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114 lines
4.8 KiB
JavaScript
114 lines
4.8 KiB
JavaScript
const fs = require("fs"),
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path = require("path"),
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cache_dir = "./.cache",
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args = require('args-parser')(process.argv);
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let cache = {};
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let logger = require("winston");
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/**
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* Sets the logger for logging
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* @param {Object} newLogger
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*/
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exports.setLogger = function (newLogger) {
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logger = newLogger;
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};
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/**
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* Returns the data from files that were cached
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* @param {String} filename The name of the file that has been cached
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* @return {String} The data stored in the file
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*/
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exports.getCached = function (filename) {
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let cf = cache[filename];
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let call_passed = (Date.now() - cf.last_call) / 1000; // calculate the time since the last call of the file
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if (cf.call_count > 10 && call_passed < 60) {
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cf.data = fs.readFileSync(cf.path); // store the file's data into the json
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} else if (call_passed > 3600) {
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cf.call_count = 0; // reset the counter when an hour has passed since the last call
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cf.data = null; // reset the data to free memory
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}
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cf.last_call = Date.now(); // set the last call to now
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cf.call_count += 1; // increase the call count
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if (cf.data != null) return cf.data;
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logger.debug("Returning cached data for %s : %s", filename, cf.path);
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return fs.readFileSync(cf.path); // return either the data or read the file
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};
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/**
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* Safes the file with it's corresponding data in the cache directory
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* @param {String} filename The name of the file
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* @param {String} data The data form the file
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*/
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exports.cache = function (filename, data) {
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logger.verbose("Creating cache entry for %s", filename);
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if (!fs.existsSync("./.cache")) fs.mkdirSync("./.cache"); // if the cache folder doesn't exist, create it
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let cache_fn = filename.replace(/[^\w.]/g, "__"); // remove invalid path characters
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let count = 0;
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while (fs.existsSync(filename + count + ".cache")) count++; // check if a file with the same name already exists and increase count
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let cache_path = path.join(cache_dir, cache_fn + count + ".cache"); // create the final file path. Cachedir + cached filename (without invalid) + count + .cache
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logger.debug("Creating file %s", cache_path);
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fs.writeFile(cache_path, data, (err) => {
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if (err !== null) logger.error(err);
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else {
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logger.debug("Created file cache entry for %s", filename);
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cache[filename] = { // create a cache-entry with the file's path when the file is written (so it won't be accessed before)
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"path": cache_path, // the last call to the file, the count of calls and an
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"last_call": null, // empty data field to store the file's data if the file
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"call_count": 0, // was called often
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"data": null,
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"creation_time": Date.now(),
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"changed": false
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}
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}
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fs.watch(filename, (eventType) => { // watch the file for changes
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logger.debug("Change detected on %s", filename);
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if (eventType === 'change') cache[filename].changed = true; // if the event change is detected set the change attribute to true
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});
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}); // write the data asynchronously to the file
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};
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/**
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* Returns if the file is already cached. It returns false if changes were detected in the file
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* @param {String} filename The filename to check
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* @return {Boolean} Is it cached or not
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*/
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exports.isCached = function (filename) {
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if (args.nocache) return false; // return false if the flag nocache is set
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let cached_entry = cache[filename];
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if (cached_entry) { // check if the cache entry exists
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logger.debug("Found cache entry for %s", filename);
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if (cached_entry.changed) return false; // if a change was detected recache the file
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if (cached_entry.path) { // check if the path variable is set
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logger.debug("Found path entry for %s", filename);
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return fs.existsSync(cached_entry.path); // return if the file exists
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}
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}
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logger.debug("Found no cache entry for %s", filename);
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return false; // return false if the cache entry doesn't exist
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}
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/**
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* A function that clears the ./.cache directory
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*/
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exports.cleanup = function () {
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deleteFolder(cache_dir); // delte the cache folder and it's contents
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};
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/**
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* Deletes a folder with it's contents recursive
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* @param {string} p the path to the folder
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*/
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var deleteFolder = function(p) {
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if( fs.existsSync(p) ) {
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fs.readdirSync(p).forEach(function(file){ // get the contents of the directory
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var curPath = path.join(p, file); // create path by joining
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if(fs.lstatSync(curPath).isDirectory()) { // recurse
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deleteFolder(curPath); // call recursive
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} else { // delete file
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fs.unlinkSync(curPath); // delete file
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}
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});
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fs.rmdirSync(p); // delete directory
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}
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};
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