state_store: add initial_use to let client know its safe to load state

src/async_client.rs

@@ -610,7 +610,9 @@ impl AsyncClient {
     #[instrument]
     pub async fn sync(&self, mut sync_settings: SyncSettings) -> Result<sync_events::Response> {
         {
-            if self.base_client.read().await.is_state_store_synced() {
+            // if the client hasn't been synced from the state store don't sync again
+            if !self.base_client.read().await.is_state_store_synced() {
+                // this will bail out returning false if the store has not been set up
                 if let Ok(synced) = self.sync_with_state_store().await {
                     if synced {
                         // once synced, update the sync token to the last known state from `StateStore`.

src/base_client.rs

@@ -148,6 +148,11 @@ impl Client {
     /// Returns `true` when a sync has successfully completed.
     pub(crate) async fn sync_with_state_store(&mut self) -> Result<bool> {
         if let Some(store) = self.state_store.as_ref() {
+            // return false and continues with a sync request then saves the state and creates
+            // and populates the files during the sync
+            if !store.initial_use().await? {
+                return Ok(false);
+            }
             let ClientState {
                 session,
                 sync_token,

src/state/mod.rs

@@ -60,6 +60,10 @@ impl ClientState {
 /// Abstraction around the data store to avoid unnecessary request on client initialization.
 #[async_trait::async_trait]
 pub trait StateStore: Send + Sync {
+    /// Signals to the `AsyncClient` if this is the first time a StateStore` has been used.
+    ///
+    /// Returns true if `StateStore` has been set up and ready to be loaded from.
+    async fn initial_use(&self) -> Result<bool>;
     /// Loads the state of `BaseClient` through `StateStore::Store` type.
     async fn load_client_state(&self) -> Result<ClientState>;
     /// Load the state of a single `Room` by `RoomId`.

src/state/state_store.rs

@@ -29,6 +29,12 @@ impl JsonStore {
 
 #[async_trait::async_trait]
 impl StateStore for JsonStore {
+    async fn initial_use(&self) -> Result<bool> {
+        let mut path = self.path.clone();
+        path.push("client.json");
+        Ok(fs::read_to_string(path).map_or(false, |s| !s.is_empty()))
+    }
+
     async fn load_client_state(&self) -> Result<ClientState> {
         let mut path = self.path.clone();
         path.push("client.json");
@@ -242,10 +248,8 @@ mod test {
             AsyncClient::new_with_config(homeserver.clone(), Some(session.clone()), config)
                 .unwrap();
         let sync_settings = SyncSettings::new().timeout(std::time::Duration::from_millis(3000));
-        // fake a sync to skip the load with the state store, this will fail as the files won't exist
+
-        // but the `AsyncClient::sync` will skip `StateStore::load_*`
+        // gather state to save to the db, the first time through loading will be skipped
-        assert!(client.sync_with_state_store().await.is_err());
-        // gather state to save to the db
         let _ = client.sync(sync_settings.clone()).await.unwrap();
 
         // now syncing the client will update from the state store