| Total Complexity | 57 |
| Total Lines | 513 |
| Duplicated Lines | 0 % |
| Changes | 6 | ||
| Bugs | 0 | Features | 0 |
Complex classes like ProcessCacheInvalidationEventsCommand often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use ProcessCacheInvalidationEventsCommand, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
||
| 11 | class ProcessCacheInvalidationEventsCommand extends Command |
||
| 12 | { |
||
| 13 | /** |
||
| 14 | * The name and signature of the console command. |
||
| 15 | * |
||
| 16 | * @var string |
||
| 17 | */ |
||
| 18 | protected $signature = 'supercache:process-invalidation |
||
| 19 | {--shard= : The shard number to process} |
||
| 20 | {--priority= : The priority level} |
||
| 21 | {--limit= : The maximum number of events to fetch per batch} |
||
| 22 | {--tag-batch-size= : The number of identifiers to process per invalidation batch} |
||
| 23 | {--connection_name= : The Redis connection name}'; |
||
| 24 | |||
| 25 | /** |
||
| 26 | * The console command description. |
||
| 27 | * |
||
| 28 | * @var string |
||
| 29 | */ |
||
| 30 | protected $description = 'Process cache invalidation events for a given shard and priority'; |
||
| 31 | |||
| 32 | /** |
||
| 33 | * Cache invalidation helper instance. |
||
| 34 | */ |
||
| 35 | protected SuperCacheInvalidationHelper $helper; |
||
| 36 | |||
| 37 | /** |
||
| 38 | * Create a new command instance. |
||
| 39 | */ |
||
| 40 | public function __construct(SuperCacheInvalidationHelper $helper) |
||
| 44 | } |
||
| 45 | |||
| 46 | private function getStoreFromConnectionName(string $connection_name): ?string |
||
| 60 | } |
||
| 61 | |||
| 62 | |||
| 63 | |||
| 64 | /** |
||
| 65 | * Process cache invalidation events. |
||
| 66 | * |
||
| 67 | * @param int $shardId The shard number to process |
||
| 68 | * @param int $priority The priority level |
||
| 69 | * @param int $limit Maximum number of events to fetch per batch |
||
| 70 | * @param int $tagBatchSize Number of identifiers to process per batch |
||
| 71 | * |
||
| 72 | * @throws \Exception |
||
| 73 | * @throws \Throwable |
||
| 74 | */ |
||
| 75 | protected function processEvents(int $shardId, int $priority, int $limit, int $tagBatchSize, string $connection_name): void |
||
| 76 | { |
||
| 77 | $processingStartTime = now(); |
||
| 78 | $invalidationWindow = config('super_cache_invalidate.invalidation_window'); |
||
| 79 | |||
| 80 | // Fetch a batch of unprocessed events |
||
| 81 | $partitionCache_invalidation_events = $this->helper->getCacheInvalidationEventsUnprocessedPartitionName($shardId, $priority); |
||
| 82 | //$this->info(now()->toDateTimeString() . ' - Partition=' . $partitionCache_invalidation_events); |
||
| 83 | $events = DB::table(DB::raw("`cache_invalidation_events` PARTITION ({$partitionCache_invalidation_events})")) |
||
| 84 | ->where('processed', '=', 0) |
||
| 85 | ->where('shard', '=', $shardId) |
||
| 86 | ->where('priority', '=', $priority) |
||
| 87 | ->where('event_time', '<', $processingStartTime) |
||
| 88 | // Cerco tutte le chiavi/tag da invalidare per questo database redis |
||
| 89 | ->where('connection_name', '=', $connection_name) |
||
| 90 | ->orderBy('event_time') |
||
| 91 | ->limit($limit) |
||
| 92 | ->get() |
||
| 93 | ; |
||
| 94 | //$this->info(now()->toDateTimeString() . ' - Trovati Eventi=' . count($events)); |
||
| 95 | if ($events->isEmpty()) { |
||
| 96 | // No more events to process |
||
