| # |
| # Copyright (C) 2016 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/>. |
| # |
| # Authors: |
| # Tristan Van Berkom <tristan.vanberkom@codethink.co.uk> |
| # Jürg Billeter <juerg.billeter@codethink.co.uk> |
| |
| # System imports |
| import os |
| import asyncio |
| import signal |
| import datetime |
| from contextlib import contextmanager |
| |
| # Local imports |
| from .queues import QueueType |
| |
| |
| # A decent return code for Scheduler.run() |
| class SchedStatus(): |
| SUCCESS = 0 |
| ERROR = -1 |
| TERMINATED = 1 |
| |
| |
| # Scheduler() |
| # |
| # The scheduler operates on a list queues, each of which is meant to accomplish |
| # a specific task. Elements enter the first queue when Scheduler.run() is called |
| # and into the next queue when complete. Scheduler.run() returns when all of the |
| # elements have been traversed or when an occurs. |
| # |
| # Using the scheduler is a matter of: |
| # a.) Deriving the Queue class and implementing its abstract methods |
| # b.) Instantiating a Scheduler with one or more queues |
| # c.) Calling Scheduler.run(elements) with a list of elements |
| # d.) Fetching results from your queues |
| # |
| # Args: |
| # context: The Context in the parent scheduling process |
| # start_time: The time at which the session started |
| # interrupt_callback: A callback to handle ^C |
| # ticker_callback: A callback call once per second |
| # job_start_callback: A callback call when each job starts |
| # job_complete_callback: A callback call when each job completes |
| # |
| class Scheduler(): |
| |
| def __init__(self, context, |
| start_time, |
| interrupt_callback=None, |
| ticker_callback=None, |
| job_start_callback=None, |
| job_complete_callback=None): |
| |
| # |
| # Public members |
| # |
| self.queues = None # Exposed for the frontend to print summaries |
| self.context = context # The Context object shared with Queues |
| self.terminated = False # Whether the scheduler was asked to terminate or has terminated |
| self.suspended = False # Whether the scheduler is currently suspended |
| |
| # These are shared with the Job, but should probably be removed or made private in some way. |
| self.loop = None # Shared for Job access to observe the message queue |
| self.internal_stops = 0 # Amount of SIGSTP signals we've introduced, this is shared with job.py |
| |
| # |
| # Private members |
| # |
| self._interrupt_callback = interrupt_callback |
| self._ticker_callback = ticker_callback |
| self._job_start_callback = job_start_callback |
| self._job_complete_callback = job_complete_callback |
| |
| self._starttime = start_time |
| self._suspendtime = None |
| self._queue_jobs = True # Whether we should continue to queue jobs |
| |
| # Initialize task tokens with the number allowed by |
| # the user configuration |
| self._job_tokens = { |
| QueueType.FETCH: context.sched_fetchers, |
| QueueType.BUILD: context.sched_builders, |
| QueueType.PUSH: context.sched_pushers |
| } |
| |
| # run() |
| # |
| # Args: |
| # queues (list): A list of Queue objects |
| # |
| # Returns: |
| # (SchedStatus): How the scheduling terminated |
| # |
| # Elements in the 'plan' will be processed by each |
| # queue in order. Processing will complete when all |
| # elements have been processed by each queue or when |
| # an error arises |
| # |
| def run(self, queues): |
| |
| # Hold on to the queues to process |
| self.queues = queues |
| |
| # Ensure that we have a fresh new event loop, in case we want |
| # to run another test in this thread. |
| self.loop = asyncio.new_event_loop() |
| asyncio.set_event_loop(self.loop) |
| |
| # Add timeouts |
| if self._ticker_callback: |
| self.loop.call_later(1, self._tick) |
| |
| # Handle unix signals while running |
| self._connect_signals() |
| |
| # Run the queues |
| self.sched() |
| self.loop.run_forever() |
| self.loop.close() |
| |
| # Stop handling unix signals |
| self._disconnect_signals() |
| |
| failed = any(any(queue.failed_elements) for queue in self.queues) |
| self.loop = None |
| |
| if failed: |
| status = SchedStatus.ERROR |
| elif self.terminated: |
| status = SchedStatus.TERMINATED |
| else: |
