# This file is part of Buildbot. Buildbot is free software: you can # redistribute it and/or modify it under the terms of the GNU General Public # License as published by the Free Software Foundation, version 2. # # This program 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 General Public License for more # details. # # You should have received a copy of the GNU General Public License along with # this program; if not, write to the Free Software Foundation, Inc., 51 # Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. # # Copyright Buildbot Team Members import copy import math import random from datetime import datetime from twisted.internet import defer from twisted.python import log from twisted.python.failure import Failure from buildbot.data import resultspec from buildbot.process import metrics from buildbot.process.buildrequest import BuildRequest from buildbot.util import deferwaiter from buildbot.util import epoch2datetime from buildbot.util import service from buildbot.util.async_sort import async_sort class BuildChooserBase: # # WARNING: This API is experimental and in active development. # # This internal object selects a new build+worker pair. It acts as a # generator, initializing its state on creation and offering up new # pairs until exhaustion. The object can be destroyed at any time # (eg, before the list exhausts), and can be "restarted" by abandoning # an old instance and creating a new one. # # The entry point is: # * bc.chooseNextBuild() - get the next (worker, [breqs]) or # (None, None) # # The default implementation of this class implements a default # chooseNextBuild() that delegates out to two other functions: # * bc.popNextBuild() - get the next (worker, breq) pair def __init__(self, bldr, master): self.bldr = bldr self.master = master self.breqCache = {} self.unclaimedBrdicts = None @defer.inlineCallbacks def chooseNextBuild(self): # Return the next build, as a (worker, [breqs]) pair worker, breq = yield self.popNextBuild() if not worker or not breq: return (None, None) return (worker, [breq]) # Must be implemented by subclass def popNextBuild(self): # Pick the next (worker, breq) pair; note this is pre-merge, so # it's just one breq raise NotImplementedError("Subclasses must implement this!") # - Helper functions that are generally useful to all subclasses - @defer.inlineCallbacks def _fetchUnclaimedBrdicts(self): # Sets up a cache of all the unclaimed brdicts. The cache is # saved at self.unclaimedBrdicts cache. If the cache already # exists, this function does nothing. If a refetch is desired, set # the self.unclaimedBrdicts to None before calling.""" if self.unclaimedBrdicts is None: # TODO: use order of the DATA API brdicts = yield self.master.data.get(('builders', (yield self.bldr.getBuilderId()), 'buildrequests'), [resultspec.Filter('claimed', 'eq', [False])]) # sort by submitted_at, so the first is the oldest brdicts.sort(key=lambda brd: brd['submitted_at']) self.unclaimedBrdicts = brdicts return self.unclaimedBrdicts @defer.inlineCallbacks def _getBuildRequestForBrdict(self, brdict): # Turn a brdict into a BuildRequest into a brdict. This is useful # for API like 'nextBuild', which operate on BuildRequest objects. breq = self.breqCache.get(brdict['buildrequestid']) if not breq: breq = yield BuildRequest.fromBrdict(self.master, brdict) if breq: self.breqCache[brdict['buildrequestid']] = breq return breq def _getBrdictForBuildRequest(self, breq): # Turn a BuildRequest back into a brdict. This operates from the # cache, which must be set up once via _fetchUnclaimedBrdicts if breq is None: return None brid = breq.id for brdict in self.unclaimedBrdicts: if brid == brdict['buildrequestid']: return brdict return None def _removeBuildRequest(self, breq): # Remove a BuildrRequest object (and its brdict) # from the caches if breq is None: return brdict = self._getBrdictForBuildRequest(breq) if brdict is not None: self.unclaimedBrdicts.remove(brdict) if breq.id in self.breqCache: del self.breqCache[breq.id] def _getUnclaimedBuildRequests(self): # Retrieve the list of BuildRequest objects for all unclaimed builds return defer.gatherResults([ self._getBuildRequestForBrdict(brdict) for brdict in self.unclaimedBrdicts]) class BasicBuildChooser(BuildChooserBase): # BasicBuildChooser generates build pairs via the configuration points: # * config.nextWorker (or random.choice if not set) # * config.nextBuild (or "pop top" if not set) # # For N workers, this will call nextWorker at most N times. If nextWorker # returns a worker that cannot satisfy the build chosen by nextBuild, # it will search for a worker that can satisfy the build. If one is found, # the workers that cannot be used are "recycled" back into a list # to be tried, in order, for the next chosen build. # # We check whether Builder.canStartBuild returns True for a particular # worker. It evaluates any Build properties that are known before build # and checks whether the worker may satisfy them. For example, the worker # must have the locks available. def __init__(self, bldr, master): super().