205 lines
6.7 KiB
PHP
205 lines
6.7 KiB
PHP
<?php
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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register_module([
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"name" => "Library: Storage box",
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"version" => "0.13",
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"author" => "Starbeamrainbowlabs",
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"description" => "A library module that provides a fast cached key-value store backed by SQLite. Used by the search engine.",
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"id" => "lib-storage-box",
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"code" => function() {
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}
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]);
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/*
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███████ ████████ ██████ ██████ █████ ██████ ███████ ██████ ██████ ██ ██
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██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██
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███████ ██ ██ ██ ██████ ███████ ██ ███ █████ ██████ ██ ██ ███
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██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██ ██
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███████ ██ ██████ ██ ██ ██ ██ ██████ ███████ ██████ ██████ ██ ██
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*/
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/**
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* Represents a key-value data store.
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*
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*/
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class StorageBox {
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const MODE_JSON = 0;
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const MODE_ARR_SIMPLE = 1;
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/**
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* The SQLite database connection.
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* @var \PDO
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*/
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private $db;
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/**
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* A cache of values.
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* @var object[]
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*/
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private $cache = [];
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/**
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* A cache of prepared SQL statements.
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* @var \PDOStatement[]
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*/
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private $query_cache = [];
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/**
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* Initialises a new store connection.
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* @param string $filename The filename that the store is located in.
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*/
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function __construct(string $filename) {
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$firstrun = !file_exists($filename);
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$this->db = new \PDO("sqlite:" . path_resolve($filename, __DIR__)); // HACK: This might not work on some systems, because it depends on the current working directory
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$this->db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
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if($firstrun) {
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$this->query("CREATE TABLE store (key TEXT UNIQUE NOT NULL, value TEXT)");
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}
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}
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/**
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* Makes a query against the database.
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* @param string $sql The (potentially parametised) query to make.
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* @param array $variables Optional. The variables to substitute into the SQL query.
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* @return \PDOStatement The result of the query, as a PDOStatement.
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*/
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private function query(string $sql, array $variables = []) {
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// Add to the query cache if it doesn't exist
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if(!isset($this->query_cache[$sql]))
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$this->query_cache[$sql] = $this->db->prepare($sql);
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$this->query_cache[$sql]->execute($variables);
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return $this->query_cache[$sql]; // fetchColumn(), fetchAll(), etc. are defined on the statement, not the return value of execute()
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}
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/**
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* Determines if the given key exists in the store or not.
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* @param string $key The key to test.
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* @return bool Whether the key exists in the store or not.
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*/
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public function has(string $key) : bool {
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if(isset($this->cache[$key]))
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return true;
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return $this->query(
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"SELECT COUNT(key) FROM store WHERE key = :key;",
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[ "key" => $key ]
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)->fetchColumn() > 0;
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}
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/**
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* Returns an iterable that returns all the keys that do not contain the given string.
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* @param string $exclude The string to search for when excluding keys.
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* @return PDOStatement The iterable. Use a foreach loop on it.
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*/
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public function get_keys(string $exclude) : \PDOStatement {
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return $this->query(
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"SELECT key FROM store WHERE key NOT LIKE :containing;",
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[ "containing" => "%$exclude%" ]
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);
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}
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/**
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* Gets a value from the store.
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* @param string $key The key value is stored under.
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* @return mixed The stored value.
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*/
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public function get(string $key) {
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// If it's not in the cache, insert it
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if(!isset($this->cache[$key])) {
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$this->cache[$key] = [ "modified" => false, "value" => json_decode($this->query(
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"SELECT value FROM store WHERE key = :key;",
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[ "key" => $key ]
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)->fetchColumn()) ];
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}
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return $this->cache[$key]["value"];
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}
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public function get_arr_simple(string $key, string $delimiter = "|") {
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// If it's not in the cache, insert it
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if(!isset($this->cache[$key])) {
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$this->cache[$key] = [
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"modified" => false,
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"value" => explode($delimiter, $this->query(
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"SELECT value FROM store WHERE key = :key;",
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[ "key" => $key ]
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)->fetchColumn())
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];
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}
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return $this->cache[$key]["value"];
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}
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/**
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* Sets a value in the data store.
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* Note that this does NOT save changes to disk until you close the connection!
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* @param string $key The key to set the value of.
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* @param mixed $value The value to store.
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*/
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public function set(string $key, $value) : void {
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if(!isset($this->cache[$key])) $this->cache[$key] = [];
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$this->cache[$key]["value"] = $value;
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$this->cache[$key]["modified"] = true;
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$this->cache[$key]["mode"] = self::MODE_JSON;
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}
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public function set_arr_simple(string $key, $value, string $delimiter = "|") : void {
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if(!isset($this->cache[$key])) $this->cache[$key] = [];
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$this->cache[$key]["value"] = $value;
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$this->cache[$key]["modified"] = true;
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$this->cache[$key]["delimiter"] = $delimiter;
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$this->cache[$key]["mode"] = self::MODE_ARR_SIMPLE;
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}
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/**
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* Deletes an item from the data store.
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* @param string $key The key of the item to delete.
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* @return bool Whether it was really deleted or not. Note that if it doesn't exist, then it can't be deleted.
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*/
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public function delete(string $key) : bool {
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// Remove it from the cache
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if(isset($this->cache[$key]))
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unset($this->cache[$key]);
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// Remove it from disk
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// TODO: Queue this action for the transaction later
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return $this->query(
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"DELETE FROM store WHERE key = :key;",
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[ "key" => $key ]
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)->rowCount() > 0;
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}
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/**
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* Empties the store.
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*/
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public function clear() : void {
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// Empty the cache;
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$this->cache = [];
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// Empty the disk
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$this->query("DELETE FROM store;");
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}
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/**
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* Syncs changes to disk and closes the PDO connection.
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*/
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public function close() : void {
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$this->db->beginTransaction();
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foreach($this->cache as $key => $value_data) {
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// If it wasn't modified, there's no point in saving it, is there?
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if(!$value_data["modified"])
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continue;
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$this->query(
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"INSERT OR REPLACE INTO store(key, value) VALUES(:key, :value)",
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[
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"key" => $key,
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"value" => $value_data["mode"] == self::MODE_ARR_SIMPLE ?
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implode($value_data["delimiter"], $value_data["value"]) :
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json_encode($value_data["value"])
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]
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);
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}
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$this->db->commit();
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$this->db = null;
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}
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}
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?>
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