some more fixes to allow sled to work

src/database.rs

@@ -447,6 +447,7 @@ impl Database {
         res
     }
 
+    #[cfg(feature = "sqlite")]
     pub fn flush_wal(&self) -> Result<()> {
         self._db.flush_wal()
     }

src/database/abstraction/sled.rs

@@ -23,6 +23,10 @@ impl DatabaseEngine for SledEngine {
     fn open_tree(self: &Arc<Self>, name: &'static str) -> Result<Arc<dyn Tree>> {
         Ok(Arc::new(SledEngineTree(self.0.open_tree(name)?)))
     }
+
+    fn flush(self: &Arc<Self>) -> Result<()> {
+        Ok(()) // noop
+    }
 }
 
 impl Tree for SledEngineTree {
@@ -40,7 +44,7 @@ impl Tree for SledEngineTree {
         Ok(())
     }
 
-    fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = (Vec<u8>, Vec<u8>)> + Send + Sync + 'a> {
+    fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = (Vec<u8>, Vec<u8>)> + Send + 'a> {
         Box::new(
             self.0
                 .iter()
@@ -58,7 +62,7 @@ impl Tree for SledEngineTree {
         &self,
         from: &[u8],
         backwards: bool,
-    ) -> Box<dyn Iterator<Item = (Vec<u8>, Vec<u8>)>> {
+    ) -> Box<dyn Iterator<Item = (Vec<u8>, Vec<u8>)> + Send> {
         let iter = if backwards {
             self.0.range(..from)
         } else {

src/main.rs

@@ -12,10 +12,7 @@ mod pdu;
 mod ruma_wrapper;
 mod utils;
 
-use std::{
-    sync::{Arc, Weak},
-    time::{Duration, Instant},
-};
+use std::sync::Arc;
 
 use database::Config;
 pub use database::Database;
@@ -33,10 +30,7 @@ use rocket::{
     },
     routes, Request,
 };
-use tokio::{
-    sync::RwLock,
-    time::{interval, timeout},
-};
+use tokio::sync::RwLock;
 use tracing::span;
 use tracing_subscriber::{prelude::*, Registry};
 
@@ -208,7 +202,15 @@ async fn main() {
         .await
         .expect("config is valid");
 
+    #[cfg(feature = "sqlite")]
     {
+        use tokio::time::{interval, timeout};
+
+        use std::{
+            sync::Weak,
+            time::{Duration, Instant},
+        };
+
         let weak: Weak<RwLock<Database>> = Arc::downgrade(&db);
 
         tokio::spawn(async {