Organize dispatch a bit (#2796)

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

25 files changed, 384 insertions, 414 deletions

diff --git a/cli/BUILD.gn b/cli/BUILD.gn
index 0a6c9875e..3a5912471 100644
--- a/cli/BUILD.gn
+++ b/cli/BUILD.gn
@@ -82,6 +82,7 @@ ts_sources = [
   "../js/diagnostics.ts",
   "../js/dir.ts",
   "../js/dispatch.ts",
+  "../js/dispatch_flatbuffers.ts",
   "../js/dispatch_minimal.ts",
   "../js/dom_types.ts",
   "../js/dom_util.ts",
diff --git a/cli/main.rs b/cli/main.rs
index 01469e442..3f8f113b2 100644
--- a/cli/main.rs
+++ b/cli/main.rs
@@ -21,7 +21,6 @@ pub mod deno_dir;
 pub mod deno_error;
 pub mod diagnostics;
 mod disk_cache;
-mod dispatch_minimal;
 mod file_fetcher;
 pub mod flags;
 pub mod fmt_errors;
@@ -114,10 +113,9 @@ fn create_worker_and_state(
     }
   });
   // TODO(kevinkassimo): maybe make include_deno_namespace also configurable?
-  let state =
-    ThreadSafeState::new(flags, argv, ops::op_selector_std, progress, true)
-      .map_err(print_err_and_exit)
-      .unwrap();
+  let state = ThreadSafeState::new(flags, argv, progress, true)
+    .map_err(print_err_and_exit)
+    .unwrap();
   let worker = Worker::new(
     "main".to_string(),
     startup_data::deno_isolate_init(),
diff --git a/cli/ops/compiler.rs b/cli/ops/compiler.rs
index 8d75668c1..efdcd2c9b 100644
--- a/cli/ops/compiler.rs
+++ b/cli/ops/compiler.rs
@@ -1,10 +1,8 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::deno_error;
 use crate::msg;
-use crate::ops::empty_buf;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::state::ThreadSafeState;
 use crate::tokio_util;
 use deno::*;
diff --git a/cli/ops/dispatch_flatbuffers.rs b/cli/ops/dispatch_flatbuffers.rs
new file mode 100644
index 000000000..2b2e5050d
--- /dev/null
+++ b/cli/ops/dispatch_flatbuffers.rs
@@ -0,0 +1,216 @@
+use super::utils::CliOpResult;
+use crate::deno_error::GetErrorKind;
+use crate::msg;
+use crate::state::ThreadSafeState;
+use deno::*;
+use flatbuffers::FlatBufferBuilder;
+use hyper::rt::Future;
+
+use super::compiler::{op_cache, op_fetch_source_file};
+use super::errors::{op_apply_source_map, op_format_error};
+use super::fetch::op_fetch;
+use super::files::{op_close, op_open, op_read, op_seek, op_write};
+use super::fs::{
+  op_chdir, op_chmod, op_chown, op_copy_file, op_cwd, op_link,
+  op_make_temp_dir, op_mkdir, op_read_dir, op_read_link, op_remove, op_rename,
+  op_stat, op_symlink, op_truncate, op_utime,
+};
+use super::metrics::op_metrics;
+use super::net::{op_accept, op_dial, op_listen, op_shutdown};
+use super::os::{
+  op_env, op_exec_path, op_exit, op_home_dir, op_is_tty, op_set_env, op_start,
+};
+use super::performance::op_now;
+use super::permissions::{op_permissions, op_revoke_permission};
+use super::process::{op_kill, op_run, op_run_status};
+use super::random::op_get_random_values;
+use super::repl::{op_repl_readline, op_repl_start};
+use super::resources::op_resources;
+use super::timers::{op_global_timer, op_global_timer_stop};
+use super::workers::{
+  op_create_worker, op_host_get_message, op_host_get_worker_closed,
+  op_host_post_message, op_worker_get_message, op_worker_post_message,
+};
+
+type CliDispatchFn = fn(
+  state: &ThreadSafeState,
+  base: &msg::Base<'_>,
+  data: Option<PinnedBuf>,
+) -> CliOpResult;
+
+/// Processes raw messages from JavaScript.
+/// This functions invoked every time Deno.core.dispatch() is called.
+/// control corresponds to the first argument of Deno.core.dispatch().
+/// data corresponds to the second argument of Deno.core.dispatch().
+pub fn dispatch(
+  state: &ThreadSafeState,
+  control: &[u8],
+  zero_copy: Option<PinnedBuf>,
+) -> CoreOp {
+  let base = msg::get_root_as_base(&control);
+  let inner_type = base.inner_type();
+  let is_sync = base.sync();
+  let cmd_id = base.cmd_id();
+
+  debug!(
+    "msg_from_js {} sync {}",
+    msg::enum_name_any(inner_type),
+    is_sync
+  );
+
+  let op_func: CliDispatchFn = match op_selector_std(inner_type) {
+    Some(v) => v,
+    None => panic!("Unhandled message {}", msg::enum_name_any(inner_type)),
+  };
+
+  let op_result = op_func(state, &base, zero_copy);
+
+  let state = state.clone();
+
+  match op_result {
+    Ok(Op::Sync(buf)) => {
+      state.metrics_op_completed(buf.len());
+      Op::Sync(buf)
+    }
+    Ok(Op::Async(fut)) => {
+      let result_fut = Box::new(
+        fut
+          .or_else(move |err: ErrBox| -> Result<Buf, ()> {
+            debug!("op err {}", err);
+            // No matter whether we got an Err or Ok, we want a serialized message to
+            // send back. So transform the DenoError into a Buf.
+            let builder = &mut FlatBufferBuilder::new();
+            let errmsg_offset = builder.create_string(&format!("{}", err));
+            Ok(serialize_response(
+              cmd_id,
+              builder,
+              msg::BaseArgs {
+                error: Some(errmsg_offset),
+                error_kind: err.kind(),
+                ..Default::default()
+              },
+            ))
