Option to pass start RevCommit to be blamed on to the BlameGenerator.

This can allow passing a FilteredRevCommit which is the filtered list of
commit graph making it easier for Blame to work on. This can
significantly improve blame performance since blame can skip expensive
RevWalk.

Change-Id: I5dab25301d6aef7df6a0bc25a4c553c730199272

1 files changed, 34 insertions, 13 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/blame/BlameGenerator.java b/org.eclipse.jgit/src/org/eclipse/jgit/blame/BlameGenerator.java
index 77967df2e5..93ddfc6607 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/blame/BlameGenerator.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/blame/BlameGenerator.java
@@ -129,6 +129,7 @@ public class BlameGenerator implements AutoCloseable {
 
 	/** Blame is currently assigned to this source. */
 	private Candidate outCandidate;
+
 	private Region outRegion;
 
 	/**
@@ -403,6 +404,35 @@ public class BlameGenerator implements AutoCloseable {
 	 * revision (if the index is interesting), and finally the working tree copy
 	 * (if the working tree is interesting).
 	 *
+	 * @param blameCommit
+	 *            ordered commits to use instead of RevWalk.
+	 * @return {@code this}
+	 * @throws java.io.IOException
+	 *             the repository cannot be read.
+	 * @since 6.3
+	 */
+	public BlameGenerator push(RevCommit blameCommit) throws IOException {
+		if (!find(blameCommit, resultPath)) {
+			return this;
+		}
+
+		Candidate c = new Candidate(getRepository(), blameCommit, resultPath);
+		c.sourceBlob = idBuf.toObjectId();
+		c.loadText(reader);
+		c.regionList = new Region(0, 0, c.sourceText.size());
+		remaining = c.sourceText.size();
+		push(c);
+		return this;
+	}
+
+	/**
+	 * Push a candidate object onto the generator's traversal stack.
+	 * <p>
+	 * Candidates should be pushed in history order from oldest-to-newest.
+	 * Applications should push the starting commit first, then the index
+	 * revision (if the index is interesting), and finally the working tree copy
+	 * (if the working tree is interesting).
+	 *
 	 * @param description
 	 *            description of the blob revision, such as "Working Tree".
 	 * @param id
@@ -428,16 +458,7 @@ public class BlameGenerator implements AutoCloseable {
 		}
 
 		RevCommit commit = revPool.parseCommit(id);
-		if (!find(commit, resultPath))
-			return this;
-
-		Candidate c = new Candidate(getRepository(), commit, resultPath);
-		c.sourceBlob = idBuf.toObjectId();
-		c.loadText(reader);
-		c.regionList = new Region(0, 0, c.sourceText.size());
-		remaining = c.sourceText.size();
-		push(c);
-		return this;
+		return push(commit);
 	}
 
 	/**
@@ -605,7 +626,7 @@ public class BlameGenerator implements AutoCloseable {
 				// Do not generate a tip of a reverse. The region
 				// survives and should not appear to be deleted.
 
-			} else /* if (pCnt == 0) */{
+			} else /* if (pCnt == 0) */ {
 				// Root commit, with at least one surviving region.
 				// Assign the remaining blame here.
 				return result(n);
@@ -846,8 +867,8 @@ public class BlameGenerator implements AutoCloseable {
 				editList = new EditList(0);
 			} else {
 				p.loadText(reader);
-				editList = diffAlgorithm.diff(textComparator,
-						p.sourceText, n.sourceText);
+				editList = diffAlgorithm.diff(textComparator, p.sourceText,
+						n.sourceText);
 			}
 
 			if (editList.isEmpty()) {