Add a method to DfsOutputStream to read as an InputStream

Change-Id: I0ec1f17a88bc14f22c10f9bc8d6f5b5118410e3a

org.eclipse.jgit.test/META-INF/MANIFEST.MF

@@ -20,6 +20,7 @@ Import-Package: javaewah;version="[0.5.6,1.0.0)",
  org.eclipse.jgit.fnmatch;version="[3.1.0,3.2.0)",
  org.eclipse.jgit.ignore;version="[3.1.0,3.2.0)",
  org.eclipse.jgit.internal;version="[3.1.0,3.2.0)",
+ org.eclipse.jgit.internal.storage.dfs;version="[3.1.0,3.2.0)",
  org.eclipse.jgit.internal.storage.file;version="[3.1.0,3.2.0)",
  org.eclipse.jgit.internal.storage.pack;version="[3.1.0,3.2.0)",
  org.eclipse.jgit.java7;version="[3.1.0,3.2.0)";resolution:=optional,

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsOutputStreamTest.java

@@ -0,0 +1,150 @@
+/*
+ * Copyright (C) 2013, 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 static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.util.RawParseUtils;
+import org.junit.Test;
+
+public class DfsOutputStreamTest {
+	@Test
+	public void testReadEmpty() throws IOException {
+		DfsOutputStream os = newDfsOutputStream(8);
+		os.write(Constants.encode(""));
+		assertEquals("", readBuffered(os.openInputStream(0)));
+		assertEquals("", readByByte(os.openInputStream(0)));
+		assertEquals("", readBuffered(os.openInputStream(1)));
+		assertEquals("", readByByte(os.openInputStream(1)));
+	}
+
+	@Test
+	public void testRead() throws IOException {
+		DfsOutputStream os = newDfsOutputStream(8);
+		os.write(Constants.encode("data"));
+		assertEquals("data", readBuffered(os.openInputStream(0)));
+		assertEquals("data", readByByte(os.openInputStream(0)));
+		assertEquals("ata", readBuffered(os.openInputStream(1)));
+		assertEquals("ata", readByByte(os.openInputStream(1)));
+		assertEquals("ta", readBuffered(os.openInputStream(2)));
+		assertEquals("ta", readByByte(os.openInputStream(2)));
+		assertEquals("a", readBuffered(os.openInputStream(3)));
+		assertEquals("a", readByByte(os.openInputStream(3)));
+		assertEquals("", readBuffered(os.openInputStream(4)));
+		assertEquals("", readByByte(os.openInputStream(4)));
+		assertEquals("", readBuffered(os.openInputStream(5)));
+		assertEquals("", readByByte(os.openInputStream(5)));
+	}
+
+	@Test
+	public void testReadSmallBuffer() throws IOException {
+		DfsOutputStream os = newDfsOutputStream(8);
+		os.write(Constants.encode("data"));
+		assertEquals("data", readBuffered(os.openInputStream(0), 2));
+		assertEquals("ata", readBuffered(os.openInputStream(1), 2));
+		assertEquals("ta", readBuffered(os.openInputStream(2), 2));
+		assertEquals("a", readBuffered(os.openInputStream(3), 2));
+		assertEquals("", readBuffered(os.openInputStream(4), 2));
+		assertEquals("", readBuffered(os.openInputStream(5), 2));
+	}
+
+	@Test
+	public void testReadMultipleBlocks() throws IOException {
+		DfsOutputStream os = newDfsOutputStream(2);
+		os.write(Constants.encode("data"));
+		assertEquals("data", readBuffered(os.openInputStream(0)));
+		assertEquals("data", readByByte(os.openInputStream(0)));
+		assertEquals("ata", readBuffered(os.openInputStream(1)));
+		assertEquals("ata", readByByte(os.openInputStream(1)));
+		assertEquals("ta", readBuffered(os.openInputStream(2)));
+		assertEquals("ta", readByByte(os.openInputStream(2)));
+		assertEquals("a", readBuffered(os.openInputStream(3)));
+		assertEquals("a", readByByte(os.openInputStream(3)));
+		assertEquals("", readBuffered(os.openInputStream(4)));
+		assertEquals("", readByByte(os.openInputStream(4)));
+		assertEquals("", readBuffered(os.openInputStream(5)));
+		assertEquals("", readByByte(os.openInputStream(5)));
+	}
+
+	private static DfsOutputStream newDfsOutputStream(final int blockSize) {
+		return new InMemoryOutputStream() {
+			@Override
+			public int blockSize() {
+				return blockSize;
+			}
+		};
+	}
+
+	private static String readBuffered(InputStream is, int bufsize)
+			throws IOException {
+		StringBuilder out = new StringBuilder();
+		byte[] buf = new byte[bufsize];
+		while (true) {
+			int n = is.read(buf, 0, buf.length);
+			if (n < 0)
+				break;
+			out.append(RawParseUtils.decode(buf, 0, n));
+		}
+		return out.toString();
+	}
+
+	private static String readBuffered(InputStream is) throws IOException {
+		return readBuffered(is, 64);
+	}
+
+	private static String readByByte(InputStream is) throws IOException {
+		StringBuilder out = new StringBuilder();
+		while (true) {
+			int c = is.read();
+			if (c < 0)
+				break;
+			out.append(RawParseUtils.decode(new byte[] {(byte) c}));
+		}
+		return out.toString();
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsOutputStream.java

