rad

rad is an abbreviation for rust-analyzer daemon. It decouples the rust-analyzer lifecycle from editor like neovim, so backend instances can outlive editor sessions. It also allows multiple editors opening the same workspace to reuse a single rust-analyzer instance.

Architecture

+----------------------+   stdio   +------------+                      +-------------+      stdio      +-----------------------+
| Neovim1              | <-------> | rad client | -------------------> |             | <-------------> | rust-analyzer A       |
| ~/source/greptimedb  |           +------------+                      |             |                 | ~/source/greptimedb   |
+----------------------+                                               |             |                 +-----------------------+
                                                                       |             |
+----------------------+   stdio   +------------+                      | rad server  |
| Neovim2              | <-------> | rad client | -------------------> | (mux/router)|      stdio      +-----------------------+
| ~/source/greptimedb  |           +------------+                      |             | <-------------> | rust-analyzer B       |
+----------------------+                                               |             |                 | ~/source/rad          |
                                                                       |             |                 +-----------------------+
+----------------------+   stdio   +------------+                      |             |
| VSCode               | <-------> | rad client | -------------------> |             |
| ~/source/rad         |           +------------+                      +-------------+
+----------------------+

Features

• Reuse existing rust-analyzer instance for the same workspace.
• Keep rust-analyzer alive when clients disconnect; idle reaper shuts it down after a configurable timeout.
• Pin a running instance by PID to exempt it from idle shutdown (see rad pin).
• Start rust-analyzer in the workspace directory to respect each project's Rust toolchain.

Configuration

The default config path is ~/.config/rad/rad.toml. Use -c / --config-file to override it.

An example config file is provided at rad.toml in the repository root.

How to Use

Run rad Server

Direct Run

rad server

systemd

For Linux setup, see deploy/systemd/README.md.

launchd (macOS)

For macOS setup, see deploy/launchd/README.md.

Configure Editor

Neovim(rustaceanvim)

An example configuration of rustaceanvim is shown below.

vim.g.rustaceanvim = {
    server = {
        cmd = function()
            return {
                vim.fn.exepath("rad"),
                "client",
            }
        end
    },
    -- other configurations
}

VSCode

VSCode's Rust Analyzer extension calls --version (-V) on the configured server binary during startup. Since rad client is a proxy command, use a wrapper script to forward version queries to the real rust-analyzer.

1. Create a wrapper script, for example ~/.local/bin/rad-ra:

#!/bin/bash

if [[ "$1" == "--version" || "$1" == "-V" ]]; then
    exec rust-analyzer --version
fi

exec rad client "$@"

2. Make it executable:

chmod +x ~/.local/bin/rad-ra

3. Configure VSCode (settings.json):

{
  "rust-analyzer.server.path": "{path}/rad-ra"
}

rad status

Show all running LSP instances:

rad status

Example output:

workspace: file:///home/user/greptimedb
  pid:      12345
  clients:  2
  idle:     1m 15s
  pinned:   yes
  healthy:  yes

workspace: file:///home/user/rad
  pid:      67890
  clients:  0
  idle:     5m 30s
  pinned:   no
  healthy:  yes

rad clean

rad clean shuts down idle instances, i.e. instances with no attached clients that are not pinned (see rad pin). Pinned instances are kept even when idle:

rad clean

rad clean -f skips all checks and removes every instance, regardless of pin state or attached clients. Instances currently serving clients are shut down as well, so use it with care:

rad clean -f

Example output:

file:///home/user/rad (pid: 67890)

rad pin

Prevent an LSP instance from being removed when it is idle:

rad pin 12345

Remove the pin:

rad pin -r 12345

Use rad status to find the instance PID and check its pin state. Pinned instances are skipped by rad clean, but can still be removed with rad clean -f.