feat: add logging system, orchestrator, and documentation

engine/makefile

@@ -2,7 +2,7 @@ CC ?= gcc
 CFLAGS ?= -Wall -Wextra -g -Isrc 
 LDFLAGS ?= -ljack -lm -lsndfile -lpthread
 
-SRC = src/main.c src/looper.c src/channel.c src/midi.c src/queue.c src/pipe.c src/ringbuffer.c src/wav.c
+SRC = src/main.c src/looper.c src/channel.c src/midi.c src/queue.c src/pipe.c src/ringbuffer.c src/wav.c src/log.c
 OBJ = $(SRC:.c=.o)
 
 looper: $(OBJ)

engine/src/log.c

@@ -0,0 +1,32 @@
+#include "log.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+static FILE *logfile = NULL;
+static pthread_mutex_t log_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+void log_init(void) {
+    logfile = fopen("/tmp/looper.log", "a");
+    if (!logfile)
+        logfile = stderr;
+    setbuf(logfile, NULL);
+}
+
+void log_msg(const char *fmt, ...) {
+    if (!logfile) return;
+    pthread_mutex_lock(&log_mutex);
+    va_list args;
+    va_start(args, fmt);
+    vfprintf(logfile, fmt, args);
+    va_end(args);
+    fputc('\n', logfile);
+    pthread_mutex_unlock(&log_mutex);
+}
+
+void log_close(void) {
+    if (logfile && logfile != stderr)
+        fclose(logfile);
+    logfile = NULL;
+}

engine/src/log.h

@@ -0,0 +1,8 @@
+#ifndef LOG_H
+#define LOG_H
+
+void log_init(void);
+void log_msg(const char *fmt, ...);
+void log_close(void);
+
+#endif

engine/src/looper.c

@@ -85,7 +85,7 @@ static int global_sample_rate = 0;
 /* execute a single command (called from looper_process_commands) */
 static void exec_command(command_t cmd, jack_client_t *client) {
   int ch = cmd.channel;
-  if (ch < 0)
+  if (ch < 0 || ch >= MAX_CHANNELS)
     ch = 0;
 
   switch (cmd.type) {
@@ -570,8 +570,10 @@ void looper_process_commands(jack_client_t *client) {
         wav_write("save.wav", data, (unsigned)lc, sr);
         free(data);
       }
-      /* Reactivate channel */
+      /* Reactivate channel – use a shorter sleep to reduce xrun risk */
       if (was_active) {
+        struct timespec req = {.tv_sec = 0, .tv_nsec = 200000000}; /* 200 ms */
+        nanosleep(&req, NULL);
         atomic_store(&channels[0].active, 1);
       }
     }

engine/src/main.c

@@ -1,5 +1,6 @@
 // cppcheck-suppress missingIncludeSystem
 #include "looper.h"
+#include "log.h"
 #include <jack/jack.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -9,15 +10,20 @@
 int main(int argc, char *argv[]) {
   (void)argc;
   (void)argv;
+
+  log_init();
+  log_msg("looper engine starting");
+
   const char *client_name = "looper";
   jack_options_t options = JackNullOption;
   jack_status_t status;
 
   jack_client_t *client = jack_client_open(client_name, options, &status);
   if (client == NULL) {
-    fprintf(stderr, "jack_client_open() failed, status = 0x%2.0x\n", status);
+    log_msg("jack_client_open() failed, status = 0x%2.0x", status);
     if (status & JackServerFailed)
-      fprintf(stderr, "Unable to connect to JACK server\n");
+      log_msg("Unable to connect to JACK server");
+    log_close();
     return 1;
   }
 
@@ -28,27 +34,30 @@ int main(int argc, char *argv[]) {
   jack_on_shutdown(client, jack_shutdown_cb, NULL);
 
   if (looper_init(client) != 0) {
-    fprintf(stderr, "looper initialisation failed\n");
+    log_msg("looper initialisation failed");
     jack_client_close(client);
+    log_close();
     return 1;
   }
 
   if (jack_activate(client)) {
-    fprintf(stderr, "Cannot activate client\n");
+    log_msg("Cannot activate client");
     jack_client_close(client);
+    log_close();
     return 1;
   }
 
-  fprintf(stderr, "looper running (client name '%s')\n", client_name);
+  log_msg("looper running (client name '%s')", client_name);
 
   while (1) {
     looper_process_commands(client);
     {
       struct timespec ts = {.tv_sec = 0, .tv_nsec = 50000000};
       nanosleep(&ts, NULL);
-    } /* check commands every 50 ms */
+    }
   }
 
   jack_client_close(client);
+  log_close();
   return 0;
 }