Add google-endpoints to third_party/.

third_party/google-endpoints/dogpile/util/langhelpers.py

+import re
+import collections
+from . import compat
+
+
+def coerce_string_conf(d):
+    result = {}
+    for k, v in d.items():
+        if not isinstance(v, compat.string_types):
+            result[k] = v
+            continue
+
+        v = v.strip()
+        if re.match(r'^[-+]?\d+$', v):
+            result[k] = int(v)
+        elif re.match(r'^[-+]?(?:\d+(?:\.\d*)?|\.\d+)(?:[eE][-+]?\d+)?$', v):
+            result[k] = float(v)
+        elif v.lower() in ('false', 'true'):
+            result[k] = v.lower() == 'true'
+        elif v == 'None':
+            result[k] = None
+        else:
+            result[k] = v
+    return result
+
+
+class PluginLoader(object):
+    def __init__(self, group):
+        self.group = group
+        self.impls = {}
+
+    def load(self, name):
+        if name in self.impls:
+            return self.impls[name]()
+        else:  # pragma NO COVERAGE
+            import pkg_resources
+            for impl in pkg_resources.iter_entry_points(
+                    self.group, name):
+                self.impls[name] = impl.load
+                return impl.load()
+            else:
+                raise Exception(
+                    "Can't load plugin %s %s" %
+                    (self.group, name))
+
+    def register(self, name, modulepath, objname):
+        def load():
+            mod = __import__(modulepath, fromlist=[objname])
+            return getattr(mod, objname)
+        self.impls[name] = load
+
+
+class memoized_property(object):
+    """A read-only @property that is only evaluated once."""
+    def __init__(self, fget, doc=None):
+        self.fget = fget
+        self.__doc__ = doc or fget.__doc__
+        self.__name__ = fget.__name__
+
+    def __get__(self, obj, cls):
+        if obj is None:
+            return self
+        obj.__dict__[self.__name__] = result = self.fget(obj)
+        return result
+
+
+def to_list(x, default=None):
+    """Coerce to a list."""
+    if x is None:
+        return default
+    if not isinstance(x, (list, tuple)):
+        return [x]
+    else:
+        return x
+
+
+class KeyReentrantMutex(object):
+
+    def __init__(self, key, mutex, keys):
+        self.key = key
+        self.mutex = mutex
+        self.keys = keys
+
+    @classmethod
+    def factory(cls, mutex):
+        # this collection holds zero or one
+        # thread idents as the key; a set of
+        # keynames held as the value.
+        keystore = collections.defaultdict(set)
+
+        def fac(key):
+            return KeyReentrantMutex(key, mutex, keystore)
+        return fac
+
+    def acquire(self, wait=True):
+        current_thread = compat.threading.current_thread().ident
+        keys = self.keys.get(current_thread)
+        if keys is not None and \
+                self.key not in keys:
+            # current lockholder, new key. add it in
+            keys.add(self.key)
+            return True
+        elif self.mutex.acquire(wait=wait):
+            # after acquire, create new set and add our key
+            self.keys[current_thread].add(self.key)
+            return True
+        else:
+            return False
+
+    def release(self):
+        current_thread = compat.threading.current_thread().ident
+        keys = self.keys.get(current_thread)
+        assert keys is not None, "this thread didn't do the acquire"
+        assert self.key in keys, "No acquire held for key '%s'" % self.key
+        keys.remove(self.key)
+        if not keys:
+            # when list of keys empty, remove
+            # the thread ident and unlock.
+            del self.keys[current_thread]
+            self.mutex.release()