Merge branch 'stable-4.6'

* stable-4.6:
  Don't remove pack when FileNotFoundException is transient

Change-Id: I82941a98385cda27c89e1e6750b7b6db4e39f414
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

2 files changed, 38 insertions, 7 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectory.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectory.java
index 1aa71e5a59..00e39533b1 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectory.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectory.java
@@ -349,6 +349,7 @@ public class ObjectDirectory extends FileObjectDatabase {
 			for (PackFile p : pList.packs) {
 				try {
 					p.resolve(matches, id, RESOLVE_ABBREV_LIMIT);
+					p.resetTransientErrorCount();
 				} catch (IOException e) {
 					handlePackError(e, p);
 				}
@@ -430,6 +431,7 @@ public class ObjectDirectory extends FileObjectDatabase {
 				for (PackFile p : pList.packs) {
 					try {
 						ObjectLoader ldr = p.get(curs, objectId);
+						p.resetTransientErrorCount();
 						if (ldr != null)
 							return ldr;
 					} catch (PackMismatchException e) {
@@ -510,6 +512,7 @@ public class ObjectDirectory extends FileObjectDatabase {
 				for (PackFile p : pList.packs) {
 					try {
 						long len = p.getObjectSize(curs, id);
+						p.resetTransientErrorCount();
 						if (0 <= len)
 							return len;
 					} catch (PackMismatchException e) {
@@ -549,6 +552,7 @@ public class ObjectDirectory extends FileObjectDatabase {
 			for (final PackFile p : pList.packs) {
 				try {
 					LocalObjectRepresentation rep = p.representation(curs, otp);
+					p.resetTransientErrorCount();
 					if (rep != null)
 						packer.select(otp, rep);
 				} catch (PackMismatchException e) {
@@ -569,6 +573,8 @@ public class ObjectDirectory extends FileObjectDatabase {
 
 	private void handlePackError(IOException e, PackFile p) {
 		String warnTmpl = null;
+		int transientErrorCount = 0;
+		String errTmpl = JGitText.get().exceptionWhileReadingPack;
 		if ((e instanceof CorruptObjectException)
 				|| (e instanceof PackInvalidException)) {
 			warnTmpl = JGitText.get().corruptPack;
@@ -576,14 +582,17 @@ public class ObjectDirectory extends FileObjectDatabase {
 			removePack(p);
 		} else if (e instanceof FileNotFoundException) {
 			if (p.getPackFile().exists()) {
-				warnTmpl = JGitText.get().packInaccessible;
+				errTmpl = JGitText.get().packInaccessible;
+				transientErrorCount = p.incrementTransientErrorCount();
 			} else {
 				warnTmpl = JGitText.get().packWasDeleted;
+				removePack(p);
 			}
-			removePack(p);
 		} else if (FileUtils.isStaleFileHandleInCausalChain(e)) {
 			warnTmpl = JGitText.get().packHandleIsStale;
 			removePack(p);
+		} else {
+			transientErrorCount = p.incrementTransientErrorCount();
 		}
 		if (warnTmpl != null) {
 			if (LOG.isDebugEnabled()) {
@@ -594,14 +603,25 @@ public class ObjectDirectory extends FileObjectDatabase {
 						p.getPackFile().getAbsolutePath()));
 			}
 		} else {
-			// Don't remove the pack from the list, as the error may be
-			// transient.
-			LOG.error(MessageFormat.format(
-					JGitText.get().exceptionWhileReadingPack, p.getPackFile()
-							.getAbsolutePath()), e);
+			if (doLogExponentialBackoff(transientErrorCount)) {
+				// Don't remove the pack from the list, as the error may be
+				// transient.
+				LOG.error(MessageFormat.format(errTmpl,
+						p.getPackFile().getAbsolutePath()),
+						Integer.valueOf(transientErrorCount), e);
+			}
 		}
 	}
 
+	/**
+	 * @param n
+	 *            count of consecutive failures
+	 * @return @{code true} if i is a power of 2
+	 */
+	private boolean doLogExponentialBackoff(int n) {
+		return (n & (n - 1)) == 0;
+	}
+
 	@Override
 	InsertLooseObjectResult insertUnpackedObject(File tmp, ObjectId id,
 			boolean createDuplicate) throws IOException {
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 d90e2cf2bf..f4a77d2a2a 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
@@ -62,6 +62,7 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.zip.CRC32;
 import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
@@ -127,6 +128,8 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 
 	private boolean invalidBitmap;
 
+	private AtomicInteger transientErrorCount = new AtomicInteger();
+
 	private byte[] packChecksum;
 
 	private PackIndex loadedIdx;
@@ -571,6 +574,14 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 		invalid = true;
 	}
 
+	int incrementTransientErrorCount() {
+		return transientErrorCount.incrementAndGet();
+	}
+
+	void resetTransientErrorCount() {
+		transientErrorCount.set(0);
+	}
+
 	private void readFully(final long position, final byte[] dstbuf,
 			int dstoff, final int cnt, final WindowCursor curs)
 			throws IOException {