bus.rst

:mod:`bus` --- Message bus

.. module:: bus
   :synopsis: Message bus.

A message bus provides a software-bus abstraction that gathers all the communications between a group of threads over a single shared virtual channel. Messages are transferred on the bus from a sender to one or more attached listeners. The concept is analogous to the bus concept found in computer hardware architecture.

Example

In this example there is a bus with three listeners attached; listerner 0, 1 and 2. Listener 0 and 1 are attached to the bus listening for message id 7, and listener 2 for message id 9.

Any thread can write a message to the bus by calling bus_write(). If a message with id 7 is written to the bus, both listerner 0 and 1 will receive the message. Listener 2 will receive messages with id 9.

Messages are read from the listener channel by the thread that owns the listener.

     +--------------+              +--------------+
     |  listener 0  |              |  listener 2  |
     | id:7, chan:0 |              | id:9, chan:2 |
     +-------+------+              +-------+------+
             |                             |
BUS  ========+==============+==============+=======
                            |
                    +-------+------+
                    |  listener 1  |
                    | id:7, chan:1 |
                    +--------------+

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Source code: :github-blob:`src/sync/bus.h`, :github-blob:`src/sync/bus.c`

Test code: :github-blob:`tst/sync/bus/main.c`

Test coverage: :codecov:`src/sync/bus.c`

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.. doxygenfile:: sync/bus.h
   :project: simba