| /* |
| * Copyright (C) 2017, Google Inc. and others |
| * |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Distribution License v. 1.0 which is available at |
| * https://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| |
| 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.errors.PackInvalidException; |
| import org.eclipse.jgit.internal.storage.pack.PackExt; |
| |
| /** Block based file stored in {@link DfsBlockCache}. */ |
| 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 desc; |
| 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; |
| |
| /** Exception that caused the packfile to be flagged as invalid */ |
| protected volatile Exception invalidatingCause; |
| |
| BlockBasedFile(DfsBlockCache cache, DfsPackDescription desc, PackExt ext) { |
| this.cache = cache; |
| this.key = desc.getStreamKey(ext); |
| this.desc = desc; |
| this.ext = ext; |
| } |
| |
| String getFileName() { |
| return desc.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 getOrLoadBlock(long pos, DfsReader ctx) throws IOException { |
| try (LazyChannel c = new LazyChannel(ctx, desc, ext)) { |
| return cache.getOrLoad(this, pos, ctx, c); |
| } |
| } |
| |
| DfsBlock readOneBlock(long pos, DfsReader ctx, ReadableChannel rc) |
| throws IOException { |
| if (invalid) { |
| throw new PackInvalidException(getFileName(), invalidatingCause); |
| } |
| |
| ctx.stats.readBlock++; |
| long start = System.nanoTime(); |
| 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 { |
| 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; |
| } |
| |
| /** |
| * A supplier of readable channel that opens the channel lazily. |
| */ |
| private static class LazyChannel |
| implements AutoCloseable, DfsBlockCache.ReadableChannelSupplier { |
| private final DfsReader ctx; |
| private final DfsPackDescription desc; |
| private final PackExt ext; |
| |
| private ReadableChannel rc; |
| |
| LazyChannel(DfsReader ctx, DfsPackDescription desc, PackExt ext) { |
| this.ctx = ctx; |
| this.desc = desc; |
| this.ext = ext; |
| } |
| |
| @Override |
| public ReadableChannel get() throws IOException { |
| if (rc == null) { |
| rc = ctx.db.openFile(desc, ext); |
| } |
| return rc; |
| } |
| |
| @Override |
| public void close() throws IOException { |
| if (rc != null) { |
| rc.close(); |
| } |
| } |
| } |
| } |