| 97 | return; |
||
| 98 | } |
||
| 99 | |||
| 100 | // Group events by type and identifier |
||
| 101 | $eventsByIdentifier = $events->groupBy(function ($event) { |
||
| 102 | return $event->type . ':' . $event->identifier; |
||
| 103 | }); |
||
| 104 | |||
| 105 | $batchIdentifiers = []; |
||
| 106 | $eventsToUpdate = []; |
||
| 107 | $counter = 0; |
||
| 108 | |||
| 109 | // Fetch associated identifiers for the events |
||
| 110 | // TODO JB 31/12/2024: per adesso commentato, da riattivare quando tutto funziona alla perfezione usando la partizione e soprattutto quando l'insertGetId è stato riattivato nll'helper |
||
| 111 | $associations = collect(); |
||
| 112 | /* |
||
| 113 | $eventIds = $events->pluck('id')->all(); |
||
| 114 | |||
| 115 | //retrive associated identifiers related to fetched event id |
||
| 116 | // Per le chiavi/tag associati non filtro per connection_name, potrebbero esserci associazioni anche in altri database |
||
| 117 | $associations = DB::table('cache_invalidation_event_associations') |
||
| 118 | ->whereIn('event_id', $eventIds) |
||
| 119 | ->get() |
||
| 120 | ->groupBy('event_id') |
||
| 121 | ; |
||
| 122 | */ |
||
| 123 | |||
| 124 | // Prepare list of all identifiers to fetch last invalidation times |
||
| 125 | $allIdentifiers = []; |
||
| 126 | foreach ($eventsByIdentifier as $key => $eventsGroup) { |
||
| 127 | $allIdentifiers[] = $key; |
||
| 128 | foreach ($eventsGroup as $event) { |
||
| 129 | $eventAssociations = $associations->where('event_id', '=', $event->id); |
||
| 130 | foreach ($eventAssociations as $assoc) { |
||
| 131 | $assocKey = $assoc->associated_type . ':' . $assoc->associated_identifier; |
||
| 132 | $allIdentifiers[] = $assocKey; |
||
| 133 | } |
||
| 134 | } |
||
| 135 | } |
||
| 136 | // Fetch last invalidation times in bulk |
||
| 137 | $lastInvalidationTimes = $this->getLastInvalidationTimes(array_unique($allIdentifiers)); |
||
| 138 | //$this->info(now()->toDateTimeString() . ' - $lastInvalidationTimes=' . count($lastInvalidationTimes)); |
||
| 139 | foreach ($eventsByIdentifier as $key => $eventsGroup) { |
||
| 140 | // Extract type and identifier |
||
| 141 | [$type, $identifier] = explode(':', $key, 2); |
||
| 142 | |||
| 143 | // Get associated identifiers for the events |
||
| 144 | $associatedIdentifiers = []; |
||
| 145 | foreach ($eventsGroup as $event) { |
||
| 146 | $eventAssociations = $associations->where('event_id', '=', $event->id); |
||
| 147 | foreach ($eventAssociations as $assoc) { |
||
| 148 | $assocKey = $assoc->associated_type . ':' . $assoc->associated_identifier; |
||
| 149 | $associatedIdentifiers[$assocKey] = [ |
||
| 150 | 'type' => $assoc->associated_type, |
||
| 151 | 'identifier' => $assoc->associated_identifier, |
||
| 152 | 'connection_name' => $assoc->connection_name, |
||
| 153 | ]; |
||
| 154 | } |
||
| 155 | } |
||
| 156 | |||
| 157 | // Build a list of all identifiers to check |
||
| 158 | $identifiersToCheck = [$key]; |
||
| 159 | $identifiersToCheck = array_merge($identifiersToCheck, array_keys($associatedIdentifiers)); |
||
| 160 | $lastInvalidationTimesSubset = array_intersect_key($lastInvalidationTimes, array_flip($identifiersToCheck)); |
||
| 161 | |||
| 162 | $shouldInvalidate = $this->shouldInvalidateMultiple($identifiersToCheck, $lastInvalidationTimesSubset, $invalidationWindow); |
||
| 163 | //$this->info(now()->toDateTimeString() . ' - $shouldInvalidate=' . $shouldInvalidate); |
