wip: add incremental mtime restore

src/incremental.ts

@@ -0,0 +1,48 @@
+import * as core from "@actions/core";
+import * as io from "@actions/io";
+import fs from "fs";
+import path from "path";
+
+import { CARGO_HOME } from "./config";
+import { exists } from "./utils";
+import { Packages } from "./workspace";
+
+
+export async function restoreIncremental(targetDir: string) {
+  core.debug(`restoring incremental directory "${targetDir}"`);
+
+
+  let dir = await fs.promises.opendir(targetDir);
+  for await (const dirent of dir) {
+    if (dirent.isDirectory()) {
+      let dirName = path.join(dir.path, dirent.name);
+      // is it a profile dir, or a nested target dir?
+      let isNestedTarget =
+        (await exists(path.join(dirName, "CACHEDIR.TAG"))) || (await exists(path.join(dirName, ".rustc_info.json")));
+
+      try {
+        if (isNestedTarget) {
+          await restoreIncremental(dirName);
+        } else {
+          await restoreIncrementalProfile(dirName);
+        } restoreIncrementalProfile
+      } catch { }
+    }
+  }
+}
+
+async function restoreIncrementalProfile(dirName: string) {
+  core.debug(`restoring incremental profile directory "${dirName}"`);
+  const incrementalJson = path.join(dirName, "incremental-restore.json");
+  if (await exists(incrementalJson)) {
+    const contents = await fs.promises.readFile(incrementalJson, "utf8");
+    const { modifiedTimes } = JSON.parse(contents);
+
+    // Write the mtimes to all the files in the profile directory
+    for (const fileName of Object.keys(modifiedTimes)) {
+      const mtime = modifiedTimes[fileName];
+      const filePath = path.join(dirName, fileName);
+      await fs.promises.utimes(filePath, new Date(mtime), new Date(mtime));
+    }
+  }
+}