contrib/pyzfs/libzfs_core/bindings/__init__.py

   1 #
   2 # Copyright 2015 ClusterHQ
   3 #
   4 # Licensed under the Apache License, Version 2.0 (the "License");
   5 # you may not use this file except in compliance with the License.
   6 # You may obtain a copy of the License at
   7 #
   8 #    http://www.apache.org/licenses/LICENSE-2.0
   9 #
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15 #
  16
  17 """
  18 The package that contains a module per each C library that
  19 `libzfs_core` uses.  The modules expose CFFI objects required
  20 to make calls to functions in the libraries.
  21 """
  22 from __future__ import absolute_import, division, print_function
  23
  24 import threading
  25 import importlib
  26
  27 from cffi import FFI
  28
  29
  30 def _setup_cffi():
  31     class LazyLibrary(object):
  32
  33         def __init__(self, ffi, libname):
  34             self._ffi = ffi
  35             self._libname = libname
  36             self._lib = None
  37             self._lock = threading.Lock()
  38
  39         def __getattr__(self, name):
  40             if self._lib is None:
  41                 with self._lock:
  42                     if self._lib is None:
  43                         self._lib = self._ffi.dlopen(self._libname)
  44
  45             return getattr(self._lib, name)
  46
  47     MODULES = ["libnvpair", "libzfs_core"]
  48     ffi = FFI()
  49
  50     for module_name in MODULES:
  51         module = importlib.import_module("." + module_name, __name__)
  52         ffi.cdef(module.CDEF)
  53         lib = LazyLibrary(ffi, module.LIBRARY)
  54         setattr(module, "ffi", ffi)
  55         setattr(module, "lib", lib)
  56
  57
  58 _setup_cffi()
  59
  60 # vim: softtabstop=4 tabstop=4 expandtab shiftwidth=4