From: Ivan Frade <ifrade@google.com>
Date: Tue, 11 Apr 2023 19:50:52 +0000 (-0700)
Subject: DfsPackFile: Extract block aligment code
X-Git-Tag: v6.6.0.202305031100-m2~34
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=89f7378da5ba061f0662d0e7945584d6230876b3;p=jgit.git

DfsPackFile: Extract block aligment code

Loading of pack, bitmap and commit-graph copy the same code to adjust
the input stream buffering.

Extract to a common function. Besides reusing the code, the name hints
what it is doing.

This block aligment seems unnecessary as the reading is from storage
not dfs cache. The channel probably knows better. Left a TODO because
I don't know the original intention.

Change-Id: I18b77ae8189830fcd4d5932b6b5823b693ed6090
---

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
index 411777c7ad..c745b8e6ee 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
@@ -1042,15 +1042,7 @@ public final class DfsPackFile extends BlockBasedFile {
 			ctx.stats.readIdx++;
 			long start = System.nanoTime();
 			try (ReadableChannel rc = ctx.db.openFile(desc, INDEX)) {
-				InputStream in = Channels.newInputStream(rc);
-				int wantSize = 8192;
-				int bs = rc.blockSize();
-				if (0 < bs && bs < wantSize) {
-					bs = (wantSize / bs) * bs;
-				} else if (bs <= 0) {
-					bs = wantSize;
-				}
-				PackIndex idx = PackIndex.read(new BufferedInputStream(in, bs));
+				PackIndex idx = PackIndex.read(alignTo8kBlocks(rc));
 				ctx.stats.readIdxBytes += rc.position();
 				index = idx;
 				return new DfsBlockCache.Ref<>(
@@ -1094,17 +1086,8 @@ public final class DfsPackFile extends BlockBasedFile {
 			long size;
 			PackBitmapIndex bmidx;
 			try {
-				InputStream in = Channels.newInputStream(rc);
-				int wantSize = 8192;
-				int bs = rc.blockSize();
-				if (0 < bs && bs < wantSize) {
-					bs = (wantSize / bs) * bs;
-				} else if (bs <= 0) {
-					bs = wantSize;
-				}
-				in = new BufferedInputStream(in, bs);
-				bmidx = PackBitmapIndex.read(in, () -> idx(ctx),
-						() -> getReverseIdx(ctx),
+				bmidx = PackBitmapIndex.read(alignTo8kBlocks(rc),
+						() -> idx(ctx), () -> getReverseIdx(ctx),
 						ctx.getOptions().shouldLoadRevIndexInParallel());
 			} finally {
 				size = rc.position();
@@ -1133,16 +1116,7 @@ public final class DfsPackFile extends BlockBasedFile {
 			long size;
 			CommitGraph cg;
 			try {
-				InputStream in = Channels.newInputStream(rc);
-				int wantSize = 8192;
-				int bs = rc.blockSize();
-				if (0 < bs && bs < wantSize) {
-					bs = (wantSize / bs) * bs;
-				} else if (bs <= 0) {
-					bs = wantSize;
-				}
-				in = new BufferedInputStream(in, bs);
-				cg = CommitGraphLoader.read(in);
+				cg = CommitGraphLoader.read(alignTo8kBlocks(rc));
 			} finally {
 				size = rc.position();
 				ctx.stats.readCommitGraphBytes += size;
@@ -1157,4 +1131,19 @@ public final class DfsPackFile extends BlockBasedFile {
 					e);
 		}
 	}
+
+	private static InputStream alignTo8kBlocks(ReadableChannel rc) {
+		// TODO(ifrade): This is not reading from DFS, so the channel should
+		// know better the right blocksize. I don't know why this was done in
+		// the first place, verify and remove if not needed.
+		InputStream in = Channels.newInputStream(rc);
+		int wantSize = 8192;
+		int bs = rc.blockSize();
+		if (0 < bs && bs < wantSize) {
+			bs = (wantSize / bs) * bs;
+		} else if (bs <= 0) {
+			bs = wantSize;
+		}
+		return new BufferedInputStream(in, bs);
+	}
 }