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| 1 | <?php |
| 2 | |
| 3 | namespace Flow\Repository; |
| 4 | |
| 5 | use Flow\Data\FlowObjectCache; |
| 6 | use Flow\Data\ObjectManager; |
| 7 | use Flow\DbFactory; |
| 8 | use Flow\Exception\DataModelException; |
| 9 | use Flow\Model\UUID; |
| 10 | use Wikimedia\Rdbms\DBQueryError; |
| 11 | |
| 12 | /* |
| 13 | * In SQL |
| 14 | * |
| 15 | * CREATE TABLE flow_tree_node ( |
| 16 | * descendant DECIMAL(39) UNSIGNED NOT NULL, |
| 17 | * ancestor DECIMAL(39) UNSIGNED NULL, |
| 18 | * depth SMALLINT UNSIGNED NOT NULL, |
| 19 | * PRIMARY KEY ( ancestor, descendant ), |
| 20 | * UNIQUE KEY ( descendant, depth ) |
| 21 | * ); |
| 22 | * |
| 23 | * In Memcache |
| 24 | * |
| 25 | * flow:tree:subtree:<descendant> |
| 26 | * flow:tree:rootpath:<descendant> |
| 27 | * flow:tree:parent:<descendant> - should we just use rootpath? |
| 28 | * |
| 29 | * Not sure how to handle topic splits with caching yet, i can imagine |
| 30 | * a number of potential race conditions for writing root paths and sub trees |
| 31 | * during a topic split |
| 32 | */ |
| 33 | class TreeRepository { |
| 34 | |
| 35 | /** |
| 36 | * @var string |
| 37 | */ |
| 38 | protected $tableName = 'flow_tree_node'; |
| 39 | |
| 40 | /** |
| 41 | * @var DbFactory |
| 42 | */ |
| 43 | protected $dbFactory; |
| 44 | |
| 45 | /** |
| 46 | * @var FlowObjectCache |
| 47 | */ |
| 48 | protected $cache; |
| 49 | |
| 50 | /** |
| 51 | * @param DbFactory $dbFactory Factory to source connection objects from |
| 52 | * @param FlowObjectCache $cache |
| 53 | */ |
| 54 | public function __construct( DbFactory $dbFactory, FlowObjectCache $cache ) { |
| 55 | $this->dbFactory = $dbFactory; |
| 56 | $this->cache = $cache; |
| 57 | } |
| 58 | |
| 59 | /** |
| 60 | * A helper function to generate cache keys for tree repository |
| 61 | * @param string $treeType |
| 62 | * @param UUID $uuid |
| 63 | * @return string |
| 64 | */ |
| 65 | protected function cacheKey( $treeType, UUID $uuid ) { |
| 66 | return TreeCacheKey::build( $treeType, $uuid ); |
| 67 | } |
| 68 | |
| 69 | /** |
| 70 | * Insert a new tree node. If ancestor === null then this node is a root. |
| 71 | * |
| 72 | * Also delete cache entries related to this tree. |
| 73 | * @param UUID $descendant |
| 74 | * @param UUID|null $ancestor |
| 75 | * @return true |
| 76 | * @throws DataModelException |
| 77 | */ |
| 78 | public function insert( UUID $descendant, UUID $ancestor = null ) { |
| 79 | $this->cache->delete( $this->cacheKey( 'subtree', $descendant ) ); |
| 80 | $this->cache->delete( $this->cacheKey( 'parent', $descendant ) ); |
| 81 | $this->cache->delete( $this->cacheKey( 'rootpath', $descendant ) ); |
| 82 | |
| 83 | if ( $ancestor === null ) { |
| 84 | $path = [ $descendant ]; |
| 85 | } else { |
| 86 | $path = $this->findRootPath( $ancestor ); |
| 87 | $path[] = $descendant; |
| 88 | } |
| 89 | $this->deleteSubtreeCache( $descendant, $path ); |
| 90 | |
| 91 | $dbw = $this->dbFactory->getDB( DB_PRIMARY ); |
| 92 | $dbw->newInsertQueryBuilder() |
| 93 | ->insertInto( $this->tableName ) |
| 94 | ->row( [ |
| 95 | 'tree_descendant_id' => $descendant->getBinary(), |
| 96 | 'tree_ancestor_id' => $descendant->getBinary(), |
| 97 | 'tree_depth' => 0, |
| 98 | ] ) |
| 99 | ->caller( __METHOD__ ) |
| 100 | ->execute(); |
| 101 | |
| 102 | $ok = true; |
| 103 | if ( $ancestor !== null ) { |
| 104 | try { |
| 105 | if ( defined( 'MW_PHPUNIT_TEST' ) && $dbw->getType() == 'mysql' ) { |
| 106 | /* |
| 107 | * Combination of MW unit tests + MySQL DB is known to cause |
