Non-GUI, single processort inter process massaging - how?

Anders Wegge Keller wegge at wegge.dk
Mon Jul 23 10:44:44 EDT 2018


På Sat, 21 Jul 2018 09:07:23 +0100
Chris Green <cl at isbd.net> skrev:

> So - what's the best approach to this?  I've done some searching and
> most/many of the solutions seem rather heavyweight for my needs. Am I
> overlooking something obvious or should I try rethinking the original
> requirement and look for another approach?

 What do you consider heavyweight? Number of dependencies, memory footprint,
amount of code or a fourth thing? Also, which platform will the code
eventually run on?

 If your update frequency is low enough that it wont kill the filesystem and
the amount of data is reasonably small, atomic writes to a file is easy to
work with:

  def atomic_write(filename, data):
    handle, name = tempfile.mkstemp()
    os.write(handle, data)
    os.fsync(handle)
    os.close(handle)
    os.replace(tmpname, filename)

 The imports are trivial to deduce, so I removed the clutter. If you have
multiple filesystems, you may have to read into the details of calling
mkstemp.


 If you have an update frequency that will kill the filesystem (for instance
a RPi on a SD card), or have a larger data set where you only want to do
partial updates, the mmap module could be an option. It require some more
boilerplate. You will probably also have to consider a semaphore to
guarantee that the clients read a consistent result set.

-- 
//Wegge


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