add yielding IO back-end for turso-stress to test async re-entrancy

bindings/rust/Cargo.toml

@@ -19,6 +19,8 @@ pure-rust-crypto = ["turso_sdk_kit/pure-rust-crypto", "turso_sync_sdk_kit/pure-r
 fts = ["turso_sdk_kit/fts"]
 stacker = ["turso_core/stacker"]
 test_helper = ["turso_core/test_helper"]
+# Test-only: exposes the `memory_yield` VFS for stress/simulator harnesses.
+io_memory_yield = ["turso_core/io_memory_yield"]
 sync = [
     "dep:hyper",
     "dep:tokio",

core/Cargo.toml

@@ -28,7 +28,9 @@ experimental_win_iocp = []
 time = []
 fuzz = []
 omit_autovacuum = []
-simulator = ["fuzz", "serde"]
+simulator = ["fuzz", "serde", "io_memory_yield"]
+# Test only: exposed to testing/stress and the simulator, never to regular library users.
+io_memory_yield = []
 serde = ["dep:serde"]
 series = []
 encryption = []

core/ext/mod.rs

@@ -220,6 +220,8 @@ impl Database {
 
         let io: Arc<dyn IO> = match vfs {
             "memory" => Arc::new(MemoryIO::new()),
+            #[cfg(feature = "io_memory_yield")]
+            "memory_yield" => Arc::new(crate::MemoryYieldIO::new()),
             "syscall" => Arc::new(SyscallIO::new()?),
             #[cfg(all(target_os = "linux", feature = "io_uring", not(miri)))]
             "io_uring" => Arc::new(UringIO::new()?),