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# Copyright (C) 2018 Codethink Limited
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library. If not, see <http://www.gnu.org/licenses/>.
#
# Author:
# Tristan Daniël Maat <tristan.maat@codethink.co.uk>
#
import os
from contextlib import contextmanager
from ruamel import yaml
from ..._message import Message, MessageType
from ...plugin import _plugin_lookup
from ... import _signals
from .job import Job
# ElementJob()
#
# A job to run an element's commands. When this job is spawned
# `action_cb` will be called, and when it completes `complete_cb` will
# be called.
#
# Args:
# scheduler (Scheduler): The scheduler
# action_name (str): The queue action name
# max_retries (int): The maximum number of retries
# action_cb (callable): The function to execute on the child
# complete_cb (callable): The function to execute when the job completes
# element (Element): The element to work on
# kwargs: Remaining Job() constructor arguments
#
# Here is the calling signature of the action_cb:
#
# action_cb():
#
# This function will be called in the child task
#
# Args:
# element (Element): The element passed to the Job() constructor
#
# Returns:
# (object): Any abstract simple python object, including a string, int,
# bool, list or dict, this must be a simple serializable object.
#
# Here is the calling signature of the complete_cb:
#
# complete_cb():
#
# This function will be called when the child task completes
#
# Args:
# job (Job): The job object which completed
# element (Element): The element passed to the Job() constructor
# success (bool): True if the action_cb did not raise an exception
# result (object): The deserialized object returned by the `action_cb`, or None
# if `success` is False
#
class ElementJob(Job):
def __init__(self, *args, element, queue, action_cb, complete_cb, **kwargs):
super().__init__(*args, **kwargs)
self.queue = queue
self._element = element
self._action_cb = action_cb # The action callable function
self._complete_cb = complete_cb # The complete callable function
@property
def element(self):
return self._element
# _child_process()
#
# This will be executed after fork(), and is intended to perform
# the job's task.
#
# Returns:
# (any): A (simple!) object to be returned to the main thread
# as the result.
#
def _child_process(self):
return self._action_cb(self._element)
def _parent_complete(self, success, result):
self._complete_cb(self, self._element, success, self._result)
# _child_logging_enabled()
#
# Start the log for this job. This function will be given a
# template string for the path to a log file - this will contain
# "{pid}", which should be replaced with the current process'
# PID. (i.e., call something like `logfile.format(pid=os.getpid())`).
#
# Args:
# logfile (str): A template string that points to the logfile
# that should be used - replace {pid} first.
#
# Yields:
# (str) The path to the logfile with {pid} replaced.
#
@contextmanager
def _child_logging_enabled(self, logfile):
self._logfile = logfile.format(pid=os.getpid())
with open(self._logfile, 'a') as log:
# Write one last line to the log and flush it to disk
def flush_log():
# If the process currently had something happening in the I/O stack
# then trying to reenter the I/O stack will fire a runtime error.
#
# So just try to flush as well as we can at SIGTERM time
try:
# FIXME: Better logging
log.write('\n\nAction {} for element {} forcefully terminated\n'
.format(self.action_name, self._element.name))
log.flush()
except RuntimeError:
os.fsync(log.fileno())
self._element._set_log_handle(log)
with _signals.terminator(flush_log):
self._print_start_message(self._element, self._logfile)
yield self._logfile
self._element._set_log_handle(None)
self._logfile = None
# _message():
#
# Sends a message to the frontend
#
# Args:
# message_type (MessageType): The type of message to send
# message (str): The message
# kwargs: Remaining Message() constructor arguments
#
def _message(self, message_type, message, **kwargs):
args = dict(kwargs)
args['scheduler'] = True
self._scheduler.context.message(
Message(self._element._get_unique_id(),
message_type,
message,
**args))
def _print_start_message(self, element, logfile):
self._message(MessageType.START, self.action_name, logfile=logfile)
# Print the element's environment at the beginning of any element's log file.
#
# This should probably be omitted for non-build tasks but it's harmless here
elt_env = element.get_environment()
env_dump = yaml.round_trip_dump(elt_env, default_flow_style=False, allow_unicode=True)
self._message(MessageType.LOG,
"Build environment for element {}".format(element.name),
detail=env_dump, logfile=logfile)
# _child_log()
#
# Log a message returned by the frontend's main message handler
# and return it to the main process.
#
# Arguments:
# message (str): The message to log
#
# Returns:
# message (Message): A message object
#
def _child_log(self, message):
# Tag them on the way out the door...
message.action_name = self.action_name
message.task_id = self._element._get_unique_id()
# Use the plugin for the task for the output, not a plugin
# which might be acting on behalf of the task
plugin = _plugin_lookup(message.task_id)
with plugin._output_file() as output:
message_text = self._format_frontend_message(message, '[{}]'.format(plugin.name))
output.write('{}\n'.format(message_text))
output.flush()
return message
# _child_process_data()
#
# Abstract method to retrieve additional data that should be
# returned to the parent process. Note that the job result is
# retrieved independently.
#
# Values can later be retrieved in Job.child_data.
#
# Returns:
# (dict) A dict containing values later to be read by _process_sync_data
#
def _child_process_data(self):
data = {}
workspace = self._element._get_workspace()
if workspace is not None:
data['workspace'] = workspace.to_dict()
return data
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