| # |
| # Copyright (C) 2016 Codethink Limited |
| # Copyright (C) 2019 Bloomberg Finance LP |
| # |
| # 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 functools |
| import os |
| import asyncio |
| from itertools import chain |
| import signal |
| import datetime |
| import multiprocessing.forkserver |
| import sys |
| from concurrent.futures import ThreadPoolExecutor |
| |
| # Local imports |
| from .resources import Resources |
| from .jobs import JobStatus |
| from ..types import FastEnum |
| from .._profile import Topics, PROFILER |
| from ..plugin import Plugin |
| from .. import _signals |
| |
| |
| # A decent return code for Scheduler.run() |
| class SchedStatus(FastEnum): |
| SUCCESS = 0 |
| ERROR = -1 |
| TERMINATED = 1 |
| |
| |
| def reset_signals_on_exit(func): |
| @functools.wraps(func) |
| def wrapper(*args, **kwargs): |
| orig_sigint = signal.getsignal(signal.SIGINT) |
| orig_sigterm = signal.getsignal(signal.SIGTERM) |
| orig_sigtstp = signal.getsignal(signal.SIGTSTP) |
| |
| try: |
| return func(*args, **kwargs) |
| finally: |
| signal.signal(signal.SIGINT, orig_sigint) |
| signal.signal(signal.SIGTERM, orig_sigterm) |
| signal.signal(signal.SIGTSTP, orig_sigtstp) |
| |
| return wrapper |
| |
| |
| # 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 error 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 |
| # state: The state that can be made available to the frontend |
| # interrupt_callback: A callback to handle ^C |
| # ticker_callback: A callback call once per second |
| # |
| class Scheduler: |
| def __init__(self, context, start_time, state, interrupt_callback, ticker_callback): |
| |
| # |
| # 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 |
| |
| # |
| # Private members |
| # |
| self._active_jobs = [] # Jobs currently being run in the scheduler |
| self._suspendtime = None # Session time compensation for suspended state |
| self._queue_jobs = True # Whether we should continue to queue jobs |
| self._state = state |
| self._casd_process = None # handle to the casd process for monitoring purpose |
| |
| self._sched_handle = None # Whether a scheduling job is already scheduled or not |
| |
| self._ticker_callback = ticker_callback |
| self._interrupt_callback = interrupt_callback |
| |
| self.resources = Resources(context.sched_builders, context.sched_fetchers, context.sched_pushers) |
| |
| # Ensure that the forkserver is started before we start. |
| # This is best run before we do any GRPC connections to casd or have |
| # other background threads started. |
| # We ignore signals here, as this is the state all the python child |
| # processes from now on will have when starting |
| with _signals.blocked([signal.SIGINT, signal.SIGTSTP], ignore=True): |
| multiprocessing.forkserver.ensure_running() |
| |
| # run() |
| # |
| # Args: |
| # queues (list): A list of Queue objects |
| # casd_process_manager (cascache.CASDProcessManager): The subprocess which runs casd, in order to be notified |
| # of failures. |
| # |
| # 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 |
| # |
| @reset_signals_on_exit |
| def run(self, queues, casd_process_manager): |
| |
| # Hold on to the queues to process |
| self.queues = queues |
| |
| # NOTE: Enforce use of `SafeChildWatcher` as we generally don't want |
| # background threads. |
| # In Python 3.8+, `ThreadedChildWatcher` is the default watcher, and |
| # not `SafeChildWatcher`. |
| asyncio.set_child_watcher(asyncio.SafeChildWatcher()) |
| |
| # 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 |
| self.loop.call_later(1, self._tick) |
| |
| # Add exception handler |
| self.loop.set_exception_handler(self._handle_exception) |
| |
| # Handle unix signals while running |
| self._connect_signals() |
| |
| # Watch casd while running to ensure it doesn't die |
| self._casd_process = casd_process_manager.process |
| _watcher = asyncio.get_child_watcher() |
| |
| def abort_casd(pid, returncode): |
| asyncio.get_event_loop().call_soon(self._abort_on_casd_failure, pid, returncode) |
| |
| _watcher.add_child_handler(self._casd_process.pid, abort_casd) |
| |
| # Start the profiler |
| with PROFILER.profile(Topics.SCHEDULER, "_".join(queue.action_name for queue in self.queues)): |
| # This is not a no-op. Since it is the first signal registration |
| # that is set, it allows then other threads to register signal |
| # handling routines, which would not be possible if the main thread |
| # hadn't set it before. |
| # FIXME: this should be done in a cleaner way |
