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- /*
- * Copyright (C) 2008-2009, Google Inc.
- * Copyright (C) 2008, Jonas Fonseca <fonseca@diku.dk>
- * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
- * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
- * Copyright (C) 2006-2008, Shawn O. Pearce <spearce@spearce.org>
- * 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.lib;
-
- import java.io.EOFException;
- import java.io.IOException;
- import java.io.OutputStream;
-
- import org.eclipse.jgit.errors.LargeObjectException;
- import org.eclipse.jgit.errors.MissingObjectException;
- import org.eclipse.jgit.util.IO;
-
- /**
- * Base class for a set of loaders for different representations of Git objects.
- * New loaders are constructed for every object.
- */
- public abstract class ObjectLoader {
- /**
- * @return Git in pack object type, see {@link Constants}.
- */
- public abstract int getType();
-
- /**
- * @return size of object in bytes
- */
- public abstract long getSize();
-
- /**
- * @return true if this object is too large to obtain as a byte array.
- * Objects over a certain threshold should be accessed only by their
- * {@link #openStream()} to prevent overflowing the JVM heap.
- */
- public boolean isLarge() {
- try {
- getCachedBytes();
- return false;
- } catch (LargeObjectException tooBig) {
- return true;
- }
- }
-
- /**
- * Obtain a copy of the bytes of this object.
- * <p>
- * Unlike {@link #getCachedBytes()} this method returns an array that might
- * be modified by the caller.
- *
- * @return the bytes of this object.
- * @throws LargeObjectException
- * if the object won't fit into a byte array, because
- * {@link #isLarge()} returns true. Callers should use
- * {@link #openStream()} instead to access the contents.
- */
- public final byte[] getBytes() throws LargeObjectException {
- return cloneArray(getCachedBytes());
- }
-
- /**
- * Obtain a copy of the bytes of this object.
- *
- * If the object size is less than or equal to {@code sizeLimit} this method
- * will provide it as a byte array, even if {@link #isLarge()} is true. This
- * utility is useful for application code that absolutely must have the
- * object as a single contiguous byte array in memory.
- *
- * Unlike {@link #getCachedBytes(int)} this method returns an array that
- * might be modified by the caller.
- *
- * @param sizeLimit
- * maximum number of bytes to return. If the object is larger
- * than this limit, {@link LargeObjectException} will be thrown.
- * @return the bytes of this object.
- * @throws LargeObjectException
- * if the object is bigger than {@code sizeLimit}, or if
- * {@link OutOfMemoryError} occurs during allocation of the
- * result array. Callers should use {@link #openStream()}
- * instead to access the contents.
- * @throws MissingObjectException
- * the object is large, and it no longer exists.
- * @throws IOException
- * the object store cannot be accessed.
- */
- public final byte[] getBytes(int sizeLimit) throws LargeObjectException,
- MissingObjectException, IOException {
- byte[] cached = getCachedBytes(sizeLimit);
- try {
- return cloneArray(cached);
- } catch (OutOfMemoryError tooBig) {
- throw new LargeObjectException.OutOfMemory(tooBig);
- }
- }
-
- /**
- * Obtain a reference to the (possibly cached) bytes of this object.
- * <p>
- * This method offers direct access to the internal caches, potentially
- * saving on data copies between the internal cache and higher level code.
- * Callers who receive this reference <b>must not</b> modify its contents.
- * Changes (if made) will affect the cache but not the repository itself.
- *
- * @return the cached bytes of this object. Do not modify it.
- * @throws LargeObjectException
- * if the object won't fit into a byte array, because
- * {@link #isLarge()} returns true. Callers should use
- * {@link #openStream()} instead to access the contents.
- */
- public abstract byte[] getCachedBytes() throws LargeObjectException;
-
- /**
- * Obtain a reference to the (possibly cached) bytes of this object.
- *
- * If the object size is less than or equal to {@code sizeLimit} this method
- * will provide it as a byte array, even if {@link #isLarge()} is true. This
- * utility is useful for application code that absolutely must have the
- * object as a single contiguous byte array in memory.
- *
- * This method offers direct access to the internal caches, potentially
- * saving on data copies between the internal cache and higher level code.
- * Callers who receive this reference <b>must not</b> modify its contents.
- * Changes (if made) will affect the cache but not the repository itself.