| 108 | * query failures of code 1137, so instead of executing a |
| 109 | * known bad query, let's just consider it failed right away |
| 110 | * (and let catch statement deal with it) |
| 111 | */ |
| 112 | throw new DBQueryError( $dbw, 'Prevented execution of known bad query', 1137, '', __METHOD__ ); |
| 113 | } |
| 114 | |
| 115 | $dbw->insertSelect( |
| 116 | $this->tableName, |
| 117 | $this->tableName, |
| 118 | [ |
| 119 | 'tree_descendant_id' => $dbw->addQuotes( $descendant->getBinary() ), |
| 120 | 'tree_ancestor_id' => 'tree_ancestor_id', |
| 121 | 'tree_depth' => 'tree_depth + 1', |
| 122 | ], |
| 123 | [ |
| 124 | 'tree_descendant_id' => $ancestor->getBinary(), |
| 125 | ], |
| 126 | __METHOD__ |
| 127 | ); |
| 128 | } catch ( DBQueryError $e ) { |
| 129 | /* |
| 130 | * insertSelect won't work on temporary tables (as used for MW |
| 131 | * unit tests), because it refers to the same table twice, in |
| 132 | * one query. |
| 133 | * In this case, we'll do a separate select & insert. This used |
| 134 | * to always be detected via the DBQueryError, but it can also |
| 135 | * return false from insertSelect. |
| 136 | * |
| 137 | * @see https://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html |
| 138 | * @see http://dba.stackexchange.com/questions/45270/mysql-error-1137-hy000-at-line-9-cant-reopen-table-temp-table |
| 139 | */ |
| 140 | if ( $e->errno === 1137 ) { |
| 141 | $rows = $dbw->newSelectQueryBuilder() |
| 142 | ->select( [ 'tree_depth', 'tree_ancestor_id' ] ) |
| 143 | ->from( $this->tableName ) |
| 144 | ->where( [ 'tree_descendant_id' => $ancestor->getBinary() ] ) |
| 145 | ->caller( __METHOD__ ) |
| 146 | ->fetchResultSet(); |
| 147 | |
| 148 | foreach ( $rows as $row ) { |
| 149 | $dbw->newInsertQueryBuilder() |
| 150 | ->insertInto( $this->tableName ) |
| 151 | ->row( [ |
| 152 | 'tree_descendant_id' => $descendant->getBinary(), |
| 153 | 'tree_ancestor_id' => $row->tree_ancestor_id, |
| 154 | 'tree_depth' => $row->tree_depth + 1, |
| 155 | ] ) |
| 156 | ->caller( __METHOD__ ) |
| 157 | ->execute(); |
| 158 | } |
| 159 | } else { |
| 160 | $ok = false; |
| 161 | } |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | if ( !$ok ) { |
| 166 | throw new DataModelException( 'Failed inserting new tree node', 'process-data' ); |
| 167 | } |
| 168 | |
| 169 | return true; |
| 170 | } |
| 171 | |
| 172 | protected function deleteSubtreeCache( UUID $descendant, array $rootPath ) { |
| 173 | foreach ( $rootPath as $subtreeRoot ) { |
| 174 | $cacheKey = $this->cacheKey( 'subtree', $subtreeRoot ); |
| 175 | $this->cache->delete( $cacheKey ); |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | /** |
| 180 | * Deletes a descendant from the tree repo. |
| 181 | * |
| 182 | * @param UUID $descendant |
| 183 | */ |
| 184 | public function delete( UUID $descendant ) { |
| 185 | $dbw = $this->dbFactory->getDB( DB_PRIMARY ); |
| 186 | $dbw->newDeleteQueryBuilder() |
| 187 | ->deleteFrom( $this->tableName ) |
| 188 | ->where( [ |
| 189 | 'tree_descendant_id' => $descendant->getBinary(), |
| 190 | ] ) |
| 191 | ->caller( __METHOD__ ) |
| 192 | ->execute(); |
| 193 | |
| 194 | $subtreeKey = $this->cacheKey( 'subtree', $descendant ); |
| 195 | $parentKey = $this->cacheKey( 'parent', $descendant ); |
| 196 | $pathKey = $this->cacheKey( 'rootpath', $descendant ); |
| 197 | |
| 198 | $this->cache->delete( $subtreeKey ); |
| 199 | $this->cache->delete( $parentKey ); |
| 200 | $this->cache->delete( $pathKey ); |
| 201 | } |
| 202 | |
