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feat: unify add/remove commands into queue and fix race on channel removal

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Co-authored-by: aider (deepseek/deepseek-reasoner) <aider@aider.chat>
This commit is contained in:
Loic Coenen
2026-05-09 22:03:11 +00:00
parent a8a9c6164b
commit 437ac31913
4 changed files with 68 additions and 50 deletions
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4
src/command.h
View File

@@ -4,10 +4,10 @@
typedef enum { typedef enum {
CMD_CYCLE, // toggle record/stop for a channel CMD_CYCLE, // toggle record/stop for a channel
CMD_STOP, // force to idle CMD_STOP, // force to idle
// CMD_LOOP_TOGGLE not needed, CYCLE covers it
CMD_BIND_CHANNEL, // bind a channel index (data = channel) CMD_BIND_CHANNEL, // bind a channel index (data = channel)
CMD_UNBIND, // reset bind to channel 0 CMD_UNBIND, // reset bind to channel 0
// ADD and REMOVE are still driven via atomics for now CMD_ADD_CHANNEL, // add a new dynamic channel
CMD_REMOVE_CHANNEL, // remove last dynamic channel
} cmd_type_t; } cmd_type_t;
typedef struct { typedef struct {

74
src/looper.c
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@@ -16,16 +16,17 @@
struct channel_t channels[MAX_CHANNELS]; struct channel_t channels[MAX_CHANNELS];
atomic_int channel_count = 0; atomic_int channel_count = 0;
int next_channel_id = 1; int next_channel_id = 1;
atomic_int cmd_add = 0; spsc_queue_t cmd_queue_main;
atomic_int cmd_remove = 0; atomic_int global_rt_cycles = 0;
jack_port_t *midi_control_port = NULL; jack_port_t *midi_control_port = NULL;
jack_port_t *midi_clock_port = NULL; jack_port_t *midi_clock_port = NULL;
atomic_int control_key_active = 0; atomic_int control_key_active = 0;
atomic_int bind_channel = 0; atomic_int bind_channel = 0;
spsc_queue_t cmd_queue; spsc_queue_t cmd_queue;
/* Deferred removal index (1 second grace) */ /* Deferred removal index and cycle counter */
static int pending_unregister_idx = -1; static int pending_unregister_idx = -1;
static int pending_unregister_cycle = 0;
static void apply_command(command_t cmd) { static void apply_command(command_t cmd) {
switch (cmd.type) { switch (cmd.type) {
@@ -199,6 +200,7 @@ int process_callback(jack_nframes_t nframes, void *arg) {
} }
} }
atomic_fetch_add_explicit(&global_rt_cycles, 1, memory_order_release);
return 0; return 0;
} }
@@ -216,6 +218,7 @@ void jack_shutdown_cb(void *arg) {
* ---------------------------------------------------------------- */ * ---------------------------------------------------------------- */
int looper_init(jack_client_t *client) { int looper_init(jack_client_t *client) {
queue_init(&cmd_queue); queue_init(&cmd_queue);
queue_init(&cmd_queue_main);
/* channel 0 */ /* channel 0 */
channels[0].active = 1; channels[0].active = 1;
atomic_store(&channels[0].state, STATE_IDLE); atomic_store(&channels[0].state, STATE_IDLE);
@@ -250,37 +253,46 @@ int looper_init(jack_client_t *client) {
* main‑loop command processing * main‑loop command processing
* ---------------------------------------------------------------- */ * ---------------------------------------------------------------- */
void looper_process_commands(jack_client_t *client) { void looper_process_commands(jack_client_t *client) {
/* Unregister any ports that were marked for deferred removal. /* Drain main‑loop command queue (add/remove) */
By now the real‑time thread has had at least one full cycle command_t cmd;
to see the `active = 0` store. */ while (queue_pop(&cmd_queue_main, &cmd)) {
if (pending_unregister_idx != -1) { switch (cmd.type) {
int idx = pending_unregister_idx; case CMD_ADD_CHANNEL: {
if (channels[idx].audio_in) int idx;
jack_port_unregister(client, channels[idx].audio_in); for (idx = 0; idx < MAX_CHANNELS; idx++)
if (channels[idx].audio_out) if (!channels[idx].active)
jack_port_unregister(client, channels[idx].audio_out); break;
pending_unregister_idx = -1; if (idx < MAX_CHANNELS)
} channel_add(client, idx);
break;
if (atomic_exchange(&cmd_add, 0)) { }
int idx; case CMD_REMOVE_CHANNEL: {
for (idx = 0; idx < MAX_CHANNELS; idx++) int remove_idx = -1;
if (!channels[idx].active) for (int idx = 1; idx < MAX_CHANNELS; idx++)
break; if (channels[idx].active)
if (idx < MAX_CHANNELS) { remove_idx = idx;
channel_add(client, idx); if (remove_idx != -1) {
channel_remove(client, remove_idx);
pending_unregister_idx = remove_idx;
pending_unregister_cycle = atomic_load(&global_rt_cycles);
}
break;
}
default:
break;
} }
} }
if (atomic_exchange(&cmd_remove, 0)) { /* Deferred port unregistration – wait until RT thread has seen active=0 */
int remove_idx = -1; if (pending_unregister_idx != -1) {
for (int idx = 1; idx < MAX_CHANNELS; idx++) int current_cycle = atomic_load(&global_rt_cycles);
if (channels[idx].active) if (current_cycle - pending_unregister_cycle >= 1) {
remove_idx = idx; int idx = pending_unregister_idx;
if (remove_idx != -1) { if (channels[idx].audio_in)
/* Mark inactive now; ports will be unregistered next round */ jack_port_unregister(client, channels[idx].audio_in);
channel_remove(client, remove_idx); if (channels[idx].audio_out)
pending_unregister_idx = remove_idx; jack_port_unregister(client, channels[idx].audio_out);
pending_unregister_idx = -1;
} }
} }
} }

