Tracer (Oracle Database JDBC Java API Reference)

```
public interface Tracer
```
Implementers of this interface provide a method that can be called by the Oracle Database JDBC drivers to support application and system tracing. If an instance is registered with an OracleConnection, that instance's roundTrip method will be called before and after each round trip to the database executed by that connection. The roundTrip method has limited access to the Connection but can get some information about the round trip and set a trace id.

If the driver understands the type of the trace id, the driver will use that trace id in trace records generated by the driver during the round trip. If the driver does not understand the type of the trace id it will use the result of calling toString on the trace id. What trace ids the driver understands may change from release to release.

Since:

22c

Nested Class Summary

Nested Classes
Modifier and Type	Interface	Description
`static class`	`Tracer.Sequence`	Indicates if a call to `Tracer#roundTrip` is before or after the round trip to the database.
`static interface`	`Tracer.TraceContext`	Information about the round trip.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`java.lang.Object`	`roundTrip(Tracer.Sequence seq, Tracer.TraceContext traceContext, java.lang.Object userContext)`	Called before and after each round trip on the Connection if observability is enabled.

- Method Detail
  - roundTrip
```
java.lang.Object roundTrip(Tracer.Sequence seq,
                           Tracer.TraceContext traceContext,
                           java.lang.Object userContext)
```
    Called before and after each round trip on the Connection if observability is enabled. The before and after calls are always made in pairs even if observability is enabled/disabled during a round trip.
    
    Parameters:
    
    seq - BEFORE if before the round trip, AFTER if after the round trip
    
    traceContext - Information about the round trip. Valid only during the call
    
    userContext - Result of previous call on this Connection or null if no previous call or if observability was disabled since the previous call.
    
    Returns:
    
    a user context object that is passed to the next call on this Connection. May be null.