Initial JGit contribution to eclipse.org

Per CQ 3448 this is the initial contribution of the JGit project
to eclipse.org.  It is derived from the historical JGit repository
at commit 3a2dd9921c8a08740a9e02c421469e5b1a9e47cb.

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

1 files changed, 180 insertions, 0 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/WindowCursor.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/WindowCursor.java
new file mode 100644
index 0000000000..fcf43adf62
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/WindowCursor.java
@@ -0,0 +1,180 @@
+/*
+ * Copyright (C) 2008-2009, Google Inc.
+ * 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.IOException;
+import java.util.zip.DataFormatException;
+import java.util.zip.Inflater;
+
+/** Active handle to a ByteWindow. */
+public final class WindowCursor {
+	/** Temporary buffer large enough for at least one raw object id. */
+	final byte[] tempId = new byte[Constants.OBJECT_ID_LENGTH];
+
+	private Inflater inf;
+
+	private ByteWindow window;
+
+	/**
+	 * Copy bytes from the window to a caller supplied buffer.
+	 * 
+	 * @param pack
+	 *            the file the desired window is stored within.
+	 * @param position
+	 *            position within the file to read from.
+	 * @param dstbuf
+	 *            destination buffer to copy into.
+	 * @param dstoff
+	 *            offset within <code>dstbuf</code> to start copying into.
+	 * @param cnt
+	 *            number of bytes to copy. This value may exceed the number of
+	 *            bytes remaining in the window starting at offset
+	 *            <code>pos</code>.
+	 * @return number of bytes actually copied; this may be less than
+	 *         <code>cnt</code> if <code>cnt</code> exceeded the number of
+	 *         bytes available.
+	 * @throws IOException
+	 *             this cursor does not match the provider or id and the proper
+	 *             window could not be acquired through the provider's cache.
+	 */
+	int copy(final PackFile pack, long position, final byte[] dstbuf,
+			int dstoff, final int cnt) throws IOException {
+		final long length = pack.length;
+		int need = cnt;
+		while (need > 0 && position < length) {
+			pin(pack, position);
+			final int r = window.copy(position, dstbuf, dstoff, need);
+			position += r;
+			dstoff += r;
+			need -= r;
+		}
+		return cnt - need;
+	}
+
+	/**
+	 * Pump bytes into the supplied inflater as input.
+	 * 
+	 * @param pack
+	 *            the file the desired window is stored within.
+	 * @param position
+	 *            position within the file to read from.
+	 * @param dstbuf
+	 *            destination buffer the inflater should output decompressed
+	 *            data to.
+	 * @param dstoff
+	 *            current offset within <code>dstbuf</code> to inflate into.
+	 * @return updated <code>dstoff</code> based on the number of bytes
+	 *         successfully inflated into <code>dstbuf</code>.
+	 * @throws IOException
+	 *             this cursor does not match the provider or id and the proper
+	 *             window could not be acquired through the provider's cache.
+	 * @throws DataFormatException
+	 *             the inflater encountered an invalid chunk of data. Data
+	 *             stream corruption is likely.
+	 */
+	int inflate(final PackFile pack, long position, final byte[] dstbuf,
+			int dstoff) throws IOException, DataFormatException {
+		if (inf == null)
+			inf = InflaterCache.get();
+		else
+			inf.reset();
+		for (;;) {
+			pin(pack, position);
+			dstoff = window.inflate(position, dstbuf, dstoff, inf);
+			if (inf.finished())
+				return dstoff;
+			position = window.end;
+		}
+	}
+
+	void inflateVerify(final PackFile pack, long position)
+			throws IOException, DataFormatException {
+		if (inf == null)
+			inf = InflaterCache.get();
+		else
+			inf.reset();
+		for (;;) {
+			pin(pack, position);
+			window.inflateVerify(position, inf);
+			if (inf.finished())
+				return;
+			position = window.end;
+		}
+	}
+
+	private void pin(final PackFile pack, final long position)
+			throws IOException {
+		final ByteWindow w = window;
+		if (w == null || !w.contains(pack, position)) {
+			// If memory is low, we may need what is in our window field to
+			// be cleaned up by the GC during the get for the next window.
+			// So we always clear it, even though we are just going to set
+			// it again.
+			//
+			window = null;
+			window = WindowCache.get(pack, position);
+		}
+	}
+
+	/** Release the current window cursor. */
+	public void release() {
+		window = null;
+		try {
+			InflaterCache.release(inf);
+		} finally {
+			inf = null;
+		}
+	}
+
+	/**
+	 * @param curs cursor to release; may be null.
+	 * @return always null.
+	 */
+	public static WindowCursor release(final WindowCursor curs) {
+		if (curs != null)
+			curs.release();
+		return null;
+	}
+}