def _store_result(self,
task_id,
result,
state,
traceback=None,
request=None,
**kwargs):
meta = self._get_result_meta(result=result,
state=state,
traceback=traceback,
request=request)
meta['task_id'] = bytes_to_str(task_id)
# Retrieve metadata from the backend, if the status
# is a success then we ignore any following update to the state.
# This solves a task deduplication issue because of network
# partitioning or lost workers. This issue involved a race condition
# making a lost task overwrite the last successful result in the
# result backend.
current_meta = self._get_task_meta_for(task_id)
if current_meta['status'] == states.SUCCESS:
return result
try:
self._set_with_state(self.get_key_for_task(task_id),
self.encode(meta), state)
except BackendStoreError as ex:
raise BackendStoreError(str(ex), state=state,
task_id=task_id) from ex
return result
def store_result(self, task_id, result, state,
traceback=None, request=None, **kwargs):
"""Update task state and result.
if always_retry_backend_operation is activated, in the event of a recoverable exception,
then retry operation with an exponential backoff until a limit has been reached.
"""
result = self.encode_result(result, state)
retries = 0
while True:
try:
self._store_result(task_id, result, state, traceback,
request=request, **kwargs)
return result
except Exception as exc:
if self.always_retry and self.exception_safe_to_retry(exc):
if retries < self.max_retries:
retries += 1
# get_exponential_backoff_interval computes integers
# and time.sleep accept floats for sub second sleep
sleep_amount = get_exponential_backoff_interval(
self.base_sleep_between_retries_ms, retries,
self.max_sleep_between_retries_ms, True) / 1000
self._sleep(sleep_amount)
else:
raise_with_context(
BackendStoreError("failed to store result on the backend", task_id=task_id, state=state),
)
else:
raise
def set(self, key, value, **retry_policy):
if isinstance(value, str) and len(value) > self._MAX_STR_VALUE_SIZE:
raise BackendStoreError('value too large for Redis backend')
return self.ensure(self._set, (key, value), **retry_policy)