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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Base class for search engines.
*
* All search engines must extend this class.
*
* @package core_search
* @copyright 2015 Daniel Neis
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_search;
defined('MOODLE_INTERNAL') || die();
/**
* Base class for search engines.
*
* All search engines must extend this class.
*
* @package core_search
* @copyright 2015 Daniel Neis
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class engine {
/**
* The search engine configuration.
*
* @var \stdClass
*/
protected $config = null;
/**
* Last executed query error, if there was any.
* @var string
*/
protected $queryerror = null;
/**
* @var array Internal cache.
*/
protected $cachedareas = array();
/**
* @var array Internal cache.
*/
protected $cachedcourses = array();
/**
* User data required to show their fullnames. Indexed by userid.
*
* @var \stdClass[]
*/
protected static $cachedusers = array();
/**
* @var string Frankenstyle plugin name.
*/
protected $pluginname = null;
/**
* @var bool If true, should skip schema validity check when checking the search engine is ready
*/
protected $skipschemacheck = false;
/**
* Initialises the search engine configuration.
*
* Search engine availability should be checked separately.
*
* @return void
*/
public function __construct() {
$classname = get_class($this);
if (strpos($classname, '\\') === false) {
throw new \coding_exception('"' . $classname . '" class should specify its component namespace and it should be named engine.');
} else if (strpos($classname, '_') === false) {
throw new \coding_exception('"' . $classname . '" class namespace should be its frankenstyle name');
}
// This is search_xxxx config.
$this->pluginname = substr($classname, 0, strpos($classname, '\\'));
if ($config = get_config($this->pluginname)) {
$this->config = $config;
} else {
$this->config = new stdClass();
}
}
/**
* Returns a course instance checking internal caching.
*
* @param int $courseid
* @return stdClass
*/
protected function get_course($courseid) {
if (!empty($this->cachedcourses[$courseid])) {
return $this->cachedcourses[$courseid];
}
// No need to clone, only read.
$this->cachedcourses[$courseid] = get_course($courseid, false);
return $this->cachedcourses[$courseid];
}
/**
* Returns user data checking the internal static cache.
*
* Including here the minimum required user information as this may grow big.
*
* @param int $userid
* @return stdClass
*/
public function get_user($userid) {
global $DB;
if (empty(self::$cachedusers[$userid])) {
$fields = get_all_user_name_fields(true);
self::$cachedusers[$userid] = $DB->get_record('user', array('id' => $userid), 'id, ' . $fields);
}
return self::$cachedusers[$userid];
}
/**
* Clears the users cache.
*
* @return null
*/
public static function clear_users_cache() {
self::$cachedusers = [];
}
/**
* Returns a search instance of the specified area checking internal caching.
*
* @param string $areaid Area id
* @return \core_search\base
*/
protected function get_search_area($areaid) {
if (isset($this->cachedareas[$areaid]) && $this->cachedareas[$areaid] === false) {
// We already checked that area and it is not available.
return false;
}
if (!isset($this->cachedareas[$areaid])) {
// First result that matches this area.
$this->cachedareas[$areaid] = \core_search\manager::get_search_area($areaid);
if ($this->cachedareas[$areaid] === false) {
// The area does not exist or it is not available any more.
$this->cachedareas[$areaid] = false;
return false;
}
if (!$this->cachedareas[$areaid]->is_enabled()) {
// We skip the area if it is not enabled.
// Marking it as false so next time we don' need to check it again.
$this->cachedareas[$areaid] = false;
return false;
}
}
return $this->cachedareas[$areaid];
}
/**
* Returns a document instance prepared to be rendered.
*
* @param \core_search\base $searcharea
* @param array $docdata
* @return \core_search\document
*/
protected function to_document(\core_search\base $searcharea, $docdata) {
list($componentname, $areaname) = \core_search\manager::extract_areaid_parts($docdata['areaid']);
$doc = \core_search\document_factory::instance($docdata['itemid'], $componentname, $areaname, $this);
$doc->set_data_from_engine($docdata);
$doc->set_doc_url($searcharea->get_doc_url($doc));
$doc->set_context_url($searcharea->get_context_url($doc));
$doc->set_doc_icon($searcharea->get_doc_icon($doc));
// Uses the internal caches to get required data needed to render the document later.
