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Module Netplex_cenv


module Netplex_cenv: sig .. end
Container environment

Some helper functions to explore the environment from a container. Most of the following functions must be called from a container context, i.e. from a process or thread that acts as container, otherwise the exception Not_in_container_thread is raised. There are also some functions that can be called from controller context for convenience.


exception Not_in_container_thread
Raised when the caller's thread is not a container thread

Logging



Logging functions can be invoked from both container and controller contexts.
val log : Netplex_types.level -> string -> unit
Writes a log message
val logf : Netplex_types.level -> ('a, unit, string, unit) Pervasives.format4 -> 'a
Writes a log message like printf
val report_connection_string : Unix.file_descr -> string -> string
Output a log line for the netplex.connections admin message. The string is the detail to report.

Timer



Timer functions can only be invoked from container contexts. More documentation is available in Running timers in containers.
type timer 
A timer
val create_timer : (timer -> bool) -> float -> timer
create_timer f tmo: Creates a timer with timeout value tmo: In tmo seconds f is called, and if this function returns true, the timer remains active, and another round of timing is arranged. If the functions returns false or raises an exception, the timer is stopped.

Timers are also stopped on container shutdown.

Timers are attached to the container event system, and run only if this event system runs.

val cancel_timer : timer -> unit
Cancels the timer: The callback function is not called any longer
val cancel_all_timers : unit -> unit
Cancels all active timers
val timer_id : timer -> int
Returns an ID, e.g. useful for debugging

Container variables



Container variables exist once per container. Primary access is done via the var and set_var methods of the container class. The following functions are often more convenient, however.

These functions can only be invoked from container contexts.

More documentation: Container variables

exception Container_variable_not_found of string
The variable does not exist
exception Container_variable_type_mismatch of string
The (dynamically typed) variable has the wrong type
val int_var : string -> int
val string_var : string -> string
val float_var : string -> float
val bool_var : string -> bool
Access a variable with simple type. May raise Container_variable_not_found or Container_variable_type_mismatch
val set_int_var : string -> int -> unit
val set_string_var : string -> string -> unit
val set_float_var : string -> float -> unit
val set_bool_var : string -> bool -> unit
Set a variable with simple type
val make_var_type : ('a -> Netplex_types.encap) ->
(Netplex_types.encap -> 'a) -> (string -> 'a) * (string -> 'a -> unit)
Create get and set functions for any (monomorphic) type. For example, to create such function for a type foo, do

 
          module E = Netplex_encap.Make_encap(struct type t = foo end)
          let (get, set) = 
            make_var_type E.wrap E.unwrap
      

Read on for using functors to create get and set.

module type TYPE = sig .. end
Just a (monomorphic) type t
module type VAR_TYPE = sig .. end
A (monomorphic) type t with two functions get and set accessing the container variables
module Make_var_type: 
functor (T : TYPE) -> VAR_TYPE with type t = T.t
Creates get and set like make_var_type.

System control



System control functions can be invoked from both container and controller contexts.
val system_shutdown : unit -> unit
Initiates a system shutdown (like the shutdown method of the controller)
val system_restart : unit -> unit
Initiates a system restart (like the restart method of the controller)

Inter-Container Communication



These functions can only be invoked from container contexts, except send_message.
val send_message : string -> string -> string array -> unit
send_message service_pattern msg_name msg_arguments: Sends a message to all services and message receivers matching service_pattern. The pattern may include the wildcard *.

See the Netplex_types.controller.send_message method for the notification guarantees.

This function can be invoked from both container and controller contexts.

val lookup : string -> string -> string option
lookup service_name protocol_name tries to find a Unix domain socket for the service and returns it.

On Win32, the returned path refers to a file describing the IPC mechanism. Use Netplex_sockserv.any_file_client_connector to convert the path into an RPC connector.

val lookup_container_sockets : string -> string -> string array
lookup_container_sockets service_name protocol_name: returns the Unix Domain paths of all container sockets for this service and protocol. These are the sockets declared with address type "container" in the config file.

On Win32, the returned paths refer to files describing the IPC mechanism. Use Netplex_sockserv.any_file_client_connector to convert the paths into RPC connectors.

Container sockets are explained here: Sending messages to individual containers


Direct container and admin interface access


val self_cont : unit -> Netplex_types.container
Returns the container running the code of the caller, or raise Not_in_container_thread if called from outside a container context.
val self_obj : unit ->
[ `Container of Netplex_types.container
| `Controller of Netplex_types.controller ]
Returns the container or the controller running the code of the caller, or raise Not_found if called from neither a container not a controller thread.
val current_sys_id : unit -> [ `Process of int | `Thread of int ]
Returns the system-dependent thread identifier of the caller (which must be in container or controller context)
val admin_connector : unit -> Rpc_client.mode2
Determines the admin socket of the controller, and returns an RPC client connector suitable for connecting with the admin interface of the controller. For instance to initiate a system shutdown from the context of a container:

         let conn = Netplex_cenv.admin_connector() in
         let client = Netplex_ctrl_clnt.Admin.V2.create_client2 conn in
         Netplex_ctrl_clnt.Admin.V2.system_shutdown client ();
         Rpc_client.shut_down client
       

Note that the admin interface is going to evolve, and it is advisable to avoid admin calls whenever possible.

This function must be called from container context.

val run_in_controller_context : Netplex_types.controller -> (unit -> unit) -> unit
run_in_controller_context ctrl f: Arranges that f() is executed in the context of the controller. This is only possible for multi-threading but not for multi-processing style! For programs using multi-processing, see Netplex_cenv.Make_lever for a workaround.

This function can be called from any thread. The function f is executed by pushing it onto the event queue, and calling it when the pushed event is reached. This is usually a safe point for many kinds of operations, but if controller methods are invoked the details are left unspecified.

For example, this allows it to start helper threads via Netplex_kit.add_helper_service at any time.

An example can be found here: Levers - calling controller functions from containers

val run_in_container_context : Netplex_types.container -> (unit -> unit) -> unit
run_in_container_context cont f: Arranges that f() is executed in the context of the container cont. This is only possible for multi-threading but not for multi-processing style!

This function can be called from any thread. The function f is executed by pushing it onto the event queue, and calling it when the pushed event is reached. This is usually a safe point for many kinds of operations, but if container method are invoked the details are left unspecified.

There is no guarantee that f is called anytime soon - if the container is busy with something else than with the event queue the execution will be blocked until these other activities are over.


Levers are a way to send messages to the controller, and to effectively run functions there that were previously registered.

More documentation: Levers - calling controller functions from containers

module type FUN_TYPE = sig .. end
Abstraction for function types s->t
module type LEVER = sig .. end
module Make_lever: 
functor (T : FUN_TYPE) -> LEVER with type s=T.s and type r=T.r
Creates a LEVER module from a function type as specified in FUN_TYPE

Debugging


module Debug: sig .. end
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