backend/app/core/database.py

@@ -1,10 +1,8 @@
-"""SQLite database layer with async CRUD operations.
+"""SQLite database layer with WAL mode and async CRUD operations.
 
 Uses aiosqlite for async access.  ``init_db`` sets critical PRAGMAs
-(busy_timeout, journal_mode, synchronous) *before* creating any tables so
-that concurrent download workers never hit ``SQLITE_BUSY``.  WAL mode is
-preferred on local filesystems; DELETE mode is used automatically when a
-network filesystem (CIFS, NFS) is detected.
+(busy_timeout, WAL, synchronous) *before* creating any tables so that
+concurrent download workers never hit ``SQLITE_BUSY``.
 """
 
 from __future__ import annotations
@@ -92,30 +90,43 @@ async def init_db(db_path: str) -> aiosqlite.Connection:
 
     PRAGMA order matters:
       1. ``busy_timeout`` — prevents immediate ``SQLITE_BUSY`` on lock contention
-      2. ``journal_mode`` — WAL for local filesystems, DELETE for network mounts
-         (CIFS/NFS lack the shared-memory primitives WAL requires)
-      3. ``synchronous=NORMAL`` — safe durability level
+      2. ``journal_mode=WAL`` — enables concurrent readers + single writer
+         (falls back to DELETE on filesystems that lack shared-memory support,
+         e.g. CIFS/SMB mounts)
+      3. ``synchronous=NORMAL`` — safe durability level for WAL mode
 
     Returns the ready-to-use connection.
     """
-    # Detect network filesystem *before* opening the DB so we never attempt
-    # WAL on CIFS/NFS (which creates broken SHM files that persist).
-    use_wal = not _is_network_filesystem(db_path)
-
     db = await aiosqlite.connect(db_path)
     db.row_factory = aiosqlite.Row
 
     # --- PRAGMAs (before any DDL) ---
     await db.execute("PRAGMA busy_timeout = 5000")
 
-    if use_wal:
-        journal_mode = await _try_journal_mode(db, "wal")
-    else:
-        logger.info(
-            "Network filesystem detected for %s — using DELETE journal mode",
-            db_path,
+    # Attempt WAL mode; if the underlying filesystem doesn't support the
+    # shared-memory primitives WAL requires (CIFS, NFS, some FUSE mounts),
+    # the PRAGMA silently stays on the previous mode or returns an error.
+    # In that case, fall back to DELETE mode which works everywhere.
+    try:
+        result = await db.execute("PRAGMA journal_mode = WAL")
+        row = await result.fetchone()
+        journal_mode = row[0] if row else "unknown"
+    except Exception:
+        journal_mode = "error"
+
+    if journal_mode != "wal":
+        logger.warning(
+            "WAL mode unavailable (got %s) — falling back to DELETE mode "
+            "(network/CIFS filesystem?)",
+            journal_mode,
         )
-        journal_mode = await _try_journal_mode(db, "delete")
+        try:
+            result = await db.execute("PRAGMA journal_mode = DELETE")
+            row = await result.fetchone()
+            journal_mode = row[0] if row else "unknown"
+        except Exception:
+            logger.warning("Failed to set DELETE journal mode, continuing with default")
+            journal_mode = "default"
 
     logger.info("journal_mode set to %s", journal_mode)
 
@@ -129,54 +140,6 @@ async def init_db(db_path: str) -> aiosqlite.Connection:
     return db
 
 
-def _is_network_filesystem(db_path: str) -> bool:
-    """Return True if *db_path* resides on a network filesystem (CIFS, NFS, etc.).
-
-    Parses ``/proc/mounts`` (Linux) to find the filesystem type of the
-    longest-prefix mount matching the database directory.  Returns False
-    on non-Linux hosts or if detection fails.
-    """
-    import os
-
-    network_fs_types = {"cifs", "nfs", "nfs4", "smb", "smbfs", "9p", "fuse.sshfs"}
-    try:
-        db_dir = os.path.dirname(os.path.abspath(db_path))
-        with open("/proc/mounts", "r") as f:
-            mounts = f.readlines()
-        best_match = ""
-        best_fstype = ""
-        for line in mounts:
-            parts = line.split()
-            if len(parts) < 3:
-                continue
-            mountpoint, fstype = parts[1], parts[2]
-            if db_dir.startswith(mountpoint) and len(mountpoint) > len(best_match):
-                best_match = mountpoint
-                best_fstype = fstype
-        is_net = best_fstype in network_fs_types
-        if is_net:
-            logger.info(
-                "Detected %s filesystem at %s for database %s",
-                best_fstype, best_match, db_path,
-            )
-        return is_net
-    except Exception:
-        return False
-
-
-async def _try_journal_mode(
-    db: aiosqlite.Connection, mode: str,
-) -> str:
-    """Try setting *mode* and return the actual journal mode string."""
-    try:
-        result = await db.execute(f"PRAGMA journal_mode = {mode}")
-        row = await result.fetchone()
-        return (row[0] if row else "unknown").lower()
-    except Exception as exc:
-        logger.warning("PRAGMA journal_mode=%s failed: %s", mode, exc)
-        return "error"
-
-
 # ---------------------------------------------------------------------------
 # CRUD helpers
 # ---------------------------------------------------------------------------