From a0a52897ed3fb66ff8a7e1737bf854042f77f0ce Mon Sep 17 00:00:00 2001
From: "Shawn O. Pearce" <spearce@spearce.org>
Date: Mon, 26 Apr 2010 14:42:40 -0700
Subject: [PATCH] Favor earlier PackFile instances over later duplicates
There is a potential race condition during insertPack that can lead
to us having the same pack file open twice in the same directory.
A different thread can miss an object on disk, and trigger a scan
of the directory, and notice the pack that was put in by IndexPack.
So the pack winds up in the newly created PackList.
The IndexPack thread then wakes up and finishes its insertPack by
creating a new PackFile and inserting it into position 0 of the list.
We now have the same pack listed twice.
Readers will favor the earlier PackFile instance, because its the
first one they come across as they iterate through the list.
Keep that earlier one when we scan the pack directory again, as
this will avoid needing to purge out all of the windows that may
have been cached.
Of course we should also fix that race condition, but this block
was taking the wrong resolution if this error ever shows up, so
lets first fix the block to use a more sane resolution.
Change-Id: I0d339b9fd1dd8012e8fe5a564b893c0f69109e28
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
.../src/org/eclipse/jgit/lib/ObjectDirectory.java | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectDirectory.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectDirectory.java
index a8d6dda06..8f96ef5f0 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectDirectory.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectDirectory.java
@@ -416,10 +416,11 @@ private static Map<String, PackFile> reuseMap(final PackList old) {
// This should never occur. It should be impossible for us
// to have two pack files with the same name, as all of them
// came out of the same directory. If it does, we promised to
- // close any PackFiles we did not reuse, so close the one we
- // just evicted out of the reuse map.
+ // close any PackFiles we did not reuse, so close the second,
+ // readers are likely to be actively using the first.
//
- prior.close();
+ forReuse.put(prior.getPackFile().getName(), prior);
+ p.close();
}
}
return forReuse;
--
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