[Findit] Reorganizing findit_for_*.py

appengine/findit/crash/findit.py

+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import copy
+import logging
+
+from google.appengine.ext import ndb
+
+from common import appengine_util
+from common import chrome_dependency_fetcher
+from common import constants
+from common import time_util
+from crash.crash_report import CrashReport
+from crash.culprit import NullCulprit
+from model import analysis_status
+from model.crash.crash_config import CrashConfig
+from model.crash.cracas_crash_analysis import CracasCrashAnalysis
+from model.crash.fracas_crash_analysis import FracasCrashAnalysis
+
+# TODO(http://crbug.com/659346): since most of our unit tests are
+# FinditForFracas-specific, wrengr moved them to findit_for_chromecrash_test.py.
+# However, now we're missing coverage for most of this file (due to the
+# buggy way coverage is computed). Need to add a bunch of new unittests
+# to get coverage back up.
+
+# TODO: this class depends on ndb stuff, and should therefore move to
+# cr-culprit-finder/service/predator as part of the big reorganization.
+# Also, this class should be renamed to "PredatorApp" (alas, "Azalea"
+# was renamed to "Predator").
+class Findit(object):
+  def __init__(self, repository, pipeline_cls):
+    """
+    Args:
+      repository (Repository): the Git repository for getting CLs to classify.
+      pipeline_cls (class): the class for constructing pipelines in
+        ScheduleNewAnalysis. This will almost surely be
+        |crash.crash_pipeline.CrashWrapperPipeline|; but we must pass
+        the class in as a parameter in order to break an import cycle.
+    """
+    self._repository = repository
+    # TODO(http://crbug.com/659354): because self.client is volatile,
+    # we need some way of updating the Azelea instance whenever the
+    # config changes. How to do that cleanly?
+    self._azalea = None
+    self._stacktrace_parser = None
+    self._pipeline_cls = pipeline_cls
+
+  # This is a class method because it should be the same for all
+  # instances of this class. We can in fact call class methods on
+  # instances (not just on the class itself), so we could in principle
+  # get by with just this method. However, a @classmethod is treated
+  # syntactically like a method, thus we'd need to have the |()| at the
+  # end, unlike for a @property. Thus we have both the class method and
+  # the property, in order to simulate a class property.
+  @classmethod
+  def _ClientID(cls): # pragma: no cover
+    """Get the client id for this class.
+
+    This class method is private. Unless you really need to access
+    this method directly for some reason, you should use the |client_id|
+    property instead.
+
+    Returns:
+      A string which is member of the CrashClient enumeration.
+    """
+    if cls is Findit:
+      logging.warning('Findit is abstract, '
+          'but someone constructed an instance and called _ClientID')
+    else:
+      logging.warning('Findit subclass %s forgot to implement _ClientID',
+          cls.__name__)
+    raise NotImplementedError()
+
+  @property
+  def client_id(self):
+    """Get the client id from the class of this object.
+
+    N.B., this property is static and should not be overridden."""
+    return self._ClientID()
+
+  # TODO(http://crbug.com/659354): can we remove the dependency on
+  # CrashConfig entirely? It'd be better to receive method calls
+  # whenever things change, so that we know the change happened (and
+  # what in particular changed) so that we can update our internal state
+  # as appropriate.
+  @property
+  def config(self):
+    """Get the current value of the client config for the class of this object.
+
+    N.B., this property is volatile and may change asynchronously.
+
+    If the event of an error this method will return ``None``. That we do
+    not return the empty dict is intentional. All of the circumstances
+    which would lead to this method returning ``None`` indicate
+    underlying bugs in code elsewhere. (E.g., creating instances of
+    abstract classes, implementing a subclass which is not suppported by
+    ``CrashConfig``, etc.) Because we return ``None``, any subsequent
+    calls to ``__getitem__`` or ``get`` will raise method-missing errors;
+    which serve to highlight the underlying bug. Whereas, if we silently
+    returned the empty dict, then calls to ``get`` would "work" just
+    fine; thereby masking the underlying bug!
