From 1dfc58a8da35fc1c3700259571cc6f96d435cc86 Mon Sep 17 00:00:00 2001
From: Przemyslaw Hugh Kaznowski <hugh@surrealdb.com>
Date: Sat, 19 Aug 2023 13:31:51 +0100
Subject: [PATCH] Fix live queries to check predicates against previous
 document instead of current (#2452)

---
 lib/src/doc/lives.rs | 12 +++++++++--
 lib/src/kvs/tx.rs    |  1 +
 lib/tests/delete.rs  | 50 +++++++++++++++++++++++++++++++-------------
 3 files changed, 46 insertions(+), 17 deletions(-)

diff --git a/lib/src/doc/lives.rs b/lib/src/doc/lives.rs
index 7b0677ba..6cc454a7 100644
--- a/lib/src/doc/lives.rs
+++ b/lib/src/doc/lives.rs
@@ -30,8 +30,16 @@ impl<'a> Document<'a> {
 				// Create a new statement
 				let lq = Statement::from(lv);
 				// Check LIVE SELECT where condition
-				if self.check(ctx, opt, txn, &lq).await.is_err() {
-					continue;
+				if let Some(cond) = lq.conds() {
+					// Check if this is a delete statement
+					let doc = match stm.is_delete() {
+						true => &self.initial,
+						false => &self.current,
+					};
+					// Check if the expression is truthy
+					if !cond.compute(ctx, opt, txn, Some(doc)).await?.is_truthy() {
+						continue;
+					}
 				}
 				// Check what type of data change this is
 				if stm.is_delete() {
diff --git a/lib/src/kvs/tx.rs b/lib/src/kvs/tx.rs
index c9b07433..476cc013 100644
--- a/lib/src/kvs/tx.rs
+++ b/lib/src/kvs/tx.rs
@@ -2636,6 +2636,7 @@ impl Transaction {
 
 	#[allow(unused_variables)]
 	fn check_level(&mut self, check: Check) {
+		#![allow(unused_variables)]
 		match self {
 			#[cfg(feature = "kv-mem")]
 			Transaction {
diff --git a/lib/tests/delete.rs b/lib/tests/delete.rs
index 2ee885c9..5a9270a9 100644
--- a/lib/tests/delete.rs
+++ b/lib/tests/delete.rs
@@ -1,4 +1,6 @@
 mod parse;
+
+use channel::{Receiver, TryRecvError};
 use parse::Parse;
 use surrealdb::dbs::{Action, Notification, Session};
 use surrealdb::err::Error;
@@ -373,43 +375,46 @@ async fn check_permissions_auth_disabled() {
 
 #[tokio::test]
 async fn delete_filtered_live_notification() -> Result<(), Error> {
-	let sql = "
-		CREATE person:test SET value = 50;
-		LIVE SELECT * FROM person WHERE value<100;
-		DELETE person:test;
-	";
 	let dbs = Datastore::new("memory").await?.with_notifications();
 	let ses = Session::owner().with_ns("test").with_db("test").with_rt(true);
-	let res = &mut dbs.execute(sql, &ses, None).await?;
-	assert_eq!(res.len(), 3);
-	//
+	let res = &mut dbs.execute("CREATE person:test_true SET condition = true", &ses, None).await?;
+	assert_eq!(res.len(), 1);
+	// validate create response
 	let tmp = res.remove(0).result?;
 	let expected_record = Value::parse(
 		"[
 			{
-				id: person:test,
-				value: 50
+				id: person:test_true,
+				condition: true,
 			}
 		]",
 	);
 	assert_eq!(tmp, expected_record);
-	//
+
+	// Validate live query response
+	let res =
+		&mut dbs.execute("LIVE SELECT * FROM person WHERE condition = true", &ses, None).await?;
+	assert_eq!(res.len(), 1);
 	let live_id = res.remove(0).result?;
 	let live_id = match live_id {
 		Value::Uuid(id) => id,
 		_ => panic!("expected uuid"),
 	};
-	//
+
+	// Validate delete response
+	let res = &mut dbs.execute("DELETE person:test_true", &ses, None).await?;
+	assert_eq!(res.len(), 1);
 	let tmp = res.remove(0).result?;
 	let val = Value::parse("[]");
 	assert_eq!(tmp, val);
-	//
+
+	// Validate notification
 	let notifications = dbs.notifications();
 	let notifications = match notifications {
 		Some(notifications) => notifications,
 		None => panic!("expected notifications"),
 	};
-	let not = notifications.recv_blocking().unwrap();
+	let not = recv_notification(&notifications, 10, std::time::Duration::from_millis(100)).unwrap();
 	assert_eq!(
 		not,
 		Notification {
@@ -417,9 +422,24 @@ async fn delete_filtered_live_notification() -> Result<(), Error> {
 			action: Action::Delete,
 			result: Value::Thing(Thing {
 				tb: "person".to_string(),
-				id: Id::String("test".to_string()),
+				id: Id::String("test_true".to_string()),
 			}),
 		}
 	);
 	Ok(())
 }
+
+fn recv_notification(
+	notifications: &Receiver<Notification>,
+	tries: u8,
+	poll_rate: std::time::Duration,
+) -> Result<Notification, TryRecvError> {
+	for _ in 0..tries {
+		match notifications.try_recv() {
+			Ok(not) => return Ok(not),
+			Err(_) => {}
+		}
+		std::thread::sleep(poll_rate);
+	}
+	notifications.try_recv()
+}