;;;; -*- Mode: Lisp; Syntax: ANSI-Common-Lisp; Base: 10; Package: modlisp -*-
;;;; *************************************************************************
;;;; FILE IDENTIFICATION
;;;;
;;;; Name:          listener.lisp
;;;; Purpose:       Listener and worker processes
;;;; Programmer:    Kevin M. Rosenberg
;;;; Date Started:  Dec 2002
;;;;
;;;; $Id: listener.lisp,v 1.2 2003/07/09 22:12:52 kevin Exp $
;;;; *************************************************************************

(in-package #:kmrcl)

;;; Variables and data structures for Listener

(defvar *listener-count* 0
  "used to name listeners")

(defvar *worker-count* 0
  "used to name workers")

(defvar *active-listeners* nil
    "List of active listeners")

(defclass listener ()
  ((port :initarg :port :accessor port) 
   (function :initarg :function :accessor listener-function
	     :initform nil)
   (function-args :initarg :function-args :accessor function-args
		  :initform nil)
   (process :initarg :process :accessor process)
   (socket :initarg :socket :accessor socket)
   (workers :initform nil :accessor workers
	    :documentation "list of worker threads")
   (name :initform "" :accessor name :initarg :name)
   (base-name :initform "listener" :accessor base-name :initarg :base-name)
   (wait :initform nil :accessor wait :initarg :wait)
   (catch-errors :initform nil :accessor catch-errors :initarg :catch-errors)
   (format :initform :text :accessor listener-format :initarg :format)))

(defclass worker ()
  ((listener :initarg :listener :accessor listener :initform nil)
   (connection :initarg :connection :accessor connection :initform nil)
   (name :initarg :name :accessor name :initform nil)
   (thread-fun :initarg :thread-fun :accessor thread-fun :initform nil)
   (process :initarg :process :accessor process :initform nil)))

(defmethod print-object ((obj listener) s)
  (print-unreadable-object (obj s :type t :identity nil)
    (format s "port ~A" (port obj))))

(defmethod print-object ((obj worker) s)
  (print-unreadable-object (obj s :type t :identity nil)
    (format s "port ~A" (port (listener obj)))))
  
;; High-level API

(defun init/listener (listener state)
  (check-type listener listener)
  (case state
    (:start
     (when (member listener *active-listeners*)
       (warn "~&listener already started")
       (return-from init/listener listener))
     (handler-case
	 (progn
	   (setf (name listener) (next-server-name (base-name listener)))
	   (make-socket-server listener))
       (error (e)
	 (format t "~&Error while trying to start listener~&  ~A" e)
	 (decf *listener-count*)
	 nil)
       (:no-error (res)
	 (declare (ignore res))
	 (push listener *active-listeners*)
	 listener)))
    (:stop
     (unless (member listener *active-listeners*)
       (warn "~&listener is not in active list")
       (return-from init/listener listener))
     (dolist (worker (workers listener))
       (close-active-socket (connection worker))
       (destroy-process (process worker))
       (setf (connection worker) nil)
       (setf (process worker) nil))
     (setf (workers listener) nil)
     (with-slots (process socket) listener
       (errorset (close-passive-socket socket) t)
       (errorset (destroy-process process) t)
       (setf process nil)
       (setf socket nil))
     (setq *active-listeners* (remove listener *active-listeners*)))
    (:restart
     (init/listener listener :stop)
     (init/listener listener :start))))

(defun stop-all/listener ()
  (dolist (listener *active-listeners*)
    (ignore-errors
       (init/listener listener :stop))))

;; Low-level functions

(defun next-server-name (base-name)
  (format nil "~A-socket-server-~D" base-name (incf *listener-count*))) 

(defun next-worker-name (base-name)
  (format nil "~A-worker-~D" base-name (incf *worker-count*)))

(defun make-socket-server (listener)
  (setf (socket listener) (create-inet-listener
			   (port listener)
			   :format (listener-format listener)))
  (setf (process listener) (make-process
			    (name listener)
			    #'(lambda () (start-socket-server listener))))
  listener)


(defmethod initialize-instance :after
    ((self worker) &key listener connection name &allow-other-keys)
  (unless connection
    (error "connection not provided to modlisp-worker"))
  (setf (slot-value self 'listener) listener)
  (setf (slot-value self 'name) name)
  (setf (slot-value self 'connection) connection)
  (setf (slot-value self 'thread-fun)
	#'(lambda ()
	    (unwind-protect
		(if (catch-errors listener)
		    (handler-case
			(apply (listener-function listener)
			       connection
			       (function-args listener))
		      (error (e)
			(cmsg "Error ~A [~A]" e name)))
		  (apply (listener-function listener)
			 connection
			 (function-args listener)))
	  (progn
	    (errorset (close-active-socket connection) nil)
	    (cmsg-c :threads "~A ended" name)
	    (setf (workers listener)
		  (remove self (workers listener))))))))

(defun start-socket-server (listener)
  (unwind-protect
      (loop 
       (let ((connection (accept-tcp-connection (socket listener))))
	 (if (wait listener)
	     (unwind-protect
		  (apply (listener-function listener)
			 connection
			 (function-args listener))
	       (errorset (close connection) nil))
	     (let ((worker (make-instance 'worker :listener listener
					  :connection connection
					  :name (next-worker-name
						 (base-name listener)))))
	      (setf (process worker)
		(make-process (name worker) (thread-fun worker)))
	      (push worker (workers listener))))))
    (errorset (close-passive-socket (socket listener)) nil)))