+    """
+    return CrashConfig.Get().GetClientConfig(self.client_id)
+
+  # TODO(http://crbug.com/644476): rename to CanonicalizePlatform or
+  # something like that.
+  def RenamePlatform(self, platform):
+    """Remap the platform to a different one, based on the config."""
+    # TODO(katesonia): Remove the default value after adding validity check to
+    # config.
+    return self.config.get('platform_rename', {}).get(platform, platform)
+
+  def CheckPolicy(self, crash_data): # pylint: disable=W0613
+    """Check whether this client supports analyzing the given report.
+
+    Some clients only support analysis for crashes on certain platforms
+    or channels, etc. This method checks to see whether this client can
+    analyze the given crash. The default implementation on the Findit
+    base class returns None for everything, so that unsupported clients
+    reject everything, as expected.
+
+    Args:
+      crash_data (JSON): ??
+
+    Returns:
+      If satisfied, we return the |crash_data| which may have had some
+      fields modified. Otherwise returns None.
+    """
+    return None
+
+  # TODO(http://crbug.com/644476): rename this to something like
+  # _NewAnalysis, since it only does the "allocation" and needs to/will
+  # be followed up with _InitializeAnalysis anyways.
+  def CreateAnalysis(self, crash_identifiers): # pylint: disable=W0613
+    return None
+
+  def GetAnalysis(self, crash_identifiers): # pylint: disable=W0613
+    """Return the CrashAnalysis for the |crash_identifiers|, if one exists.
+
+    Args:
+      crash_identifiers (JSON): ??
+
+    Returns:
+      If a CrashAnalysis ndb.Model already exists for the
+      |crash_identifiers|, then we return it. Otherwise, returns None.
+    """
+    return None
+
+  # TODO(wrengr): this should be a method on CrashAnalysis, not on Findit.
+  # TODO(http://crbug.com/659346): coverage tests for this class, not
+  # just for FinditForFracas.
+  def _InitializeAnalysis(self, model, crash_data): # pragma: no cover
+    """(Re)Initialize a CrashAnalysis ndb.Model, but do not |put()| it yet.
+
+    This method is only ever called from _NeedsNewAnalysis which is only
+    ever called from ScheduleNewAnalysis. It is used for filling in the
+    fields of a CrashAnalysis ndb.Model for the first time (though it
+    can also be used to re-initialize a given CrashAnalysis). Subclasses
+    should extend (not override) this to (re)initialize any
+    client-specific fields they may have."""
+    # Get rid of any previous values there may have been.
+    model.Reset()
+
+    # Set the version.
+    # |handlers.crash.test.crash_handler_test.testAnalysisScheduled|
+    # provides and expects this field to be called 'chrome_version',
+    # whereas everyone else (e.g., in |crash.test.crash_pipeline_test|
+    # the tests |testAnalysisNeededIfNoAnalysisYet|,
+    # |testRunningAnalysisNoSuspectsFound|, |testRunningAnalysis|,
+    # |testAnalysisNeededIfLastOneFailed|, |testRunningAnalysisWithSuspectsCls|)
+    # expects it to be called 'crashed_version'. The latter is the
+    # better/more general name, so the former needs to be changed in
+    # order to get rid of this defaulting ugliness.
+    model.crashed_version = crash_data.get('crashed_version',
+        crash_data.get('chrome_version', None))
+
+    # Set (other) common properties.
+    model.stack_trace = crash_data['stack_trace']
+    model.signature = crash_data['signature']
+    model.platform = crash_data['platform']
+    # TODO(wrengr): The only reason to have _InitializeAnalysis as a
+    # method of the Findit class rather than as a method on CrashAnalysis
+    # is so we can assert that crash_data['client_id'] == self.client_id.
+    # So, either we should do that, or else we should move this to be
+    # a method on CrashAnalysis.
+    model.client_id = self.client_id
+
+    # Set progress properties.
+    model.status = analysis_status.PENDING
+    model.requested_time = time_util.GetUTCNow()
+
+  @ndb.transactional
+  def _NeedsNewAnalysis(self, crash_data):
+    raise NotImplementedError()
+
+  # TODO(http://crbug.com/659345): try to break the cycle re pipeline_cls.
