From c0183b8cb74135eb79249086a2278e8a950d5176 Mon Sep 17 00:00:00 2001
From: Stuart Dilts <stuart.dilts@gmail.com>
Date: Tue, 17 Mar 2026 12:06:28 -0600
Subject: [PATCH] Make bounded-queue object a struct

This allows SBCL to derive the type of the object's slots, which
removes several warnings about dynamic dispatching of `aref` calls.
+ Mark capacity slot as a fixnum, as that's what it is being treated as
  throughout the code; although the right thing appeared to be
  occuring, the usage of the `the` operator conflicted with its
  `(unsigned-byte 32)` type, which is undefined behavior.
+ Hopefully do the same thing with the value of numbers in the
  `sequences` array.
---
 src/bounded-queue.lisp | 46 +++++++++++++++++-------------------------
 1 file changed, 18 insertions(+), 28 deletions(-)

diff --git a/src/bounded-queue.lisp b/src/bounded-queue.lisp
index 0a3a9c8..7ad6ce5 100644
--- a/src/bounded-queue.lisp
+++ b/src/bounded-queue.lisp
@@ -8,38 +8,28 @@
 ;; bounded queue based on the algorithm described by Dmitry Vyukov.
 ;; It is immune to livelock, which is why we use it for bounded queue over a michael scott variant.
 
-(defclass bounded-queue ()
-  ((buffer :reader bounded-queue-buffer :initarg :buffer
-           :type (simple-array t (*)))
-   (sequences :reader bounded-queue-sequences :initarg :sequences
-              :type (simple-array t (*)))
-   (capacity :reader bounded-queue-capacity :initarg :capacity
-             :type (unsigned-byte 32))
-   (mask :reader bounded-queue-mask :type (unsigned-byte 32))
-   ;; Head/Tail counters track the total number of pops/pushes initiated.
-   (head :reader bounded-queue-head :initform (make-atomic-ref 0))
-   (tail :reader bounded-queue-tail :initform (make-atomic-ref 0))))
-
-(defmethod initialize-instance :after ((queue bounded-queue) &key)
-  (declare (type bounded-queue queue))
-  (setf (slot-value queue 'mask)
-        (the (unsigned-byte 32) (1- (bounded-queue-capacity queue))))
-  ;; Initialize the sequence array. Slot `i` is initially ready for push `i`.
-  (let ((sequences (bounded-queue-sequences queue)))
-    (declare (type (simple-array t (*)) sequences))
-    (dotimes (i (bounded-queue-capacity queue))
-      (setf (aref sequences i) (make-atomic-ref (the fixnum i))))))
+(defstruct (bounded-queue (:constructor %make-bounded-queue (capacity buffer sequences mask)))
+  (buffer (make-array 0) :type (simple-array t (*)) :read-only t)
+  (sequences (make-array 0) :type (simple-array t (*)) :read-only t)
+  (capacity 0 :type fixnum :read-only t)
+  (mask 0 :type (unsigned-byte 32) :read-only t)
+  ;; Head/Tail counters track the total number of pops/pushes initiated.
+  (head (make-atomic-ref 0) :type atomic-ref :read-only t)
+  (tail (make-atomic-ref 0) :type atomic-ref :read-only t))
 
 (defun make-bounded-queue (capacity)
   "Creates a new lock-free, bounded queue. Capacity MUST be a power of two."
   (declare (type (unsigned-byte 32) capacity))
   (unless (and (> capacity 0) (= (logcount capacity) 1))
     (error "Bounded queue capacity must be a power of two."))
-  (make-instance 'bounded-queue
-                 :capacity capacity
-                 :buffer (make-array capacity :initial-element nil)
-                 ;; Provide a valid initial-element to satisfy the compiler.
-                 :sequences (make-array capacity :initial-element nil)))
+  (let ((buffer (make-array capacity :initial-element nil))
+        (sequences (make-array capacity :initial-element nil))
+        (mask (1- capacity)))
+    ;; Initialize the sequence array. Slot `i` is initially ready for push `i`.
+    (dotimes (i capacity)
+      (declare (type fixnum i))
+      (setf (aref sequences i) (make-atomic-ref i)))
+    (%make-bounded-queue (coerce capacity 'fixnum) buffer sequences mask)))
 
 (declaim (inline bounded-queue-push))
 (defun bounded-queue-push (queue object)
@@ -120,7 +110,7 @@
         ;; Check if there is enough space for the whole batch.
         (when (> (+ (- tail head) batch-size) (bounded-queue-capacity queue))
           (return-from bounded-queue-push-batch nil))
-        
+
         ;; Try to claim the block of slots.
         (when (eq tail (cas (bounded-queue-tail queue) tail (+ tail batch-size)))
           ;; Successfully claimed the block. Now we fill it.
@@ -148,7 +138,7 @@
              (tail (the fixnum (atomic-ref-value (bounded-queue-tail queue))))
              (available (- tail head))
              (batch-size (min count available)))
-        
+
         (when (zerop batch-size)
           (return-from bounded-queue-pop-batch (values nil nil)))