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<?php |
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/** |
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* Efficiently run operations on batches of results for any function |
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* that supports an options array. |
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* |
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* This is usually used with elgg_get_entities() and friends, |
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* elgg_get_annotations(), and elgg_get_metadata(). |
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* |
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* If you pass a valid PHP callback, all results will be run through that |
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* callback. You can still foreach() through the result set after. Valid |
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* PHP callbacks can be a string, an array, or a closure. |
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* {@link http://php.net/manual/en/language.pseudo-types.php} |
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* |
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* The callback function must accept 3 arguments: an entity, the getter |
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* used, and the options used. |
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* |
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* Results from the callback are stored in callbackResult. If the callback |
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* returns only booleans, callbackResults will be the combined result of |
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* all calls. If no entities are processed, callbackResults will be null. |
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* |
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* If the callback returns anything else, callbackresult will be an indexed |
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* array of whatever the callback returns. If returning error handling |
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* information, you should include enough information to determine which |
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* result you're referring to. |
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* |
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* Don't combine returning bools and returning something else. |
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* |
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* Note that returning false will not stop the foreach. |
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* |
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* @warning If your callback or foreach loop deletes or disable entities |
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* you MUST call setIncrementOffset(false) or set that when instantiating. |
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* This forces the offset to stay what it was in the $options array. |
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* |
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* @example |
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* <code> |
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* // using foreach |
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* $batch = new \ElggBatch('elgg_get_entities', array()); |
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* $batch->setIncrementOffset(false); |
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* |
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* foreach ($batch as $entity) { |
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* $entity->disable(); |
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* } |
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* |
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* // using both a callback |
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* $callback = function($result, $getter, $options) { |
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* var_dump("Looking at annotation id: $result->id"); |
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* return true; |
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* } |
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* |
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* $batch = new \ElggBatch('elgg_get_annotations', array('guid' => 2), $callback); |
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* </code> |
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* |
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* @package Elgg.Core |
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* @subpackage DataModel |
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* @since 1.8 |
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*/ |
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class ElggBatch |
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implements \Iterator { |
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/** |
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* The objects to interator over. |
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* |
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* @var array |
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*/ |
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private $results = array(); |
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/** |
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* The function used to get results. |
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* |
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* @var mixed A string, array, or closure, or lamda function |
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*/ |
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private $getter = null; |
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/** |
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* The number of results to grab at a time. |
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* |
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* @var int |
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*/ |
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private $chunkSize = 25; |
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/** |
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* A callback function to pass results through. |
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* |
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* @var mixed A string, array, or closure, or lamda function |
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*/ |
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private $callback = null; |
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/** |
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* Start after this many results. |
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* |
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* @var int |
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*/ |
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private $offset = 0; |
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/** |
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* Stop after this many results. |
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* |
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* @var int |
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*/ |
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private $limit = 0; |
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/** |
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* Number of processed results. |
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* |
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* @var int |
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*/ |
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private $retrievedResults = 0; |
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/** |
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* The index of the current result within the current chunk |
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* |
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* @var int |
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*/ |
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private $resultIndex = 0; |
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/** |
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* The index of the current chunk |
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* |
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* @var int |
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*/ |
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private $chunkIndex = 0; |
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/** |
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* The number of results iterated through |
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* |
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* @var int |
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*/ |
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private $processedResults = 0; |
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/** |
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* Is the getter a valid callback |
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* |
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* @var bool |