@@ -44,6 +44,7 @@
 package org.eclipse.jgit.internal.storage.dfs;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
 
@@ -96,4 +97,62 @@ public abstract class DfsOutputStream extends OutputStream {
 	 *             to DFS errors.
 	 */
 	public abstract int read(long position, ByteBuffer buf) throws IOException;
+
+	/**
+	 * Open a stream to read back a portion of already written data.
+	 * <p>
+	 * The writing position of the output stream is not affected by a read. The
+	 * input stream can be read up to the current writing position. Closing the
+	 * returned stream has no effect on the underlying {@link DfsOutputStream}.
+	 *
+	 * @param position
+	 *            offset to read from.
+	 * @return new input stream
+	 */
+	public InputStream openInputStream(final long position) {
+		return new ReadBackStream(position);
+	}
+
+	private class ReadBackStream extends InputStream {
+		private final ByteBuffer buf;
+		private long position;
+
+		private ReadBackStream(long position) {
+			int bs = blockSize();
+			this.position = position;
+			buf = ByteBuffer.allocate(bs > 0 ? bs : 8192);
+			buf.position(buf.limit());
+		}
+
+		@Override
+		public int read(byte[] b, int off, int len) throws IOException {
+			int cnt = 0;
+			while (0 < len) {
+				if (!buf.hasRemaining()) {
+					buf.rewind();
+					int nr = DfsOutputStream.this.read(position, buf);
+					if (nr < 0) {
+						buf.position(buf.limit());
+						break;
+					}
+					position += nr;
+					buf.flip();
+				}
+				int n = Math.min(len, buf.remaining());
+				buf.get(b, off, n);
+				off += n;
+				len -= n;
+				cnt += n;
+			}
+			if (cnt == 0 && len > 0) return -1;
+			return cnt;
+		}
+
+		@Override
+		public int read() throws IOException {
+			byte[] b = new byte[1];
+			int n = read(b);
+			return n == 1 ? b[0] & 0xff : -1;
+		}
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/InMemoryOutputStream.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2013, 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.ByteArrayOutputStream;
+import java.nio.ByteBuffer;
+
+class InMemoryOutputStream extends DfsOutputStream {
+	private final ByteArrayOutputStream dst = new ByteArrayOutputStream();
+
+	private byte[] data;
+
+	@Override
+	public void write(byte[] buf, int off, int len) {
+		data = null;
+		dst.write(buf, off, len);
+	}
+
+	@Override
+	public int read(long position, ByteBuffer buf) {
+		byte[] d = getData();
+		int n = Math.min(buf.remaining(), d.length - (int) position);
+		if (n <= 0)
+			return -1;
+		buf.put(d, (int) position, n);
+		return n;
+	}
+
+	byte[] getData() {
+		if (data == null)
+			data = dst.toByteArray();
+		return data;
+	}
+
+	@Override
+	public void flush() {
+		// Default implementation does nothing;
+	}
+
+	@Override
+	public void close() {
+		flush();
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/InMemoryRepository.java

@@ -1,6 +1,5 @@
 package org.eclipse.jgit.internal.storage.dfs;
 
-import java.io.ByteArrayOutputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -117,7 +116,7 @@ public class InMemoryRepository extends DfsRepository {
 		protected DfsOutputStream writeFile(
 				DfsPackDescription desc, final PackExt ext) throws IOException {
 			final MemPack memPack = (MemPack) desc;
-			return new Out() {
+			return new InMemoryOutputStream() {
 				@Override
 				public void flush() {
 					memPack.fileMap.put(ext, getData());
@@ -135,43 +134,6 @@ public class InMemoryRepository extends DfsRepository {
 		}
 	}
 
-	private abstract static class Out extends DfsOutputStream {
-		private final ByteArrayOutputStream dst = new ByteArrayOutputStream();
-
-		private byte[] data;
-
-		@Override
-		public void write(byte[] buf, int off, int len) {
-			data = null;
-			dst.write(buf, off, len);
-		}
-
-		@Override
-		public int read(long position, ByteBuffer buf) {
-			byte[] d = getData();
-			int n = Math.min(buf.remaining(), d.length - (int) position);
-			if (n == 0)
-				return -1;
-			buf.put(d, (int) position, n);
-			return n;
-		}
-
-		byte[] getData() {
-			if (data == null)
-				data = dst.toByteArray();
-			return data;
-		}
-
-		@Override
-		public abstract void flush();
-
-		@Override
-		public void close() {
-			flush();
-		}
-
-	}
-
 	private static class ByteArrayReadableChannel implements ReadableChannel {
 		private final byte[] data;