Cleanup, javadocs

community/common/src/main/java/org/neo4j/time/Clocks.java

@@ -22,27 +22,54 @@
 import java.time.Clock;
 import java.util.concurrent.TimeUnit;
 
+/**
+ * This class consists of {@code static} utility methods for operating
+ * on clocks. These utilities include factory methods for different type of clocks.
+ */
 public class Clocks
 {
     private static final Clock SYSTEM_CLOCK = Clock.systemUTC();
 
+    private Clocks()
+    {
+        // non-instantiable
+    }
+
+    /**
+     * Returns system clock.
+     * @return system clock
+     */
     public static Clock systemClock()
     {
         return SYSTEM_CLOCK;
     }
 
-    public static Clock nanoClock()
+    /**
+     * Returns clock that allow to get current nanos.
+     * @return clock with nano time support
+     */
+    public static SystemNanoClock nanoClock()
     {
-        return new SystemNanoClock();
+        return SystemNanoClock.INSTANCE;
     }
 
+    /**
+     * Return new fake clock instance.
+     * @return fake clock
+     */
     public static FakeClock fakeClock()
     {
-        return fakeClock();
+        return new FakeClock();
     }
 
-    public static FakeClock fakeClock( long delta, TimeUnit unit )
+    /**
+     * Return new fake clock instance.
+     * @param initialTime initial fake clock time
+     * @param unit initialTime fake clock time unit
+     * @return fake clock
+     */
+    public static FakeClock fakeClock( long initialTime, TimeUnit unit )
     {
-        return new FakeClock( delta, unit );
+        return new FakeClock( initialTime, unit );
     }
 }

community/common/src/main/java/org/neo4j/time/FakeClock.java

@@ -30,15 +30,15 @@
  */
 public class FakeClock extends SystemNanoClock
 {
-    private long nanos = 0;
+    private long nanoTime = 0;
 
     FakeClock()
     {
     }
 
-    FakeClock( long delta, TimeUnit unit )
+    FakeClock( long initialTime, TimeUnit unit )
     {
-        forward( delta, unit );
+        forward( initialTime, unit );
     }
 
     @Override
@@ -56,18 +56,18 @@ public Clock withZone( ZoneId zone )
     @Override
     public Instant instant()
     {
-        return Instant.ofEpochMilli( TimeUnit.NANOSECONDS.toMillis( nanos ) );
+        return Instant.ofEpochMilli( TimeUnit.NANOSECONDS.toMillis( nanoTime ) );
     }
 
     @Override
     public long nanos()
     {
-        return nanos;
+        return nanoTime;
     }
 
     public FakeClock forward( long delta, TimeUnit unit )
     {
-        nanos += unit.toNanos( delta );
+        nanoTime += unit.toNanos( delta );
         return this;
     }
 }

community/common/src/main/java/org/neo4j/time/SystemNanoClock.java

@@ -24,9 +24,13 @@
 import java.time.ZoneId;
 import java.time.ZoneOffset;
 
+/**
+ * {@link Clock} that support nano time resolution.
+ * @see Clocks
+ */
 public class SystemNanoClock extends Clock
 {
-    public static final SystemNanoClock INSTANCE = new SystemNanoClock();
+    static final SystemNanoClock INSTANCE = new SystemNanoClock();
 
     protected SystemNanoClock()
     {

community/kernel/src/main/java/org/neo4j/helpers/Clock.java

@@ -21,6 +21,7 @@
 
 /**
  * @deprecated please use {@link java.time.Clock} instead
+ * @see org.neo4j.time.Clocks
  */
 @Deprecated
 public interface Clock

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

@@ -32,6 +32,7 @@
 import org.neo4j.kernel.impl.transaction.tracing.TransactionEvent;
 import org.neo4j.kernel.impl.transaction.tracing.TransactionTracer;
 import org.neo4j.kernel.impl.util.JobScheduler;
+import org.neo4j.time.Clocks;
 import org.neo4j.time.SystemNanoClock;
 
 public class DefaultTransactionTracer implements TransactionTracer, LogRotationMonitor
@@ -155,7 +156,7 @@ public void setReadOnly( boolean wasReadOnly )
 
     public DefaultTransactionTracer( Monitor monitor, JobScheduler jobScheduler )
     {
-        this( SystemNanoClock.INSTANCE, monitor, jobScheduler );
+        this( Clocks.nanoClock(), monitor, jobScheduler );
     }
 
     public DefaultTransactionTracer( SystemNanoClock clock, Monitor monitor, JobScheduler jobScheduler )

community/kernel/src/main/java/org/neo4j/kernel/impl/transaction/log/checkpoint/DefaultCheckPointerTracer.java

@@ -27,6 +27,7 @@
 import org.neo4j.kernel.impl.transaction.tracing.LogForceEvent;
 import org.neo4j.kernel.impl.transaction.tracing.LogForceWaitEvent;
 import org.neo4j.kernel.impl.util.JobScheduler;
+import org.neo4j.time.Clocks;
 import org.neo4j.time.SystemNanoClock;
 
 public class DefaultCheckPointerTracer implements CheckPointTracer, CheckPointerMonitor
@@ -68,7 +69,7 @@ public LogForceEvent beginLogForce()
 
     public DefaultCheckPointerTracer( Monitor monitor, JobScheduler jobScheduler )
     {
-        this( SystemNanoClock.INSTANCE, monitor, jobScheduler );
+        this( Clocks.nanoClock(), monitor, jobScheduler );
     }
 
     public DefaultCheckPointerTracer( SystemNanoClock clock, Monitor monitor, JobScheduler jobScheduler )