| 203 | public function findParent( UUID $descendant ) { |
| 204 | $map = $this->fetchParentMap( [ $descendant ] ); |
| 205 | return $map[$descendant->getAlphadecimal()] ?? null; |
| 206 | } |
| 207 | |
| 208 | /** |
| 209 | * Given a list of nodes, find the path from each node to the root of its tree. |
| 210 | * the root must be the first element of the array, $node must be the last element. |
| 211 | * @param UUID[] $descendants Array of UUID objects to find the root paths for. |
| 212 | * @return UUID[][] Associative array, key is the post ID in hex, value is the path as an array. |
| 213 | */ |
| 214 | public function findRootPaths( array $descendants ) { |
| 215 | // alphadecimal => cachekey |
| 216 | $cacheKeys = []; |
| 217 | // alphadecimal => cache result ( distance => parent uuid obj ) |
| 218 | $cacheValues = []; |
| 219 | // list of binary values for db query |
| 220 | $missingValues = []; |
| 221 | // alphadecimal => distance => parent uuid obj |
| 222 | $paths = []; |
| 223 | |
| 224 | foreach ( $descendants as $descendant ) { |
| 225 | $cacheKeys[$descendant->getAlphadecimal()] = $this->cacheKey( 'rootpath', $descendant ); |
| 226 | } |
| 227 | |
| 228 | $cacheResult = $this->cache->getMulti( array_values( $cacheKeys ) ); |
| 229 | foreach ( $descendants as $descendant ) { |
| 230 | $alpha = $descendant->getAlphadecimal(); |
| 231 | if ( isset( $cacheResult[$cacheKeys[$alpha]] ) ) { |
| 232 | $cacheValues[$alpha] = $cacheResult[$cacheKeys[$alpha]]; |
| 233 | } else { |
| 234 | $missingValues[] = $descendant->getBinary(); |
| 235 | $paths[$alpha] = []; |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | if ( !count( $missingValues ) ) { |
| 240 | return $cacheValues; |
| 241 | } |
| 242 | |
| 243 | $dbr = $this->dbFactory->getDB( DB_REPLICA ); |
| 244 | $res = $dbr->newSelectQueryBuilder() |
| 245 | ->select( [ 'tree_descendant_id', 'tree_ancestor_id', 'tree_depth' ] ) |
| 246 | ->from( $this->tableName ) |
| 247 | ->where( [ |
| 248 | 'tree_descendant_id' => $missingValues, |
| 249 | ] ) |
| 250 | ->caller( __METHOD__ ) |
| 251 | ->fetchResultSet(); |
| 252 | |
| 253 | if ( $res->numRows() === 0 ) { |
| 254 | return $cacheValues; |
| 255 | } |
| 256 | |
| 257 | foreach ( $res as $row ) { |
| 258 | $alpha = UUID::create( $row->tree_descendant_id )->getAlphadecimal(); |
| 259 | $paths[$alpha][$row->tree_depth] = UUID::create( $row->tree_ancestor_id ); |
| 260 | } |
| 261 | |
| 262 | foreach ( $paths as $descendantId => &$path ) { |
| 263 | if ( !$path ) { |
| 264 | $path = null; |
| 265 | continue; |
| 266 | } |
| 267 | |
| 268 | // sort by reverse distance, so furthest away |
| 269 | // parent (root) is at position 0. |
| 270 | ksort( $path ); |
| 271 | $path = array_reverse( $path ); |
| 272 | |
| 273 | $this->cache->set( $cacheKeys[$descendantId], $path ); |
| 274 | } |
| 275 | |
| 276 | return $paths + $cacheValues; |
| 277 | } |
| 278 | |
| 279 | /** |
| 280 | * Finds the root path for a single post ID. |
| 281 | * @param UUID $descendant Post ID |
| 282 | * @return UUID[]|null Path to the root of that node. |
| 283 | */ |
| 284 | public function findRootPath( UUID $descendant ) { |
| 285 | $paths = $this->findRootPaths( [ $descendant ] ); |
| 286 | |
| 287 | return $paths[$descendant->getAlphadecimal()] ?? null; |
| 288 | } |
| 289 | |
| 290 | /** |
| 291 | * Finds the root posts of a list of posts. |
| 292 | * @param UUID[] $descendants Array of PostRevision objects to find roots for. |
| 293 | * @return UUID[] Associative array of post ID (as hex) to UUID object representing its root. |
