# Notes 

## TODO:

- Web Server
  - Async servlet
  - Reactive servlet
- Zuul
- Web Clients
  - Reactive WebClient
  - Feign
- Async
  - TraceExecutors etc.
  - Runnable / Callable
  - @Async
- Hystrix
- Messaging
- Reactor
- RxJava
- Scheduling
  
## Done:

- Web Server
  - Simple handler interceptor
- Web Clients
  - RestTemplate
- Slf4j
  - with Brave in place it will also work for any other implementation (e.g. log4j)

## Removed features

- `SpanLogger`
  - Name pattern of Span Logger will not be applicable
- `Sampler`
  - TODO: describe the new sampling mechanism
- `Metric` 
  - TODO: discuss what happens to `SpanMetricReporter` - is anybody actually using it?

# Migrations

## Sleuth's Tracer to brave.Tracing

Before

```
import org.springframework.cloud.sleuth.Tracer;

Tracer tracer;
```

After

```
import brave.Tracing;

Tracing tracing;
```

## Child span creation

Before

```
Span child = tracer.createSpan("name");
```

After

```
// tracing is brave.Tracing injected instead of Sleuth's Tracer
brave.Span span = tracing.tracer().nextSpan().name("name");
```

## Span closing

Before

```
Span child = tracer.createSpan("name");
try {
  // do sth
} finally {
  tracer.close(child);
}
```

After

```
// tracing is brave.Tracing injected instead of Sleuth's Tracer
brave.Span span = this.tracing.tracer().nextSpan().name("name");
try {
  // do sth
} finally {
  span.finish();
}
```

## Span tagging

Before

```
tracer.addTag("foo", "bar");
```

After

```
// tracing is brave.Tracing injected instead of Sleuth's Tracer
this.tracing.tracer().currentSpan().tag("foo", "bar");
```

## `TraceRunnable` and `TraceCallable` moved to `instrument.async`

Before

```
org.springframework.cloud.sleuth.TraceRunnable
org.springframework.cloud.sleuth.TraceCallable
```

After

```
org.springframework.cloud.sleuth.instrument.async.TraceRunnable
org.springframework.cloud.sleuth.instrument.async.TraceCallable
```

## `ArayListSpanAccumulator` renamed to `ArrayListSpanReporter`

Before

```
org.springframework.cloud.sleuth.util.ArrayListSpanAccumulator
```

After

```
org.springframework.cloud.sleuth.util.ArrayListSpanReporter
```

## `org.springframework.cloud.brave.sampler.SamplerProperties#percentage` renamed to `org.springframework.cloud.brave.sampler.SamplerProperties#probability`

Related to https://github.com/spring-cloud/spring-cloud-sleuth/issues/397