async_durable

Durable connections for use with async
IN THIS PACKAGE
Module Async_durable
type 'a t
val create : to_create:( unit -> 'a Async_kernel.Deferred.Or_error.t ) -> is_broken:( 'a -> bool ) -> ?to_rebuild:( 'a -> 'a Async_kernel.Deferred.Or_error.t ) -> unit -> 'a t

to_create tells the Durable how to build a fresh 'a value. If to_create raises, the exception is treated as if an Error was returned. If to_create needs to fail permanently when exceptions occur, then consider using Scheduler.within' ~monitor:Monitor.main inside of to_create, so that the exceptions go to a monitor that will abend the app.

is_broken tests whether the current 'a value can be used. It should return true when you want the Durable to attempt to rebuild or recreate the 'a.

to_rebuild Is called on the broken 'a. It should return a "fixed" 'a.

When the function with_ below is called, it uses is_broken to test if the current Durable value is broken. If so, it calls either to_create or to_rebuild. If to_rebuild is None (as in the default case), the Durable will try to create a fresh value with to_create.

create does not create the Durable value. The first call to to_create will be made on the first use of with_.

val create_or_fail : to_create:( unit -> 'a Async_kernel.Deferred.Or_error.t ) -> is_broken:( 'a -> bool ) -> ?to_rebuild:( 'a -> 'a Async_kernel.Deferred.Or_error.t ) -> unit -> 'a t Core.Or_error.t Async_kernel.Deferred.t

create_or_fail immediately calls to_create, returning an error if that first attempt fails. This function will also return an error if the initial durable value is broken.

with_ applies the given function to the Durable value if is_broken returns false. If is_broken return true, it first calls to_create or to_rebuild. This function will return an error if either to_create or to_rebuild returns an error, or if the rebuilt or recreated durable value is broken. is_broken is checked immediately before calling f.

We will only make one attempt to rebuild a broken value. If a call to to_rebuild returns Error _, we will drop the previously built value. The next call to with_ will call to_create.

with_ will raise if f raises.

val is_intact_bus : 'a t -> ( bool -> unit ) Bus.Read_only.t

is_intact exposes whether the Durable value is in a valid state (i.e. it has been built and it is not currently broken).

module Subscription : sig ... end
module Pipe_rpc : sig ... end

This module is designed to help processess maintain update subscriptions that will automatically recover from lost connections. It exposes to the client when the subscription has been lost or recovered, so the client can choose how to handle a lost connection.

module State_rpc : sig ... end

This module is designed to help processess maintain state RPCs that will automatically recover from lost connections. It exposes to the client when the subscription has been lost or recovered, so the client can choose how to handle a lost connection.