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Start refactoring the search system to use a new key-value store backend

....but it's not finished yet.

It should improve performance significantly when it's done & optimised, 
as we won't have to load the entire search index into memory & decode it 
just to perform a single query.
This commit is contained in:
Starbeamrainbowlabs 2019-08-18 18:52:29 +01:00
parent 38badd3c1f
commit ce6df06817
Signed by: sbrl
GPG key ID: 1BE5172E637709C2
3 changed files with 215 additions and 89 deletions

View file

@ -4,15 +4,10 @@ register_module([
"version" => "0.9",
"author" => "Starbeamrainbowlabs",
"description" => "Adds proper search functionality to Pepperminty Wiki using an inverted index to provide a full text search engine. If pages don't show up, then you might have hit a stop word. If not, try requesting the `invindex-rebuild` action to rebuild the inverted index from scratch.",
"extra_data" => [
"StorageBox.php" => "https://gist.githubusercontent.com/sbrl/c3bfbbbb3d1419332e9ece1bac8bb71c/raw/c4c858831e63d24fcecb2e221375486735cf3109/StorageBox.php"
],
"id" => "feature-search",
"code" => function() {
global $settings, $paths;
require_once("$paths->extra_data_directory/feature-search/StorageBox.php");
/**
* @api {get} ?action=index&page={pageName} Get an index of words for a given page
* @apiName SearchIndex
@ -39,7 +34,7 @@ register_module([
$source = file_get_contents("$env->storage_prefix$env->page.md");
$index = search::index($source);
$index = search::index_generate($source);
echo("Page name: $env->page\n");
echo("--------------- Source ---------------\n");
@ -83,7 +78,7 @@ register_module([
$_POST["secret"] === $settings->secret
)
)
search::rebuild_invindex();
search::invindex_rebuild();
else
{
http_response_code(401);
@ -128,7 +123,7 @@ register_module([
// Create the inverted index if it doesn't exist.
// todo In the future perhaps a CLI for this would be good?
if(!file_exists($paths->searchindex))
search::rebuild_invindex(false);
search::invindex_rebuild(false);
if(!isset($_GET["query"]))
exit(page_renderer::render("No Search Terms - Error - $settings->sitename", "<p>You didn't specify any search terms. Try typing some into the box above.</p>"));
@ -137,7 +132,7 @@ register_module([
$time_start = microtime(true);
$invindex = search::load_invindex($paths->searchindex);
$invindex = search::invindex_load($paths->searchindex);
$env->perfdata->invindex_decode_time = round((microtime(true) - $time_start)*1000, 3);
$time_start = microtime(true);
@ -308,7 +303,7 @@ register_module([
}
$env->perfdata->searchindex_decode_start = microtime(true);
$searchIndex = search::load_invindex($paths->searchindex);
$searchIndex = search::invindex_load($paths->searchindex);
$env->perfdata->searchindex_decode_time = (microtime(true) - $env->perfdata->searchindex_decode_start) * 1000;
$env->perfdata->searchindex_query_start = microtime(true);
$searchResults = search::query_invindex($_GET["query"], $searchIndex);
@ -480,6 +475,117 @@ window.addEventListener("load", function(event) {
}
]);
/*
███████ ████████ ██████ ██████ █████ ██████ ███████ ██████ ██████ ██ ██
██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██
███████ ██ ██ ██ ██████ ███████ ██ ███ █████ ██████ ██ ██ ███
██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██
███████ ██ ██████ ██ ██ ██ ██ ██████ ███████ ██████ ██████ ██ ██
*/
/**
* Represents a key-value data store.
*/
class StorageBox {
/**
* The SQLite database connection.
* @var \PDO
*/
private $db;
/**
* Initialises a new store connection.
* @param string $filename The filename that the store is located in.
*/
function __construct(string $filename) {
$firstrun = !file_exists($filename);
$this->db = new \PDO("sqlite:$filename");
if($firstrun) {
$this->query("CREATE TABLE store (key TEXT UNIQUE NOT NULL, value TEXT)");
}
}
/**
* Makes a query against the database.
* @param string $sql The (potentially parametised) query to make.
* @param array $variables Optional. The variables to substitute into the SQL query.
* @return \PDOStatement The result of the query, as a PDOStatement.
*/
private function query(string $sql, array $variables = []) {
// FUTURE: Optionally cache prepared statements?
$statement = $this->db->prepare($sql);
$statement->execute($variables);
return $statement; // fetchColumn(), fetchAll(), etc. are defined on the statement, not the return value of execute()
}
/**
* Determines if the given key exists in the store or not.
* @param string $key The key to test.
* @return bool Whether the key exists in the store or not.
*/
public function has(string $key) : bool {
return $this->query(
"SELECT COUNT(key) FROM store WHERE key = :key;",
[ "key" => $key ]
)->fetchColumn() > 0;
}
/**
* Gets a value from the store.
* @param string $key The key to store the value under.
* @return string The value to store.
*/
public function get(string $key) : string {
return $this->query(
"SELECT value FROM store WHERE key = :key;",
[ "key" => $key ]
)->fetchColumn();
}
/**
* Sets a value in the data store.
* @param string $key The key to set the value of.
* @param string $value The value to store.
*/
public function set(string $key, string $value) : void {
$this->query(
"INSERT OR REPLACE INTO store(key, value) VALUES(:key, :value)",
[
"key" => $key,
"value" => $value
]
);
}
/**
