perf(desktop): collect orphaned draft blobs after the window is up (#49797)

packages/desktop/src/main/storage/drafts.test.ts

@@ -17,17 +17,29 @@ describe("draft store", () => {
     expect(database.db.all(sql`SELECT key FROM document`)).toEqual([])
   })
 
-  test("stores blobs by content hash and collects unreferenced ones on open", () => {
+  test("stores blobs by content hash and collects unreferenced ones shortly after open", async () => {
     const database = openDatabase(":memory:")
-    const first = createDraftStore(database.db, { delay: 1_000 })
+    let clock = 0
+    const first = createDraftStore(database.db, { delay: 1_000, now: () => clock })
     const used = first.putBlob(new Uint8Array([1, 2, 3]))
     const unused = first.putBlob(new Uint8Array([4, 5, 6]))
     expect(first.putBlob(new Uint8Array([1, 2, 3]))).toBe(used)
     first.set("doc", JSON.stringify({ parts: [{ blob: { id: used } }] }))
     first.flush()
-    const second = createDraftStore(database.db, { delay: 1_000 })
-    expect(second.getBlob(used)).toEqual(new Uint8Array([1, 2, 3]))
-    expect(second.getBlob(unused)).toBeNull()
+    first.close()
+    // The startup collection runs off the window's critical path and keeps the usual grace, so a
+    // blob from a session that ended within the grace period is still there...
+    const second = createDraftStore(database.db, { delay: 1_000, now: () => clock, collectDelay: 0 })
+    await new Promise((resolve) => setTimeout(resolve, 5))
+    expect(second.getBlob(unused)).toEqual(new Uint8Array([4, 5, 6]))
+    second.close()
+    // ...and gone once the grace has passed.
+    clock = blobGrace + 1
+    const third = createDraftStore(database.db, { delay: 1_000, now: () => clock, collectDelay: 0 })
+    await new Promise((resolve) => setTimeout(resolve, 5))
+    expect(third.getBlob(used)).toEqual(new Uint8Array([1, 2, 3]))
+    expect(third.getBlob(unused)).toBeNull()
+    third.close()
   })
 
   test("collects a retired chunk only once it is unreferenced and past the grace period", () => {

packages/desktop/src/main/storage/drafts.ts

@@ -27,11 +27,14 @@ const referenced = (value: unknown) => sql`
 
 export function createDraftStore(
   db: Database,
-  input: { delay?: number; onError?: (error: unknown) => void; now?: () => number } = {},
+  input: { delay?: number; collectDelay?: number; onError?: (error: unknown) => void; now?: () => number } = {},
 ) {
   const now = input.now ?? Date.now
-  // Nothing outside this process can hold a blob id at startup, so no grace applies.
-  collectBlobs(db, Infinity)
+  // Orphans left by an earlier session are collected once the window is up rather than before it:
+  // the scan walks every stored document, and the usual grace keeps anything a renderer has
+  // uploaded in the meantime.
+  const startup = setTimeout(() => collectBlobs(db, now() - blobGrace), input.collectDelay ?? 10_000)
+  startup.unref()
   let collected = now()
   let orphans = false
   const byKey = eq(document.key, sql.placeholder("key"))
@@ -104,7 +107,10 @@ export function createDraftStore(
       return data ? (data as Uint8Array<ArrayBuffer>) : null
     },
     flush: writer.flush,
-    close: writer.close,
+    close() {
+      clearTimeout(startup)
+      writer.close()
+    },
   }
 }