Add some javadocs and clarifications.

community/kernel/src/main/java/org/neo4j/graphdb/factory/GraphDatabaseSettings.java

@@ -206,9 +206,6 @@ public abstract class GraphDatabaseSettings
     @Description("The maximum time interval of a transaction within which it should be completed.")
     public static final Setting<Long> transaction_timeout = setting( "dbms.transaction.timeout", DURATION, "60s" );
 
-    @Description("The maximum time interval of a query within which it should be completed.")
-    public static final Setting<Long> statement_timeout = setting( "dbms.statement.timeout", DURATION, "10s" );
-
     @Description( "The maximum amount of time to wait for running transactions to complete before allowing "
                   + "initiated database shutdown to continue" )
     @Internal

community/kernel/src/main/java/org/neo4j/kernel/GraphDatabaseQueryService.java

@@ -37,13 +37,32 @@
 public interface GraphDatabaseQueryService
 {
     DependencyResolver getDependencyResolver();
+
     Node createNode();
+
     Node createNode( Label... labels );
-    Node getNodeById(long id);
-    Relationship getRelationshipById(long id);
 
+    Node getNodeById( long id );
+
+    Relationship getRelationshipById( long id );
+
+    /**
+     * Begin new internal transaction with with default timeout.
+     *
+     * @param type transaction type
+     * @param accessMode transaction access mode
+     * @return internal transaction
+     */
     InternalTransaction beginTransaction( KernelTransaction.Type type, AccessMode accessMode );
 
+    /**
+     * Begin new internal transaction with specified timeout in milliseconds.
+     *
+     * @param type transaction type
+     * @param accessMode transaction access mode
+     * @param timeout transaction timeout in milliseconds
+     * @return internal transaction
+     */
     InternalTransaction beginTransaction( KernelTransaction.Type type, AccessMode accessMode, long timeout );
 
     URL validateURLAccess( URL url ) throws URLAccessValidationError;

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

@@ -46,11 +46,11 @@ public interface KernelAPI
 
     /**
      * Creates and returns a new {@link KernelTransaction} capable of modifying the
-     * underlying graph.
+     * underlying graph with custom timeout in milliseconds.
      *
      * @param type the type of the new transaction: implicit (internally created) or explicit (created by the user)
      * @param accessMode transaction access mode
-     * @param timeout transaction timeout
+     * @param timeout transaction timeout in millisiseconds
      */
     KernelTransaction newTransaction( KernelTransaction.Type type, AccessMode accessMode, long timeout )
             throws TransactionFailureException;

community/kernel/src/main/java/org/neo4j/kernel/guard/Guard.java

@@ -21,6 +21,10 @@
 
 import org.neo4j.kernel.impl.api.KernelStatement;
 
+/**
+ * Guard that check entities for compatibility with some kind of guard criteria.
+ * As soon as entity do not satisfy that criteria {@link GuardException } will be thrown.
+ */
 public interface Guard
 {
     void check( KernelStatement statement );

community/kernel/src/main/java/org/neo4j/kernel/guard/TimeoutGuard.java

@@ -25,6 +25,10 @@
 import org.neo4j.kernel.impl.api.KernelTransactionImplementation;
 import org.neo4j.logging.Log;
 
+/**
+ * Guard that checks kernel transaction for timeout.
+ * As soon as transaction timeout time reached {@link GuardTimeoutException } will be thrown.
+ */
 public class TimeoutGuard implements Guard
 {
     private final Log log;

community/kernel/src/main/java/org/neo4j/kernel/impl/factory/GraphDatabaseFacade.java

@@ -149,7 +149,7 @@ public interface SPI
         KernelTransaction beginTransaction( KernelTransaction.Type type, AccessMode accessMode );
 
         /**
-         * Begin a new kernel transaction with specified timeout.
+         * Begin a new kernel transaction with specified timeout in milliseconds.
          * If a transaction is already associated to the current context
          * (meaning, non-null is returned from {@link #currentTransaction()}), this should fail.
          *

community/kernel/src/main/java/org/neo4j/kernel/impl/query/TransactionalContext.java

@@ -51,6 +51,10 @@ public interface TransactionalContext
 
     Statement statement();
 
+    /**
+     * Check that current context satisfy current execution guard.
+     * In case if guard criteria is not satisfied {@link org.neo4j.kernel.guard.GuardException} will be thrown.
+     */
     void check();
 
     TxStateHolder stateView();

community/kernel/src/test/java/org/neo4j/kernel/guard/TimeoutGuardTest.java

@@ -42,7 +42,6 @@
 public class TimeoutGuardTest extends KernelTransactionTestBase
 {
 
-    private static final long STATEMENT_TEST_TIMEOUT = 1000L;
     private AssertableLogProvider logProvider = new AssertableLogProvider( true );
 
     @Before
@@ -69,24 +68,7 @@ public void detectTimedTransaction()
     }
 
     @Test
-    public void detectTimedStatement()
-    {
-        long transactionTimeout = 100000L;
-        long overtime = 5L;
-        TimeoutGuard timeoutGuard = buildGuard( logProvider );
-        initClock();
-
-        KernelStatement kernelStatement = getKernelStatement( transactionTimeout );
-        clock.forward( STATEMENT_TEST_TIMEOUT + overtime, TimeUnit.MILLISECONDS );
-        String message = "Statement timeout. (Overtime: 5 ms).";
-
-        check( timeoutGuard, kernelStatement, overtime, message );
-
-        logProvider.assertContainsMessageContaining( message );
-    }
-
-    @Test
-    public void allowToProceedWhenStatementAndTransactionTimeoutNotReached()
+    public void allowToProceedWhenTransactionTimeoutNotReached()
     {
         long transactionTimeout = 100000L;
         long overtime = 5L;