fixup! feat(xsnap): stream start snapshot over pipe

streamline logic with new load snapshot handler
Agoric · Apr 28, 2023 · 6c276c5 · 6c276c5
1 parent 62872a7
commit 6c276c5
Showing 1 changed file with 73 additions and 50 deletions.
diff --git a/packages/xsnap/src/xsnap.js b/packages/xsnap/src/xsnap.js
@@ -104,6 +104,64 @@ export async function xsnap(options) {
   /** @type {(opts: import('tmp').TmpNameOptions) => Promise<string>} */
   const ptmpName = fs.tmpName && promisify(fs.tmpName);
 
+  const makeLoadSnapshotHandlerWithFS = async () => {
+    assert(snapshotStream);
+    const snapPath = await ptmpName({
+      template: `load-snapshot-${safeHintFromDescription(
+        snapshotDescription,
+      )}-XXXXXX.xss`,
+    });
+
+    const cleanup = async () => fs.unlink(snapPath);
+    const afterSpawn = async () => {};
+
+    try {
+      // eslint-disable-next-line @jessie.js/no-nested-await
+      const tmpSnap = await fs.open(snapPath, 'w');
+      // eslint-disable-next-line @jessie.js/no-nested-await
+      await tmpSnap.writeFile(
+        // @ts-expect-error incorrect typings, does support AsyncIterable
+        snapshotStream,
+      );
+      // eslint-disable-next-line @jessie.js/no-nested-await
+      await tmpSnap.close();
+    } catch (e) {
+      // eslint-disable-next-line @jessie.js/no-nested-await
+      await cleanup();
+      throw e;
+    }
+
+    return harden({
+      snapPath,
+      afterSpawn,
+      cleanup,
+    });
+  };
+
+  const makeLoadSnapshotHandlerWithPipe = async () => {
+    let done = Promise.resolve();
+
+    const cleanup = async () => done;
+
+    /** @param {Writable} loadSnapshotsStream */
+    const afterSpawn = async loadSnapshotsStream => {
+      assert(snapshotStream);
+      const destStream = loadSnapshotsStream;
+
+      const sourceStream = Readable.from(snapshotStream);
+      sourceStream.pipe(destStream, { end: false });
+
+      done = finished(sourceStream);
+      done.catch(noop).then(() => sourceStream.unpipe(destStream));
+    };
+
+    return harden({
+      snapPath: '@8',
+      afterSpawn,
+      cleanup,
+    });
+  };
+
   let bin = new URL(
     `../xsnap-native/xsnap/build/bin/${platform}/${
       debug ? 'debug' : 'release'
@@ -116,52 +174,17 @@ export async function xsnap(options) {
 
   assert(!/^-/.test(name), `name '${name}' cannot start with hyphen`);
 
-  let args = [name];
-  const postStart = await (snapshotStream &&
+  let loadSnapshotHandler = await (snapshotStream &&
     (snapshotUseFs
-      ? async () => {
-          const tmpSnapPath = await ptmpName({
-            template: `load-snapshot-${safeHintFromDescription(
-              snapshotDescription,
-            )}-XXXXXX.xss`,
-          });
-
-          const cleanup = async () => fs.unlink(tmpSnapPath);
-
-          try {
-            // eslint-disable-next-line @jessie.js/no-nested-await
-            const tmpSnap = await fs.open(tmpSnapPath, 'w');
-            // eslint-disable-next-line @jessie.js/no-nested-await
-            await tmpSnap.writeFile(
-              // @ts-expect-error incorrect typings, does support AsyncIterable
-              snapshotStream,
-            );
-            // eslint-disable-next-line @jessie.js/no-nested-await
-            await tmpSnap.close();
-          } catch (e) {
-            // eslint-disable-next-line @jessie.js/no-nested-await
-            await cleanup();
-            throw e;
-          }
-
-          args.push('-r', tmpSnapPath);
-          return async () => cleanup;
-        }
-      : async () => {
-          args.push('-r', '@8');
+      ? makeLoadSnapshotHandlerWithFS
+      : makeLoadSnapshotHandlerWithPipe)());
 
-          return async () => {
-            // eslint-disable-next-line no-use-before-define
-            const destStream = loadSnapshotsStream;
+  let args = [name];
 
-            const sourceStream = Readable.from(snapshotStream);
-            sourceStream.pipe(destStream, { end: false });
+  if (loadSnapshotHandler) {
+    args.push('-r', loadSnapshotHandler.snapPath);
+  }
 
-            const done = finished(sourceStream);
-            done.catch(noop).then(() => sourceStream.unpipe(destStream));
-            return async () => done;
-          };
-        })());
   if (meteringLimit) {
     args.push('-l', `${meteringLimit}`);
   }
@@ -230,13 +253,13 @@ export async function xsnap(options) {
   const savedSnapshotsStream = xsnapProcessStdio[7];
   const loadSnapshotsStream = xsnapProcessStdio[8];
 
-  let startCleanup = await postStart?.();
+  await loadSnapshotHandler?.afterSpawn(loadSnapshotsStream);
 
-  if (startCleanup) {
+  if (loadSnapshotHandler) {
     vatExit.promise.catch(noop).then(() => {
-      if (startCleanup) {
-        const cleanup = startCleanup;
-        startCleanup = undefined;
+      if (loadSnapshotHandler) {
+        const { cleanup } = loadSnapshotHandler;
+        loadSnapshotHandler = undefined;
         return cleanup();
       }
     });
@@ -258,9 +281,9 @@ export async function xsnap(options) {
   async function runToIdle() {
     for await (const _ of forever) {
       const iteration = await messagesFromXsnap.next(undefined);
-      if (startCleanup) {
-        const cleanup = startCleanup;
-        startCleanup = undefined;
+      if (loadSnapshotHandler) {
+        const { cleanup } = loadSnapshotHandler;
+        loadSnapshotHandler = undefined;
         // eslint-disable-next-line @jessie.js/no-nested-await
         await cleanup();
       }