||
| 164 | if ($shouldInvalidate) { |
||
| 165 | // Proceed to invalidate |
||
| 166 | $latestEvent = $eventsGroup->last(); |
||
| 167 | |||
| 168 | // Accumulate identifiers and events |
||
| 169 | $batchIdentifiers[] = [ |
||
| 170 | 'type' => $type, |
||
| 171 | 'identifier' => $identifier, |
||
| 172 | 'event' => $latestEvent, |
||
| 173 | 'connection_name' => $connection_name, |
||
| 174 | 'associated' => array_values($associatedIdentifiers), |
||
| 175 | ]; |
||
| 176 | |||
| 177 | // Update last invalidation times for all identifiers |
||
| 178 | $this->updateLastInvalidationTimes($identifiersToCheck); |
||
| 179 | //$this->info(now()->toDateTimeString() . ' - updateLastInvalidationTimes=OK'); |
||
| 180 | // Mark all events in the group as processed |
||
| 181 | foreach ($eventsGroup as $event) { |
||
| 182 | $eventsToUpdate[] = ['id' => $event->id, 'event_time' => $event->event_time, 'partition_key' => $event->partition_key]; |
||
| 183 | } |
||
| 184 | } else { |
||
| 185 | // Within the invalidation window, skip invalidation |
||
| 186 | // Mark all events except the last one as processed |
||
| 187 | $eventsToProcess = $eventsGroup->slice(0, -1); |
||
| 188 | foreach ($eventsToProcess as $event) { |
||
| 189 | $eventsToUpdate[] = ['id' => $event->id, 'event_time' => $event->event_time, 'partition_key' => $event->partition_key]; |
||
| 190 | } |
||
| 191 | // The last event remains unprocessed |
||
| 192 | } |
||
| 193 | |||
| 194 | $counter++; |
||
| 195 | |||
| 196 | // When we reach the batch size, process the accumulated identifiers |
||
| 197 | if ($counter % $tagBatchSize === 0) { |
||
| 198 | $this->processBatch($batchIdentifiers, $eventsToUpdate, $shardId, $priority); |
||
| 199 | |||
| 200 | // Reset the accumulators |
||
| 201 | $batchIdentifiers = []; |
||
| 202 | $eventsToUpdate = []; |
||
| 203 | } |
||
| 204 | } |
||
| 205 | |||
| 206 | if (empty($batchIdentifiers)) { |
||
| 207 | return; |
||
| 208 | } |
||
| 209 | |||
| 210 | // Process any remaining identifiers in the batch |
||
| 211 | $this->processBatch($batchIdentifiers, $eventsToUpdate, $shardId, $priority); |
||
| 212 | } |
||
| 213 | |||
| 214 | /** |
||
| 215 | * Fetch last invalidation times for identifiers in bulk. |
||
| 216 | * |
||
| 217 | * @param array $identifiers Array of 'type:identifier' strings |
||
| 218 | * @return array Associative array of last invalidation times |
||
| 219 | */ |
||
| 220 | protected function getLastInvalidationTimes(array $identifiers): array |
||
| 221 | { |
||
| 222 | // Extract types and identifiers into tuples |
||
| 223 | $tuples = array_map(static function ($key) { |
||
| 224 | return explode(':', $key, 2); |
||
| 225 | }, $identifiers); |
||
| 226 | |||
| 227 | if (empty($tuples)) { |
||
| 228 | return []; |
||
| 229 | } |
||
| 230 | |||
| 231 | $records = $this->getRecordsFromDb($tuples); |
||
| 232 | |||
| 233 | // Build associative array |
||
| 234 | $lastInvalidationTimes = []; |
||
| 235 | foreach ($records as $record) { |
||
| 236 | $key = $record->identifier_type . ':' . $record->identifier; |
||
| 237 | $lastInvalidationTimes[$key] = Carbon::parse($record->last_invalidated); |
||
| 238 | } |
||
| 239 | |||
| 240 | return $lastInvalidationTimes; |
||
| 241 | } |
||
| 242 | |||
| 243 | /** |
||
| 244 | * Execute Query to get records from DB |
||
| 245 | */ |
||
| 246 | protected function getRecordsFromDb(array $tuples): array |
||
| 247 | { |
