getOrElseUpdate and http context

I am having the following issue. When I use this java method I am loosing the http context.

Reporting a bug?

1. Version of play-redis: 1.6.0
2. Version of Scala 2.12
3. Version of Play 2.6.6
4. Describe the environment if applies (usually in cloud etc.)
5. Describe the expected behavior: it should return a CompletionStage with the http.context

[tzimisce012]

Great. I also believe that the workaround is good but It would be cool if we can fix this topic from the implementation of RedisCache 😃

[tzimisce012]

The context is stored on the thread local. When you do something like: CompletableFuture.supplyAsyn(()-> doSomething()) you are executing a task on the common-fork-join and leaving behind the akka dispatcher from play. That means that if you later do something like:

promise.thenApply(something -> something + request().getHeader("myheader")) you will get a RuntimeException since the method request() is trying to get the Http context and you don’t have it anymore.

Play offers you a class called HttpExecutionContext that will allows you execute a asynchronous task in the same akka dispatcher and keeping your http context available as explained here. Even though you are still in the same executor, you might jump to a different thread, so you still need to move the http context from the previous thread to the new one.

In scala you don’t have these problems, but if you are doing a java version you still need to be aware of this topic. In the class JavaRedis you are doing Future.sequence() and implicitly you are passing your execution context. When you do this, the CompletionStage that you return does not have the http context anymore. Still, scala play api offers you a nice utility method called fromThread that would allow you to assign the context to the new thread of the executor. My knowledge on scala ends here, so I hope you have enough information to solve the problem from there.