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| 1 | <?php |
| 2 | |
| 3 | namespace GrowthExperiments\NewcomerTasks\TaskSuggester; |
| 4 | |
| 5 | use GrowthExperiments\NewcomerTasks\Task\TaskSet; |
| 6 | use GrowthExperiments\NewcomerTasks\Task\TaskSetFilters; |
| 7 | use GrowthExperiments\NewcomerTasks\TaskSetListener; |
| 8 | use JobQueueGroup; |
| 9 | use LogicException; |
| 10 | use MediaWiki\Json\JsonCodec; |
| 11 | use MediaWiki\User\UserIdentity; |
| 12 | use Psr\Log\LoggerAwareInterface; |
| 13 | use Psr\Log\LoggerAwareTrait; |
| 14 | use Psr\Log\NullLogger; |
| 15 | use StatusValue; |
| 16 | use WANObjectCache; |
| 17 | |
| 18 | /** |
| 19 | * A TaskSuggester decorator which uses WANObjectCache to get/set TaskSets. |
| 20 | */ |
| 21 | class CacheDecorator implements TaskSuggester, LoggerAwareInterface { |
| 22 | |
| 23 | use LoggerAwareTrait; |
| 24 | |
| 25 | private const CACHE_VERSION = 4; |
| 26 | |
| 27 | /** @var TaskSuggester */ |
| 28 | private $taskSuggester; |
| 29 | |
| 30 | /** @var WANObjectCache */ |
| 31 | private $cache; |
| 32 | |
| 33 | /** @var JobQueueGroup */ |
| 34 | private $jobQueueGroup; |
| 35 | |
| 36 | /** @var TaskSetListener */ |
| 37 | private $taskSetListener; |
| 38 | |
| 39 | /** @var JsonCodec */ |
| 40 | private $jsonCodec; |
| 41 | |
| 42 | /** |
| 43 | * @param TaskSuggester $taskSuggester |
| 44 | * @param JobQueueGroup $jobQueueGroup |
| 45 | * @param WANObjectCache $cache |
| 46 | * @param TaskSetListener $taskSetListener |
| 47 | * @param JsonCodec $jsonCodec |
| 48 | */ |
| 49 | public function __construct( |
| 50 | TaskSuggester $taskSuggester, |
| 51 | JobQueueGroup $jobQueueGroup, |
| 52 | WANObjectCache $cache, |
| 53 | TaskSetListener $taskSetListener, |
| 54 | JsonCodec $jsonCodec |
| 55 | ) { |
| 56 | $this->taskSuggester = $taskSuggester; |
| 57 | $this->cache = $cache; |
| 58 | $this->jobQueueGroup = $jobQueueGroup; |
| 59 | $this->logger = new NullLogger(); |
| 60 | $this->taskSetListener = $taskSetListener; |
| 61 | $this->jsonCodec = $jsonCodec; |
| 62 | } |
| 63 | |
| 64 | /** @inheritDoc */ |
| 65 | public function suggest( |
| 66 | UserIdentity $user, |
| 67 | TaskSetFilters $taskSetFilters, |
| 68 | ?int $limit = null, |
| 69 | ?int $offset = null, |
| 70 | array $options = [] |
| 71 | ) { |
| 72 | $useCache = $options['useCache'] ?? true; |
| 73 | $resetCache = $options['resetCache'] ?? false; |
| 74 | $revalidateCache = $options['revalidateCache'] ?? true; |
| 75 | $excludePageIds = $options['excludePageIds'] ?? []; |
| 76 | $debug = $options['debug'] ?? false; |
| 77 | $limit ??= SearchTaskSuggester::DEFAULT_LIMIT; |
| 78 | |
| 79 | if ( $debug || $limit > SearchTaskSuggester::DEFAULT_LIMIT ) { |
| 80 | return $this->taskSuggester->suggest( $user, $taskSetFilters, $limit, $offset, $options ); |
| 81 | } |
| 82 | |
| 83 | $json = $this->cache->getWithSetCallback( |
| 84 | $this->cache->makeKey( |
| 85 | 'GrowthExperiments-NewcomerTasks-TaskSet', |
| 86 | $user->getId() |
| 87 | ), |
| 88 | $this->cache::TTL_WEEK, |
| 89 | function ( $oldValue, &$ttl ) use ( |
| 90 | $user, $taskSetFilters, $limit, $useCache, $resetCache, $revalidateCache, $excludePageIds |
| 91 | ) { |
