docs for v4

Author: CMogilko

CHANGELOG.md

@@ -2,6 +2,19 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+## v4.0.0 - 2017-12-14
+
+### Fixed
+
+ - `Connection` work with sockets, now only a single goroutine reads from socket.
+ - Optimized threadsafe operations in `Connection` with channels and atomics instead of mutex.
+ - All tests with real db moved to integration folder
+
+### Added
+
+ - Added support for tracing with `opentracing-go`
+ - Added a brand-new unit tests for `Connection` 
+
 ## v3.0.5 - 2017-09-28
 
 - Fixed typo at http opts

README.md

@@ -9,7 +9,7 @@
 
 ![GoRethink Logo](https://raw.github.com/wiki/gorethink/gorethink/gopher-and-thinker-s.png "Golang Gopher and RethinkDB Thinker")
 
-Current version: v3.0.5 (RethinkDB v2.3)
+Current version: v4.0.0 (RethinkDB v2.3)
 
 <!-- This project is no longer maintained, for more information see the [v3.0.0 release](https://github.com/gorethink/gorethink/releases/tag/v3.0.0)-->
 
@@ -23,7 +23,7 @@ If you need any help you can find me on the [RethinkDB slack](http://slack.rethi
 go get gopkg.in/gorethink/gorethink.v4
 ```
 
-Replace `v3` with `v2` or `v1` to use previous versions.
+Replace `v4` with `v3` or `v2` to use previous versions.
 
 ## Example
 
@@ -413,6 +413,15 @@ r.Log.Out = os.Stderr
 r.Log.Out = ioutil.Discard
 ```
 
+## Tracing
+
+The driver supports [opentracing-go](https://github.com/opentracing/opentracing-go/). You can enable this feature by setting `UseOpentracing` to true in the `ConnectOpts`. Then driver will expect `opentracing.Span` in the `RunOpts.Context` and will start new child spans for queries.
+Also you need to configure tracer in your program by yourself.
+
+The driver starts span for the whole query, from the first byte is sent to the cursor closed, and second-level span for each query for fetching data.
+
+So you can trace how much time you program spends for RethinkDB queries.  
+
 ## Mocking
 
 The driver includes the ability to mock queries meaning that you can test your code without needing to talk to a real RethinkDB cluster, this is perfect for ensuring that your application has high unit test coverage.