BitmapWalker.java
/*
* Copyright (C) 2012, 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
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* - Redistributions in binary form must reproduce the above
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package org.eclipse.jgit.revwalk;
import java.io.IOException;
import java.util.Arrays;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.internal.revwalk.AddToBitmapFilter;
import org.eclipse.jgit.internal.revwalk.AddUnseenToBitmapFilter;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.BitmapIndex;
import org.eclipse.jgit.lib.BitmapIndex.Bitmap;
import org.eclipse.jgit.lib.BitmapIndex.BitmapBuilder;
import org.eclipse.jgit.lib.NullProgressMonitor;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.revwalk.filter.ObjectFilter;
/**
* Helper class to do ObjectWalks with pack index bitmaps.
*
* @since 4.10
*/
public final class BitmapWalker {
private final ObjectWalk walker;
private final BitmapIndex bitmapIndex;
private final ProgressMonitor pm;
private long countOfBitmapIndexMisses;
/**
* Create a BitmapWalker.
*
* @param walker walker to use when traversing the object graph.
* @param bitmapIndex index to obtain bitmaps from.
* @param pm progress monitor to report progress on.
*/
public BitmapWalker(
ObjectWalk walker, BitmapIndex bitmapIndex, ProgressMonitor pm) {
this.walker = walker;
this.bitmapIndex = bitmapIndex;
this.pm = (pm == null) ? NullProgressMonitor.INSTANCE : pm;
}
/**
* Return the number of objects that had to be walked because they were not covered by a
* bitmap.
*
* @return the number of objects that had to be walked because they were not covered by a
* bitmap.
*/
public long getCountOfBitmapIndexMisses() {
return countOfBitmapIndexMisses;
}
/**
* Return, as a bitmap, the objects reachable from the objects in start.
*
* @param start
* the objects to start the object traversal from.
* @param seen
* the objects to skip if encountered during traversal.
* @param ignoreMissing
* true to ignore missing objects, false otherwise.
* @return as a bitmap, the objects reachable from the objects in start.
* @throws org.eclipse.jgit.errors.MissingObjectException
* the object supplied is not available from the object
* database. This usually indicates the supplied object is
* invalid, but the reference was constructed during an earlier
* invocation to
* {@link org.eclipse.jgit.revwalk.RevWalk#lookupAny(AnyObjectId, int)}.
* @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
* the object was not parsed yet and it was discovered during
* parsing that it is not actually the type of the instance
* passed in. This usually indicates the caller used the wrong
* type in a
* {@link org.eclipse.jgit.revwalk.RevWalk#lookupAny(AnyObjectId, int)}
* call.
* @throws java.io.IOException
* a pack file or loose object could not be read.
*/
public BitmapBuilder findObjects(Iterable<? extends ObjectId> start, BitmapBuilder seen,
boolean ignoreMissing)
throws MissingObjectException, IncorrectObjectTypeException,
IOException {
if (!ignoreMissing) {
return findObjectsWalk(start, seen, false);
}
try {
return findObjectsWalk(start, seen, true);
} catch (MissingObjectException ignore) {
// An object reachable from one of the "start"s is missing.
// Walk from the "start"s one at a time so it can be excluded.
}
final BitmapBuilder result = bitmapIndex.newBitmapBuilder();
for (ObjectId obj : start) {
Bitmap bitmap = bitmapIndex.getBitmap(obj);
if (bitmap != null) {
result.or(bitmap);
}
}
for (ObjectId obj : start) {
if (result.contains(obj)) {
continue;
}
try {
result.or(findObjectsWalk(Arrays.asList(obj), result, false));
} catch (MissingObjectException ignore) {
// An object reachable from this "start" is missing.
//
// This can happen when the client specified a "have" line
// pointing to an object that is present but unreachable:
// "git prune" and "git fsck" only guarantee that the object
// database will continue to contain all objects reachable
// from a ref and does not guarantee connectivity for other
// objects in the object database.
//
// In this situation, skip the relevant "start" and move on
// to the next one.
//
// TODO(czhen): Make findObjectsWalk resume the walk instead
// once RevWalk and ObjectWalk support that.
}
}
return result;
}
private BitmapBuilder findObjectsWalk(Iterable<? extends ObjectId> start, BitmapBuilder seen,
boolean ignoreMissingStart)
throws MissingObjectException, IncorrectObjectTypeException,
IOException {
walker.reset();
final BitmapBuilder bitmapResult = bitmapIndex.newBitmapBuilder();
for (ObjectId obj : start) {
Bitmap bitmap = bitmapIndex.getBitmap(obj);
if (bitmap != null)
bitmapResult.or(bitmap);
}
boolean marked = false;
for (ObjectId obj : start) {
try {
if (!bitmapResult.contains(obj)) {
walker.markStart(walker.parseAny(obj));
marked = true;
}
} catch (MissingObjectException e) {
if (ignoreMissingStart)
continue;
throw e;
}
}
if (marked) {
if (seen == null) {
walker.setRevFilter(new AddToBitmapFilter(bitmapResult));
} else {
walker.setRevFilter(
new AddUnseenToBitmapFilter(seen, bitmapResult));
}
walker.setObjectFilter(new BitmapObjectFilter(bitmapResult));
while (walker.next() != null) {
// Iterate through all of the commits. The BitmapRevFilter does
// the work.
//
// filter.include returns true for commits that do not have
// a bitmap in bitmapIndex and are not reachable from a
// bitmap in bitmapIndex encountered earlier in the walk.
// Thus the number of commits returned by next() measures how
// much history was traversed without being able to make use
// of bitmaps.
pm.update(1);
countOfBitmapIndexMisses++;
}
RevObject ro;
while ((ro = walker.nextObject()) != null) {
bitmapResult.addObject(ro, ro.getType());
pm.update(1);
}
}
return bitmapResult;
}
/**
* Filter that excludes objects already in the given bitmap.
*/
static class BitmapObjectFilter extends ObjectFilter {
private final BitmapBuilder bitmap;
BitmapObjectFilter(BitmapBuilder bitmap) {
this.bitmap = bitmap;
}
@Override
public final boolean include(ObjectWalk walker, AnyObjectId objid)
throws MissingObjectException, IncorrectObjectTypeException,
IOException {
return !bitmap.contains(objid);
}
}
}