| 92 | // This callback is always invoked each time getWithSetCallback is called, |
| 93 | // because we need to examine the contents of the cache (if any) before |
| 94 | // deciding whether to return those contents or if they need to be regenerated. |
| 95 | |
| 96 | if ( $oldValue !== false ) { |
| 97 | $oldValue = $this->unserialize( $oldValue ); |
| 98 | } |
| 99 | |
| 100 | if ( $useCache |
| 101 | && !$resetCache |
| 102 | && $oldValue instanceof TaskSet |
| 103 | && $oldValue->filtersEqual( $taskSetFilters ) |
| 104 | && $oldValue->count() |
| 105 | ) { |
| 106 | // There's a cached value we can use; we need to randomize and potentially |
| 107 | // revalidate it. |
| 108 | // &$ttl needs to be set to UNCACHEABLE so that WANObjectCache |
| 109 | // doesn't attempt a set() after returning the existing value. |
| 110 | $ttl = $this->cache::TTL_UNCACHEABLE; |
| 111 | |
| 112 | if ( $revalidateCache ) { |
| 113 | // Filter out cached tasks which have already been done. |
| 114 | // Filter before limiting, so they can be replaced by other tasks. |
| 115 | $newValue = $this->taskSuggester->filter( $user, $oldValue ); |
| 116 | } else { |
| 117 | $newValue = $oldValue; |
| 118 | } |
| 119 | $this->logger->debug( 'CacheDecorator hit', [ |
| 120 | 'user' => $user->getName(), |
| 121 | 'taskTypes' => implode( '|', $taskSetFilters->getTaskTypeFilters() ), |
| 122 | 'topics' => implode( '|', $taskSetFilters->getTopicFilters() ) ?: null, |
| 123 | 'limit' => $limit, |
| 124 | 'revalidateCache' => $revalidateCache, |
| 125 | 'ttl' => $ttl, |
| 126 | 'cachedTaskCount' => $oldValue->count(), |
| 127 | 'validTaskCount' => ( $newValue instanceof TaskSet ) ? $newValue->count() : null, |
| 128 | ] ); |
| 129 | if ( $newValue instanceof TaskSet ) { |
| 130 | // Shuffle the contents again (they were shuffled when first placed into the |
| 131 | // cache) and return only the subset of tasks that the requester asked for. |
| 132 | $newValue->randomSort(); |
| 133 | } |
| 134 | return $this->serialize( $newValue ); |
| 135 | } |
| 136 | |
| 137 | // We don't have a task set, or the taskset filters in the request don't match |
| 138 | // what is stored in the cache, or using the cached value was explicitly diallowed |
| 139 | // by the caller. Call the search backend and return the results. |
| 140 | // N.B. we cache whatever the taskSuggester returns, which could be a StatusValue, |
| 141 | // so when retrieving items from the cache we need to check the type before assuming |
| 142 | // we are working with a TaskSet. |
| 143 | $result = $this->taskSuggester->suggest( |
| 144 | $user, |
| 145 | $taskSetFilters, |
| 146 | SearchTaskSuggester::DEFAULT_LIMIT, |
| 147 | null, |
| 148 | [ 'excludePageIds' => $excludePageIds ] |
| 149 | ); |
| 150 | if ( $result instanceof TaskSet && $result->count() ) { |
| 151 | $result->randomSort(); |
| 152 | if ( $useCache || $resetCache ) { |
| 153 | // Schedule a job to refresh the taskset before the cache |
| 154 | // expires. |
| 155 | try { |
| 156 | $this->jobQueueGroup->lazyPush( |
| 157 | new NewcomerTasksCacheRefreshJob( [ |
| 158 | 'userId' => $user->getId(), |
| 159 | 'jobReleaseTimestamp' => (int)wfTimestamp() + |
| 160 | // Process the job the day before the cache expires. |
