CommitGraphWriter: add option for writing/using bloom filters

Currently, bloom filters are written and used without any way to turn
them off. Add a per-repo config variable to control whether bloom
filters are written. As for reading, add a JGit option to control this.
(A JGit option is used instead of a per-repo config variable as there is
usually no reason not to use the bloom filters if they are present, but
a global control to disable them is useful if there turns out to be an
issue with the implementation of bloom filters.)

The config that controls reading is the same as C Git, but the config
for writing is not: C Git has no config to control writing, but whether
bloom filters are written depends on whether bloom filters are already
present and what arguments are passed to "git commit-graph write". See
the manpage of "git commit-graph" for more information.

Change-Id: I1b7b25340387673506252b9260b22bfe147bde58

6 files changed, 102 insertions, 11 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphLoader.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphLoader.java
index d6310e0a85..867d522e08 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphLoader.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/commitgraph/CommitGraphLoader.java
@@ -27,9 +27,12 @@ import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.internal.JGitText;
+import org.eclipse.jgit.lib.ConfigConstants;
 import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.NB;
+import org.eclipse.jgit.util.SystemReader;
 import org.eclipse.jgit.util.io.SilentFileInputStream;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -139,6 +142,17 @@ public class CommitGraphLoader {
 			chunks.add(new ChunkSegment(id, offset));
 		}
 
+		boolean readChangedPathFilters;
+		try {
+			readChangedPathFilters = SystemReader.getInstance()
+					.getJGitConfig()
+					.getBoolean(ConfigConstants.CONFIG_COMMIT_GRAPH_SECTION,
+						ConfigConstants.CONFIG_KEY_READ_CHANGED_PATHS, false);
+		} catch (ConfigInvalidException e) {
+			// Use the default value if, for some reason, the config couldn't be read.
+			readChangedPathFilters = false;
+		}
+
 		CommitGraphBuilder builder = CommitGraphBuilder.builder();
 		for (int i = 0; i < numberOfChunks; i++) {
 			long chunkOffset = chunks.get(i).offset;
@@ -167,10 +181,14 @@ public class CommitGraphLoader {
 				builder.addExtraList(buffer);
 				break;
 			case CHUNK_ID_BLOOM_FILTER_INDEX:
-				builder.addBloomFilterIndex(buffer);
+				if (readChangedPathFilters) {
+					builder.addBloomFilterIndex(buffer);
+				}
 				break;
 			case CHUNK_ID_BLOOM_FILTER_DATA:
-				builder.addBloomFilterData(buffer);
+				if (readChangedPathFilters) {
+					builder.addBloomFilterData(buffer);
+				}
 				break;
 			default:
 				LOG.warn(MessageFormat.format(
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 eb9dfb4d9c..9d1c33959f 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
@@ -73,6 +73,8 @@ public class CommitGraphWriter {
 
 	private final GraphCommits graphCommits;
 
+	private final boolean generateChangedPathFilters;
+
 	/**
 	 * Create commit-graph writer for these commits.
 	 *
@@ -80,8 +82,22 @@ public class CommitGraphWriter {
 	 *            the commits which will be writen to the commit-graph.
 	 */
 	public CommitGraphWriter(@NonNull GraphCommits graphCommits) {
+		this(graphCommits, false);
+	}
+
+	/**
+	 * Create commit-graph writer for these commits.
+	 *
+	 * @param graphCommits
+	 *            the commits which will be writen to the commit-graph.
+	 * @param generateChangedPathFilters
+	 *            whether changed path filters are generated
+	 */
+	public CommitGraphWriter(@NonNull GraphCommits graphCommits,
+			boolean generateChangedPathFilters) {
 		this.graphCommits = graphCommits;
 		this.hashsz = OBJECT_ID_LENGTH;
+		this.generateChangedPathFilters = generateChangedPathFilters;
 	}
 
 	/**
@@ -140,11 +156,14 @@ public class CommitGraphWriter {
 			chunks.add(new ChunkHeader(CHUNK_ID_EXTRA_EDGE_LIST,
 					graphCommits.getExtraEdgeCnt() * 4));
 		}
-		BloomFilterChunks bloomFilterChunks = computeBloomFilterChunks(stats);
-		chunks.add(new ChunkHeader(CHUNK_ID_BLOOM_FILTER_INDEX,
-				bloomFilterChunks.index));
-		chunks.add(new ChunkHeader(CHUNK_ID_BLOOM_FILTER_DATA,
-				bloomFilterChunks.data));
+		if (generateChangedPathFilters) {
+			BloomFilterChunks bloomFilterChunks = computeBloomFilterChunks(
+					stats);
+			chunks.add(new ChunkHeader(CHUNK_ID_BLOOM_FILTER_INDEX,
+					bloomFilterChunks.index));
+			chunks.add(new ChunkHeader(CHUNK_ID_BLOOM_FILTER_DATA,
+					bloomFilterChunks.data));
+		}
 		return chunks;
 	}
 
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollector.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollector.java
index 9f415782fa..8cb94dcf4b 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollector.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsGarbageCollector.java
@@ -81,6 +81,8 @@ public class DfsGarbageCollector {
 	private ReftableConfig reftableConfig;
 	private boolean convertToReftable = true;
 	private boolean writeCommitGraph;
+
+	private boolean writeBloomFilter;
 	private boolean includeDeletes;
 	private long reftableInitialMinUpdateIndex = 1;
 	private long reftableInitialMaxUpdateIndex = 1;
@@ -299,6 +301,20 @@ public class DfsGarbageCollector {
 	}
 
