1 # Copyright 2017 The Chromium OS Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 from __future__ import absolute_import 6 from __future__ import print_function 7 8 import logging 9 10 import common 11 from autotest_lib.server.hosts import host_info 12 from chromite.lib import metrics 13 14 15 _METRICS_PREFIX = 'chromeos/autotest/autoserv/host_info/shadowing_store/' 16 _REFRESH_METRIC_NAME = _METRICS_PREFIX + 'refresh_count' 17 _COMMIT_METRIC_NAME = _METRICS_PREFIX + 'commit_count' 18 19 20 logger = logging.getLogger(__file__) 21 22 class ShadowingStore(host_info.CachingHostInfoStore): 23 """A composite CachingHostInfoStore that maintains a main and shadow store. 24 25 ShadowingStore accepts two CachingHostInfoStore objects - primary_store and 26 shadow_store. All refresh/commit operations are serviced through 27 primary_store. In addition, shadow_store is updated and compared with this 28 information, leaving breadcrumbs when the two differ. Any errors in 29 shadow_store operations are logged and ignored so as to not affect the user. 30 31 This is a transitional CachingHostInfoStore that allows us to continue to 32 use an AfeStore in practice, but also create a backing FileStore so that we 33 can validate the use of FileStore in prod. 34 """ 35 36 def __init__(self, primary_store, shadow_store, 37 mismatch_callback=None): 38 """ 39 @param primary_store: A CachingHostInfoStore to be used as the primary 40 store. 41 @param shadow_store: A CachingHostInfoStore to be used to shadow the 42 primary store. 43 @param mismatch_callback: A callback used to notify whenever we notice a 44 mismatch between primary_store and shadow_store. The signature 45 of the callback must match: 46 callback(primary_info, shadow_info) 47 where primary_info and shadow_info are HostInfo objects obtained 48 from the two stores respectively. 49 Mostly used by unittests. Actual users don't know / nor care 50 that they're using a ShadowingStore. 51 """ 52 super(ShadowingStore, self).__init__() 53 self._primary_store = primary_store 54 self._shadow_store = shadow_store 55 self._mismatch_callback = ( 56 mismatch_callback if mismatch_callback is not None 57 else _log_info_mismatch) 58 try: 59 self._shadow_store.commit(self._primary_store.get()) 60 except host_info.StoreError as e: 61 metrics.Counter( 62 _METRICS_PREFIX + 'initialization_fail_count').increment() 63 logger.exception( 64 'Failed to initialize shadow store. ' 65 'Expect primary / shadow desync in the future.') 66 67 def __str__(self): 68 return '%s[%s, %s]' % (type(self).__name__, self._primary_store, 69 self._shadow_store) 70 71 def _refresh_impl(self): 72 """Obtains HostInfo from the primary and compares against shadow""" 73 primary_info = self._refresh_from_primary_store() 74 try: 75 shadow_info = self._refresh_from_shadow_store() 76 except host_info.StoreError: 77 logger.exception('Shadow refresh failed. ' 78 'Skipping comparison with primary.') 79 return primary_info 80 self._verify_store_infos(primary_info, shadow_info) 81 return primary_info 82 83 def _commit_impl(self, info): 84 """Commits HostInfo to both the primary and shadow store""" 85 self._commit_to_primary_store(info) 86 self._commit_to_shadow_store(info) 87 88 def _commit_to_primary_store(self, info): 89 try: 90 self._primary_store.commit(info) 91 except host_info.StoreError: 92 metrics.Counter(_COMMIT_METRIC_NAME).increment( 93 fields={'file_commit_result': 'skipped'}) 94 raise 95 96 def _commit_to_shadow_store(self, info): 97 try: 98 self._shadow_store.commit(info) 99 except host_info.StoreError: 100 logger.exception( 101 'shadow commit failed. ' 102 'Expect primary / shadow desync in the future.') 103 metrics.Counter(_COMMIT_METRIC_NAME).increment( 104 fields={'file_commit_result': 'fail'}) 105 else: 106 metrics.Counter(_COMMIT_METRIC_NAME).increment( 107 fields={'file_commit_result': 'success'}) 108 109 def _refresh_from_primary_store(self): 110 try: 111 return self._primary_store.get(force_refresh=True) 112 except host_info.StoreError: 113 metrics.Counter(_REFRESH_METRIC_NAME).increment( 114 fields={'validation_result': 'skipped'}) 115 raise 116 117 def _refresh_from_shadow_store(self): 118 try: 119 return self._shadow_store.get(force_refresh=True) 120 except host_info.StoreError: 121 metrics.Counter(_REFRESH_METRIC_NAME).increment(fields={ 122 'validation_result': 'fail_shadow_store_refresh'}) 123 raise 124 125 def _verify_store_infos(self, primary_info, shadow_info): 126 if primary_info == shadow_info: 127 metrics.Counter(_REFRESH_METRIC_NAME).increment( 128 fields={'validation_result': 'success'}) 129 else: 130 self._mismatch_callback(primary_info, shadow_info) 131 metrics.Counter(_REFRESH_METRIC_NAME).increment( 132 fields={'validation_result': 'fail_mismatch'}) 133 self._shadow_store.commit(primary_info) 134 135 136 def _log_info_mismatch(primary_info, shadow_info): 137 """Log the two HostInfo instances. 138 139 Used as the default mismatch_callback. 140 """ 141 logger.warning('primary / shadow disagree on refresh.') 142 logger.warning('primary: %s', primary_info) 143 logger.warning('shadow: %s', shadow_info) 144
