Fix concurrent read / write issue in LockFile on Windows

LockFile.commit fails if another thread concurrently reads
the base file. The problem is fixed by retrying the rename
operation if it fails.

Change-Id: I6bb76ea7f2e6e90e3ddc45f9dd4d69bd1b6fa1eb
Bug: 308506
Signed-off-by: Jens Baumgart <jens.baumgart@sap.com>

1 files changed, 22 insertions, 8 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java b/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java
index cc10fad2b4..60238c3d8b 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java
@@ -67,6 +67,7 @@ import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectInserter;
 import org.eclipse.jgit.storage.file.LockFile;
+import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.MutableInteger;
 import org.eclipse.jgit.util.NB;
@@ -129,7 +130,7 @@ public class DirCache {
 	 *         memory).
 	 */
 	public static DirCache newInCore() {
-		return new DirCache(null);
+		return new DirCache(null, null);
 	}
 
 	/**
@@ -141,6 +142,9 @@ public class DirCache {
 	 *
 	 * @param indexLocation
 	 *            location of the index file on disk.
+	 * @param fs
+	 *            the file system abstraction which will be necessary to perform
+	 *            certain file system operations.
 	 * @return a cache representing the contents of the specified index file (if
 	 *         it exists) or an empty cache if the file does not exist.
 	 * @throws IOException
@@ -149,9 +153,9 @@ public class DirCache {
 	 *             the index file is using a format or extension that this
 	 *             library does not support.
 	 */
-	public static DirCache read(final File indexLocation)
+	public static DirCache read(final File indexLocation, final FS fs)
 			throws CorruptObjectException, IOException {
-		final DirCache c = new DirCache(indexLocation);
+		final DirCache c = new DirCache(indexLocation, fs);
 		c.read();
 		return c;
 	}
@@ -161,11 +165,14 @@ public class DirCache {
 	 * <p>
 	 * The new index will be locked and then read before it is returned to the
 	 * caller. Read failures are reported as exceptions and therefore prevent
-	 * the method from returning a partially populated index.  On read failure,
+	 * the method from returning a partially populated index. On read failure,
 	 * the lock is released.
 	 *
 	 * @param indexLocation
 	 *            location of the index file on disk.
+	 * @param fs
+	 *            the file system abstraction which will be necessary to perform
+	 *            certain file system operations.
 	 * @return a cache representing the contents of the specified index file (if
 	 *         it exists) or an empty cache if the file does not exist.
 	 * @throws IOException
@@ -175,9 +182,9 @@ public class DirCache {
 	 *             the index file is using a format or extension that this
 	 *             library does not support.
 	 */
-	public static DirCache lock(final File indexLocation)
+	public static DirCache lock(final File indexLocation, final FS fs)
 			throws CorruptObjectException, IOException {
-		final DirCache c = new DirCache(indexLocation);
+		final DirCache c = new DirCache(indexLocation, fs);
 		if (!c.lock())
 			throw new IOException(MessageFormat.format(JGitText.get().cannotLock, indexLocation));
 
@@ -215,6 +222,9 @@ public class DirCache {
 	/** Our active lock (if we hold it); null if we don't have it locked. */
 	private LockFile myLock;
 
+	/** file system abstraction **/
+	private final FS fs;
+
 	/**
 	 * Create a new in-core index representation.
 	 * <p>
@@ -223,9 +233,13 @@ public class DirCache {
 	 *
 	 * @param indexLocation
 	 *            location of the index file on disk.
+	 * @param fs
+	 *            the file system abstraction which will be necessary to perform
+	 *            certain file system operations.
 	 */
-	public DirCache(final File indexLocation) {
+	public DirCache(final File indexLocation, final FS fs) {
 		liveFile = indexLocation;
+		this.fs = fs;
 		clear();
 	}
 
@@ -429,7 +443,7 @@ public class DirCache {
 	public boolean lock() throws IOException {
 		if (liveFile == null)
 			throw new IOException(JGitText.get().dirCacheDoesNotHaveABackingFile);
-		final LockFile tmp = new LockFile(liveFile);
+		final LockFile tmp = new LockFile(liveFile, fs);
 		if (tmp.lock()) {
 			tmp.setNeedStatInformation(true);
 			myLock = tmp;