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UnionInputStream: combines sequential InputStreams into one

The UnionInputStream utility class combines multiple sequential
InputStreams so they appear to the caller as a single stream with
no gaps.  This can be used to concentate streams coming from multiple
independent HTTP connections (for example).

The companion unit test covers the class's full functionality.

Change-Id: I0676c7b5e082a5886bf0e8f43f9fd6c46a666228
Signed-off-by: Shawn O. Pearce <sop@google.com>
stable-0.7
Shawn O. Pearce 15 years ago committed by Shawn O. Pearce
parent
commit
2ef29ed106
  1. 217
      org.eclipse.jgit.test/tst/org/eclipse/jgit/util/io/UnionInputStreamTest.java
  2. 208
      org.eclipse.jgit/src/org/eclipse/jgit/util/io/UnionInputStream.java

217
org.eclipse.jgit.test/tst/org/eclipse/jgit/util/io/UnionInputStreamTest.java

@ -0,0 +1,217 @@
/*
* Copyright (C) 2009, 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.util.io;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.Arrays;
import junit.framework.TestCase;
public class UnionInputStreamTest extends TestCase {
public void testEmptyStream() throws IOException {
final UnionInputStream u = new UnionInputStream();
assertTrue(u.isEmpty());
assertEquals(-1, u.read());
assertEquals(-1, u.read(new byte[1], 0, 1));
assertEquals(0, u.available());
assertEquals(0, u.skip(1));
u.close();
}
public void testReadSingleBytes() throws IOException {
final UnionInputStream u = new UnionInputStream();
assertTrue(u.isEmpty());
u.add(new ByteArrayInputStream(new byte[] { 1, 0, 2 }));
u.add(new ByteArrayInputStream(new byte[] { 3 }));
u.add(new ByteArrayInputStream(new byte[] { 4, 5 }));
assertFalse(u.isEmpty());
assertEquals(3, u.available());
assertEquals(1, u.read());
assertEquals(0, u.read());
assertEquals(2, u.read());
assertEquals(0, u.available());
assertEquals(3, u.read());
assertEquals(0, u.available());
assertEquals(4, u.read());
assertEquals(1, u.available());
assertEquals(5, u.read());
assertEquals(0, u.available());
assertEquals(-1, u.read());
assertTrue(u.isEmpty());
u.add(new ByteArrayInputStream(new byte[] { (byte) 255 }));
assertEquals(255, u.read());
assertEquals(-1, u.read());
assertTrue(u.isEmpty());
}
public void testReadByteBlocks() throws IOException {
final UnionInputStream u = new UnionInputStream();
u.add(new ByteArrayInputStream(new byte[] { 1, 0, 2 }));
u.add(new ByteArrayInputStream(new byte[] { 3 }));
u.add(new ByteArrayInputStream(new byte[] { 4, 5 }));
final byte[] r = new byte[5];
assertEquals(5, u.read(r, 0, 5));
assertTrue(Arrays.equals(new byte[] { 1, 0, 2, 3, 4 }, r));
assertEquals(1, u.read(r, 0, 5));
assertEquals(5, r[0]);
assertEquals(-1, u.read(r, 0, 5));
}
public void testArrayConstructor() throws IOException {
final UnionInputStream u = new UnionInputStream(
new ByteArrayInputStream(new byte[] { 1, 0, 2 }),
new ByteArrayInputStream(new byte[] { 3 }),
new ByteArrayInputStream(new byte[] { 4, 5 }));
final byte[] r = new byte[5];
assertEquals(5, u.read(r, 0, 5));
assertTrue(Arrays.equals(new byte[] { 1, 0, 2, 3, 4 }, r));
assertEquals(1, u.read(r, 0, 5));
assertEquals(5, r[0]);
assertEquals(-1, u.read(r, 0, 5));
}
public void testMarkSupported() {
final UnionInputStream u = new UnionInputStream();
assertFalse(u.markSupported());
u.add(new ByteArrayInputStream(new byte[] { 1, 0, 2 }));
assertFalse(u.markSupported());
}
public void testSkip() throws IOException {
final UnionInputStream u = new UnionInputStream();
u.add(new ByteArrayInputStream(new byte[] { 1, 0, 2 }));
u.add(new ByteArrayInputStream(new byte[] { 3 }));
u.add(new ByteArrayInputStream(new byte[] { 4, 5 }));
assertEquals(0, u.skip(0));
assertEquals(4, u.skip(4));
assertEquals(4, u.read());
assertEquals(1, u.skip(5));
assertEquals(0, u.skip(5));
assertEquals(-1, u.read());
u.add(new ByteArrayInputStream(new byte[] { 20, 30 }) {
public long skip(long n) {
return 0;
}
});
assertEquals(2, u.skip(8));
assertEquals(-1, u.read());
}
public void testAutoCloseDuringRead() throws IOException {
final UnionInputStream u = new UnionInputStream();
final boolean closed[] = new boolean[2];
u.add(new ByteArrayInputStream(new byte[] { 1 }) {
public void close() {
closed[0] = true;
}
});
u.add(new ByteArrayInputStream(new byte[] { 2 }) {
public void close() {
closed[1] = true;
}
});
assertFalse(closed[0]);
assertFalse(closed[1]);
assertEquals(1, u.read());
assertFalse(closed[0]);
assertFalse(closed[1]);
assertEquals(2, u.read());
assertTrue(closed[0]);
assertFalse(closed[1]);
assertEquals(-1, u.read());
assertTrue(closed[0]);
assertTrue(closed[1]);
}
public void testCloseDuringClose() throws IOException {
final UnionInputStream u = new UnionInputStream();
final boolean closed[] = new boolean[2];
u.add(new ByteArrayInputStream(new byte[] { 1 }) {
public void close() {
closed[0] = true;
}
});
u.add(new ByteArrayInputStream(new byte[] { 2 }) {
public void close() {
closed[1] = true;
}
});
assertFalse(closed[0]);
assertFalse(closed[1]);
u.close();
assertTrue(closed[0]);
assertTrue(closed[1]);
}
public void testExceptionDuringClose() {
final UnionInputStream u = new UnionInputStream();
u.add(new ByteArrayInputStream(new byte[] { 1 }) {
public void close() throws IOException {
throw new IOException("I AM A TEST");
}
});
try {
u.close();
fail("close ignored inner stream exception");
} catch (IOException e) {
assertEquals("I AM A TEST", e.getMessage());
}
}
}

