#13: Beginning work on outbound queue

src/cljc/youyesyet/outqueue.cljc

@@ -0,0 +1,115 @@
+(ns youyesyet.outqueue
+  (:require
+  #?(:clj [clojure.core]
+     :cljs [reagent.core :refer [atom]])))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;
+;;;; youyesyet.outqueue: queue of messages waiting to be sent to the server.
+;;;;
+;;;; This program is free software; you can redistribute it and/or
+;;;; modify it under the terms of the GNU General Public License
+;;;; as published by the Free Software Foundation; either version 2
+;;;; of the License, or (at your option) any later version.
+;;;;
+;;;; This program is distributed in the hope that it will be useful,
+;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;;; GNU General Public License for more details.
+;;;;
+;;;; You should have received a copy of the GNU General Public License
+;;;; along with this program; if not, write to the Free Software
+;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+;;;; USA.
+;;;;
+;;;; Copyright (C) 2016 Simon Brooke for Radical Independence Campaign
+;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;;; The items are (obviously) the actual items in the queue;
+;;; the queue is locked if an attempt is currently being made to transmit
+;;; an item.
+
+(defn new-queue
+  "Create a new queue"
+  ([]
+   (new-queue '()))
+  ([items]
+  (atom {:locked false
+         :items (if
+                  (seq? items)
+                  (reverse items)
+                  (list items))})))
+
+(defn add!
+  "Add this item to the queue."
+  [q item]
+  (swap! q
+         (fn [a]
+           (assoc a :items
+             (cons item (:items a))))))
+
+(defn q?
+  [x]
+  (try
+    (let [q (deref x)
+          locked (:locked q)]
+      (and
+       (seq? (:items q))
+       (or (true? locked) (false? locked))))
+      (catch #?(:clj Exception :cljs js/Object) any
+        #?(:clj (print (.getMessage any))
+                :cljs (js/console.log (str any))))))
+
+(defn peek
+  "Look at the next item which could be removed from the queue."
+  [q]
+  (last (:items (deref q))))
+
+(defn locked?
+  [q]
+  (:locked (deref q)))
+
+(defn unlock!
+  ([q ]
+   (unlock! q true))
+  ([q value]
+   (swap! q (fn [a] (assoc a :locked (not (true? value)))))))
+
+(defn lock!
+  [q]
+  (unlock! q false))
+
+
+(defn count
+  "Return the count of items currently in the queue."
+  [q]
+  (count (deref q)))
+
+(defn take!
+  "Return the first item from the queue, rebind the queue to the remaining
+  items. If the queue is empty return nil."
+  [q]
+  (swap! q (fn [a]
+             (let [items (reverse (:items a))
+                   item (first items)
+                   new-queue (reverse (rest items))]
+               (assoc (assoc a :items new-queue) :v item))))
+  (:v (deref q)))
+
+(defn maybe-process-next
+  "Apply this process, assumed to be a function of one argument, to the next
+  item in the queue, if the queue is not currently locked; return the value
+  returned by process."
+  [q process]
+  (if (and (q? q)(not (locked? q)))
+    (try
+      (lock! q)
+      (let [v (apply process (list (peek q)))]
+        (take! q)
+        v)
+      (catch #?(:clj Exception :cljs js/Object) any
+        #?(:clj (print (.getMessage any))
+                :cljs (js/console.log (str any))))
+      (finally (unlock! q)))
+    ))

src/cljs/youyesyet/db.cljs

@@ -58,6 +58,8 @@
     :motd "This is a test version only. There is no real data."
     ;;; the options from among which electors can select.
     :options [{:id :yes :description "Yes"} {:id :no :description "No"}]
+    ;;; the number of requests created by the user in the current session
+    :requests 0
     ;;; the currently displayed 'page' within the app.
     :page :home
     })

src/cljs/youyesyet/subscriptions.cljs

@@ -39,6 +39,11 @@
   (fn [db _]
     (:addresses db)))
 
+(reg-sub
+ :changes
+ (fn [db _]
+   (:changes db)))
+
 (reg-sub
   :elector
   (fn [db _]

src/cljs/youyesyet/views/about.cljs

@@ -5,7 +5,7 @@
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;
-;;;; youyesyet.views.electors: about/credits view for youyesyet.
+;;;; youyesyet.views.about: about/credits view for youyesyet.
 ;;;;
 ;;;; This program is free software; you can redistribute it and/or
 ;;;; modify it under the terms of the GNU General Public License

src/cljs/youyesyet/views/electors.cljs

@@ -1,5 +1,6 @@
 (ns youyesyet.views.electors
-  (:require [re-frame.core :refer [reg-sub subscribe]]
+  (:require [reagent.core :refer [atom]]
+            [re-frame.core :refer [reg-sub subscribe]]
             [youyesyet.ui-utils :as ui]))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -47,12 +48,14 @@
         image (if gender (name gender) "unknown")]
     [:td {:key (:id elector)} [:img {:src (str "img/gender/" image ".png") :alt image}]]))
 
+
 (defn genders-row
   [electors]
   [:tr
    (map
      #(gender-cell %) electors)])
 
+
 (defn name-cell
   [elector]
   [:td {:key (str "name-" (:id elector))} (:name elector)])
@@ -63,6 +66,7 @@
    (map
      #(name-cell %) electors)])
 
+
 (defn options-row
   [electors option]
   (let [optid (:id option)
@@ -77,6 +81,7 @@
             [:img {:src image :alt optname}]]])
        electors)]))
 
+
 (defn issue-cell
   "Create an issue cell for a particular elector"
   [elector]
@@ -98,7 +103,8 @@
   (let [address @(subscribe [:address])
         addresses @(subscribe [:addresses])
         electors (:electors address)
-        options @(subscribe [:options])]
+        options @(subscribe [:options])
+        changes @(subscribe [:changes])]
     (if address
       [:div
        [:h1 (:address address)]