speeds up fate lock acquisition

core/src/main/java/org/apache/accumulo/core/fate/zookeeper/FateLock.java

@@ -47,7 +47,7 @@
 public class FateLock implements QueueLock {
   private static final Logger log = LoggerFactory.getLogger(FateLock.class);
 
-  private static final String PREFIX = "flock#";
+  static final String PREFIX = "flock#";
 
   private final ZooReaderWriter zoo;
   private final FateLockPath path;
@@ -78,11 +78,11 @@ public static class FateLockNode implements Comparable<FateLockNode> {
     public final long sequence;
     public final String lockData;
 
-    private FateLockNode(String nodeName) {
+    FateLockNode(String nodeName) {
       int len = nodeName.length();
       Preconditions.checkArgument(nodeName.startsWith(PREFIX) && nodeName.charAt(len - 11) == '#',
           "Illegal node name %s", nodeName);
-      sequence = Long.parseLong(nodeName.substring(len - 10));
+      sequence = Long.parseUnsignedLong(nodeName.substring(len - 10), 10);
       lockData = nodeName.substring(PREFIX.length(), len - 11);
     }
 

core/src/test/java/org/apache/accumulo/core/fate/zookeeper/FateLockTest.java

@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.accumulo.core.fate.zookeeper;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.UUID;
+
+import org.apache.accumulo.core.fate.FateId;
+import org.apache.accumulo.core.fate.FateInstanceType;
+import org.junit.jupiter.api.Test;
+
+public class FateLockTest {
+
+  @Test
+  public void testParsing() {
+    var fateId = FateId.from(FateInstanceType.USER, UUID.randomUUID());
+    // ZooKeeper docs state that sequence numbers are formatted using %010d
+    var lockNode = new FateLock.FateLockNode(
+        FateLock.PREFIX + fateId.canonical() + "#" + String.format("%010d", 40));
+    assertEquals(40, lockNode.sequence);
+    assertEquals(fateId.canonical(), lockNode.lockData);
+
+    assertThrows(IllegalArgumentException.class,
+        () -> new FateLock.FateLockNode(fateId.canonical() + "#" + String.format("%010d", 40)));
+    assertThrows(IllegalArgumentException.class, () -> new FateLock.FateLockNode(
+        FateLock.PREFIX + fateId.canonical() + "#" + String.format("%d", 40)));
+    assertThrows(IllegalArgumentException.class, () -> new FateLock.FateLockNode(
+        FateLock.PREFIX + fateId.canonical() + "#" + String.format("%09d", 40)));
+    assertThrows(IllegalArgumentException.class, () -> new FateLock.FateLockNode(
+        FateLock.PREFIX + fateId.canonical() + "#" + String.format("%011d", 40)));
+    assertThrows(IllegalArgumentException.class,
+        () -> new FateLock.FateLockNode(FateLock.PREFIX + fateId.canonical() + "#abc"));
+    assertThrows(IllegalArgumentException.class, () -> new FateLock.FateLockNode(
+        FateLock.PREFIX + fateId.canonical() + String.format("%010d", 40)));
+
+    // ZooKeeper docs state that sequence numbers can roll and become negative. The FateLock code
+    // does not support this, so make sure it fails if this happens.
+    for (int i : new int[] {Integer.MIN_VALUE, Integer.MIN_VALUE / 2, Integer.MIN_VALUE / 10,
+        Integer.MIN_VALUE / 1000, -40}) {
+      assertThrows(IllegalArgumentException.class, () -> new FateLock.FateLockNode(
+          FateLock.PREFIX + fateId.canonical() + "#" + String.format("%010d", i)));
+    }
+
+    assertThrows(IllegalArgumentException.class, () -> new FateLock.FateLockNode(
+        FateLock.PREFIX + fateId.canonical() + "#" + String.format("%d", -40)));
+  }
+}