Class: Ticketing::Conn

Inherits:
Object
  • Object
show all
Defined in:
lib/ticketing/connection.rb

Overview

One persistent TCP connection to a lock server, managed on a background thread. A dropped connection is retried automatically without disturbing others. Requests are pipelined: a reply is matched back to its waiter by (op, key).

Constant Summary collapse

RECONNECT_INTERVAL = 
3.0

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(addr, logger) ⇒ Conn

Returns a new instance of Conn.



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# File 'lib/ticketing/connection.rb', line 54

def initialize(addr, logger)
  @addr = addr
  @logger = logger
  @host, @port = parse_addr(addr)
  @status = :down
  @writer = nil
  @socket = nil
  @running = true
  @thread = nil
  @writer_mutex = Mutex.new
  @pending_mutex = Mutex.new
  @acquire_waiters = {}
  @release_waiters = {}
end

Instance Attribute Details

#addr ⇒ Object (readonly)

Returns the value of attribute addr.



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# File 'lib/ticketing/connection.rb', line 52

def addr
  @addr
end

Instance Method Details

#request(op, key, frame) ⇒ Object

Enqueues a waiter under (op, key), writes the frame, then blocks until the reader thread resolves it. Raises IoError if the write fails or the connection is not up.



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# File 'lib/ticketing/connection.rb', line 77

def request(op, key, frame)
  waiter = Waiter.new
  @writer_mutex.synchronize do
    w = @writer or raise Ticketing.closed_error

    @pending_mutex.synchronize do
      (waiters(op)[key] ||= []).push(waiter)
    end

    begin
      w.write(frame)
      w.flush
    rescue IOError, SystemCallError => e
      @pending_mutex.synchronize do
        queue = waiters(op)[key]
        if queue
          queue.pop
          waiters(op).delete(key) if queue.empty?
        end
      end
      raise IoError.new(e)
    end
  end
  waiter.await
end

#start_connector ⇒ Object

Starts the background connect/read/reconnect loop.



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# File 'lib/ticketing/connection.rb', line 104

def start_connector
  @thread = Thread.new do
    ever_connected = false
    while @running
      sock = connect_socket
      next if sock.nil?

      @socket = sock
      @writer = sock
      @status = :up
      @logger.warn("reconnected: #{@addr}") if ever_connected
      ever_connected = true

      begin
        read_loop(sock)
      rescue StandardError
        nil
      end

      teardown(sock)
      @logger.warn("connection lost: #{@addr} — reconnecting every #{RECONNECT_INTERVAL}s")
      sleep RECONNECT_INTERVAL if @running
    end
  end
end

#stop ⇒ Object

Stops the background thread, closes the socket, and fails all waiters.



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# File 'lib/ticketing/connection.rb', line 131

def stop
  @running = false
  @status = :down
  thread = @thread
  begin
    @socket&.close
  rescue StandardError
    nil
  end
  thread&.kill
  clear_pending
end

#usable? ⇒ Boolean

True while at least one reply can currently be sent and received.

Returns:

  • (Boolean) 


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# File 'lib/ticketing/connection.rb', line 70

def usable?
  @status == :up
end