000L;
	}
	}