From af2008cbcf3207fdecb6c986cd67887b2abeb24a Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Tue, 25 Jun 2019 18:07:15 -0400
Subject: [PATCH] WIP

---
 libs/cyclone/shared-queue.sld | 48 +++++++++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 10 deletions(-)

diff --git a/libs/cyclone/shared-queue.sld b/libs/cyclone/shared-queue.sld
index 46ea89a6..b0101ef5 100644
--- a/libs/cyclone/shared-queue.sld
+++ b/libs/cyclone/shared-queue.sld
@@ -18,13 +18,26 @@
 ;- queue-capacity (max size until resize occurs)
 ;- queue-empty?
 
+(define-library (shared-queue)
+
 (import (scheme base)
         (cyclone test)
         (cyclone concurrent)
         (srfi 18)
         (scheme write))
 
-(define *default-table-size* 64)
+(export
+  queue?
+  make-queue
+  queue
+  queue-add!
+  %queue-add! ;; DEBUG
+  %queue-remove!
+)
+
+(begin
+
+(define *default-table-size* 4) ;; TODO: 64)
 
 ;TODO: how will data structure work?
 ;probably want a circular queue, add at end and remove from start
@@ -58,14 +71,17 @@
         (%queue-add! q elem))
       (reverse elems))))
 
+(define (inc index capacity)
+  (if (= index (- capacity 1))
+      0
+      (+ index 1)))
+
 ;; Inner add, assumes we already have the lock
 (define (%queue-add! q obj)
-  (vector-set! (q:store q) (q:size q) (make-shared obj))
-  (cond
-    ((= (q:size q) (vector-length (q:store)))
+  (vector-set! (q:store q) (q:end q) (make-shared obj))
+  (q:set-end! q (inc (q:end q) (vector-length (q:store q))))
+  (when (= (q:start q) (q:end q))
      (%queue-resize! q))
-    (else
-      (q:set-size! q (+ (q:size q) 1))))
 )
 
 (define (queue-add! q obj)
@@ -74,7 +90,8 @@
   (mutex-unlock! (q:lock q))
 )
 
-;(define (%queue-resize! q)
+(define (%queue-resize! q)
+  (write "TODO: resize the queue")(newline)
 ;  ;; TODO: assumes we already have the lock
 ;  ;; TODO: error if size is larger than fixnum??
 ;  (let ((old-store (q:store q))
@@ -84,12 +101,22 @@
 ;      (when (not (zero? i))
 ;        (%queue-add! q (vector-ref 
 ;        (loop (- i 1)))))
-;)
+)
 
-;- (queue ...) constructor
-;- queue-add! - add item to the queue
 ;- queue-remove! - remove item (when to block? would be nice if we can block until an item becomes available)
 ;            maybe block by default, but have an optional timeout
+
+;; TODO: queue-remove! which locks and call this function
+(define (%queue-remove! q)
+  (cond
+    ((= (q:start q) (q:end q))
+     (write "queue is already empty"))
+    (else
+      (let ((result (vector-ref (q:store q) (q:start q))))
+        (q:set-start! q (inc (q:start q) (vector-length (q:store q))))
+        result)))
+)
+
 ;- queue-get - ?? 
 ;- queue-clear!
 ;- queue->list
@@ -100,3 +127,4 @@
 ;(test-group "basic")
 ;(test #t (shared-queue? (make-queue)))
 ;(test-exit)
+))