simplify and improve db iter State init interface

Signed-off-by: Jason Volk <jason@zemos.net>

src/database/pool.rs

@@ -273,29 +273,6 @@ fn handle_iter(&self, mut cmd: Seek) {
 	let _chan_sent = chan_result.is_ok();
 }
 
-#[implement(Pool)]
-#[tracing::instrument(
-	name = "seek",
-	level = "trace",
-	skip_all,
-	fields(%cmd.map),
-)]
-fn _handle_seek(&self, mut cmd: Seek) {
-	let chan = cmd.res.take().expect("missing result channel");
-
-	if chan.is_canceled() {
-		return;
-	}
-
-	match cmd.dir {
-		| Direction::Forward => cmd.state.seek_fwd(),
-		| Direction::Reverse => cmd.state.seek_rev(),
-	};
-
-	let chan_result = chan.send(into_send_seek(cmd.state));
-	let _chan_sent = chan_result.is_ok();
-}
-
 #[implement(Pool)]
 #[tracing::instrument(
 	name = "get",

src/database/stream.rs

@@ -56,20 +56,30 @@ impl<'a> State<'a> {
 	}
 
 	pub(super) fn init_fwd(mut self, from: From<'_>) -> Self {
+		debug_assert!(self.init, "init must be set to make this call");
+		debug_assert!(!self.seek, "seek must not be set to make this call");
+
 		if let Some(key) = from {
 			self.inner.seek(key);
-			self.seek = true;
+		} else {
+			self.inner.seek_to_first();
 		}
 
+		self.seek = true;
 		self
 	}
 
 	pub(super) fn init_rev(mut self, from: From<'_>) -> Self {
+		debug_assert!(self.init, "init must be set to make this call");
+		debug_assert!(!self.seek, "seek must not be set to make this call");
+
 		if let Some(key) = from {
 			self.inner.seek_for_prev(key);
-			self.seek = true;
+		} else {
+			self.inner.seek_to_last();
 		}
 
+		self.seek = true;
 		self
 	}