- *
- * @param sizeLimit
- * maximum number of bytes to return. If the object size is
- * larger than this limit and {@link #isLarge()} is true,
- * {@link LargeObjectException} will be thrown.
- * @return the cached bytes of this object. Do not modify it.
- * @throws LargeObjectException
- * if the object is bigger than {@code sizeLimit}, or if
- * {@link OutOfMemoryError} occurs during allocation of the
- * result array. Callers should use {@link #openStream()}
- * instead to access the contents.
- * @throws MissingObjectException
- * the object is large, and it no longer exists.
- * @throws IOException
- * the object store cannot be accessed.
- */
- public byte[] getCachedBytes(int sizeLimit) throws LargeObjectException,
- MissingObjectException, IOException {
- if (!isLarge())
- return getCachedBytes();
-
- ObjectStream in = openStream();
- try {
- long sz = in.getSize();
- if (sizeLimit < sz)
- throw new LargeObjectException.ExceedsLimit(sizeLimit, sz);
-
- if (Integer.MAX_VALUE < sz)
- throw new LargeObjectException.ExceedsByteArrayLimit();
-
- byte[] buf;
- try {
- buf = new byte[(int) sz];
- } catch (OutOfMemoryError notEnoughHeap) {
- throw new LargeObjectException.OutOfMemory(notEnoughHeap);
- }
-
- IO.readFully(in, buf, 0, buf.length);
- return buf;
- } finally {
- in.close();
- }
- }
-
- /**
- * Obtain an input stream to read this object's data.
- *
- * @return a stream of this object's data. Caller must close the stream when
- * through with it. The returned stream is buffered with a
- * reasonable buffer size.
- * @throws MissingObjectException
- * the object no longer exists.
- * @throws IOException
- * the object store cannot be accessed.
- */
- public abstract ObjectStream openStream() throws MissingObjectException,
- IOException;
-
- /**
- * Copy this object to the output stream.
- * <p>
- * For some object store implementations, this method may be more efficient
- * than reading from {@link #openStream()} into a temporary byte array, then
- * writing to the destination stream.
- * <p>
- * The default implementation of this method is to copy with a temporary
- * byte array for large objects, or to pass through the cached byte array
- * for small objects.
- *
- * @param out
- * stream to receive the complete copy of this object's data.
- * Caller is responsible for flushing or closing this stream
- * after this method returns.
- * @throws MissingObjectException
- * the object no longer exists.
- * @throws IOException
- * the object store cannot be accessed, or the stream cannot be
- * written to.
- */
- public void copyTo(OutputStream out) throws MissingObjectException,
- IOException {
- if (isLarge()) {
- ObjectStream in = openStream();
- try {
- final long sz = in.getSize();
- byte[] tmp = new byte[8192];
- long copied = 0;
- while (copied < sz) {
- int n = in.read(tmp);
- if (n < 0)
- throw new EOFException();
- out.write(tmp, 0, n);
- copied += n;
- }
- if (0 <= in.read())
- throw new EOFException();
- } finally {
- in.close();
- }
- } else {
- out.write(getCachedBytes());
- }
- }
-
- private static byte[] cloneArray(final byte[] data) {
- final byte[] copy = new byte[data.length];
- System.arraycopy(data, 0, copy, 0, data.length);
- return copy;
- }
-
- /**
- * Simple loader around the cached byte array.
- * <p>
- * ObjectReader implementations can use this stream type when the object's
- * content is small enough to be accessed as a single byte array.
- */
- public static class SmallObject extends ObjectLoader {
- private final int type;
-
- private final byte[] data;
-
- /**
- * Construct a small object loader.
- *
- * @param type
- * type of the object.
- * @param data
- * the object's data array. This array will be returned as-is
- * for the {@link #getCachedBytes()} method.
- */
- public SmallObject(int type, byte[] data) {
- this.type = type;
- this.data = data;
- }
-
- @Override
- public int getType() {
- return type;
- }
-
- @Override
- public long getSize() {
- return getCachedBytes().length;
- }
-
- @Override
- public boolean isLarge() {
- return false;
- }
-
- @Override
- public byte[] getCachedBytes() {
- return data;
- }
-
- @Override
- public ObjectStream openStream() {
- return new ObjectStream.SmallStream(this);
- }
- }
- }
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