jgit/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/LargePackedDeltaObject.java

/*
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 * 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
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package org.eclipse.jgit.internal.storage.file;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.DataFormatException;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.InflaterInputStream;

import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.LargeObjectException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.internal.storage.pack.BinaryDelta;
import org.eclipse.jgit.internal.storage.pack.DeltaStream;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.ObjectStream;
import org.eclipse.jgit.util.io.TeeInputStream;

class LargePackedDeltaObject extends ObjectLoader {
	private static final long SIZE_UNKNOWN = -1;

	private int type;

	private long size;

	private final long objectOffset;

	private final long baseOffset;

	private final int headerLength;

	private final PackFile pack;

	private final FileObjectDatabase db;

	LargePackedDeltaObject(long objectOffset,
			long baseOffset, int headerLength, PackFile pack,
			FileObjectDatabase db) {
		this.type = Constants.OBJ_BAD;
		this.size = SIZE_UNKNOWN;
		this.objectOffset = objectOffset;
		this.baseOffset = baseOffset;
		this.headerLength = headerLength;
		this.pack = pack;
		this.db = db;
	}

	@Override
	public int getType() {
		if (type == Constants.OBJ_BAD) {
			WindowCursor wc = new WindowCursor(db);
			try {
				type = pack.getObjectType(wc, objectOffset);
			} catch (IOException packGone) {
				// If the pack file cannot be pinned into the cursor, it
				// probably was repacked recently. Go find the object
				// again and get the type from that location instead.
				//
				try {
					type = wc.open(getObjectId()).getType();
				} catch (IOException packGone2) {
					// "He's dead, Jim." We just can't discover the type
					// and the interface isn't supposed to be lazy here.
					// Report an invalid type code instead, callers will
					// wind up bailing out with an error at some point.
				}
			} finally {
				wc.release();
			}
		}
		return type;
	}

	@Override
	public long getSize() {
		if (size == SIZE_UNKNOWN) {
			WindowCursor wc = new WindowCursor(db);
			try {
				byte[] b = pack.getDeltaHeader(wc, objectOffset + headerLength);
				size = BinaryDelta.getResultSize(b);
			} catch (DataFormatException objectCorrupt) {
				// The zlib stream for the delta is corrupt. We probably
				// cannot access the object. Keep the size negative and
				// report that bogus result to the caller.
			} catch (IOException packGone) {
				// If the pack file cannot be pinned into the cursor, it
				// probably was repacked recently. Go find the object
				// again and get the size from that location instead.
				//
				try {
					size = wc.open(getObjectId()).getSize();
				} catch (IOException packGone2) {
					// "He's dead, Jim." We just can't discover the size
					// and the interface isn't supposed to be lazy here.
					// Report an invalid type code instead, callers will
					// wind up bailing out with an error at some point.
				}
			} finally {
				wc.release();
			}
		}
		return size;
	}

	@Override
	public boolean isLarge() {
		return true;
	}

	@Override
	public byte[] getCachedBytes() throws LargeObjectException {
		try {
			throw new LargeObjectException(getObjectId());
		} catch (IOException cannotObtainId) {
			LargeObjectException err = new LargeObjectException();
			err.initCause(cannotObtainId);
			throw err;
		}
	}

	@Override
	public ObjectStream openStream() throws MissingObjectException, IOException {
		// If the object was recently unpacked, its available loose.
		// The loose format is going to be faster to access than a
		// delta applied on top of a base. Use that whenever we can.
		//
		final ObjectId myId = getObjectId();
		final WindowCursor wc = new WindowCursor(db);
		ObjectLoader ldr = db.openLooseObject(wc, myId);
		if (ldr != null)
			return ldr.openStream();

		InputStream in = open(wc);
		in = new BufferedInputStream(in, 8192);

		// While we inflate the object, also deflate it back as a loose
		// object. This will later be cleaned up by a gc pass, but until
		// then we will reuse the loose form by the above code path.
		//
		int myType = getType();
		long mySize = getSize();
		final ObjectDirectoryInserter odi = db.newInserter();
		final File tmp = odi.newTempFile();
		DeflaterOutputStream dOut = odi.compress(new FileOutputStream(tmp));
		odi.writeHeader(dOut, myType, mySize);

		in = new TeeInputStream(in, dOut);
		return new ObjectStream.Filter(myType, mySize, in) {
			@Override
			public void close() throws IOException {
				super.close();

				odi.release();
				wc.release();
				db.insertUnpackedObject(tmp, myId, true /* force creation */);
			}
		};
	}

	private InputStream open(final WindowCursor wc)
			throws MissingObjectException, IOException,
			IncorrectObjectTypeException {
		InputStream delta;
		try {
			delta = 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()).openStream();
		}
		delta = new InflaterInputStream(delta);

		final ObjectLoader base = pack.load(wc, baseOffset);
		DeltaStream ds = new DeltaStream(delta) {
			private long baseSize = SIZE_UNKNOWN;

			@Override
			protected InputStream openBase() throws IOException {
				InputStream in;
				if (base instanceof LargePackedDeltaObject)
					in = ((LargePackedDeltaObject) base).open(wc);
				else
					in = base.openStream();
				if (baseSize == SIZE_UNKNOWN) {
					if (in instanceof DeltaStream)
						baseSize = ((DeltaStream) in).getSize();
					else if (in instanceof ObjectStream)
						baseSize = ((ObjectStream) in).getSize();
				}
				return in;
			}

			@Override
			protected long getBaseSize() throws IOException {
				if (baseSize == SIZE_UNKNOWN) {
					// This code path should never be used as DeltaStream
					// is supposed to open the stream first, which would
					// initialize the size for us directly from the stream.
					baseSize = base.getSize();
				}
				return baseSize;
			}
		};
		if (type == Constants.OBJ_BAD) {
			if (!(base instanceof LargePackedDeltaObject))
				type = base.getType();
		}
		if (size == SIZE_UNKNOWN)
			size = ds.getSize();
		return ds;
	}

	private ObjectId getObjectId() throws IOException {
		return pack.findObjectForOffset(objectOffset);
	}
}