From f829f5f838e0f9c17373ea6cb3407976a8f395ff Mon Sep 17 00:00:00 2001 From: Kaushik Lingarkar Date: Mon, 29 Nov 2021 12:14:56 -0800 Subject: [PATCH] RefDirectory.scanRef: Re-use file existence check done in snapshot creation Return immediately in scanRef if the loose ref was identified as missing when a snapshot was attempted for the ref. This will help performance of scanRef when the ref is packed but has a corresponding empty dir in 'refs/'. For example, consider the case where we create 50k sharded refs in a new namespace called 'new-refs' using an atomic 'BatchRefUpdate'. The refs are named like 'refs/new-refs/01/1/1', 'refs/new-refs/01/1/2', 'refs/new-refs/01/1/3' and so on. After the refs are created, the 'new-refs' namespace looks like below: $ find refs/new-refs -type f | wc -l 0 $ find refs/new-refs -type d | wc -l 5101 At this point, an 'exactRef' call on each of the 50k refs without this change takes ~2.5s, where as with this change it takes ~1.5s. Change-Id: I926bc41b9ae89a1a792b1b5ec9a17b05271c906b Signed-off-by: Kaushik Lingarkar --- .../eclipse/jgit/internal/storage/file/FileSnapshot.java | 9 +++++++++ .../eclipse/jgit/internal/storage/file/RefDirectory.java | 4 ++++ 2 files changed, 13 insertions(+) diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileSnapshot.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileSnapshot.java index 487ae0601..654e98d81 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileSnapshot.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/FileSnapshot.java @@ -439,6 +439,15 @@ public boolean equals(Object obj) { return equals(other); } + /** + * Check if the file exists + * + * @return true if the file exists + */ + public boolean fileExists() { + return !MISSING_FILEKEY.equals(this.fileKey); + } + /** {@inheritDoc} */ @Override public int hashCode() { diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java index f7a52a54b..c15e26cd4 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/RefDirectory.java @@ -1103,6 +1103,10 @@ LooseRef scanRef(LooseRef ref, String name) throws IOException { final int limit = 4096; final byte[] buf; FileSnapshot otherSnapshot = FileSnapshot.save(path); + if (!otherSnapshot.fileExists()) { + return null; + } + try { buf = IO.readSome(path, limit); } catch (FileNotFoundException noFile) {