The new dispatch.retry package provides support for retrying
requests that end in failure. Failure can be defined in terms of
Either with a Left, Option with a None, or any
Success.predicate defined by the application.
def remoteProcedure: Promise[Either[String,String]] ...
val p = retry.Directly(5)(remoteProcedure)This would retry the request immediately, up to five times, when a
result is a Left. Since it's not always the best thing to hammer a
service that is having trouble, we also have retry.Pause which takes
a fixed pause interval, and retry.Backoff which implements an
exponential backoff.
Retries are implemented with non-blocking promise composition and a shared HashedWheelTimer.
Contributed by casualjim, the modules dispatch-json4s-native
and dispatch-json4s-jackson each provide handlers as.json4s.Json for
complete responses and as.json.stream.Json for streaming
responses. Choose one module as a dependency; the handlers inside have
the same names.
To facilitate use of Dispatch in the Scala console, in automated
tests, in other libraries, we've ferreted out the threadpools in
underlying libraries and provided them with a factory for daemon
threads. As a result, you won't have to call Http#shutdown so
studiously.
Server applications may continue to call Http#shutdown from their
own graceful shutdown procedures.
As was helpfully pointed out on github, the factory methods on Http
were like lame versions of the copy method of case
classes. Realizing this was true, we made Http a case class with
default values for all parameters. This way, you can customize the
Http instance and we can add parameters later, if necessary, without
breaking your code.
The Http singleton object is an instance of this class with all
parameters set to their defaults. The waiting and threads factory
methods are still there, now based on copy.
The Http case class refactor is likely to break code that does any
significant customization of its Http instance. If you extend Http,
you'll get a warning for extending a case class. Instead of doing
that, construct the case class with the values you were supplying
before in method overrides.
The Http class extends a trait that used to be called Executor, but
now it's called HttpExecutor to avoid namespace collisions with
juc's Executor. Where possible you should use the Http class for
customization, since more abstract methods may be added to this trait
in the future. With the case class you benefit from default values.
This release of Dispatch supports all Scala versions from 2.8.1 to
2.9.2. The core module has been compiled with Scala 2.10.0-RC1 and
published as dispatch-core_2.10-0.9.3.