Class: Muxr::ControlServer

Inherits:
Object
  • Object
show all
Defined in:
lib/muxr/control_server.rb

Overview

ControlServer is the second listener on the muxr server: it accepts multiple concurrent JSON-RPC clients over a Unix socket at ~/.muxr/sockets/<name>.ctrl.sock and lets them inspect or drive the session. The primary client of this socket is the MCP bridge (bin/muxr-mcp) that exposes the methods as MCP tools for Claude Code, but anything that can read/write NDJSON can drive a session — ‘nc` is enough for poking around by hand.

Wire format: one JSON object per line. Requests carry an ‘id`; responses echo it back. Server-pushed events (used by `pane.subscribe`) have no `id` and instead set a `method` of `“event.<topic>”`.

--> {"id":1,"method":"panes.list"}
<-- {"id":1,"result":{"panes":[...]}}
<-- {"method":"event.pane.output","params":{"pane":"a3f9b2","data":"..."}}

The TTY socket (.sock) and the control socket (.ctrl.sock) are deliberately separate: the TTY socket is single-client (only one human attaches at a time), the control socket is multi-client, and a connected control client never counts as “attached” — Renderer is unaffected.

Constant Summary collapse

PARSE_ERROR =

JSON-RPC error code conventions.

-32700
INVALID_REQUEST = 
-32600
METHOD_NOT_FOUND = 
-32601
INVALID_PARAMS = 
-32602
INTERNAL_ERROR = 
-32603
READ_CHUNK = 
64 * 1024

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app, socket_path) ⇒ ControlServer

Returns a new instance of ControlServer.



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# File 'lib/muxr/control_server.rb', line 37

def initialize(app, socket_path)
  @app = app
  @socket_path = socket_path
  @server = nil
  @clients = {}        # io => { read_buffer:, write_buffer: }
  @subscriptions = {}  # io => Set[pane_id]  (populated in step 3)
  @pending_runs  = []  # in-flight pane.run waiters (populated in step 3)
  @dispatcher = Dispatcher.new(app, self)
end

Instance Attribute Details

#app ⇒ Object (readonly)

Returns the value of attribute app.



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# File 'lib/muxr/control_server.rb', line 47

def app
  @app
end

#socket_path ⇒ Object (readonly)

Returns the value of attribute socket_path.



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# File 'lib/muxr/control_server.rb', line 47

def socket_path
  @socket_path
end

Instance Method Details

#accept_client ⇒ Object

—– internals —–



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# File 'lib/muxr/control_server.rb', line 173

def accept_client
  sock = @server.accept
  @clients[sock] = { read_buffer: +"", write_buffer: +"".b }
rescue StandardError
  # Accept may transiently fail on a closed peer; ignore.
end

#add_subscription(client_io, pane_id) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 158

def add_subscription(client_io, pane_id)
  @subscriptions[client_io] ||= Set.new
  @subscriptions[client_io].add(pane_id.to_s)
end

#complete_run(run, timed_out:, now:) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 241

def complete_run(run, timed_out:, now:)
  pane = pane_by_id(run[:pane_id])
  unless pane
    respond_error(run[:client_io], id: run[:request_id],
                  code: INVALID_PARAMS,
                  message: "pane #{run[:pane_id]} no longer exists")
    return
  end
  term = pane.terminal
  respond_result(run[:client_io], id: run[:request_id], result: {
    "pane"       => pane.id.to_s,
    "timed_out"  => timed_out,
    "had_output" => run[:had_output],
    "elapsed_ms" => ((now - run[:started_at]) * 1000).round,
    "text"       => term.dump_text,
    "cursor"     => { "row" => term.cursor_row, "col" => term.cursor_col }
  })
end

#consume_client(io) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 180

def consume_client(io)
  state = @clients[io]
  return unless state
  begin
    chunk = io.read_nonblock(READ_CHUNK)
  rescue IO::WaitReadable
    return
  rescue EOFError, Errno::ECONNRESET, Errno::EPIPE, IOError
    drop_client(io)
    return
  end
  state[:read_buffer] << chunk
  loop do
    nl = state[:read_buffer].index("\n")
    break unless nl
    line = state[:read_buffer].slice!(0..nl)
    line.chomp!
    next if line.empty?
    process_message(io, line)
  end
end

#drain_client(io) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 202

def drain_client(io)
  state = @clients[io]
  return unless state
  buf = state[:write_buffer]
  return if buf.empty?
  loop do
    n = io.write_nonblock(buf)
    if n >= buf.bytesize
      buf.clear
      break
    else
      # write_nonblock returns the count actually written; slice the rest.
      state[:write_buffer] = buf.byteslice(n..-1) || +"".b
      buf = state[:write_buffer]
    end
  end
rescue IO::WaitWritable
  # Kernel send buffer full; remainder stays queued.
rescue Errno::EPIPE, Errno::ECONNRESET, IOError
  drop_client(io)
end

#drop_client(io) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 224

def drop_client(io)
  @clients.delete(io)
  @subscriptions.delete(io)
  # Any pane.run waiters owned by this client are silently abandoned —
  # there's nobody to respond to.
  @pending_runs.reject! { |r| r[:client_io] == io } unless @pending_runs.empty?
  io.close rescue nil
end

#emit_event(io, method, params) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 298

def emit_event(io, method, params)
  write_json(io, { "method" => method, "params" => params })
end

#handle_read(io) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 85

def handle_read(io)
  if io == @server
    accept_client
  else
    consume_client(io)
  end
end

#handle_write(io) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 93

def handle_write(io)
  drain_client(io)
end

#monotonic_now ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 233

def monotonic_now
  Process.clock_gettime(Process::CLOCK_MONOTONIC)
end

#on_pane_output(pane_id, _data) ⇒ Object

Called whenever a pane’s PTY emits output. Drives pane.run idle detection and pane.subscribe streams.



