♻️ Extract magic numbers

src/cdn/downloadWithCurl.ts

@@ -1,5 +1,12 @@
 import * as childProcess from 'child_process';
 
+/** Minimum download speed of 10 MB/s = 80 MBit/s */
+const MINIMUM_SPEED = 10;
+/** Maximum download speed of 20 MB/s = 160 MBit/s */
+const MAXIMUM_SPEED = 20;
+/** Time interval over which the minimum speed is measured to determined whether to timeout. Given in seconds. */
+const CHECK_INTERVAL = 15;
+
 /**
  * Downloads a file using a curl child process, to allow for speed-limiting and timeout if download is too slow.
  * Takes as input the host domain name, the path and the file size
@@ -11,9 +18,9 @@ export default function downloadWithCurl({ host, path, tempFileName }: {host: st
     const parameters: string[] = [
       //...
       '--silent',
-      '--limit-rate', '20m', //maximum speed of 20 MB/s = 160 MBit/s
+      '--limit-rate', `${MAXIMUM_SPEED}m`,
-      '--speed-limit', String(Math.round(100 * 1024 * 1024 / 15)), //abort if less than 100 MB in 15 seconds
+      '--speed-limit', String(MINIMUM_SPEED * 1024 * 1024),
-      '--speed-time', '15',
+      '--speed-time', String(CHECK_INTERVAL),
       '--output', tempFileName,
       url,
     ];