Add file-meta GC coverage

Author: lukemelia

docs/file-meta-gc-pr2-plan.md

@@ -0,0 +1,61 @@
+# Plan: File-meta GC + reference counting (PR 2)
+
+## Background
+
+- FileDef instances already live in `CardStoreWithGarbageCollection`, but GC and reference counting only consider cards.
+- Requirement: file-meta instances should participate in GC and reference counting.
+- This PR is scoped to GC/reference behavior only; explicit store read types remain in PR 1.
+
+## Goals
+
+- Keep FileDef instances alive when they have active references.
+- GC FileDef instances when their references drop to zero.
+- Avoid changing public Store read APIs in this PR.
+- Keep file-meta read-only behavior (no save/auto-save).
+
+## Non-goals
+
+- No `StoreReadType` changes or call-site updates (handled in PR 1).
+- No changes to FileMetaResource or operator-mode wiring.
+- No change to file-meta error storage strategy (can remain in StoreService for now).
+
+## Test-first plan
+
+1. Add failing tests in `packages/host/tests/integration/store-test.gts`:
+   - `file-meta instances are retained when referenced`:
+     - Write a file (e.g., `hero.png`) into the test realm.
+     - Load the FileDef via existing behavior (`storeService.get(fileUrl)` on main).
+     - Add a file-meta reference (via a new internal helper or direct map access).
+     - Run `forceGC()` and assert the FileDef is still in the store.
+   - `file-meta instances are GC'd when references drop`:
+     - Drop the file-meta reference.
+     - Run `forceGC()` and assert the FileDef is removed from the store.
+
+2. Run the tests to confirm they fail before implementation.
+
+## Implementation plan (after tests)
+
+1. Expand `CardStoreWithGarbageCollection` to understand file-meta references:
+   - Accept a second reference-count map for file-meta (or a unified typed map).
+   - Update `hasReferences()` to include both card and file-meta counts.
+   - In `sweep()`, treat FileDef instances as GC candidates and roots when referenced.
+   - Ensure `delete()` and `reset()` clear FileDef instances consistently.
+
+2. Wire StoreService to pass file-meta reference counts into CardStore:
+   - Add `fileMetaReferenceCount` on StoreService (private).
+   - Provide a minimal internal way to increment/decrement file-meta references
+     (used by tests in this PR; public API stays unchanged).
+   - Pass both reference maps into `CardStoreWithGarbageCollection`.
+
+3. Re-run tests and confirm pass.
+
+## Target files
+
+- `packages/host/app/lib/gc-card-store.ts`
+- `packages/host/app/services/store.ts`
+- `packages/host/tests/integration/store-test.gts`
+
+## Testing notes
+
+- `cd packages/host && pnpm lint`
+- `cd packages/host && ember test --path dist --filter "file-meta"`

packages/host/app/lib/gc-card-store.ts

@@ -334,20 +334,26 @@ export default class CardStoreWithGarbageCollection implements CardStore {
   sweep(api: typeof CardAPI) {
     let dependencyGraph = this.makeDependencyGraph(api);
     let reachable = new Set<string>();
-    let visited = new WeakSet<CardDef>();
+    let visited = new WeakSet<StoredInstance>();
     let rootLocalIds: string[] = [];
 
     for (let instance of this.#cards.values()) {
-      if (!instance || !isCardInstance(instance)) {
+      if (!instance || visited.has(instance)) {
         continue;
       }
-      if (visited.has(instance)) {
+      visited.add(instance);
+      if (isCardInstance(instance)) {
+        let localId = instance[localIdSymbol];
+        if (this.hasReferences(localId)) {
+          rootLocalIds.push(localId);
+        }
         continue;
       }
-      visited.add(instance);
-      let localId = instance[localIdSymbol];
-      if (this.hasReferences(localId)) {
-        rootLocalIds.push(localId);
+      if (isFileDefInstance(instance)) {
+        let fileId = instance.id;
+        if (fileId && this.hasReferences(fileId)) {
+          reachable.add(fileId);
+        }
       }
     }
 
@@ -367,32 +373,51 @@ export default class CardStoreWithGarbageCollection implements CardStore {
       }
     }
 