* Deletes an item from the data store.
* @param string $key The key of the item to delete.
* @return bool Whether it was really deleted or not. Note that if it doesn't exist, then it can't be deleted.
*/
public function delete(string $key) : bool {
$this->query(
"DELETE FROM store WHERE key = :key;",
[ "key" => $key ]
)->rowCount() > 0;
}
/**
* Empties the store.
*/
public function clear() : void {
$this->query("DELETE FROM store;");
}
}
/*
███████ ███████ █████ ██████ ██████ ██ ██
██ ██ ██ ██ ██ ██ ██ ██ ██
███████ █████ ███████ ██████ ██ ███████
██ ██ ██ ██ ██ ██ ██ ██ ██
███████ ███████ ██ ██ ██ ██ ██████ ██ ██
*/
/**
* Holds a collection to methods to manipulate various types of search index.
* @package search
@ -535,14 +641,20 @@ class search
"your", "yours", "yourself", "yourselves"
];
/**
* The StorageBox that contains the inverted index.
* @var StorageBox
*/
private static $invindex = null;
/**
* Converts a source string into an index of search terms that can be
* merged into an inverted index.
* Automatically transliterates the source string.
* @param string $source The source string to index.
* @return array An index represents the specified string.
*/
public static function index($source)
{
public static function index_generate(string $source) : array {
// We don't need to normalise or transliterate here because self::tokenize() does this for us
$source = html_entity_decode($source, ENT_QUOTES);
$source_length = mb_strlen($source);
@ -570,7 +682,7 @@ class search
* @param bool $capture_offsets Whether to capture & return the character offsets of the tokens detected. If true, then each token returned will be an array in the form [ token, char_offset ].
* @return array An array of raw tokens extracted from the specified source string.
*/
public static function tokenize($source, $capture_offsets = false) {
public static function tokenize(string $source, bool $capture_offsets = false) : array {
/** Normalises input characters for searching & indexing */
static $literator; if($literator == null) $literator = Transliterator::createFromRules(':: Any-Latin; :: Latin-ASCII; :: NFD; :: [:Nonspacing Mark:] Remove; :: Lower(); :: NFC;', Transliterator::FORWARD);
@ -579,8 +691,8 @@ class search
$flags |= PREG_SPLIT_OFFSET_CAPTURE;
// We don't need to normalise here because the transliterator handles
// this for us. Also, we can't move the literator to a static variable
// because PHP doesn't like it very much
// this for us. Also, we can't move the literator to a static member
// variable because PHP doesn't like it very much
$source = $literator->transliterate($source);
$source = preg_replace('/[\[\]\|\{\}\/]/u', " ", $source);
return preg_split("/((^\p{P}+)|(\p{P}*\s+\p{P}*)|(\p{P}+$))|\|/u", $source, -1, $flags);
@ -592,8 +704,7 @@ class search
* @param string $source The source string to process.
* @return string The stripped string.
*/
public static function strip_markup($source)
{
public static function strip_markup(string $source) : string {
return preg_replace('/([\"*_\[\]]| - |`)/u', "", $source);
}
@ -601,8 +712,7 @@ class search
* Rebuilds the master inverted index and clears the page id index.
* @param bool $output Whether to send progress information to the user's browser.
*/
public static function rebuild_invindex($output = true)
{
public static function invindex_rebuild(bool $output = true) : void {
global $pageindex, $env, $paths, $settings;
if($output) {
@ -613,8 +723,11 @@ class search
// Clear the id index out
ids::clear();
// Clear the existing inverted index out
$this->invindex->clear();
$this->invindex->set("|termlist|", "[]");
// Reindex each page in turn
$invindex = [];
$i = 0; $max = count(get_object_vars($pageindex));
$missing_files = 0;
foreach($pageindex as $pagename => $pagedetails)
@ -627,10 +740,10 @@ class search
continue;
}
// We do not transliterate or normalise here because the indexer will take care of this for us
$index = self::index(file_get_contents($page_filename));
$index = self::index_generate(file_get_contents($page_filename));
$pageid = ids::getid($pagename);
self::merge_into_invindex($invindex, $pageid, $index);
self::invindex_merge($pageid, $index);
if($output) {
echo("data: [" . ($i + 1) . " / $max] Added $pagename (id #$pageid) to the new search index.\n\n");
@ -646,7 +759,7 @@ class search
echo("data: Done! Saving new search index to '$paths->searchindex'.\n\n");
}
self::save_invindex($paths->searchindex, $invindex);
// No need to save, it's an SQLite DB backend
}
/**
@ -655,10 +768,7 @@ class search
* sequential search.
* @param array $index The index to sort.
*/
public static function sort_index(&$index)
{
ksort($index, SORT_NATURAL);
}
public static function index_sort(&$index) { ksort($index, SORT_NATURAL); }
/**
* Compares two *regular* indexes to find the differences between them.
@ -667,7 +777,7 @@ class search
* @param array $changed An array to be filled with the nterms of all the changed entries.
* @param array $removed An array to be filled with the nterms of all the removed entries.
*/
public static function compare_indexes($oldindex, $newindex, &$changed, &$removed) {
public static function index_compare($oldindex, $newindex, &$changed, &$removed) {
foreach($oldindex as $nterm => $entry) {
if(!isset($newindex[$nterm]))
$removed[] = $nterm;
@ -681,77 +791,95 @@ class search
/**
