Code snippet of Cradle's Firestore watcher

watch.py

def callback(docs: List[firestore.DocumentSnapshot],
                 changes: List[DocumentChange],
                 _: DatetimeWithNanoseconds):
        try:
            for document, change in zip(docs, changes):
                if change.type in {ChangeType.ADDED, ChangeType.MODIFIED}:
                    job_doc = firestore.DocumentReference(*document.reference._path, client=db_client)
                    if not job_doc.path.startswith(f'{firestore_prefix}users'):
                        continue
                    pre_status = document.get('status')
                    if pre_status in ['PENDING', 'MSA_COMPLETE']:
                        if pre_status == 'PENDING':  # check that quota wasn't exceeded (by tampering with client check)
                            user_doc = job_doc.parent
                            active_job_count = mark_stale_jobs(user_doc)
                            if active_job_count >= MAX_ACTIVE_COUNT:
                                job_doc.update(
                                    {'status': 'FOLDING_FAILED', 'pdb_error': 'Maximum number of active jobs exceeded'})
                                logging.warning(f'Job {job_doc.id} is not sent for processing. Too many active jobs')
                                continue

                        logging.info(f'Found new job {document.reference.path} with status {pre_status}')