Move common libs to libs/common

libs/common/dogpile/cache/util.py

@@ -0,0 +1,145 @@
+from hashlib import sha1
+from ..util import compat
+from ..util import langhelpers
+
+
+def function_key_generator(namespace, fn, to_str=compat.string_type):
+    """Return a function that generates a string
+    key, based on a given function as well as
+    arguments to the returned function itself.
+
+    This is used by :meth:`.CacheRegion.cache_on_arguments`
+    to generate a cache key from a decorated function.
+
+    An alternate function may be used by specifying
+    the :paramref:`.CacheRegion.function_key_generator` argument
+    for :class:`.CacheRegion`.
+
+    .. seealso::
+
+        :func:`.kwarg_function_key_generator` - similar function that also
+        takes keyword arguments into account
+
+    """
+
+    if namespace is None:
+        namespace = '%s:%s' % (fn.__module__, fn.__name__)
+    else:
+        namespace = '%s:%s|%s' % (fn.__module__, fn.__name__, namespace)
+
+    args = compat.inspect_getargspec(fn)
+    has_self = args[0] and args[0][0] in ('self', 'cls')
+
+    def generate_key(*args, **kw):
+        if kw:
+            raise ValueError(
+                "dogpile.cache's default key creation "
+                "function does not accept keyword arguments.")
+        if has_self:
+            args = args[1:]
+
+        return namespace + "|" + " ".join(map(to_str, args))
+    return generate_key
+
+
+def function_multi_key_generator(namespace, fn, to_str=compat.string_type):
+
+    if namespace is None:
+        namespace = '%s:%s' % (fn.__module__, fn.__name__)
+    else:
+        namespace = '%s:%s|%s' % (fn.__module__, fn.__name__, namespace)
+
+    args = compat.inspect_getargspec(fn)
+    has_self = args[0] and args[0][0] in ('self', 'cls')
+
+    def generate_keys(*args, **kw):
+        if kw:
+            raise ValueError(
+                "dogpile.cache's default key creation "
+                "function does not accept keyword arguments.")
+        if has_self:
+            args = args[1:]
+        return [namespace + "|" + key for key in map(to_str, args)]
+    return generate_keys
+
+
+def kwarg_function_key_generator(namespace, fn, to_str=compat.string_type):
+    """Return a function that generates a string
+    key, based on a given function as well as
+    arguments to the returned function itself.
+
+    For kwargs passed in, we will build a dict of
+    all argname (key) argvalue (values) including
+    default args from the argspec and then
+    alphabetize the list before generating the
+    key.
+
+    .. versionadded:: 0.6.2
+
+    .. seealso::
+
+        :func:`.function_key_generator` - default key generation function
+
+    """
+
+    if namespace is None:
+        namespace = '%s:%s' % (fn.__module__, fn.__name__)
+    else:
+        namespace = '%s:%s|%s' % (fn.__module__, fn.__name__, namespace)
+
+    argspec = compat.inspect_getargspec(fn)
+    default_list = list(argspec.defaults or [])
+    # Reverse the list, as we want to compare the argspec by negative index,
+    # meaning default_list[0] should be args[-1], which works well with
+    # enumerate()
+    default_list.reverse()
+    # use idx*-1 to create the correct right-lookup index.
+    args_with_defaults = dict((argspec.args[(idx*-1)], default)
+                              for idx, default in enumerate(default_list, 1))
+    if argspec.args and argspec.args[0] in ('self', 'cls'):
+        arg_index_start = 1
+    else:
+        arg_index_start = 0
+
+    def generate_key(*args, **kwargs):
+        as_kwargs = dict(
+            [(argspec.args[idx], arg)
+             for idx, arg in enumerate(args[arg_index_start:],
+                                       arg_index_start)])
+        as_kwargs.update(kwargs)
+        for arg, val in args_with_defaults.items():
+            if arg not in as_kwargs:
+                as_kwargs[arg] = val
+
+        argument_values = [as_kwargs[key]
+                           for key in sorted(as_kwargs.keys())]
+        return namespace + '|' + " ".join(map(to_str, argument_values))
+    return generate_key
+
+
+def sha1_mangle_key(key):
+    """a SHA1 key mangler."""
+
+    return sha1(key).hexdigest()
+
+
+def length_conditional_mangler(length, mangler):
+    """a key mangler that mangles if the length of the key is
+    past a certain threshold.
+
+    """
+    def mangle(key):
+        if len(key) >= length:
+            return mangler(key)
+        else:
+            return key
+    return mangle
+
+# in the 0.6 release these functions were moved to the dogpile.util namespace.
+# They are linked here to maintain compatibility with older versions.
+
+coerce_string_conf = langhelpers.coerce_string_conf
+KeyReentrantMutex = langhelpers.KeyReentrantMutex
+memoized_property = langhelpers.memoized_property
+PluginLoader = langhelpers.PluginLoader
+to_list = langhelpers.to_list