Fuck around with the session middleware
| author |
Steve Losh <steve@stevelosh.com> |
| date |
Tue, 22 Sep 2015 18:18:29 +0000 |
| parents |
48d26670e7a1 |
| children |
9038eaf084b9 |
; (in-package :nrepl)
(ql:quickload "bencode")
(ql:quickload "usocket")
(ql:quickload "flexi-streams")
(ql:quickload "bordeaux-threads")
(ql:quickload "uuid")
(ql:quickload "fset")
(require 'sb-introspect)
;;;; Variables ----------------------------------------------------------------
(defvar *server-thread* nil)
;;;; Utilities ----------------------------------------------------------------
(defun make-hash (&rest keyvals)
(do ((h (make-hash-table :test #'equal))
(kvs keyvals (cddr kvs)))
((not kvs) h)
(setf (gethash (first kvs) h) (second kvs))))
(defmacro when-let (bindings &rest body)
(labels ((build (bindings body)
(if (not bindings)
body
`(let ((,(caar bindings) ,(cadar bindings)))
(when ,(caar bindings)
,(build (cdr bindings) body))))))
(build bindings `(progn ,@body))))
(defmacro if-let (bindings then else)
`(let (,@bindings)
(if (and ,@(mapcar #'car bindings))
,then
,else)))
(defun set-when (h &rest keyvals)
(loop for (key val) on keyvals by #'cddr
do (when val (setf (gethash key h) val))))
(defmethod print-object ((object hash-table) stream)
(format stream "#HASH{~{~{(~a : ~a)~}~^ ~}}"
(loop for key being the hash-keys of object
using (hash-value value)
collect (list key value))))
(defun read-all-from-string (s)
(labels ((read-next-from-string (s results)
(if (equal (string-trim " " s) "")
results
(multiple-value-bind (i pos) (read-from-string s)
(read-next-from-string (subseq s pos) (cons i results))))))
(nreverse (read-next-from-string s ()))))
(defmacro comment (&rest body)
(declare (ignore body))
nil)
(defun curry (fn &rest curried-args)
(lambda (&rest args)
(apply fn (append curried-args args))))
(defun random-uuid ()
(format nil "~a" (uuid:make-v4-uuid)))
(defun hash-keys (h)
(loop for key being the hash-keys of h
collect key))
;;;; Sockets ------------------------------------------------------------------
(defun get-stream (sock)
"Make a flexi stream of the kind bencode wants from the socket."
(flex:make-flexi-stream
(usocket:socket-stream sock)
:external-format :utf-8))
(defun write-object (socket lock o)
"Write an object O (bencoded) to SOCKET while holding LOCK."
(bt:with-lock-held (lock)
(bencode:encode o (get-stream socket))
(force-output (get-stream socket))))
(defun read-object (socket)
"Read an object (and bdecode it) from *socket*."
(bencode:decode (get-stream socket)))
;;;; NREPL --------------------------------------------------------------------
;;; Utils
(defun respond (message response)
(set-when response
"id" (gethash "id" message)
"session" (gethash "session" message))
(funcall (gethash "transport" message) response))
(defmacro handle-op (message op fallback &rest body)
`(if (equal ,op (gethash "op" ,message))
(progn ,@body)
(funcall ,fallback ,message)))
;;; Sessions
(defvar *sessions* (make-hash-table :test #'equal))
(defvar *session* nil)
(defun clear-sessions! ()
(setf *sessions* (make-hash-table :test #'equal)))
(defun create-session ()
(make-hash-table :test #'equal))
(defun register-session! (id session)
(setf (gethash id *sessions*) session))
(defun remove-session! (id)
(remhash id *sessions*))
(defun get-session (id)
(gethash id *sessions*))
(defun get-sessions ()
(hash-keys *sessions*))
(defun wrap-session (h)
"Handle wrapping incoming messages in sessions.
If a message contains a session key, look up that session in the list of
registered sessions and bind it into *session*.
If a message comes in without a session id, create a new session for it and
patch the session id into the message before continuing on down the
middleware stack. Also binds the session into *session*. Note that this
will NOT register the session into the main map of sessions.