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# File 'lib/muxr/control_server.rb', line 101

def on_pane_output(pane_id, _data)
  pid = pane_id.to_s
  now = monotonic_now
  unless @pending_runs.empty?
    @pending_runs.each do |run|
      next unless run[:pane_id] == pid
      run[:last_output_at] = now
      run[:had_output] = true
    end
  end
  unless @subscriptions.empty?
    pane = pane_by_id(pid)
    return unless pane
    text = pane.terminal.dump_text
    cursor = { "row" => pane.terminal.cursor_row, "col" => pane.terminal.cursor_col }
    @subscriptions.each do |io, ids|
      next unless ids.include?(pid)
      emit_event(io, "event.pane.output", { "pane" => pid, "text" => text, "cursor" => cursor })
    end
  end
end

#owns?(io) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/muxr/control_server.rb', line 81

def owns?(io)
  io == @server || @clients.key?(io)
end

#pane_by_id(id) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 237

def pane_by_id(id)
  @app.session.window.panes.find { |p| p.id.to_s == id.to_s }
end

#process_message(io, line) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 260

def process_message(io, line)
  msg = JSON.parse(line)
rescue JSON::ParserError => e
  respond_error(io, id: nil, code: PARSE_ERROR, message: "Parse error: #{e.message}")
  return
else
  id = msg["id"]
  method = msg["method"]
  params = msg["params"] || {}
  unless method.is_a?(String)
    respond_error(io, id: id, code: INVALID_REQUEST, message: "missing method")
    return
  end
  begin
    # The dispatcher may either return a Hash (synchronous result) or the
    # symbol :deferred (it will later push a response when ready — used
    # by pane.run / pane.subscribe in step 3).
    result = @dispatcher.call(method: method, params: params, client_io: io, request_id: id)
    respond_result(io, id: id, result: result) if id && result != :deferred
  rescue Dispatcher::Error => e
    respond_error(io, id: id, code: e.code, message: e.message)
  rescue StandardError => e
    respond_error(io, id: id, code: INTERNAL_ERROR, message: "#{e.class}: #{e.message}")
  end
end

#read_ios ⇒ Object

IO arrays the Application splices into its IO.select read/write sets.



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# File 'lib/muxr/control_server.rb', line 68

def read_ios
  return [] unless @server
  ios = [@server]
  ios.concat(@clients.keys)
  ios
end

#register_pending_run(client_io:, request_id:, pane_id:, idle_seconds:, timeout_seconds:) ⇒ Object

Called from the Dispatcher when a pane.run request arrives. Registers a waiter that #tick later resolves.



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# File 'lib/muxr/control_server.rb', line 143

def register_pending_run(client_io:, request_id:, pane_id:, idle_seconds:, timeout_seconds:)
  now = monotonic_now
  @pending_runs << {
    client_io: client_io,
    request_id: request_id,
    pane_id: pane_id.to_s,
    idle_seconds: idle_seconds,
    timeout_seconds: timeout_seconds,
    last_output_at: now,
    had_output: false,
    deadline_at: now + timeout_seconds,
    started_at: now
  }
end

#remove_subscription(client_io, pane_id) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 163

def remove_subscription(client_io, pane_id)
  set = @subscriptions[client_io]
  return false unless set
  removed = set.delete?(pane_id.to_s)
  @subscriptions.delete(client_io) if set.empty?
  !removed.nil?
end

#respond_error(io, id:, code:, message:, data: nil) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 292

def respond_error(io, id:, code:, message:, data: nil)
  err = { "code" => code, "message" => message }
  err["data"] = data unless data.nil?
  write_json(io, { "id" => id, "error" => err })
end

#respond_result(io, id:, result:) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 288

def respond_result(io, id:, result:)
  write_json(io, { "id" => id, "result" => result })
end

#start ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 49

def start
  File.unlink(@socket_path) if File.exist?(@socket_path)
  @server = UNIXServer.new(@socket_path)
  File.chmod(0o600, @socket_path) rescue nil
end

#stop ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 55

def stop
  @clients.each_key { |c| c.close rescue nil }
  @clients.clear
  @subscriptions.clear
  @pending_runs.clear
  if @server
    @server.close rescue nil
    @server = nil
  end
  File.unlink(@socket_path) if File.exist?(@socket_path)
end

#tick ⇒ Object

Called once per IO.select tick. Resolves any pane.run waiters whose idle window has elapsed or whose timeout has fired.



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# File 'lib/muxr/control_server.rb', line 125

def tick
  return if @pending_runs.empty?
  now = monotonic_now
  completed = []
  @pending_runs.each do |run|
    if now >= run[:deadline_at]
      complete_run(run, timed_out: true, now: now)
      completed << run
    elsif run[:had_output] && (now - run[:last_output_at]) >= run[:idle_seconds]
      complete_run(run, timed_out: false, now: now)
      completed << run
    end
  end
  @pending_runs -= completed unless completed.empty?
end

#write_ios ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 75

def write_ios
  @clients.each_with_object([]) do |(io, state), acc|
    acc << io unless state[:write_buffer].empty?
  end
end

#write_json(io, hash) ⇒ Object 



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# File 'lib/muxr/control_server.rb', line 302

def write_json(io, hash)
  return unless @clients.key?(io)
  line = JSON.generate(hash) + "\n"
  @clients[io][:write_buffer] << line.b
  drain_client(io)
end