| 294 | */ |
| 295 | public function findRoots( array $descendants ) { |
| 296 | $paths = $this->findRootPaths( $descendants ); |
| 297 | $roots = []; |
| 298 | |
| 299 | foreach ( $descendants as $descendant ) { |
| 300 | $alpha = $descendant->getAlphadecimal(); |
| 301 | if ( isset( $paths[$alpha] ) ) { |
| 302 | $roots[$alpha] = $paths[$alpha][0]; |
| 303 | } |
| 304 | } |
| 305 | |
| 306 | return $roots; |
| 307 | } |
| 308 | |
| 309 | /** |
| 310 | * Given a specific child node find the associated root node |
| 311 | * |
| 312 | * @param UUID $descendant |
| 313 | * @return UUID |
| 314 | * @throws DataModelException |
| 315 | */ |
| 316 | public function findRoot( UUID $descendant ) { |
| 317 | // To simplify caching we will work through the root path instead |
| 318 | // of caching our own value |
| 319 | $path = $this->findRootPath( $descendant ); |
| 320 | if ( !$path ) { |
| 321 | throw new DataModelException( $descendant->getAlphadecimal() . ' has no root post. Probably is a root post.', 'process-data' ); |
| 322 | } |
| 323 | |
| 324 | $root = array_shift( $path ); |
| 325 | |
| 326 | return $root; |
| 327 | } |
| 328 | |
| 329 | /** |
| 330 | * Fetch a node and all its descendants. Children are returned in the |
| 331 | * same order they were inserted. |
| 332 | * |
| 333 | * @param UUID|UUID[] $roots |
| 334 | * @return array Multi-dimensional tree. The top level is a map from the uuid of a node |
| 335 | * to attributes about that node. The top level contains not just the parents, but all nodes |
| 336 | * within this tree. Within each node there is a 'children' key that contains a map from |
| 337 | * the child uuid's to references back to the top level of this identity map. As such this |
| 338 | * result can be read either as a list or a tree. |
| 339 | * @throws DataModelException When invalid data is received from self::fetchSubtreeNodeList |
| 340 | */ |
| 341 | public function fetchSubtreeIdentityMap( $roots ) { |
| 342 | $roots = ObjectManager::makeArray( $roots ); |
| 343 | if ( !$roots ) { |
| 344 | return []; |
| 345 | } |
| 346 | $nodes = $this->fetchSubtreeNodeList( $roots ); |
| 347 | if ( !$nodes ) { |
| 348 | throw new DataModelException( |
| 349 | 'subtree node list should have at least returned root: ' . implode( ', ', $roots ), |
| 350 | 'process-data' |
| 351 | ); |
| 352 | } elseif ( count( $nodes ) === 1 ) { |
| 353 | $parentMap = $this->fetchParentMap( reset( $nodes ) ); |
| 354 | } else { |
| 355 | $parentMap = $this->fetchParentMap( array_merge( ...array_values( $nodes ) ) ); |
| 356 | } |
| 357 | $identityMap = []; |
| 358 | foreach ( $parentMap as $child => $parent ) { |
| 359 | if ( !array_key_exists( $child, $identityMap ) ) { |
| 360 | $identityMap[$child] = [ 'children' => [] ]; |
| 361 | } |
| 362 | // Root nodes have no parent |
| 363 | if ( $parent !== null ) { |
| 364 | $identityMap[$parent->getAlphadecimal()]['children'][$child] =& $identityMap[$child]; |
| 365 | } |
| 366 | } |
| 367 | foreach ( array_keys( $identityMap ) as $parent ) { |
| 368 | ksort( $identityMap[$parent]['children'] ); |
| 369 | } |
| 370 | |
| 371 | return $identityMap; |
| 372 | } |
| 373 | |
| 374 | public function fetchSubtree( UUID $root ) { |
| 375 | $identityMap = $this->fetchSubtreeIdentityMap( $root ); |
| 376 | if ( !isset( $identityMap[$root->getAlphadecimal()] ) ) { |
| 377 | throw new DataModelException( 'No root exists in the identityMap', 'process-data' ); |
| 378 | } |
| 379 | |
| 380 | return $identityMap[$root->getAlphadecimal()]; |
