Added status code for AcquireLockTimeoutException

to better help a client, i.e. a driver, to classify the error for end users.

AcquireLockTimeoutException is mainly used in CE to indicate that we cannot grab a lock on a `Leader`. There is a chance that we will get this exception if a leadership switch happened after we've checked the the server where we are going to get the lock is the `Leader`, but before we really start to take a lock.

community/common/src/main/java/org/neo4j/kernel/api/exceptions/Status.java

@@ -185,7 +185,9 @@ enum Transaction implements Status
         LockClientStopped( TransientError,
                 "Transaction terminated, no more locks can be acquired." ),
         Terminated( TransientError,
-                "Explicitly terminated by the user." );
+                "Explicitly terminated by the user." ),
+        Interrupted( TransientError,
+                "Interrupted while waiting." );
 
         private final Code code;
 

community/kernel/src/main/java/org/neo4j/kernel/impl/util/concurrent/LockWaitStrategies.java

@@ -22,6 +22,8 @@
 import org.neo4j.storageengine.api.lock.AcquireLockTimeoutException;
 import org.neo4j.storageengine.api.lock.WaitStrategy;
 
+import static org.neo4j.kernel.api.exceptions.Status.Transaction.Interrupted;
+
 public enum LockWaitStrategies implements WaitStrategy<AcquireLockTimeoutException>
 {
     SPIN
@@ -73,7 +75,7 @@ public void apply( long iteration ) throws AcquireLockTimeoutException
             catch(InterruptedException e)
             {
                 Thread.interrupted();
-                throw new AcquireLockTimeoutException( e , "Interrupted while waiting.");
+                throw new AcquireLockTimeoutException( e , "Interrupted while waiting.", Interrupted );
             }
         }
     };

community/kernel/src/main/java/org/neo4j/storageengine/api/lock/AcquireLockTimeoutException.java

@@ -19,19 +19,31 @@
  */
 package org.neo4j.storageengine.api.lock;
 
+import org.neo4j.kernel.api.exceptions.Status;
+
 /**
  * Acquiring a lock failed. This is a runtime exception now to ease the transition from the old lock interface, but
  * it should be made into a {@link org.neo4j.kernel.api.exceptions.KernelException} asap.
  */
-public class AcquireLockTimeoutException extends RuntimeException
+public class AcquireLockTimeoutException extends RuntimeException implements Status.HasStatus
 {
-    public AcquireLockTimeoutException( Throwable cause, String message, Object... parameters )
+    private final Status statusCode;
+
+    public AcquireLockTimeoutException( Throwable cause, String message, Status statusCode )
     {
-        super( String.format(message, parameters), cause );
+        super( message, cause );
+        this.statusCode = statusCode;
     }
 
-    public AcquireLockTimeoutException( String message )
+    public AcquireLockTimeoutException( String message, Status statusCode )
     {
         super( message );
+        this.statusCode = statusCode;
+    }
+
+    @Override
+    public Status status()
+    {
+        return statusCode;
     }
 }

enterprise/core-edge/src/main/java/org/neo4j/coreedge/core/state/machines/locks/LeaderOnlyLockManager.java

@@ -21,18 +21,20 @@
 
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
-import java.util.concurrent.TimeoutException;
 
 import org.neo4j.coreedge.core.consensus.LeaderLocator;
 import org.neo4j.coreedge.core.consensus.NoLeaderFoundException;
 import org.neo4j.coreedge.core.replication.Replicator;
 import org.neo4j.coreedge.core.state.machines.tx.ReplicatedTransactionStateMachine;
 import org.neo4j.coreedge.identity.MemberId;
+import org.neo4j.kernel.api.exceptions.Status;
 import org.neo4j.kernel.impl.locking.Locks;
 import org.neo4j.storageengine.api.lock.AcquireLockTimeoutException;
 import org.neo4j.storageengine.api.lock.ResourceType;
 
-import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static org.neo4j.kernel.api.exceptions.Status.Cluster.NoLeaderAvailable;
+import static org.neo4j.kernel.api.exceptions.Status.Cluster.NotALeader;
+import static org.neo4j.kernel.api.exceptions.Status.Transaction.Interrupted;
 
 /**
  * Each member of the cluster uses its own {@link LeaderOnlyLockManager} which wraps a local {@link Locks} manager.
@@ -109,7 +111,7 @@ private synchronized int acquireTokenOrThrow()
         }
         catch ( InterruptedException e )
         {
-            throw new AcquireLockTimeoutException( e, "Interrupted acquiring token." );
+            throw new AcquireLockTimeoutException( e, "Interrupted acquiring token.", Interrupted );
         }
 
         try
@@ -121,17 +123,18 @@ private synchronized int acquireTokenOrThrow()
             }
             else
             {
-                throw new AcquireLockTimeoutException( "Failed to acquire lock token. Was taken by another candidate." );
+                throw new AcquireLockTimeoutException( "Failed to acquire lock token. Was taken by another candidate.",
+                        NotALeader);
             }
         }
         catch ( ExecutionException e )
         {
-            throw new AcquireLockTimeoutException( e, "Failed to acquire lock token." );
+            throw new AcquireLockTimeoutException( e, "Failed to acquire lock token.", NotALeader );
         }
         catch ( InterruptedException e )
         {
             Thread.currentThread().interrupt();
-            throw new AcquireLockTimeoutException( e, "Failed to acquire lock token." );
+            throw new AcquireLockTimeoutException( e, "Failed to acquire lock token.", Interrupted );
         }
     }
 
@@ -145,12 +148,12 @@ private void ensureLeader()
         }
         catch ( NoLeaderFoundException e )
         {
-            throw new AcquireLockTimeoutException( e, "Could not acquire lock token." );
+            throw new AcquireLockTimeoutException( e, "Could not acquire lock token.", NoLeaderAvailable );
         }
 
         if ( !leader.equals( myself ) )
         {
-            throw new AcquireLockTimeoutException( LOCK_NOT_ON_LEADER_ERROR_MESSAGE );
+            throw new AcquireLockTimeoutException( LOCK_NOT_ON_LEADER_ERROR_MESSAGE, NotALeader );
         }
     }
 
@@ -195,7 +198,7 @@ private void ensureHoldingToken()
             }
             else if ( lockTokenId != lockTokenStateMachine.currentToken().id() )
             {
-                throw new AcquireLockTimeoutException( "Local instance lost lock token." );
+                throw new AcquireLockTimeoutException( "Local instance lost lock token.", NotALeader );
             }
         }