def write_varenv(self, qs, varenv):
"""Write to the graph the specified "query"."""
if getattr(self, 'readonly', None):
raise GraphConnectionError(
'Tried to write to a read-only graph',
http_code=500,
app_code='/mqlwrite/backend/read_only')
dateline_in = varenv.get('write_dateline', None)
self.write_occurred = 1
try:
r = self._generate_and_transmit_query(qs, varenv, WriteMode)
except MQLDatelineInvalidError:
# see read_varenv comment on this
LOG.info('mqlwrite.dateline.delete',
'got an invalid dateline, deleting from varenv',
varenv.get('write_dateline'))
varenv['write_dateline'] = ''
r = self._generate_and_transmit_query(qs, varenv, WriteMode)
dateline_out = r.dateline
# update our write_dateline in case we do subsequent reads
# or writes. The new 'write_dateline' is returned to the
# user for use with subsequent mqlreads or mqlwrites they do
varenv['write_dateline'] = dateline_out
varenv['last_write_time'] = time.time()
log_graph_write(varenv, dateline_in, dateline_out)
LOG.debug(
'graph.write_dateline.set',
'',
last_write_time=varenv['last_write_time'],
write_dateline=varenv['write_dateline'])
# Record that a write has happened and following writes should set
# the continuation flag.
varenv['is_write_continuation'] = True
return r
def read_varenv(self, qs, varenv):
"""Read from the graph the specified "query"."""
try:
# the pymql user provides a 'write_dateline', which should be a valid
# dateline returned to said user by a previous mqlwrite query
dateline_in = varenv.get('write_dateline', None)
r = self._generate_and_transmit_query(qs, varenv, ReadMode)
except MQLDatelineInvalidError:
# Drop the datelines out of the varenv,
# re-generate the query and try again.
# the main use case here is when sandbox is refreshed
# and the instance id in the dateline changes. The user's dateline
# (usually in a cookie) is now invalid until they do a write, or a touch
LOG.info('mqlread.dateline.delete',
'got an invalid dateline, deleting from varenv',
varenv.get('write_dateline'))
varenv['write_dateline'] = ''
r = self._generate_and_transmit_query(qs, varenv, ReadMode)
if not r and varenv.get('graph_noisy'):
raise EmptyResult('query %s' % qs)
dateline_out = r.dateline
# 'dateline' is returned to the original caller of pymql read.
# though, in practice, it is not passed on by frapi and
# they really should only update their dateline after doing
# a write.
# we do *not* update the internal 'write_dateline' varenv, here.
# in the case of reads, the idea being the user only needs to
# demand the level of freshness of their last write, so
# subsequent reads in this session will use the original
# 'write_dateline' provided by the caller of pymql read/write.
# the 'write_dateline' is updated in the event that a write
# occurs in this session.
varenv['dateline'] = dateline_out
log_graph_read(varenv, dateline_in, dateline_out)
LOG.debug('graph.dateline.set', '', dateline=varenv['dateline'])
return r
def __init__(self,
no_timeouts=False,
policy_map=None,
default_policy=None,
custom_policy=None):
self.reset_cost()
self.timeout_policies = policy_map
if default_policy:
self.default_policy = default_policy
else:
self.default_policy = self.DEFAULT_POLICY_NAME
self.no_timeouts = no_timeouts
if custom_policy:
LOG.info('gc.custom.timeout.policy', '', policy=str(custom_policy))
self.timeout_policies['custom'] = custom_policy
self.default_policy = 'custom'
response['request_id'] = sq['request_id']
# should only looking either at sq['query'] for a single query or
# sq['queries'] for multiple queries
for id, subq in valid_queries:
# assuming querier is a bound method here..
LOG.notice('Query',
'%s.%s' % (querier.im_class.__name__, querier.__name__),
subq=subq)
try:
results[id] = querier(subq, varenv)
response.extend(status='200 OK')
except EmptyResult, e:
LOG.info('emptyresult', '%s' % e)
response.log('empty result for query %s' % subq)
result = None
# exceptions should be packed into response['error']
except ParameterizedError, e:
if isinstance(e, MQLInternalError):
response.extend(status='500 Internal Server Error')
else:
response.extend(status='400 Bad Request')
tb = json_traceback(response=response, exception=e)
response.log('parse exception: %s' % e, level='error')
result = None
except Exception, e:
LOG.exception('python.exception')