27
src/midi.c
View File

@@ -8,10 +8,9 @@
#include <stdatomic.h> #include <stdatomic.h>
extern atomic_int control_key_active; extern atomic_int control_key_active;
extern atomic_int cmd_add;
extern atomic_int cmd_remove;
extern atomic_int bind_channel; extern atomic_int bind_channel;
extern spsc_queue_t cmd_queue; extern spsc_queue_t cmd_queue;
extern spsc_queue_t cmd_queue_main;
void midi_handle_events(void *port_buffer, jack_nframes_t nframes) { void midi_handle_events(void *port_buffer, jack_nframes_t nframes) {
(void)nframes; (void)nframes;
@@ -42,11 +41,15 @@ void midi_handle_events(void *port_buffer, jack_nframes_t nframes) {
} else { } else {
switch (note) { switch (note) {
case 60: case 60:
atomic_store(&cmd_add, 1); {
break; command_t cmd = { .type = CMD_ADD_CHANNEL, .channel = -1, .data = 0 };
queue_push(&cmd_queue_main, cmd);
} break;
case 61: case 61:
atomic_store(&cmd_remove, 1); {
break; command_t cmd = { .type = CMD_REMOVE_CHANNEL, .channel = -1, .data = 0 };
queue_push(&cmd_queue_main, cmd);
} break;
case 62: case 62:
{ {
int bch = atomic_load(&bind_channel); int bch = atomic_load(&bind_channel);
@@ -73,11 +76,15 @@ void midi_handle_events(void *port_buffer, jack_nframes_t nframes) {
queue_push(&cmd_queue, cmd); queue_push(&cmd_queue, cmd);
} break; } break;
case 60: case 60:
atomic_store(&cmd_add, 1); {
break; command_t cmd = { .type = CMD_ADD_CHANNEL, .channel = -1, .data = 0 };
queue_push(&cmd_queue_main, cmd);
} break;
case 61: case 61:
atomic_store(&cmd_remove, 1); {
break; command_t cmd = { .type = CMD_REMOVE_CHANNEL, .channel = -1, .data = 0 };
queue_push(&cmd_queue_main, cmd);
} break;
default: default:
break; break;
} }

13
src/pipe.c
View File

@@ -13,12 +13,9 @@
#define FIFO_PATH "/tmp/looper_cmd" #define FIFO_PATH "/tmp/looper_cmd"
#define LINE_MAX 256 #define LINE_MAX 256
/* forward‑declare the global queue (defined in looper.c) */ /* forward‑declare the global queues (defined in looper.c) */
extern spsc_queue_t cmd_queue; extern spsc_queue_t cmd_queue;
extern spsc_queue_t cmd_queue_main;
/* external atomic flags for add/remove (defined in looper.c) */
extern atomic_int cmd_add;
extern atomic_int cmd_remove;
static void *pipe_thread_func(void *arg) { static void *pipe_thread_func(void *arg) {
(void)arg; (void)arg;
@@ -35,9 +32,11 @@ static void *pipe_thread_func(void *arg) {
line[len-1] = '\0'; line[len-1] = '\0';
if (strcmp(line, "add") == 0) { if (strcmp(line, "add") == 0) {
atomic_store(&cmd_add, 1); command_t cmd = { .type = CMD_ADD_CHANNEL, .channel = -1, .data = 0 };
queue_push(&cmd_queue_main, cmd);
} else if (strcmp(line, "remove") == 0) { } else if (strcmp(line, "remove") == 0) {
atomic_store(&cmd_remove, 1); command_t cmd = { .type = CMD_REMOVE_CHANNEL, .channel = -1, .data = 0 };
queue_push(&cmd_queue_main, cmd);
} else if (strncmp(line, "record ", 7) == 0) { } else if (strncmp(line, "record ", 7) == 0) {
int ch = atoi(line + 7); int ch = atoi(line + 7);
command_t cmd = { .type = CMD_CYCLE, .channel = ch, .data = 0 }; command_t cmd = { .type = CMD_CYCLE, .channel = ch, .data = 0 };