+          })
+          .and_then(move |buf: Buf| -> Result<Buf, ()> {
+            // Handle empty responses. For sync responses we just want
+            // to send null. For async we want to send a small message
+            // with the cmd_id.
+            let buf = if buf.len() > 0 {
+              buf
+            } else {
+              let builder = &mut FlatBufferBuilder::new();
+              serialize_response(
+                cmd_id,
+                builder,
+                msg::BaseArgs {
+                  ..Default::default()
+                },
+              )
+            };
+            state.metrics_op_completed(buf.len());
+            Ok(buf)
+          })
+          .map_err(|err| panic!("unexpected error {:?}", err)),
+      );
+      Op::Async(result_fut)
+    }
+    Err(err) => {
+      debug!("op err {}", err);
+      // No matter whether we got an Err or Ok, we want a serialized message to
+      // send back. So transform the DenoError into a Buf.
+      let builder = &mut FlatBufferBuilder::new();
+      let errmsg_offset = builder.create_string(&format!("{}", err));
+      let response_buf = serialize_response(
+        cmd_id,
+        builder,
+        msg::BaseArgs {
+          error: Some(errmsg_offset),
+          error_kind: err.kind(),
+          ..Default::default()
+        },
+      );
+      state.metrics_op_completed(response_buf.len());
+      Op::Sync(response_buf)
+    }
+  }
+}
+
+pub fn serialize_response(
+  cmd_id: u32,
+  builder: &mut FlatBufferBuilder<'_>,
+  mut args: msg::BaseArgs<'_>,
+) -> Buf {
+  args.cmd_id = cmd_id;
+  let base = msg::Base::create(builder, &args);
+  msg::finish_base_buffer(builder, base);
+  let data = builder.finished_data();
+  // println!("serialize_response {:x?}", data);
+  data.into()
+}
+
+/// Standard ops set for most isolates
+pub fn op_selector_std(inner_type: msg::Any) -> Option<CliDispatchFn> {
+  match inner_type {
+    msg::Any::Accept => Some(op_accept),
+    msg::Any::ApplySourceMap => Some(op_apply_source_map),
+    msg::Any::Cache => Some(op_cache),
+    msg::Any::Chdir => Some(op_chdir),
+    msg::Any::Chmod => Some(op_chmod),
+    msg::Any::Chown => Some(op_chown),
+    msg::Any::Close => Some(op_close),
+    msg::Any::CopyFile => Some(op_copy_file),
+    msg::Any::CreateWorker => Some(op_create_worker),
+    msg::Any::Cwd => Some(op_cwd),
+    msg::Any::Dial => Some(op_dial),
+    msg::Any::Environ => Some(op_env),
+    msg::Any::ExecPath => Some(op_exec_path),
+    msg::Any::Exit => Some(op_exit),
+    msg::Any::Fetch => Some(op_fetch),
+    msg::Any::FetchSourceFile => Some(op_fetch_source_file),
+    msg::Any::FormatError => Some(op_format_error),
+    msg::Any::GetRandomValues => Some(op_get_random_values),
+    msg::Any::GlobalTimer => Some(op_global_timer),
+    msg::Any::GlobalTimerStop => Some(op_global_timer_stop),
+    msg::Any::HostGetMessage => Some(op_host_get_message),
+    msg::Any::HostGetWorkerClosed => Some(op_host_get_worker_closed),
+    msg::Any::HostPostMessage => Some(op_host_post_message),
+    msg::Any::IsTTY => Some(op_is_tty),
+    msg::Any::Kill => Some(op_kill),
+    msg::Any::Link => Some(op_link),
+    msg::Any::Listen => Some(op_listen),
+    msg::Any::MakeTempDir => Some(op_make_temp_dir),
+    msg::Any::Metrics => Some(op_metrics),
+    msg::Any::Mkdir => Some(op_mkdir),
+    msg::Any::Now => Some(op_now),
+    msg::Any::Open => Some(op_open),
+    msg::Any::PermissionRevoke => Some(op_revoke_permission),
+    msg::Any::Permissions => Some(op_permissions),
+    msg::Any::Read => Some(op_read),
+    msg::Any::ReadDir => Some(op_read_dir),
+    msg::Any::Readlink => Some(op_read_link),
+    msg::Any::Remove => Some(op_remove),
+    msg::Any::Rename => Some(op_rename),
+    msg::Any::ReplReadline => Some(op_repl_readline),
+    msg::Any::ReplStart => Some(op_repl_start),
+    msg::Any::Resources => Some(op_resources),
+    msg::Any::Run => Some(op_run),
+    msg::Any::RunStatus => Some(op_run_status),
+    msg::Any::Seek => Some(op_seek),
+    msg::Any::SetEnv => Some(op_set_env),
+    msg::Any::Shutdown => Some(op_shutdown),
+    msg::Any::Start => Some(op_start),
+    msg::Any::Stat => Some(op_stat),
+    msg::Any::Symlink => Some(op_symlink),
+    msg::Any::Truncate => Some(op_truncate),
+    msg::Any::HomeDir => Some(op_home_dir),
+    msg::Any::Utime => Some(op_utime),
+    msg::Any::Write => Some(op_write),
+
+    // TODO(ry) split these out so that only the appropriate Workers can access
+    // them.
+    msg::Any::WorkerGetMessage => Some(op_worker_get_message),
+    msg::Any::WorkerPostMessage => Some(op_worker_post_message),
+
+    _ => None,
+  }
+}
diff --git a/cli/dispatch_minimal.rs b/cli/ops/dispatch_minimal.rs
index 322094be2..37ad56813 100644
--- a/cli/dispatch_minimal.rs
+++ b/cli/ops/dispatch_minimal.rs
@@ -7,13 +7,13 @@
 use crate::state::ThreadSafeState;
 use deno::Buf;
 use deno::CoreOp;
+use deno::ErrBox;
 use deno::Op;
-use deno::OpId;
 use deno::PinnedBuf;
 use futures::Future;
 