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*/ |
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private $validGetter = null; |
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/** |
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* The result of running all entities through the callback function. |
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* |
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* @var mixed |
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*/ |
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public $callbackResult = null; |
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/** |
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* If false, offset will not be incremented. This is used for callbacks/loops that delete. |
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* |
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* @var bool |
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*/ |
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private $incrementOffset = true; |
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/** |
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* Entities that could not be instantiated during a fetch |
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* |
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* @var \stdClass[] |
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*/ |
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private $incompleteEntities = array(); |
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/** |
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* Total number of incomplete entities fetched |
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* |
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* @var int |
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*/ |
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private $totalIncompletes = 0; |
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/** |
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* Batches operations on any elgg_get_*() or compatible function that supports |
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* an options array. |
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* |
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* Instead of returning all objects in memory, it goes through $chunk_size |
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* objects, then requests more from the server. This avoids OOM errors. |
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* |
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* @param string $getter The function used to get objects. Usually |
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* an elgg_get_*() function, but can be any valid PHP callback. |
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* @param array $options The options array to pass to the getter function. If limit is |
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* not set, 10 is used as the default. In most cases that is not |
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* what you want. |
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* @param mixed $callback An optional callback function that all results will be passed |
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* to upon load. The callback needs to accept $result, $getter, |
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* $options. |
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* @param int $chunk_size The number of entities to pull in before requesting more. |
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* You have to balance this between running out of memory in PHP |
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* and hitting the db server too often. |
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* @param bool $inc_offset Increment the offset on each fetch. This must be false for |
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* callbacks that delete rows. You can set this after the |
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* object is created with {@link \ElggBatch::setIncrementOffset()}. |
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*/ |
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public function __construct($getter, $options, $callback = null, $chunk_size = 25, |
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$inc_offset = true) { |
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$this->getter = $getter; |
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$this->options = $options; |
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$this->callback = $callback; |
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$this->chunkSize = $chunk_size; |
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$this->setIncrementOffset($inc_offset); |
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if ($this->chunkSize <= 0) { |
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$this->chunkSize = 25; |
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} |
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// store these so we can compare later |
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$this->offset = elgg_extract('offset', $options, 0); |
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$this->limit = elgg_extract('limit', $options, elgg_get_config('default_limit')); |
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// if passed a callback, create a new \ElggBatch with the same options |
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// and pass each to the callback. |
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if ($callback && is_callable($callback)) { |
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$batch = new \ElggBatch($getter, $options, null, $chunk_size, $inc_offset); |
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$all_results = null; |
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foreach ($batch as $result) { |
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$result = call_user_func($callback, $result, $getter, $options); |
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if (!isset($all_results)) { |
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if ($result === true || $result === false || $result === null) { |
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$all_results = $result; |
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} else { |
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$all_results = array(); |
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} |
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} |
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if (($result === true || $result === false || $result === null) && !is_array($all_results)) { |
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$all_results = $result && $all_results; |
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} else { |
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$all_results[] = $result; |
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} |
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} |
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$this->callbackResult = $all_results; |
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} |
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} |
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/** |
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* Tell the process that an entity was incomplete during a fetch |
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* |
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* @param \stdClass $row |
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* |
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* @access private |
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*/ |
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public function reportIncompleteEntity(\stdClass $row) { |
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$this->incompleteEntities[] = $row; |
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} |
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/** |
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* Fetches the next chunk of results |
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* |
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* @return bool |
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*/ |
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private function getNextResultsChunk() { |
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// always reset results. |
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$this->results = array(); |
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if (!isset($this->validGetter)) { |
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$this->validGetter = is_callable($this->getter); |
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} |
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if (!$this->validGetter) { |
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return false; |
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} |
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$limit = $this->chunkSize; |
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// if someone passed limit = 0 they want everything. |
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if ($this->limit != 0) { |
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if ($this->retrievedResults >= $this->limit) { |
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return false; |
