From: Gerd Flaig <gefla@gefla-mac-zrh>
Date: Sat, 29 Nov 2008 21:03:47 +0000 (+0100)
Subject: Add thread safe queue. Use to push updates to client.
X-Git-Url: http://git.pond.sub.org/?p=eow;a=commitdiff_plain;h=bf4c8fd00a49cef4ce907a341722347e640ff83b

Add thread safe queue. Use to push updates to client.
---

diff --git a/eow.asd b/eow.asd
index 5e8e4d2..01d5450 100644
--- a/eow.asd
+++ b/eow.asd
@@ -21,7 +21,9 @@
     :components ((:file "package")
                  (:file "util"
                         :depends-on ("package"))
+                 (:file "locked-queue"
+                        :depends-on ("package"))
 		 (:file "web"
-			:depends-on ("package"))
+			:depends-on ("package" "locked-queue"))
                  (:file "empire"
                         :depends-on ("util"))))
diff --git a/locked-queue.lisp b/locked-queue.lisp
new file mode 100644
index 0000000..66f4354
--- /dev/null
+++ b/locked-queue.lisp
@@ -0,0 +1,35 @@
+(in-package :locked-queue)
+
+(declaim (optimize (space 0) (speed 0) (safety 3) (debug 3)))
+
+(defclass locked-queue ()
+  ((queue :initform nil)
+   (mutex :initform (sb-thread:make-mutex :name "queue lock"))
+   (waitq :initform (make-waitqueue))))
+
+(defun create ()
+  (make-instance 'locked-queue))
+
+(defmethod dequeue ((q locked-queue))
+  (with-slots (queue mutex waitq) q
+    (with-mutex (mutex)
+      (if (or (null queue)
+	      (null (first queue)))
+	  (condition-wait waitq mutex))
+      (prog1 (first (car queue))
+	(setf (car queue)
+	      (rest (car queue)))))))
+
+(defmethod enqueue ((q locked-queue) value)
+  (with-slots (queue mutex waitq) q
+    (with-mutex (mutex)
+      (let ((last (list value)))
+	(if (null (first queue))
+	    (progn
+	      (setf queue (cons last last))
+	      (condition-notify waitq))
+	    (progn
+	      (setf (rest (cdr queue))
+		    last
+		    (cdr queue) last)
+	      (cons (car queue) last)))))))
diff --git a/package.lisp b/package.lisp
index f801b62..c06705a 100644
--- a/package.lisp
+++ b/package.lisp
@@ -11,6 +11,9 @@
     (:export :read-message-loop
              :read-message
 	     :make-connection))
+  (defpackage :locked-queue
+    (:use :cl :sb-thread)
+    (:export :create :enqueue :dequeue))
   (defpackage :empire-web
     (:use :cl :hunchentoot)
     (:export :start)))
diff --git a/static/eow.js b/static/eow.js
index f856075..00b34ee 100644
--- a/static/eow.js
+++ b/static/eow.js
@@ -8,8 +8,9 @@ function eowOut(output) {
 function hello() {
   dojo.xhrGet( {
     // The following URL must match that used to test the server.
-    url: "/eow/static/ajax.txt", 
+    url: "/eow/update", 
     handleAs: "javascript",
+    //handleAs: "text",
 
     timeout: 5000, // Time in milliseconds
 
diff --git a/web.lisp b/web.lisp
index 763b6f3..40b7406 100644
--- a/web.lisp
+++ b/web.lisp
@@ -30,10 +30,17 @@
          (fullname (concatenate 'string +static-files-root+ fname)))
     (handle-static-file fullname)))
 
+(defvar *update-queue* (locked-queue:create))
+
+(defun update ()
+  "Send stream of updates to client"
+  (locked-queue:dequeue *update-queue*))
+
 (defun dispatch (request)
   (let ((script-name (script-name request)))
     (cond
       ((not (string-starts-with script-name +web-root+)) nil) ; do not handle this request
+      ((string= script-name "/eow/update") 'update)
       ((or (string-equal script-name +web-root-base+)
            (string-equal script-name +web-root+)) (redirect +root-url+)) ; go to the start page
       ((string-starts-with script-name +static-web-root+) 'serve-static)))) ; serve static file