-const OP_READ: OpId = 1;
-const OP_WRITE: OpId = 2;
+pub type MinimalOp = dyn Future<Item = i32, Error = ErrBox> + Send;
+pub type Dispatcher = fn(i32, Option<PinnedBuf>) -> Box<MinimalOp>;
 
 #[derive(Copy, Clone, Debug, PartialEq)]
 // This corresponds to RecordMinimal on the TS side.
@@ -72,21 +72,24 @@ fn test_parse_min_record() {
   assert_eq!(parse_min_record(&buf), None);
 }
 
-pub fn dispatch_minimal(
+pub fn dispatch(
+  d: Dispatcher,
   state: &ThreadSafeState,
-  op_id: OpId,
-  mut record: Record,
+  control: &[u8],
   zero_copy: Option<PinnedBuf>,
 ) -> CoreOp {
+  let mut record = parse_min_record(control).unwrap();
   let is_sync = record.promise_id == 0;
-  let min_op = match op_id {
-    OP_READ => ops::read(record.arg, zero_copy),
-    OP_WRITE => ops::write(record.arg, zero_copy),
-    _ => unimplemented!(),
-  };
+
+  // TODO(ry) Currently there aren't any sync minimal ops. This is just a sanity
+  // check. Remove later.
+  assert!(!is_sync);
 
   let state = state.clone();
 
