mpindexer.py 文件源码

def set_snapshot(xmin, snapshot_id):
    global current_xmin_snapshot_id
    if current_xmin_snapshot_id == (xmin, snapshot_id):
        return
    clear_snapshot()
    current_xmin_snapshot_id = (xmin, snapshot_id)

    while True:
        txn = transaction.begin()
        txn.doom()
        if snapshot_id is not None:
            txn.setExtendedInfo('snapshot_id', snapshot_id)
        session = app.registry[DBSESSION]()
        connection = session.connection()
        db_xmin = connection.execute(
            "SELECT txid_snapshot_xmin(txid_current_snapshot());").scalar()
        if db_xmin >= xmin:
            break
        transaction.abort()
        log.info('Waiting for xmin %r to reach %r', db_xmin, xmin)
        time.sleep(0.1)

    registry = app.registry
    request = app.request_factory.blank('/_indexing_pool')
    request.registry = registry
    request.datastore = 'database'
    apply_request_extensions(request)
    request.invoke_subrequest = app.invoke_subrequest
    request.root = app.root_factory(request)
    request._stats = {}
    manager.push({'request': request, 'registry': registry})