Merge branch 'stable-5.9' into stable-5.10

* stable-5.9:
  Prepare 5.1.17-SNAPSHOT builds
  JGit v5.1.16.202106041830-r
  BatchRefUpdate: Skip saving conflicting ref names and prefixes in memory
  BatchRefUpdateTest: Accurately assert RefsChangedEvent(s) fired
  Optimize RefDirectory.isNameConflicting()
  Update bazlets and bazel version

Change-Id: Ib1299564a4cfb9c01f422d7ada05fcfac29700f8

2 files changed, 16 insertions, 73 deletions

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 7d108feae9..17a910008c 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
@@ -244,47 +244,18 @@ public class RefDirectory extends RefDatabase {
 	/** {@inheritDoc} */
 	@Override
 	public boolean isNameConflicting(String name) throws IOException {
-		RefList<Ref> packed = getPackedRefs();
-		RefList<LooseRef> loose = getLooseRefs();
-
 		// Cannot be nested within an existing reference.
 		int lastSlash = name.lastIndexOf('/');
 		while (0 < lastSlash) {
 			String needle = name.substring(0, lastSlash);
-			if (loose.contains(needle) || packed.contains(needle))
+			if (exactRef(needle) != null) {
 				return true;
+			}
 			lastSlash = name.lastIndexOf('/', lastSlash - 1);
 		}
 
 		// Cannot be the container of an existing reference.
-		String prefix = name + '/';
-		int idx;
-
-		idx = -(packed.find(prefix) + 1);
-		if (idx < packed.size() && packed.get(idx).getName().startsWith(prefix))
-			return true;
-
-		idx = -(loose.find(prefix) + 1);
-		if (idx < loose.size() && loose.get(idx).getName().startsWith(prefix))
-			return true;
-
-		return false;
-	}
-
-	private RefList<LooseRef> getLooseRefs() {
-		final RefList<LooseRef> oldLoose = looseRefs.get();
-
-		LooseScanner scan = new LooseScanner(oldLoose);
-		scan.scan(ALL);
-
-		RefList<LooseRef> loose;
-		if (scan.newLoose != null) {
-			loose = scan.newLoose.toRefList();
-			if (looseRefs.compareAndSet(oldLoose, loose))
-				modCnt.incrementAndGet();
-		} else
-			loose = oldLoose;
-		return loose;
+		return !getRefsByPrefix(name + '/').isEmpty();
 	}
 
 	@Nullable
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchRefUpdate.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchRefUpdate.java
index 06009f885d..ef1379a238 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchRefUpdate.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/BatchRefUpdate.java
@@ -13,7 +13,6 @@ package org.eclipse.jgit.lib;
 
 import static org.eclipse.jgit.transport.ReceiveCommand.Result.NOT_ATTEMPTED;
 import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_OTHER_REASON;
-import static java.util.stream.Collectors.toCollection;
 
 import java.io.IOException;
 import java.text.MessageFormat;
@@ -29,7 +28,6 @@ import java.util.concurrent.TimeoutException;
 import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.internal.JGitText;
-import org.eclipse.jgit.lib.RefUpdate.Result;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.transport.PushCertificate;
 import org.eclipse.jgit.transport.ReceiveCommand;
@@ -495,42 +493,24 @@ public class BatchRefUpdate {
 			}
 		}
 		if (!commands2.isEmpty()) {
-			// What part of the name space is already taken
-			Collection<String> takenNames = refdb.getRefs().stream()
-					.map(Ref::getName)
-					.collect(toCollection(HashSet::new));
-			Collection<String> takenPrefixes = getTakenPrefixes(takenNames);
-
-			// Now to the update that may require more room in the name space
+			// Perform updates that may require more room in the name space
 			for (ReceiveCommand cmd : commands2) {
 				try {
 					if (cmd.getResult() == NOT_ATTEMPTED) {
 						cmd.updateType(walk);
 						RefUpdate ru = newUpdate(cmd);
-						SWITCH: switch (cmd.getType()) {
-						case DELETE:
-							// Performed in the first phase
-							break;
-						case UPDATE:
-						case UPDATE_NONFASTFORWARD:
-							RefUpdate ruu = newUpdate(cmd);
-							cmd.setResult(ruu.update(walk));
-							break;
-						case CREATE:
-							for (String prefix : getPrefixes(cmd.getRefName())) {
-								if (takenNames.contains(prefix)) {
-									cmd.setResult(Result.LOCK_FAILURE);
-									break SWITCH;
-								}
-							}
-							if (takenPrefixes.contains(cmd.getRefName())) {
-								cmd.setResult(Result.LOCK_FAILURE);
-								break SWITCH;
-							}
-							ru.setCheckConflicting(false);
-							takenPrefixes.addAll(getPrefixes(cmd.getRefName()));
-							takenNames.add(cmd.getRefName());
-							cmd.setResult(ru.update(walk));
+						switch (cmd.getType()) {
+							case DELETE:
+								// Performed in the first phase
+								break;
+							case UPDATE:
+							case UPDATE_NONFASTFORWARD:
+								RefUpdate ruu = newUpdate(cmd);
+								cmd.setResult(ruu.update(walk));
+								break;
+							case CREATE:
+								cmd.setResult(ru.update(walk));
+								break;
 						}
 					}
 				} catch (IOException err) {
@@ -602,14 +582,6 @@ public class BatchRefUpdate {
 		execute(walk, monitor, null);
 	}
 
-	private static Collection<String> getTakenPrefixes(Collection<String> names) {
-		Collection<String> ref = new HashSet<>();
-		for (String name : names) {
-			addPrefixesTo(name, ref);
-		}
-		return ref;
-	}
-
 	/**
 	 * Get all path prefixes of a ref name.
 	 *