+  let rid = record.arg;
+  let min_op = d(rid, zero_copy);
+
   let fut = Box::new(min_op.then(move |result| -> Result<Buf, ()> {
     match result {
       Ok(r) => {
@@ -109,54 +112,3 @@ pub fn dispatch_minimal(
     Op::Async(fut)
   }
 }
-
-mod ops {
-  use crate::deno_error;
-  use crate::resources;
-  use crate::tokio_write;
-  use deno::ErrBox;
-  use deno::PinnedBuf;
-  use futures::Future;
-
-  type MinimalOp = dyn Future<Item = i32, Error = ErrBox> + Send;
-
-  pub fn read(rid: i32, zero_copy: Option<PinnedBuf>) -> Box<MinimalOp> {
-    debug!("read rid={}", rid);
-    let zero_copy = match zero_copy {
-      None => {
-        return Box::new(
-          futures::future::err(deno_error::no_buffer_specified()),
-        )
-      }
-      Some(buf) => buf,
-    };
-    match resources::lookup(rid as u32) {
-      None => Box::new(futures::future::err(deno_error::bad_resource())),
-      Some(resource) => Box::new(
-        tokio::io::read(resource, zero_copy)
-          .map_err(ErrBox::from)
-          .and_then(move |(_resource, _buf, nread)| Ok(nread as i32)),
-      ),
-    }
-  }
-
-  pub fn write(rid: i32, zero_copy: Option<PinnedBuf>) -> Box<MinimalOp> {
-    debug!("write rid={}", rid);
-    let zero_copy = match zero_copy {
-      None => {
-        return Box::new(
-          futures::future::err(deno_error::no_buffer_specified()),
-        )
-      }
-      Some(buf) => buf,
-    };
-    match resources::lookup(rid as u32) {
-      None => Box::new(futures::future::err(deno_error::bad_resource())),
-      Some(resource) => Box::new(
-        tokio_write::write(resource, zero_copy)
-          .map_err(ErrBox::from)
-          .and_then(move |(_resource, _buf, nwritten)| Ok(nwritten as i32)),
-      ),
-    }
-  }
-}
diff --git a/cli/ops/errors.rs b/cli/ops/errors.rs
index 16dfc34fd..a27f3656e 100644
--- a/cli/ops/errors.rs
+++ b/cli/ops/errors.rs
@@ -1,10 +1,9 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::deno_error;
 use crate::fmt_errors::JSError;
 use crate::msg;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::source_maps::get_orig_position;
 use crate::source_maps::CachedMaps;
 use crate::state::ThreadSafeState;
diff --git a/cli/ops/fetch.rs b/cli/ops/fetch.rs
index e4f57972f..7661eb6e9 100644
--- a/cli/ops/fetch.rs
+++ b/cli/ops/fetch.rs
@@ -1,9 +1,9 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::CliOpResult;
 use crate::http_util;
 use crate::msg;
 use crate::msg_util;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::resources;
 use crate::state::ThreadSafeState;
 use deno::*;
diff --git a/cli/ops/files.rs b/cli/ops/files.rs
index ce3285623..023bd65f9 100644
--- a/cli/ops/files.rs
+++ b/cli/ops/files.rs
@@ -1,11 +1,9 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::deno_error;
 use crate::fs as deno_fs;
 use crate::msg;
-use crate::ops::empty_buf;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::resources;
 use crate::state::ThreadSafeState;
 use crate::tokio_write;
diff --git a/cli/ops/fs.rs b/cli/ops/fs.rs
index 6530e3816..d46ed91e1 100644
--- a/cli/ops/fs.rs
+++ b/cli/ops/fs.rs
@@ -1,18 +1,14 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::deno_error::DenoError;
 use crate::deno_error::ErrorKind;
 use crate::fs as deno_fs;
 use crate::msg;
-use crate::ops::blocking;
-use crate::ops::empty_buf;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::state::ThreadSafeState;
 use deno::*;
 use flatbuffers::FlatBufferBuilder;
 use remove_dir_all::remove_dir_all;
-use std;
 use std::convert::From;
 use std::fs;
 use std::path::PathBuf;
diff --git a/cli/ops/io.rs b/cli/ops/io.rs
new file mode 100644
index 000000000..610238942
--- /dev/null
+++ b/cli/ops/io.rs
@@ -0,0 +1,43 @@
+use super::dispatch_minimal::MinimalOp;
+use crate::deno_error;
+use crate::resources;
+use crate::tokio_write;
+use deno::ErrBox;
+use deno::PinnedBuf;
+use futures::Future;
+
+pub fn op_read(rid: i32, zero_copy: Option<PinnedBuf>) -> Box<MinimalOp> {
+  debug!("read rid={}", rid);
+  let zero_copy = match zero_copy {
+    None => {
+      return Box::new(futures::future::err(deno_error::no_buffer_specified()))
+    }
+    Some(buf) => buf,
+  };
+  match resources::lookup(rid as u32) {
+    None => Box::new(futures::future::err(deno_error::bad_resource())),
+    Some(resource) => Box::new(
+      tokio::io::read(resource, zero_copy)
+        .map_err(ErrBox::from)
+        .and_then(move |(_resource, _buf, nread)| Ok(nread as i32)),
+    ),
+  }
+}
+
+pub fn op_write(rid: i32, zero_copy: Option<PinnedBuf>) -> Box<MinimalOp> {
+  debug!("write rid={}", rid);
+  let zero_copy = match zero_copy {
+    None => {
+      return Box::new(futures::future::err(deno_error::no_buffer_specified()))
+    }
+    Some(buf) => buf,
+  };
+  match resources::lookup(rid as u32) {
+    None => Box::new(futures::future::err(deno_error::bad_resource())),
+    Some(resource) => Box::new(
+      tokio_write::write(resource, zero_copy)
+        .map_err(ErrBox::from)
+        .and_then(move |(_resource, _buf, nwritten)| Ok(nwritten as i32)),
+    ),
+  }
+}
diff --git a/cli/ops/metrics.rs b/cli/ops/metrics.rs
index 7d821f1fa..76f36c390 100644
--- a/cli/ops/metrics.rs
+++ b/cli/ops/metrics.rs
@@ -1,8 +1,7 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::msg;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::state::ThreadSafeState;
 use deno::*;
 use flatbuffers::FlatBufferBuilder;
diff --git a/cli/ops/mod.rs b/cli/ops/mod.rs
index 021c0fa47..92c0f8e62 100644
--- a/cli/ops/mod.rs
+++ b/cli/ops/mod.rs
@@ -1,305 +1,52 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
-use crate::deno_error::GetErrorKind;
-use crate::dispatch_minimal::dispatch_minimal;
-use crate::dispatch_minimal::parse_min_record;
-use crate::msg;
 use crate::state::ThreadSafeState;
-use crate::tokio_util;
 use deno::*;
-use flatbuffers::FlatBufferBuilder;
-use futures;
-use futures::Poll;
-use hyper;
-use hyper::rt::Future;
-use tokio_threadpool;
 
 mod compiler;
-use compiler::{op_cache, op_fetch_source_file};
+mod dispatch_flatbuffers;
+mod dispatch_minimal;
 mod errors;
-use errors::{op_apply_source_map, op_format_error};
-mod files;
-use files::{op_close, op_open, op_read, op_seek, op_write};
 mod fetch;
-use fetch::op_fetch;
+mod files;
 mod fs;
-use fs::{
-  op_chdir, op_chmod, op_chown, op_copy_file, op_cwd, op_link,
-  op_make_temp_dir, op_mkdir, op_read_dir, op_read_link, op_remove, op_rename,
-  op_stat, op_symlink, op_truncate, op_utime,
-};
+mod io;
 mod metrics;
-use metrics::op_metrics;
 mod net;
-use net::{op_accept, op_dial, op_listen, op_shutdown};
 mod os;
-use os::{
-  op_env, op_exec_path, op_exit, op_home_dir, op_is_tty, op_set_env, op_start,
-};
 mod performance;
-use performance::op_now;
 mod permissions;
-use permissions::{op_permissions, op_revoke_permission};
 mod process;
-use process::{op_kill, op_run, op_run_status};
 mod random;
-use random::op_get_random_values;
 mod repl;
-use repl::{op_repl_readline, op_repl_start};
 mod resources;
-use resources::op_resources;
 mod timers;
-use timers::{op_global_timer, op_global_timer_stop};
+mod utils;
 mod workers;
-use workers::{
-  op_create_worker, op_host_get_message, op_host_get_worker_closed,
-  op_host_post_message, op_worker_get_message, op_worker_post_message,
-};
-
-type CliOpResult = OpResult<ErrBox>;
-
-type CliDispatchFn = fn(
-  state: &ThreadSafeState,
-  base: &msg::Base<'_>,
-  data: Option<PinnedBuf>,
-) -> CliOpResult;
 
