def save_command(self, command: offchain.Command) -> None:
"""save command locks prior command by reference id, validate and save new command.
in a production implementation, the lock should be database / distributed lock to ensure
atomic process(read and write) command by the reference id.
"""
lock = self.lock(command.reference_id())
if not lock.acquire(blocking=False):
msg = f"command(reference_id={command.reference_id()}) is locked"
raise offchain.command_error(offchain.ErrorCode.conflict, msg)
try:
prior = self.saved_commands.get(command.reference_id())
if command == prior:
return
command.validate(prior)
self.saved_commands[command.reference_id()] = command
if command.is_inbound():
self._enqueue_follow_up_action(command)
else: # outbound
self.task_queue.append(lambda app: app._send_request(command))
finally:
lock.release()
def _enqueue_follow_up_action(self, command: offchain.Command) -> None:
if command.follow_up_action():
self.task_queue.append(lambda app: app._offchain_business_action(command.reference_id()))