| 161 | ( $this->cache::TTL_WEEK - $this->cache::TTL_DAY ), |
| 162 | ] ) |
| 163 | ); |
| 164 | } catch ( \JobQueueError $jobQueueError ) { |
| 165 | // Ignore jobqueue errors. |
| 166 | } |
| 167 | } |
| 168 | } |
| 169 | if ( !$useCache && !$resetCache ) { |
| 170 | $ttl = $this->cache::TTL_UNCACHEABLE; |
| 171 | } |
| 172 | $this->logger->debug( 'CacheDecorator miss', [ |
| 173 | 'user' => $user->getName(), |
| 174 | 'taskTypes' => implode( '|', $taskSetFilters->getTaskTypeFilters() ), |
| 175 | 'topics' => implode( '|', $taskSetFilters->getTopicFilters() ) ?: null, |
| 176 | 'limit' => $limit, |
| 177 | 'useCache' => $useCache, |
| 178 | 'taskCount' => ( $result instanceof TaskSet ) ? $result->count() : null, |
| 179 | ] ); |
| 180 | return $this->serialize( $result ); |
| 181 | }, |
| 182 | // minAsOf is used to reject values below the defined timestamp. By |
| 183 | // settings minAsOf = INF (PHP's constant for the infinite), we are |
| 184 | // telling WANObjectCache to always invoke the callback. See |
| 185 | // callback comment for more on why. |
| 186 | [ 'minAsOf' => INF, 'version' => self::CACHE_VERSION ] |
| 187 | ); |
| 188 | $result = $this->unserialize( $json ); |
| 189 | |
| 190 | // Discard extra items when the method was called with $limit < DEFAULT_LIMIT, |
| 191 | // and run listeners. |
| 192 | if ( $result instanceof TaskSet && $result->count() ) { |
| 193 | $result->truncate( $limit ); |
| 194 | $this->runTaskSetListener( $result ); |
| 195 | } |
| 196 | return $result; |
| 197 | } |
| 198 | |
| 199 | /** @inheritDoc */ |
| 200 | public function filter( UserIdentity $user, TaskSet $taskSet ) { |
| 201 | return $this->taskSuggester->filter( $user, $taskSet ); |
| 202 | } |
| 203 | |
| 204 | /** |
| 205 | * |
| 206 | * @param TaskSet|StatusValue $taskSet |
| 207 | */ |
| 208 | private function runTaskSetListener( $taskSet ) { |
| 209 | if ( $taskSet instanceof StatusValue ) { |
| 210 | return; |
| 211 | } |
| 212 | $this->taskSetListener->run( $taskSet ); |
| 213 | } |
| 214 | |
| 215 | /** |
| 216 | * Serialize a value for caching. Serializing StatusValue is left to the default caching logic. |
| 217 | * @param TaskSet|StatusValue $value |
| 218 | * @return string|StatusValue |
| 219 | */ |
| 220 | private function serialize( $value ) { |
| 221 | if ( $value instanceof TaskSet ) { |
| 222 | return $this->jsonCodec->serialize( $value ); |
| 223 | } elseif ( $value instanceof StatusValue ) { |
| 224 | return $value; |
| 225 | } else { |
| 226 | $type = gettype( $value ); |
| 227 | if ( $type === 'object' ) { |
| 228 | $type = get_class( $value ); |
| 229 | } |
| 230 | throw new LogicException( 'Unexpected type ' . $type ); |
| 231 | } |
| 232 | } |
| 233 | |
| 234 | /** |
| 235 | * Unserialize a cached value. StatusValue is handled by PHP serialization so we just pass |
| 236 | * it through here. |
| 237 | * @param string|StatusValue $value |
| 238 | * @return TaskSet|StatusValue |
| 239 | */ |
| 240 | private function unserialize( $value ) { |
| 241 | if ( $value instanceof StatusValue ) { |
| 242 | return $value; |
| 243 | } else { |
| 244 | return $this->jsonCodec->unserialize( $value, TaskSet::class ); |
| 245 | } |
| 246 | } |
| 247 | |
| 248 | } |