switched to proper Set and Map instances

replacing poor man's versions

Author: FND

lib/util/files/index.js

@@ -4,26 +4,26 @@ let { writeFile } = require("fs/promises");
 let { mkdirSync } = require("fs");
 let path = require("path");
 
-let KNOWN = {}; // avoids redundant `mkdirp` invocations
-let LOCKS = {};
+let KNOWN = new Set(); // avoids redundant `mkdir` invocations
+let LOCKS = new Map();
 
 // avoids concurrent write operations and creates target directory if necessary
 module.exports = function createFile(filepath, contents) {
-	let lock = LOCKS[filepath];
+	let lock = LOCKS.get(filepath);
 	if(lock) { // defer
 		return lock.then(_ => createFile(filepath, contents));
 	}
 
 	// create directory if necessary
-	if(!KNOWN[filepath]) {
-		KNOWN[filepath] = true;
+	if(!KNOWN.has(filepath)) {
+		KNOWN.add(filepath);
 		// NB: `sync` avoids race condition for subsequent operations
 		mkdirSync(path.dirname(filepath), { recursive: true });
 	}
 
 	let prom = writeFile(filepath, contents);
-	LOCKS[filepath] = prom;
+	LOCKS.set(filepath, prom);
 	return prom.then(_ => {
-		delete LOCKS[filepath];
+		LOCKS.delete(filepath);
 	});
 };