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DrydockAllocatorWorker.php
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Mon, Jul 21, 22:37

DrydockAllocatorWorker.php
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<?php
final class DrydockAllocatorWorker extends PhabricatorWorker {
private function getViewer() {
return PhabricatorUser::getOmnipotentUser();
}
private function loadLease() {
$viewer = $this->getViewer();
// TODO: Make the task data a dictionary like every other worker, and
// probably make this a PHID.
$lease_id = $this->getTaskData();
$lease = id(new DrydockLeaseQuery())
->setViewer($viewer)
->withIDs(array($lease_id))
->executeOne();
if (!$lease) {
throw new PhabricatorWorkerPermanentFailureException(
pht('No such lease "%s"!', $lease_id));
}
return $lease;
}
protected function doWork() {
$lease = $this->loadLease();
$this->allocateLease($lease);
}
private function allocateLease(DrydockLease $lease) {
$blueprints = $this->loadBlueprintsForAllocatingLease($lease);
// If we get nothing back, that means no blueprint is defined which can
// ever build the requested resource. This is a permanent failure, since
// we don't expect to succeed no matter how many times we try.
if (!$blueprints) {
$lease
->setStatus(DrydockLeaseStatus::STATUS_BROKEN)
->save();
throw new PhabricatorWorkerPermanentFailureException(
pht(
'No active Drydock blueprint exists which can ever allocate a '.
'resource for lease "%s".',
$lease->getPHID()));
}
// First, try to find a suitable open resource which we can acquire a new
// lease on.
$resources = $this->loadResourcesForAllocatingLease($blueprints, $lease);
// If no resources exist yet, see if we can build one.
if (!$resources) {
$usable_blueprints = $this->removeOverallocatedBlueprints(
$blueprints,
$lease);
// If we get nothing back here, some blueprint claims it can eventually
// satisfy the lease, just not right now. This is a temporary failure,
// and we expect allocation to succeed eventually.
if (!$blueprints) {
// TODO: More formal temporary failure here. We should retry this
// "soon" but not "immediately".
throw new Exception(
pht('No blueprints have space to allocate a resource right now.'));
}
$usable_blueprints = $this->rankBlueprints($blueprints, $lease);
$exceptions = array();
foreach ($usable_blueprints as $blueprint) {
try {
$resources[] = $blueprint->allocateResource($lease);
// Bail after allocating one resource, we don't need any more than
// this.
break;
} catch (Exception $ex) {
$exceptions[] = $ex;
}
}
if (!$resources) {
// TODO: We should distinguish between temporary and permament failures
// here. If any blueprint failed temporarily, retry "soon". If none
// of these failures were temporary, maybe this should be a permanent
// failure?
throw new PhutilAggregateException(
pht(
'All blueprints failed to allocate a suitable new resource when '.
'trying to allocate lease "%s".',
$lease->getPHID()),
$exceptions);
}
// NOTE: We have not acquired the lease yet, so it is possible that the
// resource we just built will be snatched up by some other lease before
// we can. This is not problematic: we'll retry a little later and should
// suceed eventually.
}
$resources = $this->rankResources($resources, $lease);
$exceptions = array();
$allocated = false;
foreach ($resources as $resource) {
try {
$blueprint->allocateLease($resource, $lease);
$allocated = true;
break;
} catch (Exception $ex) {
$exceptions[] = $ex;
}
}
if (!$allocated) {
// TODO: We should distinguish between temporary and permanent failures
// here. If any failures were temporary (specifically, failed to acquire
// locks)
throw new PhutilAggregateException(
pht(
'Unable to acquire lease "%s" on any resouce.',
$lease->getPHID()),
$exceptions);
}
}
/**
* Load a list of all resources which a given lease can possibly be
* allocated against.
*
* @param list<DrydockBlueprint> Blueprints which may produce suitable
* resources.
* @param DrydockLease Requested lease.
* @return list<DrydockResource> Resources which may be able to allocate
* the lease.
