Terminate watcher if database changes (#20)

* Terminate watcher if database changes

* Format

* Update watcher.cpp

* Revert "Format"

This reverts commit 72d82f4bce.

src/include/watcher.hpp

@@ -26,6 +26,7 @@ private:
   std::condition_variable cv;
   std::atomic<bool> should_run;
   HttpServer &server;
+  DatabaseInstance *watched_database;
 };
 } // namespace ui
 } // namespace duckdb

src/watcher.cpp

@@ -9,7 +9,8 @@
 namespace duckdb {
 namespace ui {
 
-Watcher::Watcher(HttpServer &_server) : should_run(false), server(_server) {}
+Watcher::Watcher(HttpServer &_server)
+    : should_run(false), server(_server), watched_database(nullptr) {}
 
 bool WasCatalogUpdated(DatabaseInstance &db, Connection &connection,
                        CatalogState &last_state) {
@@ -62,6 +63,12 @@ void Watcher::Watch() {
       break; // DB went away, nothing to watch
     }
 
+    if (watched_database == nullptr) {
+      watched_database = db.get();
+    } else if (watched_database != db.get()) {
+      break; // DB changed, stop watching, will be restarted
+    }
+
     duckdb::Connection con{*db};
     auto polling_interval = GetPollingInterval(*con.context);
     if (polling_interval == 0) {