Use Optional<String> to represent usernames for query registration pu…

…rposes

community/kernel/src/main/java/org/neo4j/kernel/api/ExecutingQuery.java

@@ -20,6 +20,7 @@
 package org.neo4j.kernel.api;
 
 import java.util.Map;
+import java.util.Optional;
 
 import static java.lang.String.format;
 
@@ -30,21 +31,21 @@ public class ExecutingQuery
 {
     private final long queryId;
 
-    private final String username;
+    private final Optional<String> username;
     private final String queryText;
     private final Map<String, Object> queryParameters;
     private final long startTime;
 
     public ExecutingQuery(
         long queryId,
-        String userNameOrNull,
+        Optional<String> username,
         String queryText,
         Map<String,Object> queryParameters,
         long startTime
     )
     {
         this.queryId = queryId;
-        this.username = userNameOrNull;
+        this.username = username;
         this.queryText = queryText;
         this.queryParameters = queryParameters;
         this.startTime = startTime;
@@ -79,7 +80,7 @@ public long kernelQueryId()
         return queryId;
     }
 
-    public String username()
+    public Optional<String> username()
     {
         return username;
     }

community/kernel/src/main/java/org/neo4j/kernel/impl/api/KernelStatement.java

@@ -19,6 +19,8 @@
  */
 package org.neo4j.kernel.impl.api;
 
+import java.util.Optional;
+
 import org.neo4j.graphdb.NotInTransactionException;
 import org.neo4j.graphdb.TransactionTerminatedException;
 import org.neo4j.kernel.api.DataWriteOperations;
@@ -203,10 +205,10 @@ final void forceClose()
         }
     }
 
-    final String username()
+    final Optional<String> username()
     {
         AccessMode mode = transaction.mode();
-        return ( mode instanceof AuthSubject ) ? ((AuthSubject) mode).username() : null;
+        return ( mode instanceof AuthSubject ) ? Optional.of( ((AuthSubject) mode).username() ) : Optional.empty();
     }
 
     final ExecutingQueryList executingQueryList()

community/kernel/src/main/java/org/neo4j/kernel/impl/api/StackingQueryRegistrationOperations.java

@@ -21,6 +21,7 @@
 
 import java.time.Clock;
 import java.util.Map;
+import java.util.Optional;
 import java.util.stream.Stream;
 
 import org.neo4j.kernel.api.ExecutingQuery;

community/kernel/src/test/java/org/neo4j/kernel/impl/api/ExecutingQueryListTest.java

@@ -23,6 +23,7 @@
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 import org.neo4j.kernel.api.ExecutingQuery;
@@ -97,6 +98,6 @@ public void removingQueryInTheMiddleKeepsOrder()
 
     private ExecutingQuery createExecutingQuery( int queryId, String query )
     {
-        return new ExecutingQuery( queryId, "me", query, Collections.emptyMap(), 10 );
+        return new ExecutingQuery( queryId, Optional.of( "me" ), query, Collections.emptyMap(), 10 );
     }
 }

enterprise/kernel/src/main/java/org/neo4j/kernel/enterprise/builtinprocs/BuiltInProcedures.java

@@ -26,6 +26,7 @@
 import java.time.ZoneId;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -138,7 +139,7 @@ public Stream<QueryStatusResult> listQueries() throws InvalidArgumentsException,
                 .activeTransactions()
                 .stream()
                 .flatMap( KernelTransactionHandle::executingQueries )
-                .filter( ( query ) -> isAdminEnterpriseAuthSubject() || authSubject.hasUsername( query.username() ) )
+                .filter( ( query ) -> isAdminEnterpriseAuthSubject() || query.username().map( authSubject::hasUsername ).orElse( false ) )
                 .map( catchThrown( InvalidArgumentsException.class, this::queryStatusResult ) );
         }
         catch ( UncaughtCheckedException uncaught )
@@ -212,7 +213,7 @@ private QueryTerminationResult killQueryTransaction( Pair<KernelTransactionHandl
             throws InvalidArgumentsException
     {
         ExecutingQuery query = pair.other();
-        if ( isAdminEnterpriseAuthSubject() || authSubject.hasUsername( query.username() ) )
+        if ( isAdminEnterpriseAuthSubject() || query.username().map( authSubject::hasUsername ).orElse( false ) )
         {
             pair.first().markForTermination( Status.Transaction.Terminated );
             return new QueryTerminationResult( queryId( query.kernelQueryId() ), query.username() );
@@ -232,29 +233,22 @@ private KernelTransactions getKernelTransactions()
 
     private Stream<TransactionTerminationResult> terminateTransactionsForValidUser( String username )
     {
-        long terminatedCount = 0;
-        for ( KernelTransactionHandle tx : getActiveTransactions() )
-        {
-            if ( getUsernameFromAccessMode( tx.mode() ).equals( username ) && !tx.isUnderlyingTransaction( this.tx ) )
-            {
-                boolean marked = tx.markForTermination( Status.Transaction.Terminated );
-                if ( marked )
-                {
-                    terminatedCount++;
-                }
-            }
-        }
+        long terminatedCount = getActiveTransactions()
+            .stream()
+            .filter( tx -> getUsernameFromAccessMode( tx.mode() ).equals( username ) && !tx.isUnderlyingTransaction( this.tx ) )
+            .map( tx -> tx.markForTermination( Status.Transaction.Terminated ) )
+            .filter( marked -> marked )
+            .count();
         return Stream.of( new TransactionTerminationResult( username, terminatedCount ) );
     }
 
     private Stream<ConnectionResult> terminateConnectionsForValidUser( String username )
     {
-        Long killCount = 0L;
-        for ( ManagedBoltStateMachine connection : getBoltConnectionTracker().getActiveConnections( username ) )
-        {
-            connection.terminate();
-            killCount += 1;
-        }
+        Long killCount = getBoltConnectionTracker()
+            .getActiveConnections( username )
+            .stream()
+            .map( conn -> { conn.terminate(); return true; } )
+            .count();
         return Stream.of( new ConnectionResult( username, killCount ) );
     }
 
@@ -337,6 +331,8 @@ private QueryStatusResult queryStatusResult( ExecutingQuery q ) throws InvalidAr
         );
     }
 
+    private static String UNAVAILABLE_USERNAME = "<unavailable>";
+
     public static class QueryStatusResult
     {
         public final String queryId;
@@ -347,11 +343,11 @@ public static class QueryStatusResult
         public final String startTime;
         public final String elapsedTime;
 
-        QueryStatusResult( QueryId queryId, String username, String query, Map<String,Object> parameters,
+        QueryStatusResult( QueryId queryId, Optional<String> username, String query, Map<String,Object> parameters,
                 long startTime, long elapsedTime )
         {
             this.queryId = queryId.toString();
-            this.username = username;
+            this.username = username.orElse( UNAVAILABLE_USERNAME );
             this.query = query;
             this.parameters = parameters;
             this.startTime = formatTime( startTime );
@@ -371,10 +367,10 @@ public static class QueryTerminationResult
         public final String queryId;
         public final String username;
 
-        public QueryTerminationResult( QueryId queryId, String username )
+        public QueryTerminationResult( QueryId queryId, Optional<String> username )
         {
             this.queryId = queryId.toString();
-            this.username = username;
+            this.username = username.orElse( UNAVAILABLE_USERNAME );
         }
     }