perf: eager poll async ops in Isolate (#3046)

2 files changed, 23 insertions, 5 deletions

diff --git a/cli/js/dispatch_json.ts b/cli/js/dispatch_json.ts
index 572ec855a..890568409 100644
--- a/cli/js/dispatch_json.ts
+++ b/cli/js/dispatch_json.ts
@@ -75,11 +75,17 @@ export async function sendAsync(
   const promiseId = nextPromiseId();
   args = Object.assign(args, { promiseId });
   const promise = util.createResolvable<Ok>();
-  promiseTable.set(promiseId, promise);
 
   const argsUi8 = encode(args);
-  const resUi8 = core.dispatch(opId, argsUi8, zeroCopy);
-  util.assert(resUi8 == null);
+  const buf = core.dispatch(opId, argsUi8, zeroCopy);
+  if (buf) {
+    // Sync result.
+    const res = decode(buf);
+    promise.resolve(res);
+  } else {
+    // Async result.
+    promiseTable.set(promiseId, promise);
+  }
 
   const res = await promise;
   return unwrapResponse(res);
diff --git a/cli/js/dispatch_minimal.ts b/cli/js/dispatch_minimal.ts
index 98636f85b..74a5e211c 100644
--- a/cli/js/dispatch_minimal.ts
+++ b/cli/js/dispatch_minimal.ts
@@ -61,8 +61,20 @@ export function sendAsyncMinimal(
   scratch32[1] = arg;
   scratch32[2] = 0; // result
   const promise = util.createResolvable<number>();
-  promiseTableMin.set(promiseId, promise);
-  core.dispatch(opId, scratchBytes, zeroCopy);
+  const buf = core.dispatch(opId, scratchBytes, zeroCopy);
+  if (buf) {
+    const buf32 = new Int32Array(
+      buf.buffer,
+      buf.byteOffset,
+      buf.byteLength / 4
+    );
+    const record = recordFromBufMinimal(opId, buf32);
+    // Sync result.
+    promise.resolve(record.result);
+  } else {
+    // Async result.
+    promiseTableMin.set(promiseId, promise);
+  }
   return promise;
 }