| 381 | } |
| 382 | |
| 383 | public function fetchFullTree( UUID $nodeId ) { |
| 384 | return $this->fetchSubtree( $this->findRoot( $nodeId ) ); |
| 385 | } |
| 386 | |
| 387 | /** |
| 388 | * Return the id's of all nodes which are a descendant of provided roots |
| 389 | * |
| 390 | * @param UUID[] $roots |
| 391 | * @return array map from root id to its descendant list |
| 392 | * @throws \Flow\Exception\InvalidInputException |
| 393 | */ |
| 394 | public function fetchSubtreeNodeList( array $roots ) { |
| 395 | $list = new MultiGetList( $this->cache ); |
| 396 | $res = $list->get( |
| 397 | 'subtree', |
| 398 | $roots, |
| 399 | [ $this, 'fetchSubtreeNodeListFromDb' ] |
| 400 | ); |
| 401 | // $idx is a binary UUID |
| 402 | $retval = []; |
| 403 | foreach ( $res as $idx => $val ) { |
| 404 | $retval[UUID::create( $idx )->getAlphadecimal()] = $val; |
| 405 | } |
| 406 | return $retval; |
| 407 | } |
| 408 | |
| 409 | public function fetchSubtreeNodeListFromDb( array $roots ) { |
| 410 | $res = $this->dbFactory->getDB( DB_REPLICA )->newSelectQueryBuilder() |
| 411 | ->select( [ 'tree_ancestor_id', 'tree_descendant_id' ] ) |
| 412 | ->from( $this->tableName ) |
| 413 | ->where( [ |
| 414 | 'tree_ancestor_id' => UUID::convertUUIDs( $roots ), |
| 415 | ] ) |
| 416 | ->caller( __METHOD__ ) |
| 417 | ->fetchResultSet(); |
| 418 | $nodes = []; |
| 419 | foreach ( $res as $node ) { |
| 420 | $ancestor = UUID::create( $node->tree_ancestor_id ); |
| 421 | $descendant = UUID::create( $node->tree_descendant_id ); |
| 422 | $nodes[$ancestor->getAlphadecimal()][$descendant->getAlphadecimal()] = $descendant; |
| 423 | } |
| 424 | |
| 425 | return $nodes; |
| 426 | } |
| 427 | |
| 428 | /** |
| 429 | * Fetch the id of the immediate parent node of all ids in $nodes. Non-existent |
| 430 | * nodes are not represented in the result set. |
| 431 | * @param array $nodes |
| 432 | * @return array |
| 433 | */ |
| 434 | public function fetchParentMap( array $nodes ) { |
| 435 | $list = new MultiGetList( $this->cache ); |
| 436 | return $list->get( |
| 437 | 'parent', |
| 438 | $nodes, |
| 439 | [ $this, 'fetchParentMapFromDb' ] |
| 440 | ); |
| 441 | } |
| 442 | |
| 443 | /** |
| 444 | * @param UUID[] $nodes |
| 445 | * @return UUID[] |
| 446 | * @throws DataModelException |
| 447 | */ |
| 448 | public function fetchParentMapFromDb( array $nodes ) { |
| 449 | // Find out who the parent is for those nodes |
| 450 | $dbr = $this->dbFactory->getDB( DB_REPLICA ); |
| 451 | $res = $dbr->newSelectQueryBuilder() |
| 452 | ->select( [ 'tree_ancestor_id', 'tree_descendant_id' ] ) |
| 453 | ->from( $this->tableName ) |
| 454 | ->where( [ |
| 455 | 'tree_descendant_id' => UUID::convertUUIDs( $nodes ), |
| 456 | 'tree_depth' => 1, |
| 457 | ] ) |
| 458 | ->caller( __METHOD__ ) |
| 459 | ->fetchResultSet(); |
| 460 | $result = []; |
| 461 | foreach ( $res as $node ) { |
| 462 | if ( isset( $result[$node->tree_descendant_id] ) ) { |
| 463 | throw new DataModelException( 'Already have a parent for ' . $node->tree_descendant_id, 'process-data' ); |
| 464 | } |
| 465 | $descendant = UUID::create( $node->tree_descendant_id ); |
| 466 | $result[$descendant->getAlphadecimal()] = UUID::create( $node->tree_ancestor_id ); |
| 467 | } |
| 468 | foreach ( $nodes as $node ) { |
| 469 | if ( !isset( $result[$node->getAlphadecimal()] ) ) { |
| 470 | // $node is a root, it has no parent |
| 471 | $result[$node->getAlphadecimal()] = null; |
| 472 | } |
| 473 | } |
| 474 | |
| 475 | return $result; |
| 476 | } |
| 477 | } |