__init__(bldr, master) self.nextWorker = self.bldr.config.nextWorker if not self.nextWorker: self.nextWorker = lambda _, workers, __: random.choice( workers) if workers else None self.workerpool = self.bldr.getAvailableWorkers() # Pick workers one at a time from the pool, and if the Builder says # they're usable (eg, locks can be satisfied), then prefer those # workers. self.preferredWorkers = [] self.nextBuild = self.bldr.config.nextBuild @defer.inlineCallbacks def popNextBuild(self): nextBuild = (None, None) while True: # 1. pick a build breq = yield self._getNextUnclaimedBuildRequest() if not breq: break # 2. pick a worker worker = yield self._popNextWorker(breq) if not worker: break # either satisfy this build or we leave it for another day self._removeBuildRequest(breq) # 3. make sure worker+ is usable for the breq recycledWorkers = [] while worker: canStart = yield self.canStartBuild(worker, breq) if canStart: break # try a different worker recycledWorkers.append(worker) worker = yield self._popNextWorker(breq) # recycle the workers that we didn't use to the head of the queue # this helps ensure we run 'nextWorker' only once per worker choice if recycledWorkers: self._unpopWorkers(recycledWorkers) # 4. done? otherwise we will try another build if worker: nextBuild = (worker, breq) break return nextBuild @defer.inlineCallbacks def _getNextUnclaimedBuildRequest(self): # ensure the cache is there yield self._fetchUnclaimedBrdicts() if not self.unclaimedBrdicts: return None if self.nextBuild: # nextBuild expects BuildRequest objects breqs = yield self._getUnclaimedBuildRequests() try: nextBreq = yield self.nextBuild(self.bldr, breqs) if nextBreq not in breqs: nextBreq = None except Exception: log.err(Failure(), f"from _getNextUnclaimedBuildRequest for builder '{self.bldr}'") nextBreq = None else: # otherwise just return the first build brdict = self.unclaimedBrdicts[0] nextBreq = yield self._getBuildRequestForBrdict(brdict) return nextBreq @defer.inlineCallbacks def _popNextWorker(self, buildrequest): # use 'preferred' workers first, if we have some ready if self.preferredWorkers: worker = self.preferredWorkers.pop(0) return worker while self.workerpool: try: worker = yield self.nextWorker(self.bldr, self.workerpool, buildrequest) except Exception: log.err(Failure(), f"from nextWorker for builder '{self.bldr}'") worker = None if not worker or worker not in self.workerpool: # bad worker or no worker returned break self.workerpool.remove(worker) return worker return None def _unpopWorkers(self, workers): # push the workers back to the front self.preferredWorkers[:0] = workers def canStartBuild(self, worker, breq): return self.bldr.canStartBuild(worker, breq) class BuildRequestDistributor(service.AsyncMultiService): """ Special-purpose class to handle distributing build requests to builders by calling their C{maybeStartBuild} method. This takes account of the C{prioritizeBuilders} configuration, and is highly re-entrant; that is, if a new build request arrives while builders are still working on the previous build request, then this class will correctly re-prioritize invocations of builders' C{maybeStartBuild} methods. """ BuildChooser = BasicBuildChooser def __init__(self, botmaster): super().__init__() self.botmaster = botmaster # lock to ensure builders are only sorted once at any time self.pending_builders_lock = defer.DeferredLock() # sorted list of names of builders that need their maybeStartBuild # method invoked. self._pending_builders = [] self.activity_lock = defer.DeferredLock() self.active = False self._deferwaiter = deferwaiter.DeferWaiter() self._activity_loop_deferred = None @defer.inlineCallbacks def stopService(self): # Lots of stuff happens asynchronously here, so we need to let it all # quiesce. First, let the parent stopService succeed between # activities; then the loop will stop calling itself, since # self.running is false. yield self.activity_lock.run(service.AsyncService.stopService, self) # now let any outstanding calls to maybeStartBuildsOn to finish, so # they don't get interrupted in mid-stride. This tends to be # particularly painful because it can occur when a generator is gc'd. # TEST-TODO: this behavior is not asserted in any way. yield self._deferwaiter.wait() @defer.inlineCallbacks def maybeStartBuildsOn(self, new_builders): """ Try to start any builds that can be started right now. This function returns immediately, and promises to trigger those builders eventually. @param