| status = SchedStatus.SUCCESS |
| |
| return self.elapsed_time(), status |
| |
| # terminate_jobs() |
| # |
| # Forcefully terminates all ongoing jobs. |
| # |
| # For this to be effective, one needs to return to |
| # the scheduler loop first and allow the scheduler |
| # to complete gracefully. |
| # |
| # NOTE: This will block SIGINT so that graceful process |
| # termination is not interrupted, and SIGINT will |
| # remain blocked after Scheduler.run() returns. |
| # |
| def terminate_jobs(self): |
| |
| # Set this right away, the frontend will check this |
| # attribute to decide whether or not to print status info |
| # etc and the following code block will trigger some callbacks. |
| self.terminated = True |
| self.loop.call_soon(self._terminate_jobs_real) |
| |
| # Block this until we're finished terminating jobs, |
| # this will remain blocked forever. |
| signal.pthread_sigmask(signal.SIG_BLOCK, [signal.SIGINT]) |
| |
| # jobs_suspended() |
| # |
| # A context manager for running with jobs suspended |
| # |
| @contextmanager |
| def jobs_suspended(self): |
| self._disconnect_signals() |
| self._suspend_jobs() |
| |
| yield |
| |
| self._resume_jobs() |
| self._connect_signals() |
| |
| # stop_queueing() |
| # |
| # Stop queueing additional jobs, causes Scheduler.run() |
| # to return once all currently processing jobs are finished. |
| # |
| def stop_queueing(self): |
| self._queue_jobs = False |
| |
| # elapsed_time() |
| # |
| # Fetches the current session elapsed time |
| # |
| # Returns: |
| # (datetime): The amount of time since the start of the session, |
| # discounting any time spent while jobs were suspended. |
| # |
| def elapsed_time(self): |
| timenow = datetime.datetime.now() |
| starttime = self._starttime |
| if not starttime: |
| starttime = timenow |
| return timenow - starttime |
| |
| # sched() |
| # |
| # The main driving function of the scheduler, it will be called |
| # automatically when Scheduler.run() is called initially, and needs |
| # to be called whenever a job can potentially be scheduled, usually |
| # when a Queue completes handling of a job. |
| # |
| # This will process the Queues and pull elements through the Queues |
| # and process anything that is ready. |
| # |
| def sched(self): |
| |
| process_queues = True |
| |
| while self._queue_jobs and process_queues: |
| |
| # Pull elements forward through queues |
| elements = [] |
| for queue in self.queues: |
| # Enqueue elements complete from the last queue |
| queue.enqueue(elements) |
| |
| # Dequeue processed elements for the next queue |
| elements = list(queue.dequeue()) |
| elements = list(elements) |
| |
| # Kickoff whatever processes can be processed at this time |
| # |
| # We start by queuing from the last queue first, because we want to |
| # give priority to queues later in the scheduling process in the case |
| # that multiple queues share the same token type. |
| # |
| # This avoids starvation situations where we dont move on to fetch |
| # tasks for elements which failed to pull, and thus need all the pulls |
| # to complete before ever starting a build |
| for queue in reversed(self.queues): |
| queue.process_ready() |
| |
| # process_ready() may have skipped jobs, adding them to the done_queue. |
| # Pull these skipped elements forward to the next queue and process them. |
| process_queues = any(q.dequeue_ready() for q in self.queues) |
| |
| # If nothings ticking, time to bail out |
| ticking = 0 |
| for queue in self.queues: |
| ticking += len(queue.active_jobs) |
| |
| if ticking == 0: |
| self.loop.stop() |
| |
| # get_job_token(): |
| # |
| # Used by the Queue object to obtain a token for |
| # processing a Job, if a Queue does not receive a token |
| # then it must wait until a later time in order to |
| # process pending jobs. |
| # |
| # Args: |
| # queue_type (QueueType): The type of token to obtain |
| # |
| # Returns: |
| # (bool): Whether a token was handed out or not |
| # |
| def get_job_token(self, queue_type): |
| if self._job_tokens[queue_type] > 0: |
| self._job_tokens[queue_type] -= 1 |
| return True |
| return False |
| |
| # put_job_token(): |
| # |
