Evict idle repodata cache entries and tighten fingerprint tests

docs/rpm/remote-github.md

@@ -53,14 +53,6 @@ derived metadata current off the client request path:
   ~once per `mutable_ttl` regardless of replica count, and the shared `etag`
   lets any replica issue the conditional request.
 
-### Repodata cache
-
-Repodata is regenerated from the metadata rows on every request by default. Set
-`cache_repodata: true` on the remote to keep the generated `repomd.xml` and its
-`primary`/`filelists`/`other` files in memory per replica. Each request checks a
-cheap row fingerprint (count + newest id) in the database and rebuilds only when
-it moved, so every replica picks up a scan's changes on its next request.
-
 ```hcl
 # Backend that serves the actual .rpm bytes from github.com.
 resource "artifactapi_remote_generic" "github" {
@@ -76,6 +68,7 @@ resource "artifactapi_remote_github_rpm" "acme-tools" {
   base_url        = "https://api.github.com/repos/acme/tools" # the releases API root
   releases_remote = "github"                                  # backend for downloads
   mutable_ttl     = 3600                                      # release re-scan interval
+  cache_repodata  = true                                      # keep generated repodata in memory
 
   # Optional: restrict which release assets become packages (regex on filename).
   patterns = [".*\\.x86_64\\.rpm$", ".*\\.noarch\\.rpm$"]
@@ -88,3 +81,11 @@ resource "artifactapi_remote_github_rpm" "acme-tools" {
 `dnf` config: `baseurl=https://artifactapi.example/api/v1/remote/acme-tools`.
 The repo is multi-arch (no `$basearch` needed) — `dnf` selects matching packages
 from the synthesized metadata.
+
+### Repodata cache
+
+Repodata is regenerated from the metadata rows on every request by default. Set
+`cache_repodata = true` on the remote to keep the generated `repomd.xml` and its
+`primary`/`filelists`/`other` files in memory per replica. Each request checks a
+cheap row fingerprint (count + newest id) in the database and rebuilds only when
+it moved, so every replica picks up a scan's changes on its next request.

internal/provider/rpm/github.go

@@ -53,6 +53,8 @@ const (
 	// retryable 503. Kept short so a client never hangs on a rate-limited derive
 	// of a large repo; small repos usually prime within this window.
 	defaultColdWait = 8 * time.Second
+	// repodataIdleTTL evicts cached indexes of remotes deleted or switched off.
+	repodataIdleTTL = time.Hour
 )
 
 // GitHubProvider is a metadata-only remote: it scans a GitHub repo's releases
@@ -100,6 +102,7 @@ type rpmFingerprinter interface {
 
 type cachedRepodata struct {
 	count, maxID int64
+	used         time.Time
 	*repodata
 }
 
@@ -295,8 +298,14 @@ func (p *GitHubProvider) cachedRepodata(ctx context.Context, store provider.RPMM
 	if err != nil {
 		return nil, err
 	}
+	now := time.Now()
 	p.repodataMu.Lock()
+	p.sweepRepodataLocked(now)
 	c, ok := p.repodataCache[name]
+	if ok {
+		c.used = now
+		p.repodataCache[name] = c
+	}
 	p.repodataMu.Unlock()
 	if ok && c.count == count && c.maxID == maxID {
 		return c.repodata, nil
@@ -311,7 +320,7 @@ func (p *GitHubProvider) cachedRepodata(ctx context.Context, store provider.RPMM
 		// worst case is one extra rebuild on the next request.
 		rd := buildRepodata(metas)
 		p.repodataMu.Lock()
-		p.repodataCache[name] = cachedRepodata{count: count, maxID: maxID, repodata: rd}
+		p.repodataCache[name] = cachedRepodata{count: count, maxID: maxID, used: time.Now(), repodata: rd}
 		p.repodataMu.Unlock()
 		return rd, nil
 	})
@@ -324,9 +333,18 @@ func (p *GitHubProvider) cachedRepodata(ctx context.Context, store provider.RPMM
 func (p *GitHubProvider) dropRepodata(name string) {
 	p.repodataMu.Lock()
 	delete(p.repodataCache, name)
+	p.sweepRepodataLocked(time.Now())
 	p.repodataMu.Unlock()
 }
 
+func (p *GitHubProvider) sweepRepodataLocked(now time.Time) {
+	for name, c := range p.repodataCache {
+		if now.Sub(c.used) > repodataIdleTTL {
+			delete(p.repodataCache, name)
+		}
+	}
+}
+
 func (p *GitHubProvider) cacheEmpty(ctx context.Context, store provider.RemoteMetadataStore, name string) bool {
 	if fp, ok := store.(rpmFingerprinter); ok {
 		count, _, err := fp.RPMMetadataFingerprint(ctx, name)

internal/provider/rpm/github_repodata_cache_test.go

@@ -27,10 +27,16 @@ func (s *fpStore) ListRPMMetadataEntries(ctx context.Context, name string) ([]pr
 }
 
 func (s *fpStore) InsertRPMMetadata(ctx context.Context, m *provider.RPMMetadata) error {
+	s.mu.Lock()
+	_, exists := s.rows[m.FilePath]
+	s.mu.Unlock()
+	if err := s.fakeStore.InsertRPMMetadata(ctx, m); err != nil || exists {
+		return err // ON CONFLICT DO NOTHING leaves max(id) unchanged
+	}
 	s.mu.Lock()
 	s.seq++
 	s.mu.Unlock()
-	return s.fakeStore.InsertRPMMetadata(ctx, m)
+	return nil
 }
 
 func (s *fpStore) RPMMetadataFingerprint(_ context.Context, _ string) (int64, int64, error) {
@@ -145,3 +151,36 @@ func TestUncachedRepodataMatchesCachedAndReadsEveryTime(t *testing.T) {
 		t.Fatal("disabling cache_repodata should drop the cached index")
 	}
 }
+
+func TestCachedRepodataRebuildsOnSameCountReinsert(t *testing.T) {
+	p, store, remote := newCacheFixture(t, true)
+	addPkg(t, store, "alpha") // conflicting insert: fingerprint must not move
+	serve(t, p, remote, store, "repodata/repomd.xml")
+	serve(t, p, remote, store, "repodata/repomd.xml")
+	if n := store.listCount(); n != 1 {
+		t.Fatalf("full reads after conflicting insert = %d, want 1", n)
+	}
+
+	if err := store.DeleteRPMMetadata(context.Background(), remote.Name, "alpha-1-1.noarch.rpm"); err != nil {
+		t.Fatal(err)
+	}
+	addPkg(t, store, "alpha")
+	serve(t, p, remote, store, "repodata/repomd.xml")
+	if n := store.listCount(); n != 2 {
+		t.Fatalf("full reads after same-count reinsert = %d, want 2", n)
+	}
+}
+
+func TestCachedRepodataEvictsIdleRemotes(t *testing.T) {
+	p, store, remote := newCacheFixture(t, true)
+	serve(t, p, remote, store, "repodata/repomd.xml")
+	p.repodataCache["gone"] = cachedRepodata{used: time.Now().Add(-2 * repodataIdleTTL), repodata: &repodata{}}
+
+	serve(t, p, remote, store, "repodata/repomd.xml")
+	if _, ok := p.repodataCache["gone"]; ok {
+		t.Fatal("idle remote's index not evicted")
+	}
+	if _, ok := p.repodataCache[remote.Name]; !ok {
+		t.Fatal("active remote's index evicted")
+	}
+}