1 /*
2 * Copyright (C) 2011, 2012 Google Inc. and others.
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.internal.storage.dfs;
45
46 import java.io.IOException;
47 import java.io.OutputStream;
48 import java.nio.ByteBuffer;
49
50 import org.eclipse.jgit.internal.storage.pack.PackExt;
51
52 /**
53 * Output stream to create a file on the DFS.
54 *
55 * @see DfsObjDatabase#writeFile(DfsPackDescription, PackExt)
56 */
57 public abstract class DfsOutputStream extends OutputStream {
58 /**
59 * Get the recommended alignment for writing.
60 * <p>
61 * Starting a write at multiples of the blockSize is more efficient than
62 * starting a write at any other position. If 0 or -1 the channel does not
63 * have any specific block size recommendation.
64 * <p>
65 * Channels should not recommend large block sizes. Sizes up to 1-4 MiB may
66 * be reasonable, but sizes above that may be horribly inefficient.
67 *
68 * @return recommended alignment size for randomly positioned reads. Does
69 * not need to be a power of 2.
70 */
71 public int blockSize() {
72 return 0;
73 }
74
75 /** {@inheritDoc} */
76 @Override
77 public void write(int b) throws IOException {
78 write(new byte[] { (byte) b });
79 }
80
81 /** {@inheritDoc} */
82 @Override
83 public abstract void write(byte[] buf, int off, int len) throws IOException;
84
85 /**
86 * Read back a portion of already written data.
87 * <p>
88 * The writing position of the output stream is not affected by a read.
89 *
90 * @param position
91 * offset to read from.
92 * @param buf
93 * buffer to populate. Up to {@code buf.remaining()} bytes will
94 * be read from {@code position}.
95 * @return number of bytes actually read.
96 * @throws java.io.IOException
97 * reading is not supported, or the read cannot be performed due
98 * to DFS errors.
99 */
100 public abstract int read(long position, ByteBuffer buf) throws IOException;
101 }