cpluginsvc.py

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# cpluginsvc is a ctypes-based wrapper for the C-exposed API of GaudiPluginService
__doc__ = """
cpluginsvc is a ctypes-based wrapper for the C-API of the GaudiPluginService.
 
e.g.:
 
>>> from GaudiPluginService import cpluginsvc
>>> for _,f in cpluginsvc.factories().items():
...     try:
...         f.load()
...     except Exception:
...         print ("** could not load [%s] for factory [%s]" % (f.library, f.name))
...         continue
...     print(f)
...     for k,v in f.properties.iteritems():
...         print ("\t%s: %s" % (k,v))
"""
 
import ctypes
import ctypes.util
import os
import platform
 
__all__ = (
    "Registry",
    "registry",
    "factories",
    "Factory",
    "Property",
)
 
_lib_basename = {
    "Darwin": "libGaudiPluginService.dylib",
    "Windows": "libGaudiPluginService.dll",
    "Linux": "libGaudiPluginService.so",
}[platform.system()]
 
 
def _find_library():
    """Locate libGaudiPluginService, searching library path env vars explicitly."""
    search_vars = (
        ["DYLD_LIBRARY_PATH", "LD_LIBRARY_PATH"]
        if platform.system() == "Darwin"
        else ["LD_LIBRARY_PATH"]
    )
    for var in search_vars:
        for directory in os.environ.get(var, "").split(os.pathsep):
            if not directory:
                continue
            candidate = os.path.join(directory, _lib_basename)
            if os.path.exists(candidate):
                return candidate
    # Fall back to bare name and let the dynamic linker resolve it
    return _lib_basename
 
 
_lib = ctypes.CDLL(_find_library(), ctypes.RTLD_GLOBAL)
 
 
class Registry(ctypes.Structure):
    """Registry holds the list of factories known by the gaudi PluginService."""
 
    _fields_ = [("_registry", ctypes.c_void_p)]
 
    @property
    def factories(self):
        facts = {}
        n = _lib.cgaudi_pluginsvc_get_factory_size(self)
        for i in range(n):
            f = _lib.cgaudi_pluginsvc_get_factory_at(self, i)
            facts[f.name] = f
        return facts
 
    pass
 
 
_instance = None
 
 
def registry():
    """registry returns the singleton-like instance of the plugin service."""
 
    global _instance
    if _instance:
        return _instance
    _instance = _lib.cgaudi_pluginsvc_instance()
    return _instance
 
 
def factories():
    """
    factories returns the list of components factory informations known to the plugin service
    """
    return registry().factories
 
 
class Factory(ctypes.Structure):
    """
    Factory holds informations about a component's factory:
    - its name
    - the library hosting that component
    - the type of component (algorithm, service, tool, ...)
    - the return type of this factory
    - the C++ class name of that component
    - the properties which may decorate that component.
    """
 
    _fields_ = [
        ("_registry", Registry),
        ("_id", ctypes.c_char_p),
    ]
 
    @property
    def name(self):
        return self._id.decode("ascii")
 
    @property
    def library(self):
        return _lib.cgaudi_factory_get_library(self).decode("ascii")
 
    @property
    def type(self):
        return _lib.cgaudi_factory_get_type(self).decode("ascii")
 
    @property
    def classname(self):
        return _lib.cgaudi_factory_get_classname(self).decode("ascii")
 
    @property
    def properties(self):
        props = {}
        nprops = _lib.cgaudi_factory_get_property_size(self)
        for i in range(nprops):
            prop = _lib.cgaudi_factory_get_property_at(self, i)
            props[prop.key] = prop.value
        return props
 
    def load(self):
        """load the C++ library hosting this factory"""
        return ctypes.CDLL(self.library, ctypes.RTLD_GLOBAL)
 
    def __repr__(self):
        return "<Factory id=%s library=%s type=%s class=%s props=%d>" % (
            self.name,
            self.library,
            self.type,
            self.classname,
            len(self.properties),
        )
 
    pass
 
 
class Property(ctypes.Structure):
    """
    Property is a pair (key, value) optionally decorating a factory.
    It is used to attach additional informations about a factory.
    """
 
    _fields_ = [
        ("_registry", Registry),
        ("_id", ctypes.c_char_p),
        ("_key", ctypes.c_char_p),
    ]
 
    @property
    def key(self):
        return _lib.cgaudi_property_get_key(self).decode("ascii")
 
    @property
    def value(self):
        return _lib.cgaudi_property_get_value(self).decode("ascii")
 
    pass
 
 
_functions_list = [
    (
        "cgaudi_pluginsvc_instance",
        [],
        Registry,
    ),
    (
        "cgaudi_pluginsvc_get_factory_size",
        [Registry],
        ctypes.c_int,
    ),
    (
        "cgaudi_pluginsvc_get_factory_at",
        [Registry, ctypes.c_int],
        Factory,
    ),
    (
        "cgaudi_factory_get_library",
        [Factory],
        ctypes.c_char_p,
    ),
    (
        "cgaudi_factory_get_type",
        [Factory],
        ctypes.c_char_p,
    ),
    (
        "cgaudi_factory_get_classname",
        [Factory],
        ctypes.c_char_p,
    ),
    (
        "cgaudi_factory_get_property_size",
        [Factory],
        ctypes.c_int,
    ),
    (
        "cgaudi_factory_get_property_at",
        [Factory, ctypes.c_int],
        Property,
    ),
    (
        "cgaudi_property_get_key",
        [Property],
        ctypes.c_char_p,
    ),
    (
        "cgaudi_property_get_value",
        [Property],
        ctypes.c_char_p,
    ),
    (
        "cgaudi_pluginsvc_plugin_search_path",
        [],
        ctypes.c_char_p,
    ),
]
 
for f in _functions_list:
    n = f[0]
    func = getattr(_lib, n)
    func.argtypes = f[1]
    func.restype = f[2]
    if len(f) == 4:
        func.errcheck = f[3]
    pass
 
 
GAUDI_DEFAULT_PLUGIN_PATH = [
    p
    for p in _lib.cgaudi_pluginsvc_plugin_search_path().decode().split(os.pathsep)
    if p
]
 
 
if __name__ == "__main__":
    print("instance: %s" % registry())
    print("factories: %d" % len(factories()))
    for _, f in factories().items():
        try:
            f.load()
        except Exception:
            print("** could not load [%s] for factory [%s]" % (f.library, f.name))
            continue
        print(f)
        for k, v in f.properties.items():
            print("\t%s: %s" % (k, v))
 
# EOF