Create CachingRietveld to automatically cache results for presubmit checks.

rietveld.py

Index: rietveld.py
diff --git a/rietveld.py b/rietveld.py
index d4ac39bab08060ea3c6414d3b9ad32b986d266f0..5d81e7396e4016831b330923a53994de67d060cf 100644
--- a/rietveld.py
+++ b/rietveld.py
@@ -14,6 +14,7 @@ The following hypothesis are made:
   - A patch set cannot be modified
 """
 
+import copy
 import json
 import logging
 import re
@@ -395,3 +396,41 @@ class Rietveld(object):
 
   # DEPRECATED.
   Send = get
+
+
+class CachingRietveld(Rietveld):
+  """Caches the common queries.
+
+  Not to be used in long-standing processes, like the commit queue.
+  """
+  def __init__(self, *args, **kwargs):
+    super(CachingRietveld, self).__init__(*args, **kwargs)
+    self._cache = {}
+
+  def _lookup(self, function_name, args, update):
+    """Caches the return values corresponding to the arguments.
+
+    It is important that the arguments are standardized, like None vs False.
+    """
+    function_cache = self._cache.setdefault(function_name, {})
+    if args not in function_cache:
+      function_cache[args] = update(*args)
+    return copy.deepcopy(function_cache[args])
+
+  def get_description(self, issue):
+    return self._lookup(
+        'get_description',
+        (issue,),
+        super(CachingRietveld, self).get_description)
+
+  def get_issue_properties(self, issue, messages):

[Isaac (away), 2012/11/26 05:12:39]

get_issue_properties(<issue>, True) returns a superset of
get_issue_properties(<issue>, False).

Could we modify this for the False call to return the True call if it is cached?

[M-A Ruel, 2012/11/27 20:15:06]

Done

+    return self._lookup(
+        'get_issue_properties',
+        (issue, bool(messages)),
+        super(CachingRietveld, self).get_issue_properties)
+
+  def get_patchset_properties(self, issue, patchset):
+    return self._lookup(
+        'get_patchset_properties',
+        (issue, patchset),
+        super(CachingRietveld, self).get_patchset_properties)