wip

src/cli.js

@@ -891,6 +891,36 @@ async function build() {
       }
     })
 
+    /**
+     * When rapidly saving files atomically a couple of situations can happen:
+     * - The file is missing since the external program has deleted it by the time we've gotten around to reading it from the earlier save.
+     * - The file is being written to by the external program by the time we're going to read it and is thus treated as busy because a lock is held.
+     *
+     * To work around this we retry reading the file a handful of times with a delay between each attempt
+     *
+     * @param {string} path
+     * @param {number} tries
+     * @returns {string}
+     * @throws {Error} If the file is still missing or busy after the specified number of tries
+     */
+    async function readFileWithRetries(path, tries = 5) {
+      for (let n = 0; n < tries; n++) {
+        try {
+          return await fs.promises.readFile(path, 'utf8')
+        } catch (err) {
+          if (n < tries) {
+            if (err.code === 'ENOENT' || err.code === 'EBUSY') {
+              await new Promise((resolve) => setTimeout(resolve, 10))
+
+              continue
+            }
+          }
+
+          throw err
+        }
+      }
+    }
+
     // Restore watching any files that are "removed"
     // This can happen when a file is pseudo-atomically replaced (a copy is created, overwritten, the old one is unlinked, and the new one is renamed)
     // TODO: An an optimization we should allow removal when the config changes