+  # TODO(http://crbug.com/659346): we don't cover anything after the
+  # call to _NeedsNewAnalysis.
+  def ScheduleNewAnalysis(self, crash_data,
+      queue_name=constants.DEFAULT_QUEUE): # pragma: no cover
+    """Create a pipeline object to perform the analysis, and start it.
+
+    If we can detect that the analysis doesn't need to be performed
+    (e.g., it was already performed, or the |crash_data| is empty so
+    there's nothig we can do), then we will skip creating the pipeline
+    at all.
+
+    Args:
+      crash_data (JSON): ??
+      queue_name (??): the name of the AppEngine queue we should start
+        the pipeline on.
+
+    Returns:
+      True if we started the pipeline; False otherwise.
+    """
+    # Check policy and tune arguments if needed.
+    crash_data = self.CheckPolicy(crash_data)
+    if crash_data is None:
+      return False
+
+    # Detect the regression range, and decide if we actually need to
+    # run a new anlaysis or not.
+    if not self._NeedsNewAnalysis(crash_data):
+      return False
+
+    crash_identifiers = crash_data['crash_identifiers']
+    # N.B., we cannot pass |self| directly to the _pipeline_cls, because
+    # it is not JSON-serializable (and there's no way to make it such,
+    # since JSON-serializability is defined by JSON-encoders rather than
+    # as methods on the objects being encoded).
+    analysis_pipeline = self._pipeline_cls(self.client_id, crash_identifiers)
+    # Attribute defined outside __init__ - pylint: disable=W0201
+    analysis_pipeline.target = appengine_util.GetTargetNameForModule(
+        constants.CRASH_BACKEND[self.client_id])
+    analysis_pipeline.start(queue_name=queue_name)
+    logging.info('New %s analysis is scheduled for %s', self.client_id,
+                 repr(crash_identifiers))
+    return True
+
+  # TODO(wrengr): does the parser actually need the version, signature,
+  # and platform? If not, then we should be able to just pass the string
+  # to be parsed (which would make a lot more sense than passing the
+  # whole model).
+  # TODO(http://crbug.com/659346): coverage tests for this class, not
+  # just for FinditForFracas.
+  def ParseStacktrace(self, model): # pragma: no cover
+    """Parse a CrashAnalysis's |stack_trace| string into a Stacktrace object.
+
+    Args:
+      model (CrashAnalysis): The model containing the stack_trace string
+        to be parsed.
+
+    Returns:
+      On success, returns a Stacktrace object; on failure, returns None.
+    """
+    stacktrace = self._stacktrace_parser.Parse(
+        model.stack_trace,
+        chrome_dependency_fetcher.ChromeDependencyFetcher(
+            self._repository
+            ).GetDependency(
+                model.crashed_version,
+                model.platform),
+        model.signature)
+    if not stacktrace:
+      logging.warning('Failed to parse the stacktrace %s', model.stack_trace)
+      return None
+
+    return stacktrace
+
+  # TODO(wrengr): This is only called by |CrashAnalysisPipeline.run|;
+  # we should be able to adjust things so that we only need to take in
+  # |crash_identifiers|, or a CrashReport, rather than taking in the
+  # whole model. And/or, we should just inline this there.
+  # TODO(http://crbug.com/659346): coverage tests for this class, not
+  # just for FinditForFracas.
+  def FindCulprit(self, model): # pragma: no cover
+    """Given a CrashAnalysis ndb.Model, return a Culprit."""
+    stacktrace = self.ParseStacktrace(model)
+    if stacktrace is None:
+      # TODO(http://crbug.com/659359): refactor things so we don't need
+      # the NullCulprit class.
+      return NullCulprit()
+
+    return self._azalea.FindCulprit(CrashReport(
+        crashed_version = model.crashed_version,
+        signature = model.signature,
+        platform = model.platform,
+        stacktrace = stacktrace,
+        regression_range = model.regression_range))