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/*
* Copyright (C) 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.revwalk;
import java.io.IOException;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
/**
* Replaces a RevCommit's parents until not colored with REWRITE.
* <p>
* Before a RevCommit is returned to the caller its parents are updated to
* create a dense DAG. Instead of reporting the actual parents as recorded when
* the commit was created the returned commit will reflect the next closest
* commit that matched the revision walker's filters.
* <p>
* This generator is the second phase of a path limited revision walk and
* assumes it is receiving RevCommits from {@link TreeRevFilter},
* after they have been fully buffered by {@link AbstractRevQueue}. The full
* buffering is necessary to allow the simple loop used within our own
* {@link #rewrite(RevCommit)} to pull completely through a strand of
* {@link RevWalk#REWRITE} colored commits and come up with a simplification
* that makes the DAG dense. Not fully buffering the commits first would cause
* this loop to abort early, due to commits not being parsed and colored
* correctly.
*
* @see TreeRevFilter
*/
class RewriteGenerator extends Generator {
private static final int REWRITE = RevWalk.REWRITE;
/** For {@link #cleanup(RevCommit[])} to remove duplicate parents. */
private static final int DUPLICATE = RevWalk.TEMP_MARK;
private final Generator source;
RewriteGenerator(final Generator s) {
source = s;
}
@Override
void shareFreeList(final BlockRevQueue q) {
source.shareFreeList(q);
}
@Override
int outputType() {
return source.outputType() & ~NEEDS_REWRITE;
}
@Override
RevCommit next() throws MissingObjectException,
IncorrectObjectTypeException, IOException {
final RevCommit c = source.next();
if (c == null) {
return null;
}
boolean rewrote = false;
final RevCommit[] pList = c.parents;
final int nParents = pList.length;
for (int i = 0; i < nParents; i++) {
final RevCommit oldp = pList[i];
final RevCommit newp = rewrite(oldp);
if (oldp != newp) {
pList[i] = newp;
rewrote = true;
}
}
if (rewrote) {
c.parents = cleanup(pList);
}
return c;
}
private RevCommit rewrite(RevCommit p) {
for (;;) {
final RevCommit[] pList = p.parents;
if (pList.length > 1) {
// This parent is a merge, so keep it.
//
return p;
}
if ((p.flags & RevWalk.UNINTERESTING) != 0) {
// Retain uninteresting parents. They show where the
// DAG was cut off because it wasn't interesting.
//
return p;
}
if ((p.flags & REWRITE) == 0) {
// This parent was not eligible for rewriting. We
// need to keep it in the DAG.
//
return p;
}
if (pList.length == 0) {
// We can't go back any further, other than to
// just delete the parent entirely.
//
return null;
}
p = pList[0];
}
}
private RevCommit[] cleanup(final RevCommit[] oldList) {
// Remove any duplicate parents caused due to rewrites (e.g. a merge
// with two sides that both simplified back into the merge base).
// We also may have deleted a parent by marking it null.
//
int newCnt = 0;
for (int o = 0; o < oldList.length; o++) {
final RevCommit p = oldList[o];
if (p == null)
continue;
if ((p.flags & DUPLICATE) != 0) {
oldList[o] = null;
continue;
}
p.flags |= DUPLICATE;
newCnt++;
}
if (newCnt == oldList.length) {
for (final RevCommit p : oldList)
p.flags &= ~DUPLICATE;
return oldList;
}
final RevCommit[] newList = new RevCommit[newCnt];
newCnt = 0;
for (final RevCommit p : oldList) {
if (p != null) {
newList[newCnt++] = p;
p.flags &= ~DUPLICATE;
}
}
return newList;
}
}
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