blob: 31fd013052efdfa0dd6df0a90f4f0a79862acd93 [file] [log] [blame]
# Copyright 2017 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
from __future__ import absolute_import
from __future__ import print_function
import logging
import common
from autotest_lib.server.hosts import host_info
from chromite.lib import metrics
_METRICS_PREFIX = 'chromeos/autotest/autoserv/host_info/shadowing_store/'
_REFRESH_METRIC_NAME = _METRICS_PREFIX + 'refresh_count'
_COMMIT_METRIC_NAME = _METRICS_PREFIX + 'commit_count'
logger = logging.getLogger(__file__)
class ShadowingStore(host_info.CachingHostInfoStore):
"""A composite CachingHostInfoStore that maintains a main and shadow store.
ShadowingStore accepts two CachingHostInfoStore objects - primary_store and
shadow_store. All refresh/commit operations are serviced through
primary_store. In addition, shadow_store is updated and compared with this
information, leaving breadcrumbs when the two differ. Any errors in
shadow_store operations are logged and ignored so as to not affect the user.
This is a transitional CachingHostInfoStore that allows us to continue to
use an AfeStore in practice, but also create a backing FileStore so that we
can validate the use of FileStore in prod.
"""
def __init__(self, primary_store, shadow_store,
mismatch_callback=None):
"""
@param primary_store: A CachingHostInfoStore to be used as the primary
store.
@param shadow_store: A CachingHostInfoStore to be used to shadow the
primary store.
@param mismatch_callback: A callback used to notify whenever we notice a
mismatch between primary_store and shadow_store. The signature
of the callback must match:
callback(primary_info, shadow_info)
where primary_info and shadow_info are HostInfo objects obtained
from the two stores respectively.
Mostly used by unittests. Actual users don't know / nor care
that they're using a ShadowingStore.
"""
super(ShadowingStore, self).__init__()
self._primary_store = primary_store
self._shadow_store = shadow_store
self._mismatch_callback = (
mismatch_callback if mismatch_callback is not None
else _log_info_mismatch)
try:
self._shadow_store.commit(self._primary_store.get())
except host_info.StoreError as e:
metrics.Counter(
_METRICS_PREFIX + 'initialization_fail_count').increment()
logger.exception(
'Failed to initialize shadow store. '
'Expect primary / shadow desync in the future.')
def __str__(self):
return '%s[%s, %s]' % (type(self).__name__, self._primary_store,
self._shadow_store)
def _refresh_impl(self):
"""Obtains HostInfo from the primary and compares against shadow"""
primary_info = self._refresh_from_primary_store()
try:
shadow_info = self._refresh_from_shadow_store()
except host_info.StoreError:
logger.exception('Shadow refresh failed. '
'Skipping comparison with primary.')
return primary_info
self._verify_store_infos(primary_info, shadow_info)
return primary_info
def _commit_impl(self, info):
"""Commits HostInfo to both the primary and shadow store"""
self._commit_to_primary_store(info)
self._commit_to_shadow_store(info)
def _commit_to_primary_store(self, info):
try:
self._primary_store.commit(info)
except host_info.StoreError:
metrics.Counter(_COMMIT_METRIC_NAME).increment(
fields={'file_commit_result': 'skipped'})
raise
def _commit_to_shadow_store(self, info):
try:
self._shadow_store.commit(info)
except host_info.StoreError:
logger.exception(
'shadow commit failed. '
'Expect primary / shadow desync in the future.')
metrics.Counter(_COMMIT_METRIC_NAME).increment(
fields={'file_commit_result': 'fail'})
else:
metrics.Counter(_COMMIT_METRIC_NAME).increment(
fields={'file_commit_result': 'success'})
def _refresh_from_primary_store(self):
try:
return self._primary_store.get(force_refresh=True)
except host_info.StoreError:
metrics.Counter(_REFRESH_METRIC_NAME).increment(
fields={'validation_result': 'skipped'})
raise
def _refresh_from_shadow_store(self):
try:
return self._shadow_store.get(force_refresh=True)
except host_info.StoreError:
metrics.Counter(_REFRESH_METRIC_NAME).increment(fields={
'validation_result': 'fail_shadow_store_refresh'})
raise
def _verify_store_infos(self, primary_info, shadow_info):
if primary_info == shadow_info:
metrics.Counter(_REFRESH_METRIC_NAME).increment(
fields={'validation_result': 'success'})
else:
self._mismatch_callback(primary_info, shadow_info)
metrics.Counter(_REFRESH_METRIC_NAME).increment(
fields={'validation_result': 'fail_mismatch'})
self._shadow_store.commit(primary_info)
def _log_info_mismatch(primary_info, shadow_info):
"""Log the two HostInfo instances.
Used as the default mismatch_callback.
"""
logger.warning('primary / shadow disagree on refresh.')
logger.warning('primary: %s', primary_info)
logger.warning('shadow: %s', shadow_info)