"
(lambda (message)
(let* ((session-id (gethash "session" message))
(session (if session-id
(get-session session-id)
(create-session)))
(session-id (or session-id (random-uuid)))
(*session* session))
(setf (gethash "session" message) session-id)
(funcall h message))))
(defun wrap-session-ls (h)
(lambda (message)
(handle-op
message "ls-sessions" h
(respond message
(make-hash "status" "done"
"sessions" (get-sessions))))))
(defun wrap-session-close (h)
(lambda (message)
(handle-op
message "close" h
(remove-session! (gethash "session" message))
(respond message
(make-hash "status" "session-closed")))))
;;; Eval
(defclass evaluator ()
((standard-input :initarg :in :reader in)
(standard-output :initarg :out :reader out)
(standard-error :initarg :err :reader err)))
(defun handle-base (message)
(respond message (make-hash "status" "unknown-op")))
(defun shuttle-stream (from-stream stream-name message)
(do ((data "" (flex:octets-to-string
(flex:get-output-stream-sequence from-stream)
:external-format :utf-8)))
((and (not (open-stream-p from-stream))
(equal data ""))
nil)
(when (not (equal data ""))
(respond message (make-hash "status" "ok"
stream-name data)))
(sleep 0.1)))
(defun wrap-eval (h)
(lambda (message)
(handle-op
message "eval" h
(let* ((code (gethash "code" message))
(captured-out (flex:make-in-memory-output-stream))
(captured-err (flex:make-in-memory-output-stream))
(*standard-output*
(flex:make-flexi-stream captured-out :external-format :utf-8))
(*error-output*
(flex:make-flexi-stream captured-err :external-format :utf-8))
(evaluator (make-instance 'evaluator
:in nil
:out captured-out
:err captured-err)))
(declare (ignore evaluator))
(unwind-protect
(progn
(bt:make-thread
(lambda () (shuttle-stream captured-out "stdout" message))
:name "NREPL stdout writer")
(bt:make-thread
(lambda () (shuttle-stream captured-err "stderr" message))
:name "NREPL stderr writer")
(loop for form in (read-all-from-string code)
do (let ((result (prin1-to-string (eval form))))
(respond message
(make-hash "form" (prin1-to-string form)
"value" result))))
(respond message (make-hash "status" "done")))
(close captured-out)
(close captured-err))))))
(defun find-lambda-list (s)
(when (fboundp s)
(sb-introspect:function-lambda-list s)))
(defun find-symbol-harder (name)
(flet ((split-string (s delim)
(let ((idx (position delim s)))
(if idx
(cons (subseq s 0 idx)
(subseq s (1+ idx)))
(cons nil s)))))
(destructuring-bind (pack . symb) (split-string (string-upcase name) #\:)
(find-symbol symb (if pack
(find-package pack)
*package*)))))
(defun wrap-documentation (h)
(lambda (message)
(handle-op
message "documentation" h
(let* ((s (find-symbol-harder (gethash "symbol" message)))
(resp (make-hash "status" "done")))
(set-when resp
"type-docstring" (documentation s 'type)
"structure-docstring" (documentation s 'structure)
"variable-docstring" (documentation s 'variable)
"setf-docstring" (documentation s 'setf)
"function-docstring" (documentation s 'function)
"function-arglist" (when-let ((arglist (find-lambda-list s)))
(prin1-to-string arglist)))
(respond message resp)))))
;;; Plumbing
(defun middleware ()
"Return the stack of middleware.
In the future we should make this less horrifyingly inefficient, but for
NREPL development its_fine.
"
(list
#'wrap-session
#'wrap-session-ls
#'wrap-session-close
#'wrap-eval
#'wrap-documentation))
(defun build-handler (base middleware)
"Collapse the stack of middleware into a single handler function."
(if middleware
(funcall (car middleware)
(build-handler base (cdr middleware)))
base))
(defun handle (message)
"Handle the given NREPL message."
(format t "Handling message:~%~A~%~%" message)
(funcall (build-handler #'handle-base (middleware)) message))
(defun handle-message (socket lock)
"Read a single message from the socket and handle it."
(let ((message (read-object socket)))
(setf (gethash "transport" message)
(curry #'write-object socket lock))
(handle message)))
(defun handler (socket lock)
"Read a series of messages from the socket, handling each."
(loop (handle-message socket lock)))
;;;; Server -------------------------------------------------------------------
(defun accept-connections (server-socket)
"Accept connections to the server and spawn threads to handle each."
(loop
(let ((client-socket (usocket:socket-accept
server-socket
:element-type '(unsigned-byte 8)))
(write-lock (bt:make-lock "NREPL client writing lock")))
(bt:make-thread
(lambda ()
(unwind-protect (handler client-socket write-lock)
(usocket:socket-close client-socket)))
:name "NREPL Connection Handler"))))
(defun start-server (address port)
"Fire up a server thread that will listen for connections."
(format t "Starting server...~%")
(let ((socket (usocket:socket-listen address port :reuse-address t)))
(setf *server-thread*
(bt:make-thread
(lambda ()
(unwind-protect
(accept-connections socket)
(format t "Closing server socket...~%")
(usocket:socket-close socket)))
:name (format nil "NREPL Server (~a/~a)" address port)))))
(defun stop-server ()
"Kill the server thread, if it exists."
(let ((s (shiftf *server-thread* nil)))
(when s
(bt:destroy-thread s))))
;;;; Scratch ------------------------------------------------------------------
(comment
(connect)
(handle-message)
(start-server "localhost" 8675)
(stop-server))
; TODO
; * Implement middleware metadata
; * Implement middleware linearization
; * Implement sessions
; * Implement Fireplace workarounds
; * Look for what ops fireplace needs
; * Look into how fireplace handles clojure namespaces
; * Implement a minimal amount of fireplace ops (eval, reload, doc)
; * Implement a minimal amount of fireplace workarounds
; * Implement other nrepl default ops
; * Check that we're not leaking threads
; * Check that we're not leaking objects
(comment
(defparameter s (flex:make-in-memory-output-stream))
(defparameter fs (flex:make-flexi-stream s :external-format :utf-8))
(close s)
(close fs)
(format fs "")
(format s "Hello, world!~%")
(open-stream-p s)
(open-stream-p fs)
(flex:octets-to-string (flex:get-output-stream-sequence s) :external-format :utf-8))