||
| 248 | // Prepare placeholders and parameters |
||
| 249 | $placeholders = implode(',', array_fill(0, count($tuples), '(?, ?)')); |
||
| 250 | $params = []; |
||
| 251 | foreach ($tuples as [$type, $identifier]) { |
||
| 252 | $params[] = $type; |
||
| 253 | $params[] = $identifier; |
||
| 254 | } |
||
| 255 | |||
| 256 | // ATTENZIONE, qui non si può usare la partizione diretta perchè i record possono essere in partizioni diverse |
||
| 257 | $sql = "SELECT identifier_type, |
||
| 258 | identifier, |
||
| 259 | last_invalidated |
||
| 260 | FROM cache_invalidation_timestamps |
||
| 261 | WHERE (identifier_type, identifier) IN ($placeholders) |
||
| 262 | "; |
||
| 263 | |||
| 264 | return DB::select($sql, $params); |
||
| 265 | } |
||
| 266 | |||
| 267 | /** |
||
| 268 | * Determine whether to invalidate based on last invalidation times for multiple identifiers. |
||
| 269 | * |
||
| 270 | * @param array $identifiers Array of 'type:identifier' strings |
||
| 271 | * @param array $lastInvalidationTimes Associative array of last invalidation times |
||
| 272 | * @param int $invalidationWindow Invalidation window in seconds |
||
| 273 | * @return bool True if should invalidate, false otherwise |
||
| 274 | */ |
||
| 275 | protected function shouldInvalidateMultiple(array $identifiers, array $lastInvalidationTimes, int $invalidationWindow): bool |
||
| 276 | { |
||
| 277 | $now = now(); |
||
| 278 | foreach ($identifiers as $key) { |
||
| 279 | $lastInvalidated = $lastInvalidationTimes[$key] ?? null; |
||
| 280 | if (!$lastInvalidated) { |
||
| 281 | continue; |
||
| 282 | } |
||
| 283 | $elapsed = $now->diffInSeconds($lastInvalidated); |
||
| 284 | if ($elapsed < $invalidationWindow) { |
||
| 285 | // At least one identifier is within the invalidation window |
||
| 286 | return false; |
||
| 287 | } |
||
| 288 | } |
||
| 289 | |||
| 290 | // All identifiers are outside the invalidation window or have no record |
||
| 291 | return true; |
||
| 292 | } |
||
| 293 | |||
| 294 | /** |
||
| 295 | * Update the last invalidation times for multiple identifiers. |
||
| 296 | * |
||
| 297 | * @param array $identifiers Array of 'type:identifier' strings |
||
| 298 | */ |
||
| 299 | protected function updateLastInvalidationTimes(array $identifiers): void |
||
| 300 | { |
||
| 301 | $now = now(); |
||
| 302 | |||
| 303 | foreach ($identifiers as $key) { |
||
| 304 | [$type, $identifier] = explode(':', $key, 2); |
||
| 305 | // Anche qui non si può usare la partizione perchè nel caso dell'update potrebbe non essere la partizione giusta temporalmente |
||
| 306 | //$partitionCache_invalidation_timestamps = $this->helper->getCacheInvalidationTimestampsPartitionName(); |
||
| 307 | DB::statement('SET FOREIGN_KEY_CHECKS=0;'); |
||
| 308 | DB::statement('SET UNIQUE_CHECKS=0;'); |
||
| 309 | |||
| 310 | DB::table('cache_invalidation_timestamps') |
||
| 311 | //DB::table(DB::raw("`cache_invalidation_timestamps` PARTITION ({$partitionCache_invalidation_timestamps})")) |
||
| 312 | ->updateOrInsert( |
||
| 313 | ['identifier_type' => $type, 'identifier' => $identifier], |
||
| 314 | ['last_invalidated' => $now] |
||
| 315 | ) |
||
| 316 | ; |
||
| 317 | |||
| 318 | // Riattiva i controlli |
||
| 319 | DB::statement('SET FOREIGN_KEY_CHECKS=1;'); |
||
| 320 | DB::statement('SET UNIQUE_CHECKS=1;'); |
||
| 321 | } |
||
| 322 | } |
||
| 323 | |||
| 324 | /** |
||
| 325 | * Process a batch of identifiers and update events. |