*/
private function loadResourcesForAllocatingLease(
array $blueprints,
DrydockLease $lease) {
assert_instances_of($blueprints, 'DrydockBlueprint');
$viewer = $this->getViewer();
$resources = id(new DrydockResourceQuery())
->setViewer($viewer)
->withBlueprintPHIDs(mpull($blueprints, 'getPHID'))
->withTypes(array($lease->getResourceType()))
->withStatuses(
array(
DrydockResourceStatus::STATUS_PENDING,
DrydockResourceStatus::STATUS_OPEN,
))
->execute();
$keep = array();
foreach ($resources as $key => $resource) {
if (!$resource->canAllocateLease($lease)) {
continue;
}
$keep[$key] = $resource;
}
return $keep;
}
/**
* Rank blueprints by suitability for building a new resource for a
* particular lease.
*
* @param list<DrydockBlueprint> List of blueprints.
* @param DrydockLease Requested lease.
* @return list<DrydockBlueprint> Ranked list of blueprints.
*/
private function rankBlueprints(array $blueprints, DrydockLease $lease) {
assert_instances_of($blueprints, 'DrydockBlueprint');
// TODO: Implement improvements to this ranking algorithm if they become
// available.
shuffle($blueprints);
return $blueprints;
}
/**
* Rank resources by suitability for allocating a particular lease.
*
* @param list<DrydockResource> List of resources.
* @param DrydockLease Requested lease.
* @return list<DrydockResource> Ranked list of resources.
*/
private function rankResources(array $resources, DrydockLease $lease) {
assert_instances_of($resources, 'DrydockResource');
// TODO: Implement improvements to this ranking algorithm if they become
// available.
shuffle($resources);
return $resources;
}
/**
* Get all the concrete @{class:DrydockBlueprint}s which can possibly
* build a resource to satisfy a lease.
*
* @param DrydockLease Requested lease.
* @return list<DrydockBlueprint> List of qualifying blueprints.
*/
private function loadBlueprintsForAllocatingLease(
DrydockLease $lease) {
$viewer = $this->getViewer();
$impls = $this->loadBlueprintImplementationsForAllocatingLease($lease);
if (!$impls) {
return array();
}
// TODO: When blueprints can be disabled, this query should ignore disabled
// blueprints.
$blueprints = id(new DrydockBlueprintQuery())
->setViewer($viewer)
->withBlueprintClasses(array_keys($impls))
->execute();
$keep = array();
foreach ($blueprints as $key => $blueprint) {
if (!$blueprint->canEverAllocateResourceForLease($lease)) {
continue;
}
$keep[$key] = $blueprint;
}
return $keep;
}
/**
* Get all the @{class:DrydockBlueprintImplementation}s which can possibly
* build a resource to satisfy a lease.
*
* This method returns blueprints which might, at some time, be able to
* build a resource which can satisfy the lease. They may not be able to
* build that resource right now.
*
* @param DrydockLease Requested lease.
* @return list<DrydockBlueprintImplementation> List of qualifying blueprint
* implementations.
*/
private function loadBlueprintImplementationsForAllocatingLease(
DrydockLease $lease) {
$impls = DrydockBlueprintImplementation::getAllBlueprintImplementations();
$keep = array();
foreach ($impls as $key => $impl) {
// Don't use disabled blueprint types.
if (!$impl->isEnabled()) {
continue;
}
// Don't use blueprint types which can't allocate the correct kind of
// resource.
if ($impl->getType() != $lease->getResourceType()) {
continue;
}
if (!$impl->canAnyBlueprintEverAllocateResourceForLease($lease)) {
continue;
}
$keep[$key] = $impl;
}
return $keep;
}
/**
* Remove blueprints which are too heavily allocated to build a resource for
* a lease from a list of blueprints.
*
* @param list<DrydockBlueprint> List of blueprints.
* @param list<DrydockBlueprint> List with fully allocated blueprints
* removed.
*/
private function removeOverallocatedBlueprints(
array $blueprints,
DrydockLease $lease) {
assert_instances_of($blueprints, 'DrydockBlueprint');
$keep = array();
foreach ($blueprints as $key => $blueprint) {
if (!$blueprint->canAllocateResourceForLease($lease)) {
continue;
}
$keep[$key] = $blueprint;
}
return $keep;
}
}

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