-pub type OpSelector = fn(inner_type: msg::Any) -> Option<CliDispatchFn>;
+pub const OP_FLATBUFFER: OpId = 44;
+pub const OP_READ: OpId = 1;
+pub const OP_WRITE: OpId = 2;
 
-#[inline]
-fn empty_buf() -> Buf {
-  Box::new([])
-}
-
-const FLATBUFFER_OP_ID: OpId = 44;
-
-pub fn dispatch_all(
+pub fn dispatch(
   state: &ThreadSafeState,
   op_id: OpId,
   control: &[u8],
   zero_copy: Option<PinnedBuf>,
-  op_selector: OpSelector,
 ) -> CoreOp {
   let bytes_sent_control = control.len();
   let bytes_sent_zero_copy = zero_copy.as_ref().map(|b| b.len()).unwrap_or(0);
-  let op = if op_id != FLATBUFFER_OP_ID {
-    let min_record = parse_min_record(control).unwrap();
-    dispatch_minimal(state, op_id, min_record, zero_copy)
-  } else {
-    dispatch_all_legacy(state, control, zero_copy, op_selector)
-  };
-  state.metrics_op_dispatched(bytes_sent_control, bytes_sent_zero_copy);
-  op
-}
 
-/// Processes raw messages from JavaScript.
-/// This functions invoked every time Deno.core.dispatch() is called.
-/// control corresponds to the first argument of Deno.core.dispatch().
-/// data corresponds to the second argument of Deno.core.dispatch().
-pub fn dispatch_all_legacy(
-  state: &ThreadSafeState,
-  control: &[u8],
-  zero_copy: Option<PinnedBuf>,
-  op_selector: OpSelector,
-) -> CoreOp {
-  let base = msg::get_root_as_base(&control);
-  let inner_type = base.inner_type();
-  let is_sync = base.sync();
-  let cmd_id = base.cmd_id();
-
-  debug!(
-    "msg_from_js {} sync {}",
-    msg::enum_name_any(inner_type),
-    is_sync
-  );
-
-  let op_func: CliDispatchFn = match op_selector(inner_type) {
-    Some(v) => v,
-    None => panic!("Unhandled message {}", msg::enum_name_any(inner_type)),
-  };
-
-  let op_result = op_func(state, &base, zero_copy);
-
-  let state = state.clone();
-
-  match op_result {
-    Ok(Op::Sync(buf)) => {
-      state.metrics_op_completed(buf.len());
-      Op::Sync(buf)
+  let op = match op_id {
+    OP_READ => {
+      dispatch_minimal::dispatch(io::op_read, state, control, zero_copy)
     }
-    Ok(Op::Async(fut)) => {
-      let result_fut = Box::new(
-        fut
-          .or_else(move |err: ErrBox| -> Result<Buf, ()> {
-            debug!("op err {}", err);
-            // No matter whether we got an Err or Ok, we want a serialized message to
-            // send back. So transform the DenoError into a Buf.
-            let builder = &mut FlatBufferBuilder::new();
-            let errmsg_offset = builder.create_string(&format!("{}", err));
-            Ok(serialize_response(
-              cmd_id,
-              builder,
-              msg::BaseArgs {
-                error: Some(errmsg_offset),
-                error_kind: err.kind(),
-                ..Default::default()
-              },
-            ))
-          })
-          .and_then(move |buf: Buf| -> Result<Buf, ()> {
-            // Handle empty responses. For sync responses we just want
-            // to send null. For async we want to send a small message
-            // with the cmd_id.
-            let buf = if buf.len() > 0 {
-              buf
-            } else {
-              let builder = &mut FlatBufferBuilder::new();
-              serialize_response(
-                cmd_id,
-                builder,
-                msg::BaseArgs {
-                  ..Default::default()
-                },
-              )
-            };
-            state.metrics_op_completed(buf.len());
-            Ok(buf)
-          })
-          .map_err(|err| panic!("unexpected error {:?}", err)),
-      );
-      Op::Async(result_fut)
+    OP_WRITE => {
+      dispatch_minimal::dispatch(io::op_write, state, control, zero_copy)
     }
-    Err(err) => {
-      debug!("op err {}", err);
-      // No matter whether we got an Err or Ok, we want a serialized message to
-      // send back. So transform the DenoError into a Buf.
-      let builder = &mut FlatBufferBuilder::new();
-      let errmsg_offset = builder.create_string(&format!("{}", err));
-      let response_buf = serialize_response(
-        cmd_id,
-        builder,
-        msg::BaseArgs {
-          error: Some(errmsg_offset),
