Introduce WPTServe for running W3C Blink Layout tests

Tools/Scripts/webkitpy/thirdparty/wpt/wpt/tools/wptserve/wptserve/stash.py

+import uuid
+
+#TODO: Consider expiring values after some fixed time for long-running
+#servers
+
+
+class Stash(object):
+    """Key-value store for persisting data across HTTP requests.
+
+    This data store specifically designed for persisting data across
+    HTTP requests. It is entirely in-memory so data will not be
+    persisted across server restarts.
+
+    This has several unusual properties. Keys are of the form (path,
+    uuid), where path is, by default, the path in the HTTP request and
+    uuid is a unique id. In addition, the store is write-once, read-once,
+    i.e. the value associated with a particular key cannot be changed once
+    written and the read operation (called "take") is destructive. Taken together,
+    these properties make it difficult for data to accidentally leak
+    between different resources or different requests for the same
+    resource.
+
+    """
+
+    data = {}
+
+    def __init__(self, default_path):
+        self.default_path = default_path
+
+    def put(self, key, value, path=None):
+        """Place a value in the stash.
+
+        :param key: A UUID to use as the data's key.
+        :param value: The data to store. This can be any python object.
+        :param path: The path that has access to read the data (by default
+                     the current request path)"""
+        if path is None:
+            path = self.default_path
+        if path not in self.data:
+            self.data[path] = PathStash(path)
+
+        self.data[path][key] = value
+
+    def take(self, key, path=None):
+        """Remove a value from the stash and return it.
+
+        :param key: A UUID to use as the data's key.
+        :param path: The path that has access to read the data (by default
+                     the current request path)"""
+        if path is None:
+            path = self.default_path
+
+        if path in self.data:
+            value = self.data[path][key]
+        else:
+            value = None
+        return value
+
+
+class PathStash(dict):
+    def __init__(self, path):
+        self.path = path
+
+    def __setitem__(self, key, value):
+        key = uuid.UUID(key)
+        if value is None:
+            raise ValueError("Stash value may not be set to None")
+        if key in self:
+            raise StashError("Tried to overwrite existing stash value "
+                             "for path %s and key %s (old value was %s, new value is %s)" %
+                             (self.path, key, self[str(key)], value))
+        else:
+            dict.__setitem__(self, key, value)
+
+    def __getitem__(self, key):
+        key = uuid.UUID(key)
+        rv = dict.get(self, key, None)
+        if rv is not None:
+            del self[key]
+        return rv
+
+
+class StashError(Exception):
+    pass