Organize dispatch a bit (#2796)

Just some clean up reorganization around flatbuffer/minimal dispatch
code. This is prep for adding a JSON dispatcher.

1 files changed, 16 insertions, 140 deletions

diff --git a/js/dispatch.ts b/js/dispatch.ts
index babea5739..423469d38 100644
--- a/js/dispatch.ts
+++ b/js/dispatch.ts
@@ -1,146 +1,22 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
-import { core } from "./core";
-import * as flatbuffers from "./flatbuffers";
-import * as msg from "gen/cli/msg_generated";
-import * as errors from "./errors";
-import * as util from "./util";
-import {
-  nextPromiseId,
-  recordFromBufMinimal,
-  handleAsyncMsgFromRustMinimal
-} from "./dispatch_minimal";
+import * as minimal from "./dispatch_minimal";
+import * as flatbuffers from "./dispatch_flatbuffers";
 
-// TODO(ry) Currently we only use three values for opId: OP_READ, OP_WRITE,
-// FLATBUFFER_OP_ID. Later on use opId for actual individual ops, not just
-// classes of ops.
-const FLATBUFFER_OP_ID = 44;
-
-const promiseTable = new Map<number, util.Resolvable<msg.Base>>();
-
-interface FlatbufferRecord {
-  promiseId: number;
-  base: msg.Base;
-}
-
-function flatbufferRecordFromBuf(buf: Uint8Array): FlatbufferRecord {
-  const bb = new flatbuffers.ByteBuffer(buf);
-  const base = msg.Base.getRootAsBase(bb);
-  return {
-    promiseId: base.cmdId(),
-    base
-  };
-}
+// These consts are shared with Rust. Update with care.
+export const OP_FLATBUFFER = 44;
+export const OP_READ = 1;
+export const OP_WRITE = 2;
 
 export function handleAsyncMsgFromRust(opId: number, ui8: Uint8Array): void {
-  const buf32 = new Int32Array(ui8.buffer, ui8.byteOffset, ui8.byteLength / 4);
-  if (opId !== FLATBUFFER_OP_ID) {
-    // Fast and new
-    const recordMin = recordFromBufMinimal(opId, buf32);
-    handleAsyncMsgFromRustMinimal(ui8, recordMin);
-  } else {
-    // Legacy
-    let { promiseId, base } = flatbufferRecordFromBuf(ui8);
-    const promise = promiseTable.get(promiseId);
-    util.assert(promise != null, `Expecting promise in table. ${promiseId}`);
-    promiseTable.delete(promiseId);
-    const err = errors.maybeError(base);
-    if (err != null) {
-      promise!.reject(err);
-    } else {
-      promise!.resolve(base);
-    }
-  }
-}
-
-function ui8FromArrayBufferView(abv: ArrayBufferView): Uint8Array {
-  return new Uint8Array(abv.buffer, abv.byteOffset, abv.byteLength);
-}
-
-function sendInternal(
-  builder: flatbuffers.Builder,
-  innerType: msg.Any,
-  inner: flatbuffers.Offset,
-  zeroCopy: undefined | ArrayBufferView,
-  isSync: true
-): Uint8Array;
-function sendInternal(
-  builder: flatbuffers.Builder,
-  innerType: msg.Any,
-  inner: flatbuffers.Offset,
-  zeroCopy: undefined | ArrayBufferView,
-  isSync: false
-): Promise<msg.Base>;
-function sendInternal(
-  builder: flatbuffers.Builder,
-  innerType: msg.Any,
-  inner: flatbuffers.Offset,
-  zeroCopy: undefined | ArrayBufferView,
-  isSync: boolean
-): Promise<msg.Base> | Uint8Array {
-  const cmdId = nextPromiseId();
-  msg.Base.startBase(builder);
-  msg.Base.addInner(builder, inner);
-  msg.Base.addInnerType(builder, innerType);
-  msg.Base.addSync(builder, isSync);
-  msg.Base.addCmdId(builder, cmdId);
-  builder.finish(msg.Base.endBase(builder));
-
-  const control = builder.asUint8Array();
-
-  const response = core.dispatch(
-    FLATBUFFER_OP_ID, // TODO(ry) Use actual opId later.
-    control,
-    zeroCopy ? ui8FromArrayBufferView(zeroCopy) : undefined
-  );
-
-  builder.inUse = false;
-
-  if (response == null) {
-    util.assert(!isSync);
-    const promise = util.createResolvable<msg.Base>();
-    promiseTable.set(cmdId, promise);
-    return promise;
-  } else {
-    if (!isSync) {
-      // We can easily and correctly allow for sync responses to async calls
-      // by creating and returning a promise from the sync response.
-      const bb = new flatbuffers.ByteBuffer(response);
-      const base = msg.Base.getRootAsBase(bb);
-      const err = errors.maybeError(base);
-      if (err != null) {
-        return Promise.reject(err);
-      } else {
-        return Promise.resolve(base);
-      }
-    }
-    return response;
-  }
-}
-
-// @internal
-export function sendAsync(
-  builder: flatbuffers.Builder,
-  innerType: msg.Any,
-  inner: flatbuffers.Offset,
-  data?: ArrayBufferView
-): Promise<msg.Base> {
-  return sendInternal(builder, innerType, inner, data, false);
-}
-
-// @internal
-export function sendSync(
-  builder: flatbuffers.Builder,
-  innerType: msg.Any,
-  inner: flatbuffers.Offset,
-  data?: ArrayBufferView
-): null | msg.Base {
-  const response = sendInternal(builder, innerType, inner, data, true);
-  if (response!.length === 0) {
-    return null;
-  } else {
-    const bb = new flatbuffers.ByteBuffer(response!);
-    const baseRes = msg.Base.getRootAsBase(bb);
-    errors.maybeThrowError(baseRes);
-    return baseRes;
+  switch (opId) {
+    case OP_FLATBUFFER:
+      flatbuffers.handleAsyncMsgFromRust(opId, ui8);
+      break;
+    case OP_WRITE:
+    case OP_READ:
+      minimal.handleAsyncMsgFromRust(opId, ui8);
+      break;
+    default:
+      throw Error("bad opId");
   }
 }