-          error_kind: err.kind(),
-          ..Default::default()
-        },
-      );
-      state.metrics_op_completed(response_buf.len());
-      Op::Sync(response_buf)
-    }
-  }
-}
-
-/// Standard ops set for most isolates
-pub fn op_selector_std(inner_type: msg::Any) -> Option<CliDispatchFn> {
-  match inner_type {
-    msg::Any::Accept => Some(op_accept),
-    msg::Any::ApplySourceMap => Some(op_apply_source_map),
-    msg::Any::Cache => Some(op_cache),
-    msg::Any::Chdir => Some(op_chdir),
-    msg::Any::Chmod => Some(op_chmod),
-    msg::Any::Chown => Some(op_chown),
-    msg::Any::Close => Some(op_close),
-    msg::Any::CopyFile => Some(op_copy_file),
-    msg::Any::CreateWorker => Some(op_create_worker),
-    msg::Any::Cwd => Some(op_cwd),
-    msg::Any::Dial => Some(op_dial),
-    msg::Any::Environ => Some(op_env),
-    msg::Any::ExecPath => Some(op_exec_path),
-    msg::Any::Exit => Some(op_exit),
-    msg::Any::Fetch => Some(op_fetch),
-    msg::Any::FetchSourceFile => Some(op_fetch_source_file),
-    msg::Any::FormatError => Some(op_format_error),
-    msg::Any::GetRandomValues => Some(op_get_random_values),
-    msg::Any::GlobalTimer => Some(op_global_timer),
-    msg::Any::GlobalTimerStop => Some(op_global_timer_stop),
-    msg::Any::HostGetMessage => Some(op_host_get_message),
-    msg::Any::HostGetWorkerClosed => Some(op_host_get_worker_closed),
-    msg::Any::HostPostMessage => Some(op_host_post_message),
-    msg::Any::IsTTY => Some(op_is_tty),
-    msg::Any::Kill => Some(op_kill),
-    msg::Any::Link => Some(op_link),
-    msg::Any::Listen => Some(op_listen),
-    msg::Any::MakeTempDir => Some(op_make_temp_dir),
-    msg::Any::Metrics => Some(op_metrics),
-    msg::Any::Mkdir => Some(op_mkdir),
-    msg::Any::Now => Some(op_now),
-    msg::Any::Open => Some(op_open),
-    msg::Any::PermissionRevoke => Some(op_revoke_permission),
-    msg::Any::Permissions => Some(op_permissions),
-    msg::Any::Read => Some(op_read),
-    msg::Any::ReadDir => Some(op_read_dir),
-    msg::Any::Readlink => Some(op_read_link),
-    msg::Any::Remove => Some(op_remove),
-    msg::Any::Rename => Some(op_rename),
-    msg::Any::ReplReadline => Some(op_repl_readline),
-    msg::Any::ReplStart => Some(op_repl_start),
-    msg::Any::Resources => Some(op_resources),
-    msg::Any::Run => Some(op_run),
-    msg::Any::RunStatus => Some(op_run_status),
-    msg::Any::Seek => Some(op_seek),
-    msg::Any::SetEnv => Some(op_set_env),
-    msg::Any::Shutdown => Some(op_shutdown),
-    msg::Any::Start => Some(op_start),
-    msg::Any::Stat => Some(op_stat),
-    msg::Any::Symlink => Some(op_symlink),
-    msg::Any::Truncate => Some(op_truncate),
-    msg::Any::HomeDir => Some(op_home_dir),
-    msg::Any::Utime => Some(op_utime),
-    msg::Any::Write => Some(op_write),
-
-    // TODO(ry) split these out so that only the appropriate Workers can access
-    // them.
-    msg::Any::WorkerGetMessage => Some(op_worker_get_message),
-    msg::Any::WorkerPostMessage => Some(op_worker_post_message),
-
-    _ => None,
-  }
-}
-
-fn serialize_response(
-  cmd_id: u32,
-  builder: &mut FlatBufferBuilder<'_>,
-  mut args: msg::BaseArgs<'_>,
-) -> Buf {
-  args.cmd_id = cmd_id;
-  let base = msg::Base::create(builder, &args);
-  msg::finish_base_buffer(builder, base);
-  let data = builder.finished_data();
-  // println!("serialize_response {:x?}", data);
-  data.into()
-}
-
-#[inline]
-fn ok_buf(buf: Buf) -> CliOpResult {
-  Ok(Op::Sync(buf))
-}
-
-// This is just type conversion. Implement From trait?
-// See https://github.com/tokio-rs/tokio/blob/ffd73a64e7ec497622b7f939e38017afe7124dc4/tokio-fs/src/lib.rs#L76-L85
-fn convert_blocking<F>(f: F) -> Poll<Buf, ErrBox>
-where
-  F: FnOnce() -> Result<Buf, ErrBox>,
-{
-  use futures::Async::*;
-  match tokio_threadpool::blocking(f) {
-    Ok(Ready(Ok(v))) => Ok(v.into()),
-    Ok(Ready(Err(err))) => Err(err),
-    Ok(NotReady) => Ok(NotReady),
-    Err(err) => panic!("blocking error {}", err),
-  }
-}
+    OP_FLATBUFFER => dispatch_flatbuffers::dispatch(state, control, zero_copy),
+    _ => panic!("bad op_id"),
+  };
 
