Source code for ska_sdp_batchlet.utils.monitor.handler

from contextlib import ExitStack, nullcontext

from .log import LogMonitor
from .resource import ResourceMonitor


# pylint: disable=R0903


class MonitorHandler:
    """
    Handles all monitoring related operations.

    It is responsible for instantiating and starting both
    :py:class:`LogMonitor` and :py:class:`ResourceMonitor` instances.

    Parameters
    ----------
    stack: ExitStack
        The ExitStack to register the monitors with.
        NOTE: The "stack" is pass by reference, and MonitorHandler
        will modify it.
    generate_reports_on_failure: bool, default=True
        Whether to generate monitoring report, even if there
        are any failures.
    resources: dict[dict], optional
        Optional dictionary of {start: {}, stop: {}} to pass
        to ResourceMonitor
    logs: dict, optional
        Optional dictionary of keyword arguments to pass
        to LogMonitor
    """

    def __init__(
        self,
        stack: ExitStack,
        generate_reports_on_failure=True,
        resources=None,
        logs=None,
    ):
        self.log_monitor = None
        self.resource_monitor = None

        if resources:
            self.resource_monitor = ResourceMonitor(
                generate_reports_on_failure=generate_reports_on_failure,
                **resources
            )

            stack.enter_context(self.resource_monitor)

        if logs:
            self.log_monitor = LogMonitor(**logs)
            stack.enter_context(self.log_monitor)

    @property
    def log_stream(self):
        """
        If log monitor is configured, start a new watcher subprocess,
        and return a io stream on which the logs of a application
        to be watched can be passed.

        If log monitor is not configured, return a nullcontext.
        """
        return (
            self.log_monitor.log_write_stream
            if self.log_monitor
            else nullcontext()
        )