#!/usr/bin/env vpython3
#
# Copyright 2013 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Sends a heart beat pulse to the currently online Android devices.
This heart beat lets the devices know that they are connected to a host.
"""
# pylint: disable=W0702

import sys
import time

import devil_chromium
from devil.android import device_utils

PULSE_PERIOD = 20


def main():
    devil_chromium.Initialize()

    while True:
        try:
            devices = device_utils.DeviceUtils.HealthyDevices(denylist=None)
            for d in devices:
                d.RunShellCommand(
                    ['touch', '/sdcard/host_heartbeat'], check_return=True
                )
        except:
            # Keep the heatbeat running bypassing all errors.
            pass
        time.sleep(PULSE_PERIOD)


if __name__ == '__main__':
    sys.exit(main())