--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebKitTools/Scripts/webkitpy/tool/bot/patchcollection.py	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,78 @@
+# Copyright (c) 2010 Google Inc. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+# 
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+# 
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+class PersistentPatchCollectionDelegate:
+    def collection_name(self):
+        raise NotImplementedError, "subclasses must implement"
+
+    def fetch_potential_patch_ids(self):
+        raise NotImplementedError, "subclasses must implement"
+
+    def status_server(self):
+        raise NotImplementedError, "subclasses must implement"
+
+    def is_terminal_status(self, status):
+        raise NotImplementedError, "subclasses must implement"
+
+
+class PersistentPatchCollection:
+    def __init__(self, delegate):
+        self._delegate = delegate
+        self._name = self._delegate.collection_name()
+        self._status = self._delegate.status_server()
+        self._status_cache = {}
+
+    def _cached_status(self, patch_id):
+        cached = self._status_cache.get(patch_id)
+        if cached:
+            return cached
+        status = self._status.patch_status(self._name, patch_id)
+        if status and self._delegate.is_terminal_status(status):
+            self._status_cache[patch_id] = status
+        return status
+
+    def _is_active_patch_id(self, patch_id):
+        """Active patches are patches waiting to be processed from this collection."""
+        status = self._cached_status(patch_id)
+        return not status or not self._delegate.is_terminal_status(status)
+
+    def _fetch_active_patch_ids(self):
+        patch_ids = self._delegate.fetch_potential_patch_ids()
+        return filter(lambda patch_id: self._is_active_patch_id(patch_id), patch_ids)
+
+    def next(self):
+        # Note: We only fetch all the ids so we can post them back to the server.
+        # This will go away once we have a feeder queue and all other queues are
+        # just pulling their next work item from the server.
+        patch_ids = self._fetch_active_patch_ids()
+        # FIXME: We're assuming self._name is a valid queue-name.
+        self._status.update_work_items(self._name, patch_ids)
+        if not patch_ids:
+            return None
+        return patch_ids[0]