Reduce contention on PackFile.idx() function.
In case of concurrent pack file access, threads may wait on the idx()
function even for already open files. This happens especially with a
slow file system.
Performance numbers are listed in the bug report.
Bug: 543739
Change-Id: Iff328d347fa65ae07ecce3267d44184161248978
Signed-off-by: Juergen Denner <j.denner@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java
index d28c04f..3e5ef21 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java
@@ -139,7 +139,7 @@ public int compare(final PackFile a, final PackFile b) {
private byte[] packChecksum;
- private PackIndex loadedIdx;
+ private volatile PackIndex loadedIdx;
private PackReverseIndex reverseIdx;
@@ -174,35 +174,44 @@ public PackFile(final File packFile, int extensions) {
length = Long.MAX_VALUE;
}
- private synchronized PackIndex idx() throws IOException {
- if (loadedIdx == null) {
- if (invalid)
- throw new PackInvalidException(packFile);
+ private PackIndex idx() throws IOException {
+ PackIndex idx = loadedIdx;
+ if (idx == null) {
+ synchronized (this) {
+ idx = loadedIdx;
+ if (idx == null) {
+ if (invalid) {
+ throw new PackInvalidException(packFile);
+ }
+ try {
+ idx = PackIndex.open(extFile(INDEX));
- try {
- final PackIndex idx = PackIndex.open(extFile(INDEX));
-
- if (packChecksum == null) {
- packChecksum = idx.packChecksum;
- } else if (!Arrays.equals(packChecksum, idx.packChecksum)) {
- throw new PackMismatchException(MessageFormat.format(
- JGitText.get().packChecksumMismatch,
- packFile.getPath(),
- ObjectId.fromRaw(packChecksum).name(),
- ObjectId.fromRaw(idx.packChecksum).name()));
+ if (packChecksum == null) {
+ packChecksum = idx.packChecksum;
+ } else if (!Arrays.equals(packChecksum,
+ idx.packChecksum)) {
+ throw new PackMismatchException(MessageFormat
+ .format(JGitText.get().packChecksumMismatch,
+ packFile.getPath(),
+ ObjectId.fromRaw(packChecksum)
+ .name(),
+ ObjectId.fromRaw(idx.packChecksum)
+ .name()));
+ }
+ loadedIdx = idx;
+ } catch (InterruptedIOException e) {
+ // don't invalidate the pack, we are interrupted from
+ // another thread
+ throw e;
+ } catch (IOException e) {
+ invalid = true;
+ throw e;
+ }
}
- loadedIdx = idx;
- } catch (InterruptedIOException e) {
- // don't invalidate the pack, we are interrupted from another thread
- throw e;
- } catch (IOException e) {
- invalid = true;
- throw e;
}
}
- return loadedIdx;
+ return idx;
}
-
/** @return the File object which locates this pack on disk. */
public File getPackFile() {
return packFile;
