src/nmutil/dynamicpipe.py

   1 # SPDX-License-Identifier: LGPL-2.1-or-later
   2 # See Notices.txt for copyright information
   3
   4 from abc import ABCMeta
   5
   6 from nmutil.singlepipe import SimpleHandshake
   7 import threading
   8
   9 # with many thanks to jsbueno on stackexchange for this one
  10 # https://stackoverflow.com/questions/57273070/
  11 # list post:
  12 # http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2019-July/002259.html
  13
  14 class Meta(ABCMeta):
  15     registry = {}
  16     recursing = threading.local()
  17     recursing.check = False
  18     mlock = threading.Lock()
  19
  20     def __call__(cls, *args, **kw):
  21         mcls = cls.__class__
  22         if mcls.recursing.check:
  23             return super().__call__(*args, **kw)
  24         spec = args[0]
  25         base = spec.pipekls # pick up the dynamic class from PipelineSpec, HERE
  26
  27         if (cls, base) not in mcls.registry:
  28             print ("__call__", args, kw, cls, base,
  29                    base.__bases__, cls.__bases__)
  30             mcls.registry[cls, base] = type(
  31                 cls.__name__,
  32                 (cls, base) + cls.__bases__[1:],
  33                 {}
  34             )
  35         real_cls = mcls.registry[cls, base]
  36
  37         with mcls.mlock:
  38             mcls.recursing.check = True
  39             instance = real_cls.__class__.__call__(real_cls, *args, **kw)
  40             mcls.recursing.check = False
  41         return instance
  42
  43
  44 # Inherit from this class instead of SimpleHandshake (or other ControlBase
  45 # derivative), and the metaclass will instead *replace* DynamicPipe -
  46 # *at runtime* - with the class that is specified *as a parameter*
  47 # in PipelineSpec.
  48 #
  49 # as explained in the list posting and in the stackexchange post, this is
  50 # needed to avoid a MASSIVE suite of duplicated multiple-inheritance classes
  51 # that "Mix in" SimpleHandshake (or other).
  52 #
  53 # unfortunately, composition does not work in this instance
  54 # (make an *instance* of SimpleHandshake or other class and pass it in)
  55 # due to the multiple level inheritance, and in several places
  56 # the inheriting class needs to do some setup that the deriving class
  57 # needs in order to function correctly.
  58
  59 class DynamicPipe(metaclass=Meta):
  60     def __init__(self, *args):
  61         print ("DynamicPipe init", super(), args)
  62         super().__init__(self, *args)
  63
  64
  65 # bad hack: the DynamicPipe metaclass ends up creating an __init__ signature
  66 # for the dynamically-derived class.  luckily, SimpleHandshake only needs
  67 # "self" as the 1st argument (it is its own "Stage").  anything else
  68 # could hypothetically be passed through the pspec.
  69 class SimpleHandshakeRedir(SimpleHandshake):
  70     def __init__(self, mod, *args):
  71         print ("redir", mod, args)
  72         stage = self
  73         if args and args[0].stage:
  74             stage = args[0].stage
  75         SimpleHandshake.__init__(self, stage)
  76