CommitGraphWriter: Unnest generation-number progress

The ProgressMonitor task to track the calculation of generation
numbers is nested inside the task that follows the writing of all
lines in the commit-graph. ProgressMonitor doesn't support nested
tasks and this confuses the counting.

Move the start/end of the "writing commit graph" task to the
writeCommitData section, after calculating the generation
numbers. Make that task track by commits instead of by lines.

Moving the start/end of the progress task to the chunk-writing
functions is clearer and easier to extend.

Logging of GC before:
Writing out commit-graph in 3 passes:  51% ( 9807/19358)
Computing commit-graph generation numbers: 100% (9551/9551)

Logging of GC after:
Computing commit-graph generation numbers: 100% (9551/9551)
Writing out commit-graph: 100% (9551/9551)

Change-Id: I87d69c06c9a3c7e75be12b6f0d1a63b5924e298a

1 files changed, 3 insertions, 10 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriter.java
index f72c1eaa8c..1c5f5b8521 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriter.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphWriter.java
@@ -31,7 +31,6 @@ import java.io.IOException;
 import java.io.InterruptedIOException;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
-import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
@@ -131,13 +130,6 @@ public class CommitGraphWriter {
 		chunks = Collections.unmodifiableList(chunks);
 
 		long expectedSize = calculateExpectedSize(chunks);
-		long writeCount = 256L + 2 * graphCommits.size()
-				+ graphCommits.getExtraEdgeCnt();
-		monitor.beginTask(
-				MessageFormat.format(JGitText.get().writingOutCommitGraph,
-						Integer.valueOf(chunks.size())),
-				(int) writeCount);
-
 		try (CancellableDigestOutputStream out = new CancellableDigestOutputStream(
 				monitor, commitGraphStream)) {
 			writeHeader(out, chunks.size());
@@ -153,8 +145,6 @@ public class CommitGraphWriter {
 		} catch (InterruptedIOException e) {
 			throw new IOException(JGitText.get().commitGraphWritingCancelled,
 					e);
-		} finally {
-			monitor.endTask();
 		}
 		return Stats.from(bloomFilterChunks);
 	}
@@ -290,6 +280,8 @@ public class CommitGraphWriter {
 	private void writeCommitData(ProgressMonitor monitor,
 			CancellableDigestOutputStream out) throws IOException {
 		int[] generations = computeGenerationNumbers(monitor);
+		monitor.beginTask(JGitText.get().writingOutCommitGraph,
+				graphCommits.size());
 		int num = 0;
 		byte[] tmp = new byte[hashsz + COMMIT_DATA_WIDTH];
 		int i = 0;
@@ -330,6 +322,7 @@ public class CommitGraphWriter {
 			out.getWriteMonitor().update(1);
 			i++;
 		}
+		monitor.endTask();
 	}
 
 	private int[] computeGenerationNumbers(ProgressMonitor monitor)