||
| 326 | * |
||
| 327 | * @param array $batchIdentifiers Array of identifiers to invalidate |
||
| 328 | * @param array $eventsToUpdate Array of event IDs to mark as processed |
||
| 329 | * |
||
| 330 | * @throws \Throwable |
||
| 331 | */ |
||
| 332 | protected function processBatch(array $batchIdentifiers, array $eventsToUpdate, int $shard, int $priority): void |
||
| 333 | { |
||
| 334 | $maxAttempts = 5; |
||
| 335 | $attempts = 0; |
||
| 336 | $updatedOk = false; |
||
| 337 | |||
| 338 | // Separate keys and tags |
||
| 339 | $keys = []; |
||
| 340 | $tags = []; |
||
| 341 | |||
| 342 | foreach ($batchIdentifiers as $item) { |
||
| 343 | switch ($item['type']) { |
||
| 344 | case 'key': |
||
| 345 | $keys[] = $item['identifier'] . '§' . $item['connection_name']; |
||
| 346 | break; |
||
| 347 | case 'tag': |
||
| 348 | $tags[] = $item['identifier'] . '§' . $item['connection_name']; |
||
| 349 | break; |
||
| 350 | } |
||
| 351 | |||
| 352 | if (empty($item['associated'])) { |
||
| 353 | continue; |
||
| 354 | } |
||
| 355 | |||
| 356 | // Include associated identifiers |
||
| 357 | foreach ($item['associated'] as $assoc) { |
||
| 358 | switch ($assoc['type']) { |
||
| 359 | case 'key': |
||
| 360 | $keys[] = $assoc['identifier'] . '§' . $assoc['connection_name']; |
||
| 361 | break; |
||
| 362 | case 'tag': |
||
| 363 | $tags[] = $assoc['identifier'] . '§' . $assoc['connection_name']; |
||
| 364 | break; |
||
| 365 | } |
||
| 366 | } |
||
| 367 | } |
||
| 368 | |||
| 369 | // Remove duplicates |
||
| 370 | $keys = array_unique($keys); |
||
| 371 | $tags = array_unique($tags); |
||
| 372 | |||
| 373 | //$this->info(now()->toDateTimeString() . ' - Invalido ' . count($keys) . ' chiavi e ' . count($tags) . ' tag'); |
||
| 374 | |||
| 375 | // Invalidate cache for keys |
||
| 376 | if (!empty($keys)) { |
||
| 377 | $this->invalidateKeys($keys); |
||
| 378 | } |
||
| 379 | |||
| 380 | // Invalidate cache for tags |
||
| 381 | if (!empty($tags)) { |
||
| 382 | $this->invalidateTags($tags); |
||
| 383 | } |
||
| 384 | |||
| 385 | $shards = config('super_cache_invalidate.total_shards', 10); |
||
| 386 | while ($attempts < $maxAttempts && !$updatedOk) { |
||
| 387 | //$partitionCache_invalidation_events_processed = $this->helper->getCacheInvalidationEventsProcessedPartitionName($shard, $priority, $eventToUpdate['event_time']); |
||
| 388 | |||
| 389 | // Begin transaction for the batch |
||
| 390 | //DB::beginTransaction(); |
||
| 391 | try { |
||
| 392 | // Disabilita i controlli delle chiavi esterne e dei vincoli univoci |
||
| 393 | DB::statement('SET FOREIGN_KEY_CHECKS=0;'); |
||
| 394 | DB::statement('SET UNIQUE_CHECKS=0;'); |
||
| 395 | |||
| 396 | // Mark event as processed |
||
| 397 | // QUI NON VA USATA PARTITION perchè la cross partition è più lenta!!! |
||
| 398 | DB::table('cache_invalidation_events') |
||
| 399 | ->whereIn('id', array_column($eventsToUpdate, 'id')) |
||
| 400 | ->whereIn('partition_key', array_column($eventsToUpdate, 'partition_key')) |
||
| 401 | ->update(['processed' => 1, 'updated_at' => now()]) |
||
| 402 | ; |
||
| 403 | // Riattiva i controlli |
||
| 404 | DB::statement('SET FOREIGN_KEY_CHECKS=1;'); |
||
| 405 | DB::statement('SET UNIQUE_CHECKS=1;'); |
||
| 406 | // Commit transaction |
||
| 407 | //DB::commit(); |
||
| 408 | $updatedOk = true; |
||
| 409 | |||