$course = $this->get_course($doc->get('courseid'));
$doc->set_extra('coursefullname', $course->fullname);
if ($doc->is_set('userid')) {
$user = $this->get_user($doc->get('userid'));
$doc->set_extra('userfullname', fullname($user));
}
return $doc;
}
/**
* Loop through given iterator of search documents
* and and have the search engine back end add them
* to the index.
*
* @param iterator $iterator the iterator of documents to index
* @param searcharea $searcharea the area for the documents to index
* @param array $options document indexing options
* @return array Processed document counts
*/
public function add_documents($iterator, $searcharea, $options) {
$numrecords = 0;
$numdocs = 0;
$numdocsignored = 0;
$lastindexeddoc = 0;
$firstindexeddoc = 0;
$partial = false;
$lastprogress = manager::get_current_time();
foreach ($iterator as $document) {
// Stop if we have exceeded the time limit (and there are still more items). Always
// do at least one second's worth of documents otherwise it will never make progress.
if ($lastindexeddoc !== $firstindexeddoc &&
!empty($options['stopat']) && manager::get_current_time() >= $options['stopat']) {
$partial = true;
break;
}
if (!$document instanceof \core_search\document) {
continue;
}
if (isset($options['lastindexedtime']) && $options['lastindexedtime'] == 0) {
// If we have never indexed this area before, it must be new.
$document->set_is_new(true);
}
if ($options['indexfiles']) {
// Attach files if we are indexing.
$searcharea->attach_files($document);
}
if ($this->add_document($document, $options['indexfiles'])) {
$numdocs++;
} else {
$numdocsignored++;
}
$lastindexeddoc = $document->get('modified');
if (!$firstindexeddoc) {
$firstindexeddoc = $lastindexeddoc;
}
$numrecords++;
// If indexing the area takes a long time, periodically output progress information.
if (isset($options['progress'])) {
$now = manager::get_current_time();
if ($now - $lastprogress >= manager::DISPLAY_INDEXING_PROGRESS_EVERY) {
$lastprogress = $now;
// The first date format is the same used in cron_trace_time_and_memory().
$options['progress']->output(date('H:i:s', $now) . ': Done to ' . userdate(
$lastindexeddoc, get_string('strftimedatetimeshort', 'langconfig')), 1);
}
}
}
return array($numrecords, $numdocs, $numdocsignored, $lastindexeddoc, $partial);
}
/**
* Returns the plugin name.
*
* @return string Frankenstyle plugin name.
*/
public function get_plugin_name() {
return $this->pluginname;
}
/**
* Gets the document class used by this search engine.
*
* Search engines can overwrite \core_search\document with \search_ENGINENAME\document class.
*
* Looks for a document class in the current search engine namespace, falling back to \core_search\document.
* Publicly available because search areas do not have access to the engine details,
* \core_search\document_factory accesses this function.
*
* @return string
*/
public function get_document_classname() {
$classname = $this->pluginname . '\\document';
if (!class_exists($classname)) {
$classname = '\\core_search\\document';
}
return $classname;
}
/**
* Run any pre-indexing operations.
*
* Should be overwritten if the search engine needs to do any pre index preparation.
*
* @param bool $fullindex True if a full index will be performed
* @return void
*/
public function index_starting($fullindex = false) {
// Nothing by default.
}
/**
* Run any post indexing operations.
*
* Should be overwritten if the search engine needs to do any post index cleanup.
*
* @param int $numdocs The number of documents that were added to the index
* @param bool $fullindex True if a full index was performed
* @return void
*/
public function index_complete($numdocs = 0, $fullindex = false) {
// Nothing by default.
}
/**
* Do anything that may need to be done before an area is indexed.
*
* @param \core_search\base $searcharea The search area that was complete
* @param bool $fullindex True if a full index is being performed
* @return void
*/
public function area_index_starting($searcharea, $fullindex = false) {
// Nothing by default.
}
/**
* Do any area cleanup needed, and do anything to confirm contents.
*
* Return false to prevent the search area completed time and stats from being updated.
*
* @param \core_search\base $searcharea The search area that was complete
* @param int $numdocs The number of documents that were added to the index
* @param bool $fullindex True if a full index is being performed
* @return bool True means that data is considered indexed
*/
public function area_index_complete($searcharea, $numdocs = 0, $fullindex = false) {
return true;
}
/**
* Optimizes the search engine.
