From c90315679f6602eed5e5f49ee08159a2c39b1db4 Mon Sep 17 00:00:00 2001
From: Manav Rathi <manav@mrmr.io>
Date: Thu, 5 Sep 2024 15:56:41 +0530
Subject: [PATCH] Migrator

---
 .../new/photos/services/migrations.ts         | 63 +++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 web/packages/new/photos/services/migrations.ts

diff --git a/web/packages/new/photos/services/migrations.ts b/web/packages/new/photos/services/migrations.ts
new file mode 100644
index 0000000000..37bd84959f
--- /dev/null
+++ b/web/packages/new/photos/services/migrations.ts
@@ -0,0 +1,63 @@
+import { isDesktop } from "@/base/app";
+import { getKVN, removeKV, setKV } from "@/base/kv";
+import log from "@/base/log";
+import localForage from "@ente/shared/storage/localForage";
+import { deleteDB } from "idb";
+
+/**
+ * App specific migrations.
+ *
+ * The app stores data in multiple places: local storage, IndexedDB, OPFS, and
+ * not all of these support DB migrations. And even when they do, those are
+ * rather heavy weight and complicated (e.g. IndexedDB).
+ *
+ * Further, there are various app level migrations, e.g. resetting the diff
+ * fetch times, that don't correspond to DB migrations, these are just changes
+ * we need to make to our locally persisted values and not the schemas
+ * themselves.
+ *
+ * Thus we introduce the concept of app level migrations. This is some code
+ * which runs early in the page load, and runs arbitrary blocks of code until it
+ * reaches the last migration number.
+ *
+ * We can put all sorts of changes here: cleanup of legacy keys, re-triggers for
+ * various fetches etc.
+ *
+ * This code usually runs fairly early on page load, but if you need specific
+ * guarantees or have dependencies in the order of operations (beyond what is
+ * captured by the sequential flow here), then this might not be appropriate.
+ */
+export const runMigrations = async () => {
+    const m = (await getKVN("migrationLevel")) ?? 0;
+    const latest = 1;
+    if (m < latest) {
+        log.info(`Running migrations ${m} => ${latest}`);
+        if (m < 1 && isDesktop) await m0();
+        await setKV("migrationLevel", latest);
+    }
+};
+
+// Some of these (indicated by "Prunable") can be no-oped in the future when
+// almost all clients would've migrated over.
+
+// Last used: Aug 2024. Prunable.
+const m0 = () =>
+    Promise.allSettled([
+        // Delete the legacy face DB v1.
+        deleteDB("mldata"),
+
+        // Delete the legacy CLIP (mostly) related keys from LocalForage.
+        localForage.removeItem("embeddings"),
+        localForage.removeItem("embedding_sync_time"),
+        localForage.removeItem("embeddings_v2"),
+        localForage.removeItem("file_embeddings"),
+        localForage.removeItem("onnx-clip-embedding_sync_time"),
+        localForage.removeItem("file-ml-clip-face-embedding_sync_time"),
+
+        // Delete keys for the legacy diff based sync.
+        removeKV("embeddingSyncTime:onnx-clip"),
+        removeKV("embeddingSyncTime:file-ml-clip-face"),
+
+        // Delete the legacy face DB v2.
+        deleteDB("face"),
+    ]);