* Reads in and parses an inverted index.
* @param string $invindex_filename The path tp the inverted index to parse.
* @param string $invindex_filename The path to the inverted index to load.
* @todo Remove this function and make everything streamable
*/
public static function load_invindex($invindex_filename) {
$invindex = json_decode(file_get_contents($invindex_filename), true);
return $invindex;
}
/**
* Reads in and parses an inverted index, measuring the time it takes to do so.
* @param string $invindex_filename The path to the file inverted index to parse.
* @return bool Whether the measurement was actually able to take place. Usually this will be true, but it will return false if it can't find the specified index.
*/
public static function measure_invindex_load_time($invindex_filename) {
public static function invindex_load(string $invindex_filename) {
global $env;
if(!file_exists($invindex_filename))
return false;
$searchindex_decode_start = microtime(true);
search::load_invindex($invindex_filename);
$env->perfdata->searchindex_decode_time = round((microtime(true) - $searchindex_decode_start)*1000, 3);
return true;
$start_time = microtime(true);
$this->invindex = new StorageBox($invindex_filename);
$env->perfdata->searchindex_load_time = round((microtime(true) - $start_time)*1000, 3);
}
/**
* Merge an index into an inverted index.
* @param array $invindex The inverted index to merge into.
* @param int $pageid The id of the page to assign to the index that's being merged.
* @param array $index The regular index to merge.
* @param array $removals An array of index entries to remove from the inverted index. Useful for applying changes to an inverted index instead of deleting and remerging an entire page's index.
*/
public static function merge_into_invindex(&$invindex, $pageid, &$index, &$removals = [])
{
public static function invindex_merge($pageid, &$index, &$removals = []) : void {
if($this->invindex == null)
throw new Exception("Error: Can't merge into an inverted index that isn't loaded.");
$termlist = json_decode($this->invindex->get("|termlist|"));
// Remove all the subentries that were removed since last time
foreach($removals as $nterm)
unset($invindex[$nterm][$pageid]);
foreach($removals as $nterm) {
// Delete the offsets
$this->invindex->delete("$nterm|$pageid");
// Delete the item from the list of pageids containing this term
$nterm_pageids = json_decode($this->invindex->get($nterm));
array_splice($nterm_pageids, array_search($pageid, $nterm_pageids), 1);
if(empty($nterm_pageids)) { // No need to keep the pageid list if there's nothing in it
$this->invindex->delete($nterm);
// Update the termlist if we're deleting the term completely
$termlist_loc = array_search($nterm, $termlist);
if($termlist_loc !== false) array_splice($termlist, $termlist_loc, 1);
}
else
$this->invindex->set($nterm, json_encode($nterm_pageids));
}
// Merge all the new / changed index entries into the inverted index
foreach($index as $nterm => $newentry) {
// If the nterm isn't in the inverted index, then create a space for it
if(!isset($invindex[$nterm])) $invindex[$nterm] = [];
$invindex[$nterm][$pageid] = $newentry;
if(!$this->invindex->has($nterm)) {
$this->invindex->set($nterm, "[]");
$termlist[] = $nterm;
}
// Update the nterm pageid list
$nterm_pageids = json_decode($this->invindex->get($nterm));
if(array_search($pageid, $nterm_pageids) === false) {
$nterm_pageids[] = $pageid;
$this->invindex->set($nterm, json_encode($nterm_pageids));
}
// Store the offset list
$this->invindex->set("$nterm|$pageid", json_encode($newentry));
}
$this->invindex->set("|termlist|", json_encode($termlist));
}
/**
* Deletes the given pageid from the given pageindex.
* @param array &$invindex The inverted index.
* @param int $pageid The pageid to remove.
*/
public static function delete_entry(&$invindex, $pageid)
{
$str_pageid = (string)$pageid;
foreach($invindex as $nterm => &$entry)
{
if(isset($entry[$pageid]))
unset($entry[$pageid]);
if(isset($entry[$str_pageid]))
unset($entry[$str_pageid]);
if(count($entry) === 0)
unset($invindex[$nterm]);
public static function invindex_delete(int $pageid) {
$termlist = json_decode($this->invindex->get("|termlist|"));
foreach($termlist as $nterm) {
$nterm_pageids = json_decode($this->invindex->get("$nterm"));
$nterm_loc = array_search($pageid, $nterm_pageids);
// If this nterm doesn't appear in the list, we're not interested
if($nterm_loc === false)
continue;
// Delete it from the ntemr list
array_splice($nterm_pageids, $nterm_loc, 1);
// Delete the offset list
$this->invindex->delete("$nterm|$pageid");
// If this term doesn't appear in any other documents, delete it
if(count($nterm_pageids) === 0) {
$this->invindex->delete($nterm);
array_splice($termlist, array_search($nterm, $termlist), 1);
}
else // Save the document id list back, since it still contains other pageids
$this->invindex->set($nterm, json_encode($nterm_pageids));
}
}
/**
* Saves the given inverted index back to disk.
* @param string $filename The path to the file to save the inverted index to.
* @param array $invindex The inverted index to save.
*/
public static function save_invindex($filename, &$invindex)
{
file_put_contents($filename, json_encode($invindex));
// Save the termlist back to the store
$this->invindex->set("|termlist|", json_encode($termlist));
}
/**

