Avoid potential race conditions by changing get_or_insert to promote …

…for pool LRU

src/client.rs

@@ -1350,7 +1350,7 @@ where
  // TODO: Consider adding the close logic that this function can send for eviction to the client buffer instead
  // In this case we don't want to send the parse message to the server since the client is sending it
  self.register_parse_to_server_cache(
- false, hash, &parse, &pool, server, &address,
+ false, &hash, &parse, &pool, server, &address,
  )
  .await?;
 
@@ -1661,7 +1661,7 @@ where
  debug!("Prepared statement `{}` found in cache", parse.name);
  // In this case we want to send the parse message to the server
  // since pgcat is initiating the prepared statement on this specific server
- self.register_parse_to_server_cache(true, *hash, parse, pool, server, address)
+ self.register_parse_to_server_cache(true, hash, parse, pool, server, address)
  .await?;
  }
 
@@ -1682,15 +1682,14 @@ where
  async fn register_parse_to_server_cache(
  &self,
  should_send_parse_to_server: bool,
- hash: u64,
+ hash: &u64,
  parse: &Arc<Parse>,
  pool: &ConnectionPool,
  server: &mut Server,
  address: &Address,
  ) -> Result<(), Error> {
- // We want to update this in the LRU to know this was recently used and add it if it isn't there already
- // This could be the case if it was evicted or if doesn't exist (ie. we reloaded and it got removed)
- pool.register_parse_to_cache(hash, parse);
+ // We want to promote this in the pool's LRU
+ pool.promote_prepared_statement_hash(hash);
 
  if let Err(err) = server
  .register_prepared_statement(parse, should_send_parse_to_server)

src/pool.rs

@@ -101,6 +101,11 @@ impl PreparedStatementCache {
  }
  }
  }
+
+ /// Marks the hash as most recently used if it exists
+ pub fn promote(&mut self, hash: &u64) {
+ self.cache.promote(hash);
+ }
 }
 
 /// An identifier for a PgCat pool,
@@ -1071,6 +1076,15 @@ impl ConnectionPool {
  None => None,
  }
  }
+
+ /// Promote a prepared statement hash in the LRU
+ pub fn promote_prepared_statement_hash(&self, hash: &u64) {
+ // We should only be calling this function if the cache is enabled
+ if let Some(ref prepared_statement_cache) = self.prepared_statement_cache {
+ let mut cache = prepared_statement_cache.lock();
+ cache.promote(hash);
+ }
+ }
 }
 
 /// Wrapper for the bb8 connection pool.