Revert json ops (#2814)

* Revert "port more ops to JSON (#2809)"

This reverts commit 137f33733d.

* Revert "port ops to JSON: compiler, errors, fetch, files (#2804)"

This reverts commit 79f82cf10e.

* Revert "Port rest of os ops to JSON (#2802)"

This reverts commit 5b2baa5c99.

js/fetch.ts

@@ -1,5 +1,6 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import { assert, createResolvable, notImplemented, isTypedArray } from "./util";
+import { sendAsync, msg, flatbuffers } from "./dispatch_flatbuffers";
 import * as domTypes from "./dom_types";
 import { TextDecoder, TextEncoder } from "./text_encoding";
 import { DenoBlob, bytesSymbol as blobBytesSymbol } from "./blob";
@@ -9,8 +10,6 @@ import { read, close } from "./files";
 import { Buffer } from "./buffer";
 import { FormData } from "./form_data";
 import { URLSearchParams } from "./url_search_params";
-import * as dispatch from "./dispatch";
-import { sendAsync } from "./dispatch_json";
 
 function getHeaderValueParams(value: string): Map<string, string> {
   const params = new Map();
@@ -321,35 +320,67 @@ export class Response implements domTypes.Response {
   }
 }
 
-interface FetchResponse {
-  bodyRid: number;
-  status: number;
-  headers: Array<[string, string]>;
+function msgHttpRequest(
+  builder: flatbuffers.Builder,
+  url: string,
+  method: null | string,
+  headers: null | domTypes.Headers
+): flatbuffers.Offset {
+  const methodOffset = !method ? 0 : builder.createString(method);
+  let fieldsOffset: flatbuffers.Offset = 0;
+  const urlOffset = builder.createString(url);
+  if (headers) {
+    const kvOffsets: flatbuffers.Offset[] = [];
+    for (const [key, val] of headers.entries()) {
+      const keyOffset = builder.createString(key);
+      const valOffset = builder.createString(val);
+      kvOffsets.push(
+        msg.KeyValue.createKeyValue(builder, keyOffset, valOffset)
+      );
+    }
+    fieldsOffset = msg.HttpHeader.createFieldsVector(builder, kvOffsets);
+  } else {
+  }
+  return msg.HttpHeader.createHttpHeader(
+    builder,
+    true,
+    methodOffset,
+    urlOffset,
+    0,
+    fieldsOffset
+  );
 }
 
-async function sendFetchReq(
+function deserializeHeaderFields(m: msg.HttpHeader): Array<[string, string]> {
+  const out: Array<[string, string]> = [];
+  for (let i = 0; i < m.fieldsLength(); i++) {
+    const item = m.fields(i)!;
+    out.push([item.key()!, item.value()!]);
+  }
+  return out;
+}
+
+async function getFetchRes(
   url: string,
   method: string | null,
   headers: domTypes.Headers | null,
   body: ArrayBufferView | undefined
-): Promise<FetchResponse> {
-  let headerArray: Array<[string, string]> = [];
-  if (headers) {
-    headerArray = Array.from(headers.entries());
-  }
+): Promise<msg.FetchRes> {
+  // Send Fetch message
+  const builder = flatbuffers.createBuilder();
+  const headerOff = msgHttpRequest(builder, url, method, headers);
+  const resBase = await sendAsync(
+    builder,
+    msg.Any.Fetch,
+    msg.Fetch.createFetch(builder, headerOff),
+    body
+  );
 
-  let zeroCopy = undefined;
-  if (body) {
-    zeroCopy = new Uint8Array(body.buffer, body.byteOffset, body.byteLength);
-  }
-
-  const args = {
-    method,
-    url,
-    headers: headerArray
-  };
-
-  return (await sendAsync(dispatch.OP_FETCH, args, zeroCopy)) as FetchResponse;
+  // Decode FetchRes
+  assert(msg.Any.FetchRes === resBase.innerType());
+  const inner = new msg.FetchRes();
+  assert(resBase.inner(inner) != null);
+  return inner;
 }
 
 /** Fetch a resource from the network. */
@@ -417,13 +448,20 @@ export async function fetch(
   }
 
   while (remRedirectCount) {
-    const fetchResponse = await sendFetchReq(url, method, headers, body);
+    const inner = await getFetchRes(url, method, headers, body);
+
+    const header = inner.header()!;
+    const bodyRid = inner.bodyRid();
+    assert(!header.isRequest());
+    const status = header.status();
+
+    const headersList = deserializeHeaderFields(header);
 
     const response = new Response(
       url,
-      fetchResponse.status,
-      fetchResponse.headers,
-      fetchResponse.bodyRid,
+      status,
+      headersList,
+      bodyRid,
       redirected
     );
     if ([301, 302, 303, 307, 308].includes(response.status)) {