Support large whole packed objects as streams

Similar to the loose object support, whole packed objects can
now be streamed back to the caller.  The streaming is less
efficient as we copy the data from the cached window array
into the InflaterInputStream's internal buffer, then inflate
it there before returning to the application.

Like with unpacked objects, there is plenty of room for some
optimization, especially for the copyTo method, where we don't
necessarily need so much buffering to exist.

Change-Id: Ie23be81289e37e24b91d17b0891e47b9da988008
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

4 files changed, 221 insertions, 3 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/LargePackedWholeObject.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/LargePackedWholeObject.java
new file mode 100644
index 0000000000..9f5b804ce4
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/LargePackedWholeObject.java
@@ -0,0 +1,130 @@
+/*
+ * Copyright (C) 2010, 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.storage.file;
+
+import java.io.BufferedInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.InflaterInputStream;
+
+import org.eclipse.jgit.errors.LargeObjectException;
+import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.ObjectStream;
+
+class LargePackedWholeObject extends ObjectLoader {
+	private final int type;
+
+	private final long size;
+
+	private final long objectOffset;
+
+	private final int headerLength;
+
+	private final PackFile pack;
+
+	private final FileObjectDatabase db;
+
+	LargePackedWholeObject(int type, long size, long objectOffset,
+			int headerLength, PackFile pack, FileObjectDatabase db) {
+		this.type = type;
+		this.size = size;
+		this.objectOffset = objectOffset;
+		this.headerLength = headerLength;
+		this.pack = pack;
+		this.db = db;
+	}
+
+	@Override
+	public int getType() {
+		return type;
+	}
+
+	@Override
+	public long getSize() {
+		return size;
+	}
+
+	@Override
+	public boolean isLarge() {
+		return true;
+	}
+
+	@Override
+	public byte[] getCachedBytes() throws LargeObjectException {
+		try {
+			throw new LargeObjectException(getObjectId());
+		} catch (IOException cannotObtainId) {
+			throw new LargeObjectException();
+		}
+	}
+
+	@Override
+	public ObjectStream openStream() throws MissingObjectException, IOException {
+		WindowCursor wc = new WindowCursor(db);
+		InputStream in;
+		try {
+			in = new PackInputStream(pack, objectOffset + headerLength, wc);
+		} catch (IOException packGone) {
+			// If the pack file cannot be pinned into the cursor, it
+			// probably was repacked recently. Go find the object
+			// again and open the stream from that location instead.
+			//
+			return wc.open(getObjectId(), type).openStream();
+		}
+
+		in = new BufferedInputStream( //
+				new InflaterInputStream( //
+						in, //
+						wc.inflater(), //
+						8192), //
+				8192);
+		return new ObjectStream.Filter(type, size, in);
+	}
+
+	private ObjectId getObjectId() throws IOException {
+		return pack.findObjectForOffset(objectOffset);
+	}
+}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackFile.java
index 9f642042ca..f955c8af9b 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackFile.java
@@ -632,8 +632,11 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 			case Constants.OBJ_TREE:
 			case Constants.OBJ_BLOB:
 			case Constants.OBJ_TAG: {
-				byte[] data = decompress(pos + p, sz, curs);
-				return new ObjectLoader.SmallObject(type, data);
+				if (sz < UnpackedObject.LARGE_OBJECT) {
+					byte[] data = decompress(pos + p, sz, curs);
+					return new ObjectLoader.SmallObject(type, data);
+				}
+				return new LargePackedWholeObject(type, sz, pos, p, this, curs.db);
 			}
 
 			case Constants.OBJ_OFS_DELTA: {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackInputStream.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackInputStream.java
new file mode 100644
index 0000000000..5425eedbe9
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/PackInputStream.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2010, 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.storage.file;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+class PackInputStream extends InputStream {
+	private final WindowCursor wc;
+
+	private final PackFile pack;
+
+	private long pos;
+
+	PackInputStream(PackFile pack, long pos, WindowCursor wc)
+			throws IOException {
+		this.pack = pack;
+		this.pos = pos;
+		this.wc = wc;
+
+		// Pin the first window, to ensure the pack is open and valid.
+		//
+		wc.pin(pack, pos);
+	}
+
+	@Override
+	public int read(byte[] b, int off, int len) throws IOException {
+		int n = wc.copy(pack, pos, b, off, len);
+		pos += n;
+		return n;
+	}
+
+	@Override
+	public int read() throws IOException {
+		byte[] buf = new byte[1];
+		int n = read(buf, 0, 1);
+		return n == 1 ? buf[0] & 0xff : -1;
+	}
+
+	@Override
+	public void close() {
+		wc.release();
+	}
+}
\ No newline at end of file
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/WindowCursor.java b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/WindowCursor.java
index 3527eb08c8..7ede751d09 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/WindowCursor.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/storage/file/WindowCursor.java
@@ -200,7 +200,7 @@ final class WindowCursor extends ObjectReader implements ObjectReuseAsIs {
 			inf.reset();
 	}
 
-	private void pin(final PackFile pack, final long position)
+	void pin(final PackFile pack, final long position)
 			throws IOException {
 		final ByteWindow w = window;
 		if (w == null || !w.contains(pack, position)) {