Process parameters
==================

The process parameters are: initial_load [neighbors...]

Communications
==============

There are two receiving channels per host: control for information
messages, and data for load transfers.

Process model
=============

Each process is made of 3 threads: a receiver thread, a computing
thread, and a load-balancer thread.

* Receiver thread
  ---------------

    Loop
    | wait for a message to come, either on data channel, or on ctrl channel
    | push received message in a buffer of received messages
    | -> ctrl messages on the one side
    | -> data messages on the other side
    +-

   The loop terminates when a "finalize" message is received on each
   channel.

* Computing thread
  ----------------

    Loop
    | if we received some real load, get it (data messages)
    | if there is some real load to send, send it
    | if we own some load, simulate some computing on it
    +-
    send CLOSE on data for all neighbors
    wait for CLOSE on data from all neighbors

  The loop terminates when process::still_running() returns false.
  (read the source for full details...)

* Load-balancing thread
  ---------------------

    Loop
    | call load-balancing algorithm
    | send ctrl messages
    | receive ctrl messages
    +-
    send CLOSE on ctrl for all neighbors
    wait for CLOSE on ctrl from all neighbors

  The loop terminates when process::still_running() returns false.
  (read the source for full details...)

Open questions
==============
 * definition of load on heterogeneous hosts?
 * how to detect convergence?
   : No need to detect convergence.  Computation stops when there
     nothing more to do.
 * how to manage link failures?