View file

@ -80,18 +80,17 @@ register_module([
// Save the new page index
save_pageindex();
// Remove the page's name from the id index
ids::deletepagename($env->page);
// Delete the page from the search index, if that module is installed
if(module_exists("feature-search"))
{
if(module_exists("feature-search")) {
$pageid = ids::getid($env->page);
$invindex = search::load_invindex($paths->searchindex);
search::delete_entry($invindex, $pageid);
search::save_invindex($paths->searchindex, $invindex);
search::invindex_load($paths->searchindex);
search::invindex_delete($pageid);
}
// Remove the page's name from the id index
ids::deletepagename($env->page);
// Delete the page from the disk
unlink("$env->storage_prefix$env->page.md");

View file

@ -454,20 +454,19 @@ DIFFSCRIPT;
if(file_exists("$env->storage_prefix$env->page.md"))
{
$oldpagedata = file_get_contents("$env->storage_prefix$env->page.md");
$oldindex = search::index($oldpagedata);
$oldindex = search::index_generate($oldpagedata);
}
$newindex = search::index($pagedata);
$newindex = search::index_generate($pagedata);
// Compare the indexes of the old and new content
$additions = [];
$removals = [];
search::compare_indexes($oldindex, $newindex, $additions, $removals);
search::index_compare($oldindex, $newindex, $additions, $removals);
// Load in the inverted index
$invindex = search::load_invindex($env->storage_prefix . "invindex.json");
search::invindex_load($paths->searchindex);
// Merge the changes into the inverted index
search::merge_into_invindex($invindex, ids::getid($env->page), $additions, $removals);
search::invindex_merge(ids::getid($env->page), $additions, $removals);
// Save the inverted index back to disk
search::save_invindex($env->storage_prefix . "invindex.json", $invindex);
// -----~~~==~~~-----