-    visited = new WeakSet<CardDef>();
+    visited = new WeakSet<StoredInstance>();
     for (let instance of this.#cards.values()) {
-      if (!instance || !isCardInstance(instance)) {
+      if (!instance || visited.has(instance)) {
         continue;
       }
-      if (visited.has(instance)) {
+      visited.add(instance);
+      if (isCardInstance(instance)) {
+        let localId = instance[localIdSymbol];
+        if (!reachable.has(localId)) {
+          if (this.#gcCandidates.has(localId)) {
+            destroy(instance);
+            // brand the instance to make it easier for debugging
+            (instance as unknown as any)[
+              Symbol.for('__instance_detached_from_store')
+            ] = true;
+            this.delete(localId);
+            if (instance.id) {
+              this.delete(instance.id);
+            }
+          } else {
+            this.#gcCandidates.add(localId);
+          }
+        } else {
+          this.#gcCandidates.delete(localId);
+        }
         continue;
       }
-      visited.add(instance);
-      let localId = instance[localIdSymbol];
-      if (!reachable.has(localId)) {
-        if (this.#gcCandidates.has(localId)) {
-          destroy(instance);
-          // brand the instance to make it easier for debugging
-          (instance as unknown as any)[
-            Symbol.for('__instance_detached_from_store')
-          ] = true;
-          this.delete(localId);
-          if (instance.id) {
-            this.delete(instance.id);
+      if (isFileDefInstance(instance)) {
+        let fileId = instance.id;
+        if (!fileId) {
+          continue;
+        }
+        if (!reachable.has(fileId)) {
+          if (this.#gcCandidates.has(fileId)) {
+            destroy(instance);
+            (instance as unknown as any)[
+              Symbol.for('__instance_detached_from_store')
+            ] = true;
+            this.delete(fileId);
+          } else {
+            this.#gcCandidates.add(fileId);
           }
         } else {
-          this.#gcCandidates.add(localId);
+          this.#gcCandidates.delete(fileId);
         }
-      } else {
-        this.#gcCandidates.delete(localId);
       }
     }
   }
@@ -569,10 +594,18 @@ export default class CardStoreWithGarbageCollection implements CardStore {
     }
   }
 
-  private hasReferences(localId: string): boolean {
-    let referenceCount = this.#referenceCount.get(localId) ?? 0;
-    for (let remoteId of this.#idResolver.getRemoteIds(localId)) {
-      referenceCount += this.#referenceCount.get(remoteId) ?? 0;
+  private hasReferences(id: string): boolean {
+    let idsToCheck = new Set<string>([id]);
+    let localId = isLocalId(id) ? id : this.#idResolver.getLocalId(id);
+    if (localId) {
+      idsToCheck.add(localId);
+      for (let remoteId of this.#idResolver.getRemoteIds(localId)) {
+        idsToCheck.add(remoteId);
+      }
+    }
+    let referenceCount = 0;
+    for (let refId of idsToCheck) {
+      referenceCount += this.#referenceCount.get(refId) ?? 0;
     }
     return referenceCount > 0;
   }

packages/host/tests/integration/store-test.gts

@@ -377,6 +377,44 @@ module('Integration | Store', function (hooks) {
     );
   });
 
+  test('file-meta instance is retained when referenced', async function (assert) {
+    await testRealm.write('hero.png', 'mock hero image');
+    let fileUrl = `${testRealmURL}hero.png`;
+
+    let fileInstance = await storeService.get(fileUrl);
+    assert.ok(fileInstance, 'file meta instance is loaded');
+    assert.ok(
+      (fileInstance as any).constructor?.isFileDef,
+      'file meta instance is a FileDef',
+    );
+
+    storeService.addReference(fileUrl);
+    forceGC();
+
+    let peekedInstance = cardStore.get(fileUrl) as unknown;
+    assert.strictEqual(
+      peekedInstance,
+      fileInstance,
+      'file meta instance is retained after GC with reference',
+    );
+  });
+
+  test('file-meta instance is garbage collected when references drop', async function (assert) {
+    await testRealm.write('hero.png', 'mock hero image');
+    let fileUrl = `${testRealmURL}hero.png`;
+
+    await storeService.get(fileUrl);
+    storeService.addReference(fileUrl);
+    storeService.dropReference(fileUrl);
+    forceGC();
+
+    assert.strictEqual(
+      cardStore.get(fileUrl),
+      undefined,
+      'file meta instance is garbage collected after reference drop',
+    );
+  });
+
   test('garbage collects cards that only consume each other', async function (assert) {
     let alpha = new PersonDef({ name: 'Alpha' });
     let beta = new PersonDef({ name: 'Beta' });