846a99de9a
remove task_path_suffix from evergreen_gen_multiversion_tasks.py replication works fix fixture API adherence test generate mongos port on startup fix sharding and reformat
83 lines
3.2 KiB
Python
83 lines
3.2 KiB
Python
"""Utility for having class declarations.
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The registry automatically causes a reference to the class to be stored along with its name.
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This pattern enables the associated class to be looked up later by using
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its name.
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"""
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import threading
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from contextlib import contextmanager
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from buildscripts.resmokelib.utils import default_if_none
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# Specifying 'LEAVE_UNREGISTERED' as the "REGISTERED_NAME" attribute will cause the class to be
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# omitted from the registry. This is particularly useful for base classes that define an interface
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# or common functionality, and aren't intended to be constructed explicitly.
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LEAVE_UNREGISTERED = object()
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GLOBAL_SUFFIX = ""
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SUFFIX_LOCK = threading.Lock()
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@contextmanager
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def suffix(suf):
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"""
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Set a global suffix that's postpended to registered names.
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This is used to enable dynamically imported classes from other branches for
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multiversion tests. These classes need a unique suffix to not conflict with
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corresponding classes on master (and possibly other) branches. The suffix has to
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be set at runtime for the duration of the import, which is why this
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contextmanager + global runtime variable is used.
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"""
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global GLOBAL_SUFFIX # pylint: disable=global-statement
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GLOBAL_SUFFIX = suf
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with SUFFIX_LOCK:
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yield suf
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GLOBAL_SUFFIX = ""
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def make_registry_metaclass(registry_store, base_metaclass=None):
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"""Return a new Registry metaclass."""
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if not isinstance(registry_store, dict):
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raise TypeError("'registry_store' argument must be a dict")
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base_metaclass = default_if_none(base_metaclass, type)
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class Registry(base_metaclass):
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"""A metaclass that stores a reference to all registered classes."""
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def __new__(mcs, class_name, base_classes, class_dict): # pylint: disable=bad-mcs-classmethod-argument,bad-classmethod-argument
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"""Create and returns a new instance of Registry.
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The registry is a class named 'class_name' derived from 'base_classes'
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that defines 'class_dict' as additional attributes.
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The returned class is added to 'registry_store' using
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class_dict["REGISTERED_NAME"] as the name, or 'class_name'
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if the "REGISTERED_NAME" attribute isn't defined. If the
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sentinel value 'LEAVE_UNREGISTERED' is specified as the
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name, then the returned class isn't added to
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'registry_store'.
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The returned class will have the "REGISTERED_NAME" attribute
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defined either as its associated key in 'registry_store' or
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the 'LEAVE_UNREGISTERED' sentinel value.
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"""
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registered_name = class_dict.setdefault("REGISTERED_NAME", class_name)
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cls = base_metaclass.__new__(mcs, class_name, base_classes, class_dict)
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if registered_name is not LEAVE_UNREGISTERED:
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name_to_register = f"{registered_name}{GLOBAL_SUFFIX}"
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if name_to_register in registry_store:
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raise ValueError(
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"The name %s is already registered; a different value for the"
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" 'REGISTERED_NAME' attribute must be chosen" % (registered_name))
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registry_store[name_to_register] = cls
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return cls
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return Registry
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