From 9d43b15b4604a59cee321462e4532c0482a7c70e Mon Sep 17 00:00:00 2001
From: Loic Coenen <loic@visua.com>
Date: Thu, 7 May 2026 20:51:06 +0000
Subject: [PATCH] fix: use atomic operations for thread-safe state access

Co-authored-by: aider (deepseek/deepseek-reasoner) <aider@aider.chat>
---
 src/main.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/main.c b/src/main.c
index 933defa..bf2898d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -5,6 +5,7 @@
 #include <signal.h>
 #include <jack/jack.h>
 #include <jack/midiport.h>
+#include <stdatomic.h>
 
 typedef enum {
     STATE_IDLE,
@@ -13,7 +14,7 @@ typedef enum {
     STATE_PAUSED
 } looper_state;
 
-static volatile looper_state current_state = STATE_IDLE;
+static atomic_int current_state = STATE_IDLE;
 
 static jack_port_t *input_port;
 static jack_port_t *output_port;
@@ -46,18 +47,19 @@ static int process(jack_nframes_t nframes, void *arg)
                 if ((ev.size >= 3) && ((ev.buffer[0] & 0xf0) == 0x90)) {
                     unsigned char note = ev.buffer[1];
                     if (note == 1) {
-                        switch (current_state) {
+                        int cur_state = atomic_load(&current_state);
+                        switch (cur_state) {
                             case STATE_IDLE:
-                                current_state = STATE_RECORD;
+                                atomic_store(&current_state, STATE_RECORD);
                                 break;
                             case STATE_RECORD:
-                                current_state = STATE_LOOPING;
+                                atomic_store(&current_state, STATE_LOOPING);
                                 break;
                             case STATE_LOOPING:
-                                current_state = STATE_PAUSED;
+                                atomic_store(&current_state, STATE_PAUSED);
                                 break;
                             case STATE_PAUSED:
-                                current_state = STATE_LOOPING;
+                                atomic_store(&current_state, STATE_LOOPING);
                                 break;
                         }
                     }
@@ -77,14 +79,16 @@ static int process(jack_nframes_t nframes, void *arg)
                     unsigned char msg = cev.buffer[0];
                     // real-time messages: Start (0xFA), Stop (0xFC), Continue (0xFB)
                     if (msg == 0xFA) { // Start transport -> begin recording if idle
-                        if (current_state == STATE_IDLE) {
-                            current_state = STATE_RECORD;
+                        int s = atomic_load(&current_state);
+                        if (s == STATE_IDLE) {
+                            atomic_store(&current_state, STATE_RECORD);
                         }
                     } else if (msg == 0xFC) { // Stop transport -> return to IDLE
-                        current_state = STATE_IDLE;
+                        atomic_store(&current_state, STATE_IDLE);
                     } else if (msg == 0xFB) { // Continue transport -> resume looping (if paused)
-                        if (current_state == STATE_PAUSED) {
-                            current_state = STATE_LOOPING;
+                        int s = atomic_load(&current_state);
+                        if (s == STATE_PAUSED) {
+                            atomic_store(&current_state, STATE_LOOPING);
                         }
                     }
                 }
@@ -104,7 +108,8 @@ static void jack_shutdown(void *arg)
 
 static void sigusr1_handler(int signo) {
     (void)signo;
-    int code = (int)current_state + 1;
+    int state = atomic_load(&current_state);
+    int code = state + 1;
     _exit(code);
 }