| # Return a job token to the scheduler. Tokens previously |
| # received with get_job_token() must be returned to |
| # the scheduler once the associated job is complete. |
| # |
| # Args: |
| # queue_type (QueueType): The type of token to obtain |
| # |
| def put_job_token(self, queue_type): |
| self._job_tokens[queue_type] += 1 |
| |
| # job_starting(): |
| # |
| # Called by the Queue when starting a Job |
| # |
| # Args: |
| # job (Job): The starting Job |
| # |
| def job_starting(self, job): |
| if self._job_start_callback: |
| self._job_start_callback(job.element, job.action_name) |
| |
| # job_completed(): |
| # |
| # Called by the Queue when a Job completes |
| # |
| # Args: |
| # queue (Queue): The Queue holding a complete job |
| # job (Job): The completed Job |
| # success (bool): Whether the Job completed with a success status |
| # |
| def job_completed(self, queue, job, success): |
| if self._job_complete_callback: |
| self._job_complete_callback(job.element, queue, job.action_name, success) |
| |
| ####################################################### |
| # Local Private Methods # |
| ####################################################### |
| |
| # _suspend_jobs() |
| # |
| # Suspend all ongoing jobs. |
| # |
| def _suspend_jobs(self): |
| if not self.suspended: |
| self._suspendtime = datetime.datetime.now() |
| self.suspended = True |
| for queue in self.queues: |
| for job in queue.active_jobs: |
| job.suspend() |
| |
| # _resume_jobs() |
| # |
| # Resume suspended jobs. |
| # |
| def _resume_jobs(self): |
| if self.suspended: |
| for queue in self.queues: |
| for job in queue.active_jobs: |
| job.resume() |
| self.suspended = False |
| self._starttime += (datetime.datetime.now() - self._suspendtime) |
| self._suspendtime = None |
| |
| # _interrupt_event(): |
| # |
| # A loop registered event callback for keyboard interrupts |
| # |
| def _interrupt_event(self): |
| # Leave this to the frontend to decide, if no |
| # interrrupt callback was specified, then just terminate. |
| if self._interrupt_callback: |
| self._interrupt_callback() |
| else: |
| # Default without a frontend is just terminate |
| self.terminate_jobs() |
| |
| # _terminate_event(): |
| # |
| # A loop registered event callback for SIGTERM |
| # |
| def _terminate_event(self): |
| self.terminate_jobs() |
| |
| # _suspend_event(): |
| # |
| # A loop registered event callback for SIGTSTP |
| # |
| def _suspend_event(self): |
| |
| # Ignore the feedback signals from Job.suspend() |
| if self.internal_stops: |
| self.internal_stops -= 1 |
| return |
| |
| # No need to care if jobs were suspended or not, we _only_ handle this |
| # while we know jobs are not suspended. |
| self._suspend_jobs() |
| os.kill(os.getpid(), signal.SIGSTOP) |
| self._resume_jobs() |
| |
| # _connect_signals(): |
| # |
| # Connects our signal handler event callbacks to the mainloop |
| # |
| def _connect_signals(self): |
| self.loop.add_signal_handler(signal.SIGINT, self._interrupt_event) |
| self.loop.add_signal_handler(signal.SIGTERM, self._terminate_event) |
| self.loop.add_signal_handler(signal.SIGTSTP, self._suspend_event) |
| |
| def _disconnect_signals(self): |
| self.loop.remove_signal_handler(signal.SIGINT) |
| self.loop.remove_signal_handler(signal.SIGTSTP) |
| self.loop.remove_signal_handler(signal.SIGTERM) |
| |
| def _terminate_jobs_real(self): |
| # 20 seconds is a long time, it can take a while and sometimes |
| # we still fail, need to look deeper into this again. |
| wait_start = datetime.datetime.now() |
| wait_limit = 20.0 |
| |
| # First tell all jobs to terminate |
| for queue in self.queues: |
| for job in queue.active_jobs: |
| job.terminate() |
| |
| # Now wait for them to really terminate |
| for queue in self.queues: |
| for job in queue.active_jobs: |
| elapsed = datetime.datetime.now() - wait_start |
| timeout = max(wait_limit - elapsed.total_seconds(), 0.0) |
| if not job.terminate_wait(timeout): |
| job.kill() |
| |
| self.loop.stop() |
| |
| # Regular timeout for driving status in the UI |
| def _tick(self): |
| elapsed = self.elapsed_time() |
| self._ticker_callback(elapsed) |
| self.loop.call_later(1, self._tick) |