-fn blocking<F>(is_sync: bool, f: F) -> CliOpResult
-where
-  F: 'static + Send + FnOnce() -> Result<Buf, ErrBox>,
-{
-  if is_sync {
-    let result_buf = f()?;
-    Ok(Op::Sync(result_buf))
-  } else {
-    Ok(Op::Async(Box::new(futures::sync::oneshot::spawn(
-      tokio_util::poll_fn(move || convert_blocking(f)),
-      &tokio_executor::DefaultExecutor::current(),
-    ))))
-  }
+  state.metrics_op_dispatched(bytes_sent_control, bytes_sent_zero_copy);
+  op
 }
diff --git a/cli/ops/net.rs b/cli/ops/net.rs
index 16a24872d..5ce562492 100644
--- a/cli/ops/net.rs
+++ b/cli/ops/net.rs
@@ -1,10 +1,9 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::deno_error;
 use crate::msg;
-use crate::ops::empty_buf;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
+use crate::resolve_addr::resolve_addr;
 use crate::resources;
 use crate::resources::Resource;
 use crate::state::ThreadSafeState;
@@ -13,16 +12,12 @@ use deno::*;
 use flatbuffers::FlatBufferBuilder;
 use futures::Future;
 use std;
+use std::convert::From;
 use std::net::Shutdown;
 use tokio;
-
-use crate::resolve_addr::resolve_addr;
-use std::convert::From;
 use tokio::net::TcpListener;
 use tokio::net::TcpStream;
 
-use crate::ops::blocking;
-
 pub fn op_accept(
   _state: &ThreadSafeState,
   base: &msg::Base<'_>,
diff --git a/cli/ops/os.rs b/cli/ops/os.rs
index cd165aa05..fbf430d7a 100644
--- a/cli/ops/os.rs
+++ b/cli/ops/os.rs
@@ -1,12 +1,10 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::ansi;
 use crate::fs as deno_fs;
 use crate::msg;
 use crate::msg_util;
-use crate::ops::empty_buf;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::state::ThreadSafeState;
 use crate::version;
 use atty;
diff --git a/cli/ops/performance.rs b/cli/ops/performance.rs
index ae2a0b860..94f6dbc38 100644
--- a/cli/ops/performance.rs
+++ b/cli/ops/performance.rs
@@ -1,8 +1,7 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::msg;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::state::ThreadSafeState;
 use deno::*;
 use flatbuffers::FlatBufferBuilder;
diff --git a/cli/ops/permissions.rs b/cli/ops/permissions.rs
index 47a9cf871..6249581fb 100644
--- a/cli/ops/permissions.rs
+++ b/cli/ops/permissions.rs
@@ -1,9 +1,7 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::msg;
-use crate::ops::empty_buf;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::state::ThreadSafeState;
 use deno::*;
 use flatbuffers::FlatBufferBuilder;
diff --git a/cli/ops/process.rs b/cli/ops/process.rs
index 914b8ba86..d7b326d14 100644
--- a/cli/ops/process.rs
+++ b/cli/ops/process.rs
@@ -1,10 +1,8 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::*;
 use crate::deno_error;
 use crate::msg;
-use crate::ops::empty_buf;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::resources;
 use crate::signal::kill;
 use crate::state::ThreadSafeState;
diff --git a/cli/ops/random.rs b/cli/ops/random.rs
index 27e120faa..0c302a080 100644
--- a/cli/ops/random.rs
+++ b/cli/ops/random.rs
@@ -1,8 +1,6 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::utils::*;
 use crate::msg;
-use crate::ops::empty_buf;
-use crate::ops::ok_buf;
-use crate::ops::CliOpResult;
 use crate::state::ThreadSafeState;
 use deno::*;
 use rand::thread_rng;
diff --git a/cli/ops/repl.rs b/cli/ops/repl.rs
index 2fff389a1..affe78739 100644
--- a/cli/ops/repl.rs
+++ b/cli/ops/repl.rs
@@ -1,9 +1,9 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::blocking;
+use super::utils::ok_buf;
+use super::utils::CliOpResult;
 use crate::msg;
-use crate::ops::blocking;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::repl;
 use crate::resources;
 use crate::state::ThreadSafeState;
diff --git a/cli/ops/resources.rs b/cli/ops/resources.rs
index 410d69c80..975d94490 100644
--- a/cli/ops/resources.rs
+++ b/cli/ops/resources.rs
@@ -1,8 +1,8 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::ok_buf;
+use super::utils::CliOpResult;
 use crate::msg;
-use crate::ops::ok_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::resources::table_entries;
 use crate::state::ThreadSafeState;
 use deno::*;
diff --git a/cli/ops/timers.rs b/cli/ops/timers.rs
index 6c5f6fcae..550d91f2c 100644
--- a/cli/ops/timers.rs
+++ b/cli/ops/timers.rs
@@ -1,9 +1,9 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::empty_buf;
+use super::utils::CliOpResult;
 use crate::deno_error;
 use crate::msg;
-use crate::ops::empty_buf;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::state::ThreadSafeState;
 use deno::*;
 use flatbuffers::FlatBufferBuilder;
diff --git a/cli/ops/utils.rs b/cli/ops/utils.rs
new file mode 100644
index 000000000..a9b0b442c
--- /dev/null
+++ b/cli/ops/utils.rs
@@ -0,0 +1,48 @@
+use crate::tokio_util;
+use deno::Buf;
+use deno::ErrBox;
+use deno::Op;
+use deno::OpResult;
+use futures::Poll;
+
+pub type CliOpResult = OpResult<ErrBox>;
+
+#[inline]
+pub fn ok_buf(buf: Buf) -> CliOpResult {
+  Ok(Op::Sync(buf))
+}
+
+#[inline]
+pub fn empty_buf() -> Buf {
+  Box::new([])
+}
+
+// This is just type conversion. Implement From trait?
+// See https://github.com/tokio-rs/tokio/blob/ffd73a64e7ec497622b7f939e38017afe7124dc4/tokio-fs/src/lib.rs#L76-L85
+fn convert_blocking<F>(f: F) -> Poll<Buf, ErrBox>
+where
+  F: FnOnce() -> Result<Buf, ErrBox>,
+{
+  use futures::Async::*;
+  match tokio_threadpool::blocking(f) {
+    Ok(Ready(Ok(v))) => Ok(v.into()),
+    Ok(Ready(Err(err))) => Err(err),
+    Ok(NotReady) => Ok(NotReady),
+    Err(err) => panic!("blocking error {}", err),
+  }
+}
+
+pub fn blocking<F>(is_sync: bool, f: F) -> CliOpResult
+where
+  F: 'static + Send + FnOnce() -> Result<Buf, ErrBox>,
+{
+  if is_sync {
+    let result_buf = f()?;
+    Ok(Op::Sync(result_buf))
+  } else {
+    Ok(Op::Async(Box::new(futures::sync::oneshot::spawn(
+      tokio_util::poll_fn(move || convert_blocking(f)),
+      &tokio_executor::DefaultExecutor::current(),
+    ))))
+  }
+}
diff --git a/cli/ops/workers.rs b/cli/ops/workers.rs
index d47aab765..1eb11420f 100644
--- a/cli/ops/workers.rs
+++ b/cli/ops/workers.rs
@@ -1,12 +1,11 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use super::dispatch_flatbuffers::serialize_response;
+use super::utils::ok_buf;
+use super::utils::CliOpResult;
 use crate::deno_error;
 use crate::deno_error::DenoError;
 use crate::deno_error::ErrorKind;
 use crate::msg;
-use crate::ops::ok_buf;
-use crate::ops::op_selector_std;
-use crate::ops::serialize_response;
-use crate::ops::CliOpResult;
 use crate::resources;
 use crate::startup_data;
 use crate::state::ThreadSafeState;
@@ -136,7 +135,6 @@ pub fn op_create_worker(
   let child_state = ThreadSafeState::new(
     parent_state.flags.clone(),
     child_argv,
-    op_selector_std,
     parent_state.progress.clone(),
     include_deno_namespace,
   )?;
diff --git a/cli/state.rs b/cli/state.rs
index 777382907..d7c610204 100644
--- a/cli/state.rs
+++ b/cli/state.rs
@@ -77,7 +77,6 @@ pub struct State {
   pub start_time: Instant,
   /// A reference to this worker's resource.
   pub resource: resources::Resource,
-  pub dispatch_selector: ops::OpSelector,
   /// Reference to global progress bar.
   pub progress: Progress,
   pub seeded_rng: Option<Mutex<StdRng>>,
@@ -110,7 +109,7 @@ impl ThreadSafeState {
     control: &[u8],
     zero_copy: Option<PinnedBuf>,
   ) -> CoreOp {
-    ops::dispatch_all(self, op_id, control, zero_copy, self.dispatch_selector)
+    ops::dispatch(self, op_id, control, zero_copy)
   }
 }
 