| with _signals.suspendable(lambda: None, lambda: None), _signals.terminator(lambda: None): |
| with ThreadPoolExecutor(max_workers=sum(self.resources._max_resources.values())) as pool: |
| self.loop.set_default_executor(pool) |
| # Run the queues |
| self._sched() |
| self.loop.run_forever() |
| self.loop.close() |
| |
| # Invoke the ticker callback a final time to render pending messages |
| self._ticker_callback() |
| |
| # Stop watching casd |
| _watcher.remove_child_handler(self._casd_process.pid) |
| self._casd_process = None |
| |
| # Stop handling unix signals |
| self._disconnect_signals() |
| |
| failed = any(queue.any_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 status |
| |
| # clear_queues() |
| # |
| # Forcibly destroys all the scheduler's queues |
| # This is needed because Queues register TaskGroups with State, |
| # which must be unique. As there is not yet any reason to have multiple |
| # Queues of the same type, old ones should be deleted. |
| # |
| def clear_queues(self): |
| if self.queues: |
| for queue in self.queues: |
| queue.destroy() |
| |
| self.queues.clear() |
| |
| # terminate() |
| # |
| # 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(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 |
| |
| # Notify the frontend that we're terminated as it might be |
| # from an interactive prompt callback or SIGTERM |
| 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]) |
| |
| # suspend() |
| # |
| # Suspend the scheduler |
| # |
| def suspend(self): |
| self._disconnect_signals() |
| self._suspend_jobs() |
| |
| # resume() |
| # |
| # Restart the scheduler |
| # |
| def resume(self): |
| self._connect_signals() |
| self._resume_jobs() |
| |
| # stop() |
| # |
| # Stop queueing additional jobs, causes Scheduler.run() |
| # to return once all currently processing jobs are finished. |
| # |
| def stop(self): |
| self._queue_jobs = False |
| |
| # job_completed(): |
| # |
| # Called when a Job completes |
| # |
| # Args: |
| # queue (Queue): The Queue holding a complete job |
| # job (Job): The completed Job |
| # status (JobStatus): The status of the completed job |
| # |
| def job_completed(self, job, status): |
| # Remove from the active jobs list |
| self._active_jobs.remove(job) |
| |
| if status == JobStatus.FAIL: |
| # If it's an elementjob, we want to compare against the failure messages |
| # and send the unique_id and display key tuple of the Element. This can then |
| # be used to load the element instance relative to the process it is running in. |
| element = job.get_element() |
| if element: |
| element_info = element._unique_id, element._get_display_key() |
| else: |
| element_info = None |
| |
| self._state.fail_task(job.id, element_info) |
| |
| self._state.remove_task(job.id) |
| |
| self._sched() |
| |
| ####################################################### |
| # Local Private Methods # |
| ####################################################### |
| |
| # _abort_on_casd_failure() |
| # |
| # Abort if casd failed while running. |
| # |
| # This will terminate immediately all jobs, since buildbox-casd is dead, |
| # we can't do anything with them anymore. |
| # |
| # Args: |
| # pid (int): the process id under which buildbox-casd was running |
| # returncode (int): the return code with which buildbox-casd exited |
| # |
| def _abort_on_casd_failure(self, pid, returncode): |
| self.context.messenger.bug("buildbox-casd died while the pipeline was active.") |
| |
| self._casd_process.returncode = returncode |
| self.terminate() |
| |
| # _start_job() |
| # |
| # Spanws a job |
| # |
| # Args: |
| # job (Job): The job to start |
| # |
| def _start_job(self, job): |
| |
| # From the scheduler perspective, the following |
| # is considered atomic; started jobs are always in the |
| # active_jobs list, and jobs in the active_jobs list |
| # are always started. |
| # |
| self._active_jobs.append(job) |
| job.start() |
| |
| self._state.add_task(job.id, job.action_name, job.name, self._state.elapsed_time()) |
| |
| # _sched_queue_jobs() |
| # |
| # Ask the queues what jobs they want to schedule and schedule |
| # them. This is done here so we can ask for new jobs when jobs |
| # from previous queues become available. |
| # |
| # This will process the Queues, pull elements through the Queues |
| # and process anything that is ready. |
| # |
| def _sched_queue_jobs(self): |
| ready = [] |
| process_queues = True |
| |
| while self._queue_jobs and process_queues: |
| |
| # Pull elements forward through queues |
| elements = [] |
