1 files changed, 59 insertions, 9 deletions

diff --git a/js/fbs_util.ts b/js/fbs_util.ts
index bb623d54d..16f3b6ca2 100644
--- a/js/fbs_util.ts
+++ b/js/fbs_util.ts
@@ -1,27 +1,77 @@
 // Copyright 2018 the Deno authors. All rights reserved. MIT license.
+// TODO Rename this file to //js/dispatch.ts
 import { libdeno } from "./libdeno";
 import { flatbuffers } from "flatbuffers";
-import { maybeThrowError } from "./errors";
 import { deno as fbs } from "gen/msg_generated";
+import * as errors from "./errors";
+import * as util from "./util";
+
+let nextCmdId = 0;
+const promiseTable = new Map<number, util.Resolvable<fbs.Base>>();
+
+export function handleAsyncMsgFromRust(ui8: Uint8Array) {
+  const bb = new flatbuffers.ByteBuffer(ui8);
+  const base = fbs.Base.getRootAsBase(bb);
+
+  const cmdId = base.cmdId();
+  const promise = promiseTable.get(cmdId);
+  util.assert(promise != null, `Expecting promise in table. ${cmdId}`);
+  promiseTable.delete(cmdId);
+  const err = errors.maybeError(base);
+  if (err != null) {
+    promise!.reject(err);
+  } else {
+    promise!.resolve(base);
+  }
+}
 
 // @internal
+export function sendAsync(
+  builder: flatbuffers.Builder,
+  msgType: fbs.Any,
+  msg: flatbuffers.Offset
+): Promise<fbs.Base> {
+  const [cmdId, resBuf] = sendInternal(builder, msgType, msg, false);
+  util.assert(resBuf == null);
+  const promise = util.createResolvable<fbs.Base>();
+  promiseTable.set(cmdId, promise);
+  return promise;
+}
+
+// TODO Rename to sendSync
+// @internal
 export function send(
   builder: flatbuffers.Builder,
   msgType: fbs.Any,
   msg: flatbuffers.Offset
 ): null | fbs.Base {
-  fbs.Base.startBase(builder);
-  fbs.Base.addMsg(builder, msg);
-  fbs.Base.addMsgType(builder, msgType);
-  builder.finish(fbs.Base.endBase(builder));
-
-  const resBuf = libdeno.send(builder.asUint8Array());
+  const [cmdId, resBuf] = sendInternal(builder, msgType, msg, true);
+  util.assert(cmdId >= 0);
   if (resBuf == null) {
     return null;
   } else {
-    const bb = new flatbuffers.ByteBuffer(new Uint8Array(resBuf!));
+    const u8 = new Uint8Array(resBuf!);
+    // console.log("recv sync message", util.hexdump(u8));
+    const bb = new flatbuffers.ByteBuffer(u8);
     const baseRes = fbs.Base.getRootAsBase(bb);
-    maybeThrowError(baseRes);
+    errors.maybeThrowError(baseRes);
     return baseRes;
   }
 }
+
+function sendInternal(
+  builder: flatbuffers.Builder,
+  msgType: fbs.Any,
+  msg: flatbuffers.Offset,
+  sync = true
+): [number, null | Uint8Array] {
+  const cmdId = nextCmdId++;
+  fbs.Base.startBase(builder);
+  fbs.Base.addMsg(builder, msg);
+  fbs.Base.addMsgType(builder, msgType);
+  fbs.Base.addSync(builder, sync);
+  fbs.Base.addCmdId(builder, cmdId);
+  builder.finish(fbs.Base.endBase(builder));
+
+  return [cmdId, libdeno.send(builder.asUint8Array())];
+}