Fix race condition when creating initial table state

1 files changed, 17 insertions, 8 deletions

diff --git a/server/src/play.rs b/server/src/play.rs
index 01f4847..256392d 100644
--- a/server/src/play.rs
+++ b/server/src/play.rs
@@ -33,7 +33,7 @@ impl DbJournal {
 #[async_trait]
 impl Journal for DbJournal {
     async fn append(&mut self, seq: i64, payload: serde_json::Value) -> Result<(), BridgeError> {
-        query!(
+        let result = query!(
             r#"
               insert into object_journal (id, seq, payload)
               values ($1, $2, $3)
@@ -43,7 +43,12 @@ impl Journal for DbJournal {
             payload,
         )
         .execute(&self.db)
-        .await?;
+            .await;
+        if let Err(sqlx::Error::Database(e)) = result {
+            if e.constraint() == Some("journal_entry") {
+                return Err(BridgeError::JournalConflict(format!("{}", self.id), seq));
+            }
+        }
         Ok(())
     }
 
@@ -81,12 +86,17 @@ impl<J: Journal> Table<J> {
 
 impl<J: Journal> Table<J> {
     pub async fn new(mut journal: J) -> Result<Self, BridgeError> {
+        let game = Self::init(&mut journal).await?;
+        Ok(Table { journal, game })
+    }
+
+    async fn init(journal: &mut J) -> Result<GameState, BridgeError> {
         let game = GameState::Bidding {
             dealer: Player::East,
             deal: bridge_engine::deal(),
         };
         journal.append(0, json!(game)).await?;
-        Ok(Table { journal, game })
+        Ok(game)
     }
 
     pub async fn replay(mut journal: J) -> Result<Self, BridgeError> {
@@ -99,12 +109,11 @@ impl<J: Journal> Table<J> {
     }
 
     pub async fn new_or_replay(mut journal: J) -> Result<Self, BridgeError> {
-        let games = journal.replay(0).await?;
-        if games.is_empty() {
-            return Self::new(journal).await;
+        let game = Self::init(&mut journal).await;
+        if let Err(BridgeError::JournalConflict(..)) = game {
+            return Self::replay(journal).await;
         }
-        let game = serde_json::from_value(games[games.len() - 1].clone())?;
-        Ok(Table { journal, game } )
+        Ok(Self { journal, game: game? } )
     }
 }