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77 lines
3.3 KiB
JavaScript
77 lines
3.3 KiB
JavaScript
const fs = require("fs"),
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path = require("path"),
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config_path = "./config/caching_dump.json",
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cache_dump = JSON.parse(fs.readFileSync(config_path)),
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cache_dir = "./.cache",
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cache = {}; // TODO: Must read from dump again
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if (cache_dump != null && cache_dump["last"] != null) cache = cache_dump["last"];
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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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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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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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fs.writeFile(cache_path, data, (error) => {
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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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};
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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
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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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* TODO: Use last access or use creation_time property to check if the file might
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* be too old. If the function returns false, a new cache-file will be created which
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* has a different name from the old. On each startup a function could check if
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* there are cache-files that are not listet in the cache_dump and delete them.
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*/
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exports.isCached = function(filename) {
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let cached_entry = cache[filename];
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if (cached_entry) {
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if (cached_entry.path) {
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return fs.existsSync(cached_entry.path);
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}
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}
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return false;
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}
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/**
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* A function that dumps the config into the config file after appending the cache to it.
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*/
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exports.cleanup = function() {
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cache_dump["last"] = cache;
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fs.writeFileSync(config_path, JSON.stringify(cache_dump));
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}
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