reuse mp3 ffi handlers

mp3-decoder.rkt

@@ -2,7 +2,9 @@
 
   (require ffi/unsafe
            "libmpg123-ffi.rkt"
-           "private/utils.rkt")
+           "private/utils.rkt"
+           (prefix-in fin: finalizer)
+           )
 
   (provide mp3-open
            mp3-valid?
@@ -26,6 +28,13 @@
 ;; Functions to do the good stuff  
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+  (define mp3-handles '())
+
+  (register-finalizer mp3-handles
+                      (λ (handles)
+                        (for-each (λ (handle)
+                                    (handle 'delete)) handles)))
+  
   (define (mp3-valid? mp3-file)
     #t)
 
@@ -43,8 +52,13 @@
   (define (mp3-open mp3-file* cb-stream-info cb-audio)
     (let ((mp3-file (if (path? mp3-file*) (path->string mp3-file*) mp3-file*)))
       (if (file-exists? mp3-file)
-          (let ((handler (mpg123-ffi-decoder-handler)))
-            (handler 'new)
+          (let ((handler (if (null? mp3-handles)
+                             (let ((h (mpg123-ffi-decoder-handler)))
+                               (h 'new)
+                               h)
+                             (let ((h (car mp3-handles)))
+                               (set! mp3-handles (cdr mp3-handles))
+                               h))))
             (handler 'init mp3-file)
             (let ((h (make-mp3-handle handler
                                       cb-stream-info
@@ -81,7 +95,6 @@
       (let loop ()
         (if (eq? (mp3-handle-stop handle) #t)
             (begin
-              (newline)
               (dbg-sound "Stopping mp3 decoding")
               (set-mp3-handle-reading! handle #f)
               'stopped-reading
@@ -102,7 +115,7 @@
               )
             ))
       (ffi-handler 'close)
-      (ffi-handler 'delete)
+      (set! mp3-handles (cons ffi-handler mp3-handles))
       )
     )