 	/**
+	 * Toggle bloom filter generation.
+	 * <p>
+	 * False by default.
+	 *
+	 * @param enable
+	 *            Whether bloom filter generation is enabled
+	 * @return {@code this}
+	 */
+	public DfsGarbageCollector setWriteBloomFilter(boolean enable) {
+		writeBloomFilter = enable;
+		return this;
+	}
+
+	/**
 	 * Create a single new pack file containing all of the live objects.
 	 * <p>
 	 * This method safely decides which packs can be expired after the new pack
@@ -774,7 +790,8 @@ public class DfsGarbageCollector {
 				RevWalk pool = new RevWalk(ctx)) {
 			GraphCommits gcs = GraphCommits.fromWalk(pm, allTips, pool);
 			CountingOutputStream cnt = new CountingOutputStream(out);
-			CommitGraphWriter writer = new CommitGraphWriter(gcs);
+			CommitGraphWriter writer = new CommitGraphWriter(gcs,
+					writeBloomFilter);
 			writer.write(pm, cnt);
 			pack.addFileExt(COMMIT_GRAPH);
 			pack.setFileSize(COMMIT_GRAPH, cnt.getCount());
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileCommitGraph.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileCommitGraph.java
index 44429a7786..5172963e2e 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileCommitGraph.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileCommitGraph.java
@@ -108,7 +108,8 @@ public class FileCommitGraph {
 				// commit-graph file was not modified
 				return this;
 			}
-			return new GraphSnapshot(file, FileSnapshot.save(file), open(file));
+			return new GraphSnapshot(file, FileSnapshot.save(file),
+					open(file));
 		}
 
 		private static CommitGraph open(File file) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
index ace0d7be7b..144ff4aa04 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
@@ -135,6 +135,8 @@ public class GC {
 
 	private static final int DEFAULT_AUTOLIMIT = 6700;
 
+	private static final boolean DEFAULT_WRITE_BLOOM_FILTER = false;
+
 	private static final boolean DEFAULT_WRITE_COMMIT_GRAPH = false;
 
 	private static volatile ExecutorService executor;
@@ -959,7 +961,8 @@ public class GC {
 		File tmpFile = null;
 		try (RevWalk walk = new RevWalk(repo)) {
 			CommitGraphWriter writer = new CommitGraphWriter(
-					GraphCommits.fromWalk(pm, wants, walk));
+					GraphCommits.fromWalk(pm, wants, walk),
+					shouldWriteBloomFilter());
 			tmpFile = File.createTempFile("commit_", //$NON-NLS-1$
 					COMMIT_GRAPH.getTmpExtension(),
 					repo.getObjectDatabase().getInfoDirectory());
@@ -1011,7 +1014,7 @@ public class GC {
 	/**
 	 * If {@code true}, will rewrite the commit-graph file when gc is run.
 	 *
-	 * @return true if commit-graph should be writen. Default is {@code false}.
+	 * @return true if commit-graph should be written. Default is {@code false}.
 	 */
 	boolean shouldWriteCommitGraphWhenGc() {
 		return repo.getConfig().getBoolean(ConfigConstants.CONFIG_GC_SECTION,
@@ -1019,6 +1022,17 @@ public class GC {
 				DEFAULT_WRITE_COMMIT_GRAPH);
 	}
 
+	/**
+	 * If {@code true}, generates bloom filter in the commit-graph file.
+	 *
+	 * @return true if bloom filter should be written. Default is {@code false}.
+	 */
+	boolean shouldWriteBloomFilter() {
+		return repo.getConfig().getBoolean(ConfigConstants.CONFIG_GC_SECTION,
+				ConfigConstants.CONFIG_KEY_WRITE_CHANGED_PATHS,
+				DEFAULT_WRITE_BLOOM_FILTER);
+	}
+
 	private static boolean isHead(Ref ref) {
 		return ref.getName().startsWith(Constants.R_HEADS);
 	}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
index 621db89f66..7776b00625 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ConfigConstants.java
@@ -109,6 +109,7 @@ public final class ConfigConstants {
 
 	/**
 	 * The "fetch" section
+	 *
 	 * @since 3.3
 	 */
 	public static final String CONFIG_FETCH_SECTION = "fetch";
@@ -947,4 +948,25 @@ public final class ConfigConstants {
 	 * @since 5.13.2
 	 */
 	public static final String CONFIG_KEY_PRUNE_PRESERVED = "prunepreserved";
+
+	/**
+	 * The "commitGraph" section
+	 *
+	 * @since 6.7
+	 */
+	public static final String CONFIG_COMMIT_GRAPH_SECTION = "commitGraph";
+
+	/**
+	 * The "writeChangedPaths" key
+	 *
+	 * @since 6.7
+	 */
+	public static final String CONFIG_KEY_WRITE_CHANGED_PATHS = "writeChangedPaths";
+
+	/**
+	 * The "readChangedPaths" key
+	 *
+	 * @since 6.7
+	 */
+	public static final String CONFIG_KEY_READ_CHANGED_PATHS = "readChangedPaths";
 }