*
* Should be overwritten if the search engine can optimize its contents.
*
* @return void
*/
public function optimize() {
// Nothing by default.
}
/**
* Does the system satisfy all the requirements.
*
* Should be overwritten if the search engine has any system dependencies
* that needs to be checked.
*
* @return bool
*/
public function is_installed() {
return true;
}
/**
* Returns any error reported by the search engine when executing the provided query.
*
* It should be called from static::execute_query when an exception is triggered.
*
* @return string
*/
public function get_query_error() {
return $this->queryerror;
}
/**
* Returns the total number of documents available for the most recent call to execute_query.
*
* This can be an estimate, but should get more accurate the higher the limited passed to execute_query is.
* To do that, the engine can use (actual result returned count + count of unchecked documents), or
* (total possible docs - docs that have been checked and rejected).
*
* Engine can limit to manager::MAX_RESULTS if there is cost to determining more.
* If this cannot be computed in a reasonable way, manager::MAX_RESULTS may be returned.
*
* @return int
*/
abstract public function get_query_total_count();
/**
* Return true if file indexing is supported and enabled. False otherwise.
*
* @return bool
*/
public function file_indexing_enabled() {
return false;
}
/**
* Clears the current query error value.
*
* @return void
*/
public function clear_query_error() {
$this->queryerror = null;
}
/**
* Is the server ready to use?
*
* This should also check that the search engine configuration is ok.
*
* If the function $this->should_skip_schema_check() returns true, then this function may leave
* out time-consuming checks that the schema is valid. (This allows for improved performance on
* critical pages such as the main search form.)
*
* @return true|string Returns true if all good or an error string.
*/
abstract function is_server_ready();
/**
* Tells the search engine to skip any time-consuming checks that it might do as part of the
* is_server_ready function, and only carry out a basic check that it can contact the server.
*
* This setting is not remembered and applies only to the current request.
*
* @since Moodle 3.5
* @param bool $skip True to skip the checks, false to start checking again
*/
public function skip_schema_check($skip = true) {
$this->skipschemacheck = $skip;
}
/**
* For use by subclasses. The engine can call this inside is_server_ready to check whether it
* should skip time-consuming schema checks.
*
* @since Moodle 3.5
* @return bool True if schema checks should be skipped
*/
protected function should_skip_schema_check() {
return $this->skipschemacheck;
}
/**
* Adds a document to the search engine.
*
* @param document $document
* @param bool $fileindexing True if file indexing is to be used
* @return bool False if the file was skipped or failed, true on success
*/
abstract function add_document($document, $fileindexing = false);
/**
* Executes the query on the engine.
*
* Implementations of this function should check user context array to limit the results to contexts where the
* user have access. They should also limit the owneruserid field to manger::NO_OWNER_ID or the current user's id.
* Engines must use area->check_access() to confirm user access.
*
* Engines should reasonably attempt to fill up to limit with valid results if they are available.
*
* The $filters object may include the following fields (optional except q):
* - q: value of main search field; results should include this text
* - title: if included, title must match this search
* - areaids: array of search area id strings (only these areas will be searched)
* - courseids: array of course ids (only these courses will be searched)
* - groupids: array of group ids (only results specifically from these groupids will be
* searched) - this option will be ignored if the search engine doesn't support groups
*
* The $accessinfo parameter has two different values (for historical compatibility). If the
* engine returns false to supports_group_filtering then it is an array of user contexts, or
* true if the user can access all contexts. (This parameter used to be called $usercontexts.)
* If the engine returns true to supports_group_filtering then it will be an object containing
* these fields:
* - everything (true if admin is searching with no restrictions)
* - usercontexts (same as above)
* - separategroupscontexts (array of context ids where separate groups are used)
* - visiblegroupscontextsareas (array of subset of those where some areas use visible groups)
* - usergroups (array of relevant group ids that user belongs to)
*
* The engine should apply group restrictions to those contexts listed in the
* 'separategroupscontexts' array. In these contexts, it shouled only include results if the
* groupid is not set, or if the groupid matches one of the values in USER_GROUPS array, or
* if the search area is one of those listed in 'visiblegroupscontextsareas' for that context.
*
* @param \stdClass $filters Query and filters to apply.