| for queue in self.queues: |
| queue.enqueue(elements) |
| elements = list(queue.dequeue()) |
| |
| # 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 |
| ready.extend(chain.from_iterable(q.harvest_jobs() for q in reversed(self.queues))) |
| |
| # harvest_jobs() may have decided to skip some jobs, making |
| # them eligible for promotion to the next queue as a side effect. |
| # |
| # If that happens, do another round. |
| process_queues = any(q.dequeue_ready() for q in self.queues) |
| |
| # Start the jobs |
| # |
| for job in ready: |
| self._start_job(job) |
| |
| # _sched() |
| # |
| # Run any jobs which are ready to run, or quit the main loop |
| # when nothing is running or is ready to run. |
| # |
| # This is the main driving function of the scheduler, it is called |
| # initially when we enter Scheduler.run(), and at the end of whenever |
| # any job completes, after any bussiness logic has occurred and before |
| # going back to sleep. |
| # |
| def _sched(self): |
| def real_schedule(): |
| |
| # Reset the scheduling handle before queuing any jobs. |
| # |
| # We do this right away because starting jobs can result |
| # in their being terminated and completed during the body |
| # of this function, and we want to be sure that we get |
| # called again in this case. |
| # |
| # This can happen if jobs are explicitly killed as a result, |
| # which might happen as a side effect of a crash in an |
| # abstracted frontend implementation handling notifications |
| # about jobs starting. |
| # |
| self._sched_handle = None |
| |
| if not self.terminated: |
| |
| # |
| # Run as many jobs as the queues can handle for the |
| # available resources |
| # |
| self._sched_queue_jobs() |
| |
| # |
| # If nothing is ticking then bail out |
| # |
| if not self._active_jobs: |
| self.loop.stop() |
| |
| if self._sched_handle is None: |
| self._sched_handle = self.loop.call_soon(real_schedule) |
| |
| # _suspend_jobs() |
| # |
| # Suspend all ongoing jobs. |
| # |
| def _suspend_jobs(self): |
| if not self.suspended: |
| self._suspendtime = datetime.datetime.now() |
| self.suspended = True |
| _signals.is_not_suspended.clear() |
| |
| for suspender in reversed(_signals.suspendable_stack): |
| suspender.suspend() |
| |
| # _resume_jobs() |
| # |
| # Resume suspended jobs. |
| # |
| def _resume_jobs(self): |
| if self.suspended: |
| for suspender in _signals.suspendable_stack: |
| suspender.resume() |
| |
| _signals.is_not_suspended.set() |
| self.suspended = False |
| # Notify that we're unsuspended |
| self._state.offset_start_time(datetime.datetime.now() - self._suspendtime) |
| self._suspendtime = None |
| |
| # _interrupt_event(): |
| # |
| # A loop registered event callback for keyboard interrupts |
| # |
| def _interrupt_event(self): |
| |
| # The event loop receives a copy of all signals that are sent while it is running |
| # This means that even though we catch the SIGINT in the question to the user, |
| # the loop will receive it too, and thus we need to skip it here. |
| if self.terminated: |
| return |
| |
| self._interrupt_callback() |
| |
| # _terminate_event(): |
| # |
| # A loop registered event callback for SIGTERM |
| # |
| def _terminate_event(self): |
| self.terminate() |
| |
| # _suspend_event(): |
| # |
| # A loop registered event callback for SIGTSTP |
| # |
| def _suspend_event(self): |
| # 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): |
| for job in self._active_jobs: |
| job.terminate() |
| |
| # Regular timeout for driving status in the UI |
| def _tick(self): |
| self._ticker_callback() |
| self.loop.call_later(1, self._tick) |
| |
| def _handle_exception(self, loop, context: dict) -> None: |
| e = context.get("exception") |
| exc = bool(e) |
| if e is None: |
| # https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.call_exception_handler |
| # If no optional Exception generate a generic exception with message value. |
| # exc will be False, instructing the global handler to skip formatting the |
| # assumed exception & related traceback. |
| e = Exception(str(context.get("message")) + " asyncio exception handler called, but no Exception() given") |
| |
| # Call the sys global exception handler directly, as to avoid the default |
| # async handler raising an unhandled exception here. App will treat this |
| # as a 'BUG', format it appropriately & exit. mypy needs to ignore parameter |
| # types here as we're overriding sys globally in App._global_exception_handler() |
| sys.excepthook(type(e), e, e.__traceback__, exc) # type: ignore |
