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MDL-34399 questions: cache to help load question definitions.

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At the moment, it takes several DB queries to load each question definition,
so this cache is potentially a big win.
This commit is contained in:
Tim Hunt 2012-10-17 17:25:04 +08:00
parent 7e8ae12a7a
commit a560d636f4
6 changed files with 137 additions and 23 deletions
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1
lang/en/cache.php
View File

@ -38,6 +38,7 @@ $string['cachedef_config'] = 'Config settings';
$string['cachedef_databasemeta'] = 'Database meta information';
$string['cachedef_eventinvalidation'] = 'Event invalidation';
$string['cachedef_locking'] = 'Locking';
$string['cachedef_questiondata'] = 'Question definitions';
$string['cachedef_string'] = 'Language string cache';
$string['cachelock_file_default'] = 'Default file locking';
$string['cachestores'] = 'Cache stores';

16
lib/db/caches.php
View File

@ -27,6 +27,7 @@
*/
$definitions = array(
// Used to store processed lang files.
'string' => array(
'mode' => cache_store::MODE_APPLICATION,
@ -35,6 +36,7 @@ $definitions = array(
'persistent' => true,
'persistentmaxsize' => 3
),
// Used to store database meta information.
'databasemeta' => array(
'mode' => cache_store::MODE_APPLICATION,
@ -44,15 +46,27 @@ $definitions = array(
'persistent' => true,
'persistentmaxsize' => 2
),
// Used to store data from the config + config_plugins table in the database.
'config' => array(
'mode' => cache_store::MODE_APPLICATION,
'persistent' => true
),
// Event invalidation cache.
'eventinvalidation' => array(
'mode' => cache_store::MODE_APPLICATION,
'persistent' => true,
'requiredataguarantee' => true
)
),
// Cache for question definitions. This is used by the question_bank class.
// Users probably do not need to know about this cache. They will just call
// question_bank::load_question.
'questiondata' => array(
'mode' => cache_store::MODE_APPLICATION,
'requiredataguarantee' => false,
'datasource' => 'question_finder',
'datasourcefile' => 'question/engine/bank.php',
),
);

27
lib/questionlib.php
View File

@ -343,6 +343,7 @@ function question_delete_question($questionid) {
// Finally delete the question record itself
$DB->delete_records('question', array('id' => $questionid));
question_bank::notify_question_edited($questionid);
}
/**
@ -607,6 +608,11 @@ function question_move_questions_to_category($questionids, $newcategoryid) {
// TODO Deal with datasets.
// Purge these questions from the cache.
foreach ($questions as $question) {
question_bank::notify_question_edited($question->id);
}
return true;
}
@ -626,6 +632,8 @@ function question_move_category_to_context($categoryid, $oldcontextid, $newconte
foreach ($questionids as $questionid => $qtype) {
question_bank::get_qtype($qtype)->move_files(
$questionid, $oldcontextid, $newcontextid);
// Purge this question from the cache.
question_bank::notify_question_edited($questionid);
}
$subcatids = $DB->get_records_menu('question_categories',
@ -860,8 +868,11 @@ function question_hash($question) {
* Saves question options
*
* Simply calls the question type specific save_question_options() method.
* @deprecated all code should now call the question type method directly.
*/
function save_question_options($question) {
debugging('Please do not call save_question_options any more. Call the question type method directly.',
DEBUG_DEVELOPER);
question_bank::get_qtype($question->qtype)->save_question_options($question);
}
@ -1393,21 +1404,11 @@ function question_require_capability_on($question, $cap) {
* Get the real state - the correct question id and answer - for a random
* question.
* @param object $state with property answer.
* @return mixed return integer real question id or false if there was an
* error..
* @deprecated this function has not been relevant since Moodle 2.1!
*/
function question_get_real_state($state) {
global $OUTPUT;
$realstate = clone($state);
$matches = array();
if (!preg_match('|^random([0-9]+)-(.*)|', $state->answer, $matches)) {
echo $OUTPUT->notification(get_string('errorrandom', 'quiz_statistics'));
return false;
} else {
$realstate->question = $matches[1];
$realstate->answer = $matches[2];
return $realstate;
}
throw new coding_exception('question_get_real_state has not been relevant since Moodle 2.1. ' .
'I am not sure what you are trying to do, but stop it at once!');
}
/**

4
question/editlib.php
View File

@ -1521,6 +1521,10 @@ class question_bank_view {
if(($unhide = optional_param('unhide', '', PARAM_INT)) and confirm_sesskey()) {
question_require_capability_on($unhide, 'edit');
$DB->set_field('question', 'hidden', 0, array('id' => $unhide));
// Purge these questions from the cache.
question_bank::notify_question_edited($unhide);
redirect($this->baseurl);
}
}

