SQLServer: Re-use already opened SQL::Database objects

Currently, we create a new SQL::Database object for each database we are
requested to open. When multiple clients connect to the same database,
the same underlying database file is opened and cached each time. This
results in updates from one client not being propagated to others.

To prevent this, when a database is requested to be open, check if it is
already open. We can then re-use that SQL::Database object for the new
connection.

2 files changed, 13 insertions, 2 deletions

diff --git a/Userland/Services/SQLServer/DatabaseConnection.cpp b/Userland/Services/SQLServer/DatabaseConnection.cpp
index 0373962cc0..581b740fb9 100644
--- a/Userland/Services/SQLServer/DatabaseConnection.cpp
+++ b/Userland/Services/SQLServer/DatabaseConnection.cpp
@@ -13,6 +13,17 @@ namespace SQLServer {
 static HashMap<SQL::ConnectionID, NonnullRefPtr<DatabaseConnection>> s_connections;
 static SQL::ConnectionID s_next_connection_id = 0;
 
+static ErrorOr<NonnullRefPtr<SQL::Database>> find_or_create_database(StringView database_path, StringView database_name)
+{
+    for (auto const& connection : s_connections) {
+        if (connection.value->database_name() == database_name)
+            return connection.value->database();
+    }
+
+    auto database_file = DeprecatedString::formatted("{}/{}.db", database_path, database_name);
+    return SQL::Database::try_create(move(database_file));
+}
+
 RefPtr<DatabaseConnection> DatabaseConnection::connection_for(SQL::ConnectionID connection_id)
 {
     if (s_connections.contains(connection_id))
@@ -26,8 +37,7 @@ ErrorOr<NonnullRefPtr<DatabaseConnection>> DatabaseConnection::create(StringView
     if (LexicalPath path(database_name); (path.title() != database_name) || (path.dirname() != "."))
         return Error::from_string_view("Invalid database name"sv);
 
-    auto database_file = DeprecatedString::formatted("{}/{}.db", database_path, database_name);
-    auto database = SQL::Database::construct(move(database_file));
+    auto database = TRY(find_or_create_database(database_path, database_name));
 
     if (auto result = database->open(); result.is_error()) {
         warnln("Could not open database: {}", result.error().error_string());
diff --git a/Userland/Services/SQLServer/DatabaseConnection.h b/Userland/Services/SQLServer/DatabaseConnection.h
index bab3ff87f3..d43e449b2c 100644
--- a/Userland/Services/SQLServer/DatabaseConnection.h
+++ b/Userland/Services/SQLServer/DatabaseConnection.h
@@ -26,6 +26,7 @@ public:
     SQL::ConnectionID connection_id() const { return m_connection_id; }
     int client_id() const { return m_client_id; }
     NonnullRefPtr<SQL::Database> database() { return m_database; }
+    StringView database_name() const { return m_database_name; }
     void disconnect();
     SQL::ResultOr<SQL::StatementID> prepare_statement(StringView sql);