* @param \stdClass $accessinfo Information about the contexts the user can access
* @param int $limit The maximum number of results to return. If empty, limit to manager::MAX_RESULTS.
* @return \core_search\document[] Results or false if no results
*/
public abstract function execute_query($filters, $accessinfo, $limit = 0);
/**
* Delete all documents.
*
* @param string $areaid To filter by area
* @return void
*/
abstract function delete($areaid = null);
/**
* Deletes information related to a specific context id. This should be used when the context
* itself is deleted from Moodle.
*
* This only deletes information for the specified context - not for any child contexts.
*
* This function is optional; if not supported it will return false and the information will
* not be deleted from the search index.
*
* If an engine implements this function it should also implement delete_index_for_course;
* otherwise, nothing will be deleted when users delete an entire course at once.
*
* @param int $oldcontextid ID of context that has been deleted
* @return bool True if implemented
* @throws \core_search\engine_exception Engines may throw this exception for any problem
*/
public function delete_index_for_context(int $oldcontextid) {
return false;
}
/**
* Deletes information related to a specific course id. This should be used when the course
* itself is deleted from Moodle.
*
* This deletes all information relating to that course from the index, including all child
* contexts.
*
* This function is optional; if not supported it will return false and the information will
* not be deleted from the search index.
*
* If an engine implements this function then, ideally, it should also implement
* delete_index_for_context so that deletion of single activities/blocks also works.
*
* @param int $oldcourseid ID of course that has been deleted
* @return bool True if implemented
* @throws \core_search\engine_exception Engines may throw this exception for any problem
*/
public function delete_index_for_course(int $oldcourseid) {
return false;
}
/**
* Checks that the schema is the latest version. If the version stored in config does not match
* the current, this function will attempt to upgrade the schema.
*
* @return bool|string True if schema is OK, a string if user needs to take action
*/
public function check_latest_schema() {
if (empty($this->config->schemaversion)) {
$currentversion = 0;
} else {
$currentversion = $this->config->schemaversion;
}
if ($currentversion < document::SCHEMA_VERSION) {
return $this->update_schema((int)$currentversion, (int)document::SCHEMA_VERSION);
} else {
return true;
}
}
/**
* Usually called by the engine; marks that the schema has been updated.
*
* @param int $version Records the schema version now applied
*/
public function record_applied_schema_version($version) {
set_config('schemaversion', $version, $this->pluginname);
}
/**
* Requests the search engine to upgrade the schema. The engine should update the schema if
* possible/necessary, and should ensure that record_applied_schema_version is called as a
* result.
*
* If it is not possible to upgrade the schema at the moment, it can do nothing and return; the
* function will be called again next time search is initialised.
*
* The default implementation just returns, with a DEBUG_DEVELOPER warning.
*
* @param int $oldversion Old schema version
* @param int $newversion New schema version
* @return bool|string True if schema is updated successfully, a string if it needs updating manually
*/
protected function update_schema($oldversion, $newversion) {
debugging('Unable to update search engine schema: ' . $this->pluginname, DEBUG_DEVELOPER);
return get_string('schemanotupdated', 'search');
}
/**
* Checks if this search engine supports groups.
*
* Note that returning true to this function causes the parameters to execute_query to be
* passed differently!
*
* In order to implement groups and return true to this function, the search engine should:
*
* 1. Handle the fields ->separategroupscontexts and ->usergroups in the $accessinfo parameter
* to execute_query (ideally, using these to automatically restrict search results).
* 2. Support the optional groupids parameter in the $filter parameter for execute_query to
* restrict results to only those where the stored groupid matches the given value.
*
* @return bool True if this engine supports searching by group id field
*/
public function supports_group_filtering() {
return false;
}
/**
* Obtain a list of results orders (and names for them) that are supported by this
* search engine in the given context.
*
* By default, engines sort by relevance only.
*
* @param \context $context Context that the user requested search from
* @return array Array from order name => display text
*/
public function get_supported_orders(\context $context) {
return ['relevance' => get_string('order_relevance', 'search')];
}
/**
* Checks if the search engine supports searching by user.
*
* If it returns true to this function, the search engine should support the 'userids' option
* in the $filters value passed to execute_query(), returning only items where the userid in
* the search document matches one of those user ids.
*
* @return bool True if the search engine supports searching by user
*/
public function supports_users() {
return false;
}
}