109
question/engine/bank.php
View File

@ -51,8 +51,6 @@ abstract class question_bank {
/** @var array question type name => 1. Records which question definitions have been loaded. */
private static $loadedqdefs = array();
protected static $questionfinder = null;
/** @var boolean nasty hack to allow unit tests to call {@link load_question()}. */
private static $testmode = false;
private static $testdata = array();
@ -240,6 +238,23 @@ abstract class question_bank {
self::$loadedqdefs[$qtypename] = 1;
}
/**
* This method needs to be called whenever a question is edited.
*/
public static function notify_question_edited($questionid) {
question_finder::get_instance()->uncache_question($questionid);
}
/**
* Load a question definition data from the database. The data will be
* returned as a plain stdClass object.
* @param int $questionid the id of the question to load.
* @return object question definition loaded from the database.
*/
public static function load_question_data($questionid) {
return question_finder::get_instance()->load_question_data($questionid);
}
/**
* Load a question definition from the database. The object returned
* will actually be of an appropriate {@link question_definition} subclass.
@ -256,12 +271,8 @@ abstract class question_bank {
return self::return_test_question_data($questionid);
}
$questiondata = $DB->get_record_sql('
SELECT q.*, qc.contextid
FROM {question} q
JOIN {question_categories} qc ON q.category = qc.id
WHERE q.id = :id', array('id' => $questionid), MUST_EXIST);
get_question_options($questiondata);
$questiondata = self::load_question_data($questionid);
if (!$allowshuffle) {
$questiondata->options->shuffleanswers = false;
}
@ -282,6 +293,7 @@ abstract class question_bank {
* @return question_finder a question finder.
*/
public static function get_finder() {
return question_finder::get_instance();
if (is_null(self::$questionfinder)) {
self::$questionfinder = new question_finder();
}
@ -418,7 +430,55 @@ abstract class question_bank {
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class question_finder {
class question_finder implements cache_data_source {
/** @var question_finder the singleton instance of this class. */
protected static $questionfinder = null;
/** @var cache the question definition cache. */
protected $cache = null;
/**
* @return question_finder a question finder.
*/
public static function get_instance() {
if (is_null(self::$questionfinder)) {
self::$questionfinder = new question_finder();
}
return self::$questionfinder;
}
/* See cache_data_source::get_instance_for_cache. */
public static function get_instance_for_cache(cache_definition $definition) {
return self::get_instance();
}
/**
* @return get the question definition cache we are using.
*/
protected function get_data_cache() {
if ($this->cache == null) {
$this->cache = cache::make('core', 'questiondata');
}
return $this->cache;
}
/**
* This method needs to be called whenever a question is edited.
*/
public function uncache_question($questionid) {
$this->get_data_cache()->delete($questionid);
}
/**
* Load a question definition data from the database. The data will be
* returned as a plain stdClass object.
* @param int $questionid the id of the question to load.
* @return object question definition loaded from the database.
*/
public function load_question_data($questionid) {
return $this->get_data_cache()->get($questionid);
}
/**
* Get the ids of all the questions in a list of categoryies.
* @param array $categoryids either a categoryid, or a comma-separated list
@ -444,4 +504,35 @@ class question_finder {
AND hidden = 0
$extraconditions", $qcparams + $extraparams, '', 'id,id AS id2');
}
/* See cache_data_source::load_for_cache. */
public function load_for_cache($questionid) {
global $DB;
$questiondata = $DB->get_record_sql('
SELECT q.*, qc.contextid
FROM {question} q
JOIN {question_categories} qc ON q.category = qc.id
WHERE q.id = :id', array('id' => $questionid), MUST_EXIST);
get_question_options($questiondata);
return $questiondata;
}
/* See cache_data_source::load_many_for_cache. */
public function load_many_for_cache(array $questionids) {
global $DB;
list($idcondition, $params) = $DB->get_in_or_equal($questionids);
$questiondata = $DB->get_records_sql('
SELECT q.*, qc.contextid
FROM {question} q
JOIN {question_categories} qc ON q.category = qc.id
WHERE q.id ' . $idcondition, $params);
foreach ($questionids as $id) {
if (!array_key_exists($id, $questionids)) {
throw new dml_missing_record_exception('question', '', array('id' => $id));
}
get_question_options($questiondata[$id]);
}
return $questiondata;
}
}

3
question/question.php
View File

@ -281,6 +281,9 @@ if ($mform->is_cancelled()) {
}
}
// Purge this question from the cache.
question_bank::notify_question_edited($question->id);
if (($qtypeobj->finished_edit_wizard($fromform)) || $movecontext) {
if ($inpopup) {
echo $OUTPUT->notification(get_string('changessaved'), '');