| 410 | //$this->info(now()->toDateTimeString() . ' - cache_invalidation_events UPDATED Ok - count( ' . count($eventsToUpdate) . ' )'); |
||
| 411 | } catch (\Throwable $e) { |
||
| 412 | // Rollback transaction on error |
||
| 413 | //DB::rollBack(); |
||
| 414 | $attempts++; |
||
| 415 | $this->warn(now()->toDateTimeString() . ": Tentativo $attempts di $maxAttempts: " . $e->getMessage()); |
||
| 416 | // Logica per gestire i tentativi falliti |
||
| 417 | if ($attempts >= $maxAttempts) { |
||
| 418 | // Salta il record dopo il numero massimo di tentativi |
||
| 419 | throw $e; |
||
| 420 | } |
||
| 421 | } |
||
| 422 | } |
||
| 423 | } |
||
| 424 | |||
| 425 | /** |
||
| 426 | * Invalidate cache keys. |
||
| 427 | * |
||
| 428 | * @param array $keys Array of cache keys to invalidate |
||
| 429 | */ |
||
| 430 | protected function invalidateKeys(array $keys): void |
||
| 431 | { |
||
| 432 | $callback = config('super_cache_invalidate.key_invalidation_callback'); |
||
| 433 | |||
| 434 | |||
| 435 | // Anche in questo caso va fatto un loop perchè le chiavi potrebbero stare in database diversi |
||
| 436 | foreach ($keys as $keyAndConnectionName) { |
||
| 437 | [$key, $connection_name] = explode('§', $keyAndConnectionName); |
||
| 438 | |||
| 439 | // Metodo del progetto |
||
| 440 | if (is_callable($callback)) { |
||
| 441 | $callback($key, $connection_name); |
||
| 442 | |||
| 443 | return; |
||
| 444 | } |
||
| 445 | |||
| 446 | // oppure di default uso Laravel |
||
| 447 | $storeName = $this->getStoreFromConnectionName($connection_name); |
||
| 448 | |||
| 449 | if ($storeName === null) { |
||
| 450 | return; |
||
| 451 | } |
||
| 452 | Cache::store($storeName)->forget($key); |
||
| 453 | } |
||
| 454 | } |
||
| 455 | |||
| 456 | /** |
||
| 457 | * Invalidate cache tags. |
||
| 458 | * |
||
| 459 | * @param array $tags Array of cache tags to invalidate |
||
| 460 | */ |
||
| 461 | protected function invalidateTags(array $tags): void |
||
| 462 | { |
||
| 463 | $callback = config('super_cache_invalidate.tag_invalidation_callback'); |
||
| 464 | |||
| 465 | $groupByConnection = []; |
||
| 466 | |||
| 467 | // Anche in questo caso va fatto un loop perchè i tags potrebbero stare in database diversi, |
||
| 468 | // ma per ottimizzare possiamo raggruppare le operazioni per connessione |
||
| 469 | foreach ($tags as $tagAndConnectionName) { |
||
| 470 | // chiave e connessione |
||
| 471 | [$key, $connection] = explode('§', $tagAndConnectionName); |
||
| 472 | |||
| 473 | // Aggiungo la chiave alla connessione appropriata |
||
| 474 | $groupByConnection[$connection][] = $key; |
||
| 475 | } |
||
| 476 | if (is_callable($callback)) { |
||
| 477 | foreach ($groupByConnection as $connection_name => $arrTags) { |
||
| 478 | $callback($arrTags, $connection_name); |
||
| 479 | } |
||
| 480 | |||
| 481 | return; |
||
| 482 | } |
||
| 483 | foreach ($groupByConnection as $connection_name => $arrTags) { |
||
| 484 | $storeName = $this->getStoreFromConnectionName($connection_name); |
||
| 485 | if ($storeName === null) { |
||
| 486 | return; |
||
| 487 | } |
||
| 488 | Cache::store($storeName)->tags($arrTags)->flush(); |
||
| 489 | } |
||
| 490 | } |
||
| 491 | |||
| 492 | /** |
||
| 493 | * Execute the console command. |
||
| 494 | */ |
||
| 495 | public function handle(): void |
||
| 524 | } |
||
| 525 | } |
||
| 526 | } |
||
| 527 |
This check looks for parameters that have been defined for a function or method, but which are not used in the method body.