new_builders: names of new builders that should be given the opportunity to check for new requests. """ if not self.running: return try: yield self._deferwaiter.add(self._maybeStartBuildsOn(new_builders)) except Exception as e: # pragma: no cover log.err(e, f"while starting builds on {new_builders}") @defer.inlineCallbacks def _maybeStartBuildsOn(self, new_builders): new_builders = set(new_builders) existing_pending = set(self._pending_builders) # if we won't add any builders, there's nothing to do if new_builders < existing_pending: return None # reset the list of pending builders @defer.inlineCallbacks def resetPendingBuildersList(new_builders): try: # re-fetch existing_pending, in case it has changed # while acquiring the lock existing_pending = set(self._pending_builders) # then sort the new, expanded set of builders self._pending_builders = \ yield self._sortBuilders( list(existing_pending | new_builders)) # start the activity loop, if we aren't already # working on that. if not self.active: self._activity_loop_deferred = self._activityLoop() except Exception: # pragma: no cover log.err(Failure(), f"while attempting to start builds on {self.name}") yield self.pending_builders_lock.run( resetPendingBuildersList, new_builders) return None @defer.inlineCallbacks def _defaultSorter(self, master, builders): timer = metrics.Timer("BuildRequestDistributor._defaultSorter()") timer.start() @defer.inlineCallbacks def key(bldr): # Sort by time of oldest build request time = yield bldr.getOldestRequestTime() if time is None: # for builders that do not have pending buildrequest, we just use large number time = math.inf else: if isinstance(time, datetime): time = time.timestamp() return (time, bldr.name) yield async_sort(builders, key) timer.stop() return builders @defer.inlineCallbacks def _sortBuilders(self, buildernames): timer = metrics.Timer("BuildRequestDistributor._sortBuilders()") timer.start() # note that this takes and returns a list of builder names # convert builder names to builders builders_dict = self.botmaster.builders builders = [builders_dict.get(n) for n in buildernames if n in builders_dict] # find a sorting function sorter = self.master.config.prioritizeBuilders if not sorter: sorter = self._defaultSorter # run it try: builders = yield sorter(self.master, builders) except Exception: log.err(Failure(), "prioritizing builders; order unspecified") # and return the names rv = [b.name for b in builders] timer.stop() return rv @defer.inlineCallbacks def _activityLoop(self): self.active = True timer = metrics.Timer('BuildRequestDistributor._activityLoop()') timer.start() pending_builders = [] while True: yield self.activity_lock.acquire() if not self.running: self.activity_lock.release() break if not pending_builders: # lock pending_builders, pop an element from it, and release yield self.pending_builders_lock.acquire() # bail out if we shouldn't keep looping if not self._pending_builders: self.pending_builders_lock.release() self.activity_lock.release() break # take that builder list, and run it until the end # we make a copy of it, as it could be modified meanwhile pending_builders = copy.copy(self._pending_builders) self._pending_builders = [] self.pending_builders_lock.release() bldr_name = pending_builders.pop(0) # get the actual builder object bldr = self.botmaster.builders.get(bldr_name) try: if bldr: yield self._maybeStartBuildsOnBuilder(bldr) except Exception: log.err(Failure(), f"from maybeStartBuild for builder '{bldr_name}'") self.activity_lock.release() timer.stop() self.active = False @defer.inlineCallbacks def _maybeStartBuildsOnBuilder(self, bldr): # create a chooser to give us our next builds # this object is temporary and will go away when we're done bc = self.createBuildChooser(bldr, self.master) while True: worker, breqs = yield bc.chooseNextBuild() if not worker or not breqs: break # claim brid's brids = [br.id for br in breqs] claimed_at_epoch = self.master.reactor.seconds() claimed_at = epoch2datetime(claimed_at_epoch) if not (yield self.master.data.updates.claimBuildRequests( brids, claimed_at=claimed_at)): # some brids were already claimed, so start over bc = self.createBuildChooser(bldr, self.master) continue buildStarted = yield bldr.maybeStartBuild(worker, breqs) if not buildStarted: yield self.master.data.updates.unclaimBuildRequests(brids) # try starting builds again. If we still have a working worker, # then this may re-claim the same buildrequests self.botmaster.maybeStartBuildsForBuilder(self.name) def createBuildChooser(self, bldr, master): # just instantiate the build chooser requested return self.BuildChooser(bldr, master) @defer.inlineCallbacks def _waitForFinish(self): if self._activity_loop_deferred is not None: yield self._activity_loop_deferred