1# Copyright 2017, Google LLC 
    2# 
    3# Licensed under the Apache License, Version 2.0 (the "License"); 
    4# you may not use this file except in compliance with the License. 
    5# You may obtain a copy of the License at 
    6# 
    7#     http://www.apache.org/licenses/LICENSE-2.0 
    8# 
    9# Unless required by applicable law or agreed to in writing, software 
    10# distributed under the License is distributed on an "AS IS" BASIS, 
    11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
    12# See the License for the specific language governing permissions and 
    13# limitations under the License. 
    14 
    15"""Private helpers for futures.""" 
    16 
    17import logging 
    18import threading 
    19 
    20 
    21_LOGGER = logging.getLogger(__name__) 
    22 
    23 
    24def start_daemon_thread(*args, **kwargs): 
    25    """Starts a thread and marks it as a daemon thread.""" 
    26    thread = threading.Thread(*args, **kwargs) 
    27    thread.daemon = True 
    28    thread.start() 
    29    return thread 
    30 
    31 
    32def safe_invoke_callback(callback, *args, **kwargs): 
    33    """Invoke a callback, swallowing and logging any exceptions.""" 
    34    # pylint: disable=bare-except 
    35    # We intentionally want to swallow all exceptions. 
    36    try: 
    37        return callback(*args, **kwargs) 
    38    except Exception: 
    39        _LOGGER.exception("Error while executing Future callback.")