/*
* Copyright (C) 2019, Google LLC.
* 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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package org.eclipse.jgit.revwalk;
import static java.util.Objects.requireNonNull;
import java.io.IOException;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.internal.revwalk.AddToBitmapFilter;
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.ProgressMonitor;
Calculate the bitmap indicating what other commits are reachable from certain
commit.
This bitmap refers only to commits. For a bitmap with ALL objects reachable from certain object, see BitmapWalker.
/**
* Calculate the bitmap indicating what other commits are reachable from certain
* commit.
* <p>
* This bitmap refers only to commits. For a bitmap with ALL objects reachable
* from certain object, see {@code BitmapWalker}.
*/
class BitmapCalculator {
private final RevWalk walk;
private final BitmapIndex bitmapIndex;
BitmapCalculator(RevWalk walk) throws IOException {
this.walk = walk;
this.bitmapIndex = requireNonNull(
walk.getObjectReader().getBitmapIndex());
}
Get the reachability bitmap from certain commit to other commits.
This will return a precalculated bitmap if available or walk building one
until finding a precalculated bitmap (and returning the union).
Beware that the returned bitmap it is guaranteed to include ONLY the commits reachable from the initial commit. It COULD include other objects (because precalculated bitmaps have them) but caller shouldn't count on that. See BitmapWalker for a full reachability bitmap.
Params: - start – the commit. Use
walk.parseCommit(objectId) to get this object from the id. - pm –
progress monitor. Updated by one per commit browsed in the
graph
Throws: - MissingObjectException –
the supplied id doesn't exist
- IncorrectObjectTypeException –
the supplied id doesn't refer to a commit or a tag
- IOException –
if the walk cannot open a packfile or loose object
Returns: the bitmap of reachable commits (and maybe some extra objects)
for the commit
/**
* Get the reachability bitmap from certain commit to other commits.
* <p>
* This will return a precalculated bitmap if available or walk building one
* until finding a precalculated bitmap (and returning the union).
* <p>
* Beware that the returned bitmap it is guaranteed to include ONLY the
* commits reachable from the initial commit. It COULD include other objects
* (because precalculated bitmaps have them) but caller shouldn't count on
* that. See {@link BitmapWalker} for a full reachability bitmap.
*
* @param start
* the commit. Use {@code walk.parseCommit(objectId)} to get this
* object from the id.
* @param pm
* progress monitor. Updated by one per commit browsed in the
* graph
* @return the bitmap of reachable commits (and maybe some extra objects)
* for the commit
* @throws MissingObjectException
* the supplied id doesn't exist
* @throws IncorrectObjectTypeException
* the supplied id doesn't refer to a commit or a tag
* @throws IOException
* if the walk cannot open a packfile or loose object
*/
BitmapBuilder getBitmap(RevCommit start, ProgressMonitor pm)
throws MissingObjectException,
IncorrectObjectTypeException, IOException {
Bitmap precalculatedBitmap = bitmapIndex.getBitmap(start);
if (precalculatedBitmap != null) {
return asBitmapBuilder(precalculatedBitmap);
}
walk.reset();
walk.sort(RevSort.TOPO);
walk.markStart(start);
// Unbounded walk. If the repo has bitmaps, it should bump into one at
// some point.
BitmapBuilder bitmapResult = bitmapIndex.newBitmapBuilder();
walk.setRevFilter(new AddToBitmapFilter(bitmapResult));
while (walk.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);
}
return bitmapResult;
}
private BitmapBuilder asBitmapBuilder(Bitmap bitmap) {
return bitmapIndex.newBitmapBuilder().or(bitmap);
}
}