initial attempt at a memoization mechanism

memoize.php

<?php
    /**
     * Memoizes a given set of data and returns if a result has been cached or not
     * @param  array  $params Config for what to memoize
     * @param  (any)  $data   (optional) Data we wish to memoize
     * @return any            [description]
     */
    function memoize($key, $data=null) {
 
        $db = null;
 
        $dbType     = 'sqlite';
        $dbPath     = './test.db';
 
        $tableName  = 'memos';
 
        $cacheTime      = microtime(true);
        $cacheTimeLimit = 5; // in minutes
        $cacheBust      = ($cacheTime + (1000 * 60 * 60 * $cacheTimeLimit));
 
        $res = 'pants';
 
 
        // TODO: write this whole thing in SQLite?
 
$sql =
<<<SQL
 
    CREATE TABLE IF NOT EXISTS memos (
        id    INTEGER PRIMARY KEY AUTOINCREMENT,
        key   TEXT NOT NULL UNIQUE,
        data  TEXT NOT NULL,
        cache INTEGER NOT NULL
    );
 
    CREATE TEMP TABLE IF NOT EXISTS Variables (
        name TEXT PRIMARY KEY,
        value TEXT
    );
 
    -- https://stackoverflow.com/questions/7739444/declare-variable-in-sqlite-and-use-it
 
    -- Check key exists in DB
    SELECT
        data
    FROM
        $tableName
    WHERE
        key = :keyname
    ;
 
 
SQL>>>;
 
 
        // Attempt to initialize database connection
        try {
            $db = new PDO("{$dbType}:{$dbPath}");
            $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
 
            // IF table doesn't exist, create it
            $db->exec("
                CREATE TABLE IF NOT EXISTS {$tableName} (
                    id    INTEGER PRIMARY KEY AUTOINCREMENT,
                    key   TEXT NOT NULL UNIQUE,
                    data  TEXT NOT NULL,
                    cache INTEGER NOT NULL
                )
            ");
 
        } catch(PDOException $e) {
            print_r($e->getMessage());
            return;
 
        }
 
 
        // IF provided data, write it to the database
        if ($data) {
 
            $data = json_encode($data);
 
            try {
                $sql = "
                    UPDATE {$tableName}
                    SET
                        key   = :keyname,
                        data  = :data,
                        cache = :cache
                    WHERE
                        key   = :keyname
                ";
 
                $stmt = $db->prepare($sql);
 
                $stmt->execute([
                    ':keyname' => $key
                ,   ':data'    => $data
                ,   ':cache'   => $cacheTime
                ]);
 
                // $res = $stmt->fetch(\PDO::FETCH_ASSOC);
 
 
            } catch(PDOException $e) {
                print_r($e->getMessage());
                return;
 
            }
 
        }
 
 
 
        // Return the data from the record in question
        try {
            $sql = "
                SELECT
                    data
                FROM
                    $tableName
                WHERE
                    key = :keyname
            ";
 
            $stmt = $db->prepare($sql);
 
            $stmt->execute([
                ':keyname' => $key
            ]);
 
            $res = $stmt->fetch(\PDO::FETCH_ASSOC);
 
 
        } catch(PDOException $e) {
            print_r($e->getMessage());
            return;
 
        }
 
 
        // print_r($key);
        // print_r($data);
 
        // print_r($res);
 
        return $res[0];
 
    }
 
 
    echo memoize('free_thinkers_are_dangerous_sd');
 
    echo PHP_EOL;
 
    echo memoize('free_thinkers_are_dangerous_sd');
 
    echo PHP_EOL;
 
    echo memoize('free_thinkers_are_dangerous', ['keyName' => 'value']);