improve sync engine

sync/javascript/src/generator.rs

@@ -1,5 +1,9 @@
+use napi::Env;
 use napi_derive::napi;
-use std::{future::Future, sync::Mutex};
+use std::{
+    future::Future,
+    sync::{Arc, Mutex},
+};
 
 use turso_sync_engine::types::ProtocolCommand;
 
@@ -7,18 +11,18 @@ pub const GENERATOR_RESUME_IO: u32 = 0;
 pub const GENERATOR_RESUME_DONE: u32 = 1;
 
 pub trait Generator {
-    fn resume(&mut self, result: Option<String>) -> napi::Result<u32>;
+    fn resume(&mut self, env: Env, result: Option<String>) -> napi::Result<u32>;
 }
 
 impl<F: Future<Output = turso_sync_engine::Result<()>>> Generator
-    for genawaiter::sync::Gen<ProtocolCommand, turso_sync_engine::Result<()>, F>
+    for genawaiter::sync::Gen<ProtocolCommand, turso_sync_engine::Result<Env>, F>
 {
-    fn resume(&mut self, error: Option<String>) -> napi::Result<u32> {
+    fn resume(&mut self, env: Env, error: Option<String>) -> napi::Result<u32> {
         let result = match error {
             Some(err) => Err(turso_sync_engine::errors::Error::DatabaseSyncEngineError(
                 format!("JsProtocolIo error: {err}"),
             )),
-            None => Ok(()),
+            None => Ok(env),
         };
         match self.resume_with(result) {
             genawaiter::GeneratorState::Yielded(ProtocolCommand::IO) => Ok(GENERATOR_RESUME_IO),
@@ -31,15 +35,25 @@ impl<F: Future<Output = turso_sync_engine::Result<()>>> Generator
     }
 }
 
+#[napi(discriminant = "type")]
+pub enum GeneratorResponse {
+    SyncEngineStats { operations: i64, wal: i64 },
+}
+
 #[napi]
 pub struct GeneratorHolder {
     pub(crate) inner: Box<Mutex<dyn Generator>>,
+    pub(crate) response: Arc<Mutex<Option<GeneratorResponse>>>,
 }
 
 #[napi]
 impl GeneratorHolder {
     #[napi]
-    pub fn resume(&self, error: Option<String>) -> napi::Result<u32> {
-        self.inner.lock().unwrap().resume(error)
+    pub fn resume(&self, env: Env, error: Option<String>) -> napi::Result<u32> {
+        self.inner.lock().unwrap().resume(env, error)
+    }
+    #[napi]
+    pub fn take(&self) -> Option<GeneratorResponse> {
+        self.response.lock().unwrap().take()
     }
 }