Re: [JGIT PATCH 1/2] Improve end-of-file detection in DirCache
torsdag 09 april 2009 17:28:18 skrev "Shawn O. Pearce" <spearce@spearce.org>:
Show 18 quoted lines
> When reading from a BufferInputStream attached to a FileInputStream
> the available() method seems to return the number of unread bytes
> in the buffer plus the unread number of bytes in the file. There is
> no guarantee for this behavior, so we can't rely on it.
>
> Instead we read the expected 20 byte SHA1 trailer into a temporary
> buffer, and then poll for a remaining byte. If another byte is
> still present in the input stream it indicates that there is more
> than 20 bytes worth of data remaining, which means an extension
> must be available at the current position. If there is in fact
> an extension we put back the 21 bytes we read and proceed to do
> an 8 byte read for the extension header.
>
> This relies on BufferInputStream's ability to buffer at least 21
> bytes of data, and put them all back in the event that we found
> an extension. This is a much more common usage of the stream API
> and is something we can rely on working correctly all of the time,
> on any standard library implementation.
Much better. Here's a regression test, fails before, but not after.
-- robin
>From b6561578a5ff48309f69a8d442cf47ec1b51bc49 Mon Sep 17 00:00:00 2001
From: Robin Rosenberg <robin.rosenberg@dewire.com>
Date: Fri, 10 Apr 2009 04:16:31 +0200
Subject: [EGIT PATCH] Test case for the DirCache reading code.
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
---
.../spearce/jgit/dircache/DirCacheTreeTest.java | 33 ++++++++++++++++++++
1 files changed, 33 insertions(+), 0 deletions(-)
diff --git a/org.spearce.jgit.test/tst/org/spearce/jgit/dircache/DirCacheTreeTest.java b/org.spearce.jgit.test/tst/org/spearce/jgit/dircache/DirCacheTreeTest.java
index b37095d..aca0b90 100644
--- a/org.spearce.jgit.test/tst/org/spearce/jgit/dircache/DirCacheTreeTest.java
+++ b/org.spearce.jgit.test/tst/org/spearce/jgit/dircache/DirCacheTreeTest.java
@@ -37,6 +37,9 @@
package org.spearce.jgit.dircache;
+import java.io.IOException;
+
+import org.spearce.jgit.errors.CorruptObjectException;
import org.spearce.jgit.lib.RepositoryTestCase;
public class DirCacheTreeTest extends RepositoryTestCase {
@@ -147,4 +150,34 @@ public void testTwoLevelSubtree() throws Exception {
assertEquals(acLast - acFirst + 1, acTree.getEntrySpan());
assertFalse(acTree.isValid());
}
+
+ /**
+ * We had bugs related to buffer size in the DirCache. This test creates an
+ * index larger than the default BufferedInputStream buffer size. This made
+ * the DirCache unable to read the extensions when index size exceeded the
+ * buffer size (in some cases at least).
+ *
+ * @throws CorruptObjectException
+ * @throws IOException
+ */
+ public void testWriteReadTree() throws CorruptObjectException, IOException {
+ final DirCache dc = DirCache.lock(db);
+
+ final String A = String.format("a%2000s", "a");
+ final String B = String.format("b%2000s", "b");
+ final String[] paths = { A + ".", A + "." + B, A + "/" + B, A + "0" + B };
+ final DirCacheEntry[] ents = new DirCacheEntry[paths.length];
+ for (int i = 0; i < paths.length; i++)
+ ents[i] = new DirCacheEntry(paths[i]);
+
+ final DirCacheBuilder b = dc.builder();
+ for (int i = 0; i < ents.length; i++)
+ b.add(ents[i]);
+
+ b.commit();
+ DirCache read = DirCache.read(db);
+
+ assertEquals(paths.length, read.getEntryCount());
+ assertEquals(1, read.getCacheTree(true).getChildCount());
+ }
}
Robin Rosenberg <robin.rosenberg.lists@dewire.com>