[Predator] Switch from anonymous dict to CrashData.

appengine/findit/crash/crash_report.py

Index: appengine/findit/crash/crash_report.py
diff --git a/appengine/findit/crash/crash_report.py b/appengine/findit/crash/crash_report.py
index fcae4a253189bd187f2593b523e6b4b2a7541234..2fd96d23cc27314bac2f27982da6cf5302f8722d 100644
--- a/appengine/findit/crash/crash_report.py
+++ b/appengine/findit/crash/crash_report.py
@@ -2,16 +2,35 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import logging
+from collections import defaultdict
 from collections import namedtuple
+import logging
+
+
+class _FrozenDict(dict):
+  """An immutable ``dict`` (or some approximation thereof).
 
-from crash.stacktrace import Stacktrace
+  The goal of this class is to render a ``dict`` hashable, so
+  that it can be used as a key in other ``dict``s, so that in
+  turn we can use our ``MemoizedFunction`` on functions taking
+  ``CrashReportWithDependencies`` as an argument.
+
+  For now, we simply define the ``__hash__`` method and assume clients
+  will not try to mutate instances after they have been stored as keys
+  in another ``dict``. In the future it may be worth taking further
+  steps to make it more difficult for clients to do such mutation.
+
+  N.B., the ``__init__`` method will clone the ``dict`` argument. There
+  doesn't seem to be an easy way around this.
+  """
+  def __hash__(self):
+      return hash(tuple(sorted(self.items())))
 
 
-class CrashReport(namedtuple('CrashReport',
-    ['crashed_version', 'signature', 'platform', 'stacktrace',
-     'regression_range'])):
-  """A reported crash we want to analyze.
+class CrashReport(namedtuple(
+    'CrashReport', ['crashed_version', 'signature', 'platform', 'stacktrace',
+                    'regression_range', 'dependencies', 'dependency_rolls'])):
+  """A crash report with all information needed for analysis for clients.
 
   This class comprises the inputs to the Predator library; as distinguished
   from the Culprit class, which comprises the outputs/results of Predator's
@@ -19,41 +38,32 @@ class CrashReport(namedtuple('CrashReport',
   a single CrashAnalysis(ndb.Model) class, but that's up to them; in
   the library we keep inputs and outputs entirely distinct.
 
-  Args:
+  Properties:
     crashed_version (str): The version of Chrome in which the crash occurred.
     signature (str): The signature of the crash on the Chrome crash server.
-    platform (str): The platform name; e.g., 'win', 'mac', 'linux', 'android',
-      'ios', etc.
+    platform (str): The platform affected by the crash; e.g., 'win',
+      'mac', 'linux', 'android', 'ios', etc.
     stacktrace (Stacktrace): The stacktrace of the crash. N.B., this is
       an object generated by parsing the string containing the stack trace;
       we do not store the string itself.
-    regression_range (pair or None): a pair of the last-good and first-bad
-      versions. N.B., because this is an input, it is up to clients
-      to call ``DetectRegressionRange`` (or whatever else) in order to
-      provide this information. In addition, while this class does
-      support storing ``None`` to indicate a missing regression range
-      (because the ClusterFuzz client wants that feature), the
-      CL-classifier doesn't actually support that so you won't get a
-      very good Culprit. The Component- and project-classifiers do still
-      return some results at least.
+    regression_range (pair of str or None): a pair of ``last_good_version`` and
+      ``first_bad_version``. The regression_range can be ``None``.
+    dependencies (_FrozenDict): An immutable dict from dependency paths to
+      ``Dependency`` objects. The keys are all those deps which are
+      used by both the ``crashed_version`` of the code, and at least
+      one frame in the ``stacktrace.crash_stack``.
+    dependency_rolls (_FrozenDict) An immutable dict from dependency
+      paths to ``DependencyRoll`` objects. The keys are all those
+      dependencies which (1) occur in the regression range for the
+      ``platform`` where the crash occurred, (2) neither add nor delete
+      a dependency, and (3) are also keys of ``dependencies``.
   """
   __slots__ = ()
 
   def __new__(cls, crashed_version, signature, platform, stacktrace,
-      regression_range):
-    assert isinstance(stacktrace, Stacktrace), TypeError(
-        'In the fourth argument to CrashReport constructor, '
-        'expected Stacktrace object, but got %s object instead.'
-        % stacktrace.__class__.__name__)
-
-    if regression_range is None: # pragma: no cover
-      logging.warning('CrashReport.__init__: '
-          'Got ``None`` for the regression range.')
-    else:
-      # We must ensure that the regression range is immutable, both
-      # for semantic reasons and so that it is hashable as is required
-      # for memoization.
-      regression_range = tuple(regression_range)
-
-    return super(cls, CrashReport).__new__(
-        cls, crashed_version, signature, platform, stacktrace, regression_range)
+              regression_range, dependencies, dependency_rolls):
+    return super(CrashReport, cls).__new__(
+        cls, crashed_version, signature, platform, stacktrace,
+        tuple(regression_range) if regression_range else None,
+        _FrozenDict(dependencies) if dependencies else {},
+        _FrozenDict(dependency_rolls) if dependency_rolls else {})