refactor(electron): sqlite db data workflow (remove symlink & fs watcher) (#2491)

apps/electron/layers/main/src/db/ensure-db.ts

@@ -0,0 +1,94 @@
+import { app } from 'electron';
+import {
+  defer,
+  firstValueFrom,
+  from,
+  fromEvent,
+  interval,
+  Observable,
+} from 'rxjs';
+import {
+  distinctUntilChanged,
+  filter,
+  ignoreElements,
+  last,
+  map,
+  shareReplay,
+  startWith,
+  switchMap,
+  takeUntil,
+  tap,
+} from 'rxjs/operators';
+
+import { appContext } from '../context';
+import { logger } from '../logger';
+import { getWorkspaceMeta$ } from '../workspace';
+import { SecondaryWorkspaceSQLiteDB } from './secondary-db';
+import type { WorkspaceSQLiteDB } from './workspace-db-adapter';
+import { openWorkspaceDatabase } from './workspace-db-adapter';
+
+const db$Map = new Map<string, Observable<WorkspaceSQLiteDB>>();
+
+const beforeQuit$ = defer(() => fromEvent(app, 'before-quit'));
+
+function getWorkspaceDB$(id: string) {
+  if (!db$Map.has(id)) {
+    db$Map.set(
+      id,
+      from(openWorkspaceDatabase(appContext, id)).pipe(
+        switchMap(db => {
+          return startPollingSecondaryDB(db).pipe(
+            ignoreElements(),
+            startWith(db),
+            takeUntil(beforeQuit$),
+            tap({
+              complete: () => {
+                logger.info('[ensureSQLiteDB] close db connection');
+                db.destroy();
+                db$Map.delete(id);
+              },
+            })
+          );
+        }),
+        shareReplay(1)
+      )
+    );
+  }
+  return db$Map.get(id)!;
+}
+
+// fixme: this function has issue on registering multiple times...
+function startPollingSecondaryDB(db: WorkspaceSQLiteDB) {
+  const meta$ = getWorkspaceMeta$(db.workspaceId);
+  const secondaryDB$ = meta$.pipe(
+    map(meta => meta?.secondaryDBPath),
+    distinctUntilChanged(),
+    filter((p): p is string => !!p),
+    switchMap(path => {
+      const secondaryDB = new SecondaryWorkspaceSQLiteDB(path, db);
+      return new Observable<SecondaryWorkspaceSQLiteDB>(observer => {
+        observer.next(secondaryDB);
+        return () => {
+          secondaryDB.destroy();
+        };
+      });
+    })
+  );
+
+  // pull every 30 seconds
+  const poll$ = interval(30000).pipe(
+    switchMap(() => secondaryDB$),
+    tap({
+      next: secondaryDB => {
+        secondaryDB.pull();
+      },
+    }),
+    shareReplay(1)
+  );
+
+  return poll$.pipe(takeUntil(db.update$.pipe(last())), shareReplay(1));
+}
+
+export function ensureSQLiteDB(id: string) {
+  return firstValueFrom(getWorkspaceDB$(id));
+}