@@ -163,7 +162,6 @@ impl ThreadSafeState {
   pub fn new(
     flags: flags::DenoFlags,
     argv_rest: Vec<String>,
-    dispatch_selector: ops::OpSelector,
     progress: Progress,
     include_deno_namespace: bool,
   ) -> Result<Self, ErrBox> {
@@ -224,7 +222,6 @@ impl ThreadSafeState {
       workers: Mutex::new(UserWorkerTable::new()),
       start_time: Instant::now(),
       resource,
-      dispatch_selector,
       progress,
       seeded_rng,
       file_fetcher,
@@ -333,7 +330,6 @@ impl ThreadSafeState {
     ThreadSafeState::new(
       flags::DenoFlags::default(),
       argv,
-      ops::op_selector_std,
       Progress::new(),
       true,
     )
@@ -382,7 +378,6 @@ fn import_map_given_for_repl() {
       ..flags::DenoFlags::default()
     },
     vec![String::from("./deno")],
-    ops::op_selector_std,
     Progress::new(),
     true,
   );
diff --git a/cli/worker.rs b/cli/worker.rs
index f639c3d6d..cb551453a 100644
--- a/cli/worker.rs
+++ b/cli/worker.rs
@@ -123,7 +123,6 @@ impl Future for Worker {
 mod tests {
   use super::*;
   use crate::flags;
-  use crate::ops::op_selector_std;
   use crate::progress::Progress;
   use crate::resources;
   use crate::startup_data;
@@ -140,7 +139,6 @@ mod tests {
     let state = ThreadSafeState::new(
       flags::DenoFlags::default(),
       argv,
-      op_selector_std,
       Progress::new(),
       true,
     )
@@ -170,7 +168,6 @@ mod tests {
     let state = ThreadSafeState::new(
       flags::DenoFlags::default(),
       argv,
-      op_selector_std,
       Progress::new(),
       true,
     )
@@ -200,8 +197,7 @@ mod tests {
     let mut flags = flags::DenoFlags::default();
     flags.reload = true;
     let state =
-      ThreadSafeState::new(flags, argv, op_selector_std, Progress::new(), true)
-        .unwrap();
+      ThreadSafeState::new(flags, argv, Progress::new(), true).unwrap();
     let state_ = state.clone();
     tokio_util::run(lazy(move || {
       let mut worker = Worker::new(