spruce up comments, fix dependency

scylla-server/Cargo.toml

@@ -30,7 +30,7 @@ serde_json = "1.0.128"
 diesel_migrations = { version = "2.2.0", features = ["postgres"] }
 rangemap = "1.5.1"
 axum-macros = "0.5.0"
-diesel-async = { version = "0.5.2", features = ["postgres", "bb8", "async-connection-wrapper", "sync-connection-wrapper"] }
+diesel-async = { version = "0.5.2", features = ["postgres", "bb8", "async-connection-wrapper", "sync-connection-wrapper", "tokio"] }
 rustc-hash = "2.1.0"
 [target.'cfg(not(target_env = "msvc"))'.dependencies]
 tikv-jemallocator = "0.6"

scylla-server/src/db_handler.rs

@@ -188,11 +188,11 @@ impl DbHandler {
                     if !self.data_queue.is_empty() {
                         // set a new max if this batch is larger
                         max_batch_size = usize::max(max_batch_size, self.data_queue.len());
-                        // mem::take allows us to assign the value of data queue vec::new() while maintaining the memory for data_channel ownership
                         data_channel
                             .send(self.data_queue)
                             .await
                             .expect("Could not comm data to db thread");
+                        // give a vector a size that hopefully is big enough to fit the next batch
                         self.data_queue = Vec::with_capacity((max_batch_size as f32 * 1.05) as usize);
                     }
                 }