208
org.eclipse.jgit/src/org/eclipse/jgit/util/io/UnionInputStream.java

@ -0,0 +1,208 @@
/*
* Copyright (C) 2009, 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.util.io;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.LinkedList;
/**
* An InputStream which reads from one or more InputStreams.
* <p>
* This stream may enter into an EOF state, returning -1 from any of the read
* methods, and then later successfully read additional bytes if a new
* InputStream is added after reaching EOF.
* <p>
* Currently this stream does not support the mark/reset APIs. If mark and later
* reset functionality is needed the caller should wrap this stream with a
* {@link java.io.BufferedInputStream}.
* */
public class UnionInputStream extends InputStream {
private static final InputStream EOF = new InputStream() {
@Override
public int read() throws IOException {
return -1;
}
};
private final LinkedList<InputStream> streams = new LinkedList<InputStream>();
/** Create an empty InputStream that is currently at EOF state. */
public UnionInputStream() {
// Do nothing.
}
/**
* Create an InputStream that is a union of the individual streams.
* <p>
* As each stream reaches EOF, it will be automatically closed before bytes
* from the next stream are read.
*
* @param inputStreams
* streams to be pushed onto this stream.
*/
public UnionInputStream(InputStream... inputStreams) {
for (InputStream i : inputStreams)
add(i);
}
private InputStream head() {
return streams.isEmpty() ? EOF : streams.getFirst();
}
private void pop() throws IOException {
if (!streams.isEmpty())
streams.removeFirst().close();
}
/**
* Add the given InputStream onto the end of the stream queue.
* <p>
* When the stream reaches EOF it will be automatically closed.
*
* @param in
* the stream to add; must not be null.
*/
public void add(final InputStream in) {
streams.add(in);
}
/**
* Returns true if there are no more InputStreams in the stream queue.
* <p>
* If this method returns {@code true} then all read methods will signal EOF
* by returning -1, until another InputStream has been pushed into the queue
* with {@link #add(InputStream)}.
*
* @return true if there are no more streams to read from.
*/
public boolean isEmpty() {
return streams.isEmpty();
}
@Override
public int read() throws IOException {
for (;;) {
final InputStream in = head();
final int r = in.read();
if (0 <= r)
return r;
else if (in == EOF)
return -1;
else
pop();
}
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
int cnt = 0;
while (0 < len) {
final InputStream in = head();
final int n = in.read(b, off, len);
if (0 < n) {
cnt += n;
off += n;
len -= n;
} else if (in == EOF)
return 0 < cnt ? cnt : -1;
else
pop();
}
return cnt;
}
@Override
public int available() throws IOException {
return head().available();
}
@Override
public long skip(long len) throws IOException {
long cnt = 0;
while (0 < len) {
final InputStream in = head();
final long n = in.skip(len);
if (0 < n) {
cnt += n;
len -= n;
} else if (in == EOF) {
return cnt;
} else {
// Is this stream at EOF? We can't tell from skip alone.
// Read one byte to test for EOF, discard it if we aren't
// yet at EOF.
//
final int r = in.read();
if (r < 0) {
pop();
} else {
cnt += 1;
len -= 1;
}
}
}
return cnt;
}
@Override
public void close() throws IOException {
IOException err = null;
for (Iterator<InputStream> i = streams.iterator(); i.hasNext();) {
try {
i.next().close();
} catch (IOException closeError) {
err = closeError;
}
i.remove();
}
if (err != null)
throw err;
}
}
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