Make VFS locking APIs explicit by removing default lock/unlock implementations

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 All notable changes will be documented in this file.
 
+## 0.7.0 (unreleased)
+
+- BREAKING: `Vfs::lock`, `Vfs::unlock`, and `Vfs::check_reserved_lock` no longer have default implementations and must be implemented by every `Vfs`.
+
 ## 0.6.0 - 2026-02-19
 
 Added `check_reserved_lock` to Vfs. This method allows you to inform SQLite if any threads or processes currently hold a lock on the specified file. It is recommended to implement this method if you also implement the lock and unlock methods.

examples/memvfs.rs

@@ -129,6 +129,11 @@ impl Vfs for MemVfs {
         Ok(())
     }
 
+    fn check_reserved_lock(&self, handle: &mut Self::Handle) -> VfsResult<bool> {
+        log::debug!("check_reserved_lock: file={:?}", handle.name);
+        Ok(false)
+    }
+
     fn write(&self, handle: &mut Self::Handle, offset: usize, buf: &[u8]) -> VfsResult<usize> {
         log::debug!(
             "write: file={:?}, offset={}, len={}",

src/mock.rs

@@ -14,7 +14,7 @@ use alloc::format;
 use alloc::sync::Arc;
 use parking_lot::{Mutex, MutexGuard};
 
-use crate::flags::{self, AccessFlags, OpenOpts};
+use crate::flags::{self, AccessFlags, LockLevel, OpenOpts};
 use crate::logger::{SqliteLogLevel, SqliteLogger};
 use crate::vars;
 use crate::vfs::{
@@ -257,6 +257,24 @@ impl Vfs for MockVfs {
         Ok(())
     }
 
+    fn lock(&self, meta: &mut Self::Handle, level: LockLevel) -> VfsResult<()> {
+        let state = self.state();
+        state.log(format_args!("lock: handle={meta:?} level={level:?}"));
+        Ok(())
+    }
+
+    fn unlock(&self, meta: &mut Self::Handle, level: LockLevel) -> VfsResult<()> {
+        let state = self.state();
+        state.log(format_args!("unlock: handle={meta:?} level={level:?}"));
+        Ok(())
+    }
+
+    fn check_reserved_lock(&self, meta: &mut Self::Handle) -> VfsResult<bool> {
+        let state = self.state();
+        state.log(format_args!("check_reserved_lock: handle={meta:?}"));
+        Ok(false)
+    }
+
     fn close(&self, meta: Self::Handle) -> VfsResult<()> {
         let mut state = self.state();
         state.log(format_args!("close: handle={meta:?}"));

src/vfs.rs

@@ -158,17 +158,11 @@ pub trait Vfs: Send + Sync {
     fn write(&self, handle: &mut Self::Handle, offset: usize, data: &[u8]) -> VfsResult<usize>;
     fn read(&self, handle: &mut Self::Handle, offset: usize, data: &mut [u8]) -> VfsResult<usize>;
 
-    fn lock(&self, handle: &mut Self::Handle, level: LockLevel) -> VfsResult<()> {
-        Ok(())
-    }
+    fn lock(&self, handle: &mut Self::Handle, level: LockLevel) -> VfsResult<()>;
 
-    fn unlock(&self, handle: &mut Self::Handle, level: LockLevel) -> VfsResult<()> {
-        Ok(())
-    }
+    fn unlock(&self, handle: &mut Self::Handle, level: LockLevel) -> VfsResult<()>;
 
-    fn check_reserved_lock(&self, handle: &mut Self::Handle) -> VfsResult<bool> {
-        Ok(false)
-    }
+    fn check_reserved_lock(&self, handle: &mut Self::Handle) -> VfsResult<bool>;
 
     fn sync(&self, handle: &mut Self::Handle) -> VfsResult<()> {
         Ok(())