API: compteur de consommation SQLite asynchrone (#78)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/api/tracking.py

@@ -0,0 +1,67 @@
+import queue
+import threading
+from typing import Optional
+
+from src.api import tokens_db
+from src.utils import logger
+
+_STOP_SENTINEL = object()
+_queue: Optional[queue.Queue] = None
+_worker_thread: Optional[threading.Thread] = None
+_db_path: Optional[str] = None
+
+
+def _worker_loop(q: queue.Queue, db_path: str) -> None:
+    while True:
+        item = q.get()
+        try:
+            if item is _STOP_SENTINEL:
+                return
+            kind, payload = item
+            if kind == "counter":
+                token_id = payload
+                try:
+                    tokens_db.increment_usage(db_path, token_id)
+                except Exception:  # noqa: BLE001
+                    logger.warning(
+                        "tracking: échec increment_usage token_id=%s",
+                        token_id,
+                        exc_info=True,
+                    )
+        finally:
+            q.task_done()
+
+
+def start_worker(db_path: str) -> None:
+    global _queue, _worker_thread, _db_path
+    if _worker_thread is not None and _worker_thread.is_alive():
+        return
+    _db_path = db_path
+    _queue = queue.Queue()
+    _worker_thread = threading.Thread(
+        target=_worker_loop, args=(_queue, db_path), daemon=True
+    )
+    _worker_thread.start()
+
+
+def stop_worker() -> None:
+    global _worker_thread, _queue
+    if _worker_thread is None:
+        return
+    _queue.put(_STOP_SENTINEL)
+    _worker_thread.join(timeout=2.0)
+    _worker_thread = None
+    _queue = None
+
+
+def enqueue_counter_update(token_id: int) -> None:
+    if _queue is None:
+        return  # tracking désactivé (tests par ex.)
+    _queue.put(("counter", token_id))
+
+
+def flush(timeout: float = 2.0) -> None:
+    """Attend que la queue soit drainée. Utile en test."""
+    if _queue is None:
+        return
+    _queue.join()