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} |
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// if original limit < chunk size, set limit to original limit |
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// else if the number of results we'll fetch if greater than the original limit |
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if ($this->limit < $this->chunkSize) { |
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$limit = $this->limit; |
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} elseif ($this->retrievedResults + $this->chunkSize > $this->limit) { |
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// set the limit to the number of results remaining in the original limit |
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$limit = $this->limit - $this->retrievedResults; |
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} |
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} |
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if ($this->incrementOffset) { |
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$offset = $this->offset + $this->retrievedResults; |
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} else { |
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$offset = $this->offset + $this->totalIncompletes; |
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} |
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$current_options = array( |
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'limit' => $limit, |
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'offset' => $offset, |
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'__ElggBatch' => $this, |
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); |
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$options = array_merge($this->options, $current_options); |
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$this->incompleteEntities = array(); |
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$this->results = call_user_func($this->getter, $options); |
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// batch result sets tend to be large; we don't want to cache these. |
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_elgg_services()->db->disableQueryCache(); |
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$num_results = count($this->results); |
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$num_incomplete = count($this->incompleteEntities); |
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$this->totalIncompletes += $num_incomplete; |
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if ($this->incompleteEntities) { |
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// pad the front of the results with nulls representing the incompletes |
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array_splice($this->results, 0, 0, array_pad(array(), $num_incomplete, null)); |
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// ...and skip past them |
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reset($this->results); |
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for ($i = 0; $i < $num_incomplete; $i++) { |
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next($this->results); |
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} |
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} |
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if ($this->results) { |
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$this->chunkIndex++; |
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// let the system know we've jumped past the nulls |
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$this->resultIndex = $num_incomplete; |
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$this->retrievedResults += ($num_results + $num_incomplete); |
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if ($num_results == 0) { |
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// This fetch was *all* incompletes! We need to fetch until we can either |
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// offer at least one row to iterate over, or give up. |
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return $this->getNextResultsChunk(); |
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} |
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_elgg_services()->db->enableQueryCache(); |
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return true; |
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} else { |
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_elgg_services()->db->enableQueryCache(); |
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return false; |
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} |
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} |
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/** |
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* Increment the offset from the original options array? Setting to |
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* false is required for callbacks that delete rows. |
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* |
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* @param bool $increment Set to false when deleting data |
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* @return void |
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*/ |
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public function setIncrementOffset($increment = true) { |
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$this->incrementOffset = (bool) $increment; |
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} |
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/** |
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* Implements Iterator |
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*/ |
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/** |
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* PHP Iterator Interface |
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* |
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* @see Iterator::rewind() |
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* @return void |
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*/ |
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public function rewind() { |
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$this->resultIndex = 0; |
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$this->retrievedResults = 0; |
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$this->processedResults = 0; |
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// only grab results if we haven't yet or we're crossing chunks |
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if ($this->chunkIndex == 0 || $this->limit > $this->chunkSize) { |
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$this->chunkIndex = 0; |
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$this->getNextResultsChunk(); |
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} |
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} |
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/** |
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* PHP Iterator Interface |
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* |
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* @see Iterator::current() |
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* @return mixed |
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*/ |
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public function current() { |
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return current($this->results); |
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} |
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/** |
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* PHP Iterator Interface |
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* |
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* @see Iterator::key() |
382
|
|
|
* @return int |
383
|
|
|
*/ |
384
|
|
|
public function key() { |
385
|
|
|
return $this->processedResults; |
386
|
|
|
} |
387
|
|
|
|
388
|
|
|
/** |
389
|
|
|
* PHP Iterator Interface |
390
|
|
|
* |
391
|
|
|
* @see Iterator::next() |
392
|
|
|
* @return mixed |
393
|
|
|
*/ |
394
|
|
|
public function next() { |
395
|
|
|
// if we'll be at the end. |
396
|
|
|
if (($this->processedResults + 1) >= $this->limit && $this->limit > 0) { |
397
|
|
|
$this->results = array(); |
398
|
|
|
return false; |
399
|
|
|
} |
400
|
|
|
|
401
|
|
|
// if we'll need new results. |
402
|
|
|
if (($this->resultIndex + 1) >= $this->chunkSize) { |
403
|
|
|
if (!$this->getNextResultsChunk()) { |
404
|
|
|
$this->results = array(); |
405
|
|
|
return false; |
406
|
|
|
} |
407
|
|
|
|
408
|
|
|
$result = current($this->results); |
409
|
|
|
} else { |
410
|
|
|
// the function above resets the indexes, so only inc if not |
411
|
|
|
// getting new set |
412
|
|
|
$this->resultIndex++; |
413
|
|
|
$result = next($this->results); |
414
|
|
|
} |
415
|
|
|
|
416
|
|
|
$this->processedResults++; |
417
|
|
|
return $result; |
418
|
|
|
} |
419
|
|
|
|
420
|
|
|
/** |
421
|
|
|
* PHP Iterator Interface |
422
|
|
|
* |
423
|
|
|
* @see Iterator::valid() |
424
|
|
|
* @return bool |
425
|
|
|
*/ |
426
|
|
|
public function valid() { |
427
|
|
|
if (!is_array($this->results)) { |
428
|
|
|
return false; |
429
|
|
|
} |
430
|
|
|
$key = key($this->results); |
431
|
|
|
return ($key !== null && $key !== false); |
432
|
|
|
} |
433
|
|
|
} |
434
|
|
|
|
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: