pkg/asset: report deprecation figures

Let's have a bit more introspection into the asset storage deprecation
code.

3 files changed, 28 insertions, 15 deletions

diff --git a/pkg/asset/storage.go b/pkg/asset/storage.go
index 749ec6a19..058cfc69e 100644
--- a/pkg/asset/storage.go
+++ b/pkg/asset/storage.go
@@ -217,12 +217,19 @@ var ErrUnknownBucket = errors.New("the asset is not in the currently managed buc
 
 const deletionEmbargo = time.Hour * 24 * 7
 
+type DeprecateStats struct {
+	Needed   int // The count of assets currently needed in the dashboard.
+	Existing int // The number of assets currently stored.
+	Deleted  int // How many were deleted during DeprecateAssets().
+}
+
 // Best way: convert download URLs to paths.
 // We don't want to risk killing all assets after a slight domain change.
-func (storage *Storage) DeprecateAssets() error {
+func (storage *Storage) DeprecateAssets() (DeprecateStats, error) {
+	var stats DeprecateStats
 	resp, err := storage.dash.NeededAssetsList()
 	if err != nil {
-		return fmt.Errorf("failed to query needed assets: %w", err)
+		return stats, fmt.Errorf("failed to query needed assets: %w", err)
 	}
 	needed := map[string]bool{}
 	for _, url := range resp.DownloadURLs {
@@ -233,15 +240,18 @@ func (storage *Storage) DeprecateAssets() error {
 		} else if err != nil {
 			// If we failed to parse just one URL, let's stop the entire process.
 			// Otherwise we'll start deleting still needed files we couldn't recognize.
-			return fmt.Errorf("failed to parse '%s': %w", url, err)
+			return stats, fmt.Errorf("failed to parse '%s': %w", url, err)
 		}
 		needed[path] = true
 	}
+	stats.Needed = len(needed)
 	storage.tracer.Log("queried needed assets: %#v", needed)
+
 	existing, err := storage.backend.list()
 	if err != nil {
-		return fmt.Errorf("failed to query object list: %w", err)
+		return stats, fmt.Errorf("failed to query object list: %w", err)
 	}
+	stats.Existing = len(existing)
 	toDelete := []string{}
 	intersection := 0
 	for _, obj := range existing {
@@ -265,7 +275,7 @@ func (storage *Storage) DeprecateAssets() error {
 		// This is a last-resort protection against possible dashboard bugs.
 		// If the needed assets have no intersection with the existing assets,
 		// don't delete anything. Otherwise, if it was a bug, we will lose all files.
-		return fmt.Errorf("needed assets have almost no intersection with the existing ones")
+		return stats, fmt.Errorf("needed assets have almost no intersection with the existing ones")
 	}
 	for _, path := range toDelete {
 		err := storage.backend.remove(path)
@@ -273,10 +283,11 @@ func (storage *Storage) DeprecateAssets() error {
 		// Several syz-ci's might be sharing the same storage. So let's tolerate
 		// races during file deletion.
 		if err != nil && err != ErrAssetDoesNotExist {
-			return fmt.Errorf("asset deletion failure: %w", err)
+			return stats, fmt.Errorf("asset deletion failure: %w", err)
 		}
 	}
-	return nil
+	stats.Deleted = len(toDelete)
+	return stats, nil
 }
 
 type uploadRequest struct {
diff --git a/pkg/asset/storage_test.go b/pkg/asset/storage_test.go
index 7500e9db3..e40bcffab 100644
--- a/pkg/asset/storage_test.go
+++ b/pkg/asset/storage_test.go
@@ -182,14 +182,14 @@ func TestUploadBuildAsset(t *testing.T) {
 
 	// Pretend there's an asset deletion error.
 	be.objectRemove = func(string) error { return fmt.Errorf("not now") }
-	err = storage.DeprecateAssets()
+	_, err = storage.DeprecateAssets()
 	if err == nil {
 		t.Fatalf("DeprecateAssets should have failed")
 	}
 
 	// Let the deletion be successful.
 	be.objectRemove = nil
-	err = storage.DeprecateAssets()
+	_, err = storage.DeprecateAssets()
 	if err != nil {
 		t.Fatalf("DeprecateAssets was expected to be successful, got %s", err)
 	}
@@ -204,7 +204,7 @@ func TestUploadBuildAsset(t *testing.T) {
 
 	// Delete the rest.
 	dashMock.downloadURLs = map[string]bool{}
-	err = storage.DeprecateAssets()
+	_, err = storage.DeprecateAssets()
 	if err != nil || len(be.objects) != 0 {
 		t.Fatalf("second DeprecateAssets failed: %s, len %d",
 			err, len(be.objects))
@@ -270,7 +270,7 @@ func TestRecentAssetDeletionProtection(t *testing.T) {
 
 	// Try to delete a recent file.
 	dashMock.downloadURLs = map[string]bool{}
-	err = storage.DeprecateAssets()
+	_, err = storage.DeprecateAssets()
 	if err != nil {
 		t.Fatalf("DeprecateAssets failed: %v", err)
 	} else if len(be.objects) == 0 {
@@ -368,7 +368,7 @@ func TestTwoBucketDeprecation(t *testing.T) {
 		t.Fatalf("unexpected removal")
 		return nil
 	}
-	err := storage.DeprecateAssets()
+	_, err := storage.DeprecateAssets()
 	assert.NoError(t, err)
 }
 
@@ -392,6 +392,6 @@ func TestInvalidAssetURLs(t *testing.T) {
 		t.Fatalf("unexpected removal")
 		return nil
 	}
-	err := storage.DeprecateAssets()
+	_, err := storage.DeprecateAssets()
 	assert.Error(t, err)
 }
diff --git a/syz-ci/syz-ci.go b/syz-ci/syz-ci.go
index fb3e3d2d5..28cbbbcf0 100644
--- a/syz-ci/syz-ci.go
+++ b/syz-ci/syz-ci.go
@@ -355,11 +355,13 @@ loop:
 			break loop
 		case <-time.After(sleepDuration):
 		}
-		log.Logf(0, "deprecating assets")
-		err := storage.DeprecateAssets()
+		log.Logf(1, "start asset deprecation")
+		stats, err := storage.DeprecateAssets()
 		if err != nil {
 			log.Errorf("asset deprecation failed: %v", err)
 		}
+		log.Logf(0, "asset deprecation: needed=%d, existing=%d, deleted=%d",
+			stats.Needed, stats.Existing, stats.Deleted)
 	}
 }