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.

cli/ops/os.rs

@@ -1,11 +1,15 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
 use super::dispatch_json::{Deserialize, JsonOp, Value};
+use super::utils::*;
 use crate::ansi;
 use crate::fs as deno_fs;
+use crate::msg;
 use crate::state::ThreadSafeState;
 use crate::version;
 use atty;
 use deno::*;
+use flatbuffers::FlatBufferBuilder;
 use log;
 use std::collections::HashMap;
 use std::env;
@@ -13,38 +17,97 @@ use url::Url;
 
 pub fn op_start(
   state: &ThreadSafeState,
-  _args: Value,
-  _zero_copy: Option<PinnedBuf>,
-) -> Result<JsonOp, ErrBox> {
-  Ok(JsonOp::Sync(json!({
-    "cwd": deno_fs::normalize_path(&env::current_dir().unwrap()),
-    "pid": std::process::id(),
-    "argv": state.argv,
-    "mainModule": state.main_module().map(|x| x.as_str().to_string()),
-    "debugFlag": state
-      .flags
-      .log_level
-      .map_or(false, |l| l == log::Level::Debug),
-    "versionFlag": state.flags.version,
-    "v8Version": version::v8(),
-    "denoVersion": version::DENO,
-    "noColor": !ansi::use_color(),
-    "xevalDelim": state.flags.xeval_delim.clone(),
-  })))
+  base: &msg::Base<'_>,
+  data: Option<PinnedBuf>,
+) -> CliOpResult {
+  assert!(data.is_none());
+  let mut builder = FlatBufferBuilder::new();
+
+  let state = state;
+  let argv = state.argv.iter().map(String::as_str).collect::<Vec<_>>();
+  let argv_off = builder.create_vector_of_strings(argv.as_slice());
+
+  let cwd_path = env::current_dir().unwrap();
+  let cwd_off =
+    builder.create_string(deno_fs::normalize_path(cwd_path.as_ref()).as_ref());
+
+  let v8_version = version::v8();
+  let v8_version_off = builder.create_string(v8_version);
+
+  let deno_version = version::DENO;
+  let deno_version_off = builder.create_string(deno_version);
+
+  let main_module = state
+    .main_module()
+    .map(|m| builder.create_string(&m.to_string()));
+
+  let xeval_delim = state
+    .flags
+    .xeval_delim
+    .clone()
+    .map(|m| builder.create_string(&m));
+
+  let debug_flag = state
+    .flags
+    .log_level
+    .map_or(false, |l| l == log::Level::Debug);
+
+  let inner = msg::StartRes::create(
+    &mut builder,
+    &msg::StartResArgs {
+      cwd: Some(cwd_off),
+      pid: std::process::id(),
+      argv: Some(argv_off),
+      main_module,
+      debug_flag,
+      version_flag: state.flags.version,
+      v8_version: Some(v8_version_off),
+      deno_version: Some(deno_version_off),
+      no_color: !ansi::use_color(),
+      xeval_delim,
+      ..Default::default()
+    },
+  );
+
+  ok_buf(serialize_response(
+    base.cmd_id(),
+    &mut builder,
+    msg::BaseArgs {
+      inner_type: msg::Any::StartRes,
+      inner: Some(inner.as_union_value()),
+      ..Default::default()
+    },
+  ))
 }
 
 pub fn op_home_dir(
   state: &ThreadSafeState,
-  _args: Value,
-  _zero_copy: Option<PinnedBuf>,
-) -> Result<JsonOp, ErrBox> {
+  base: &msg::Base<'_>,
+  data: Option<PinnedBuf>,
+) -> CliOpResult {
+  assert!(data.is_none());
+  let cmd_id = base.cmd_id();
+
   state.check_env()?;
+
+  let builder = &mut FlatBufferBuilder::new();
   let path = dirs::home_dir()
     .unwrap_or_default()
     .into_os_string()
     .into_string()
     .unwrap_or_default();
-  Ok(JsonOp::Sync(json!(path)))
+  let path = Some(builder.create_string(&path));
+  let inner = msg::HomeDirRes::create(builder, &msg::HomeDirResArgs { path });
+
+  ok_buf(serialize_response(
+    cmd_id,
+    builder,
+    msg::BaseArgs {
+      inner: Some(inner.as_union_value()),
+      inner_type: msg::Any::HomeDirRes,
+      ..Default::default()
+    },
+  ))
 }
 
 pub fn op_exec_path(
@@ -61,21 +124,18 @@ pub fn op_exec_path(
   Ok(JsonOp::Sync(json!(path)))
 }
 
-#[derive(Deserialize)]
-struct SetEnv {
-  key: String,
-  value: String,
-}
-
 pub fn op_set_env(
   state: &ThreadSafeState,
-  args: Value,
-  _zero_copy: Option<PinnedBuf>,
-) -> Result<JsonOp, ErrBox> {
-  let args: SetEnv = serde_json::from_value(args)?;
+  base: &msg::Base<'_>,
+  data: Option<PinnedBuf>,
+) -> CliOpResult {
+  assert!(data.is_none());
+  let inner = base.inner_as_set_env().unwrap();
+  let key = inner.key().unwrap();
+  let value = inner.value().unwrap();
   state.check_env()?;
-  env::set_var(args.key, args.value);
-  Ok(JsonOp::Sync(json!({})))
+  env::set_var(key, value);
+  ok_buf(empty_buf())
 }
 
 pub fn op_env(