pkg/{api/api0/*,storage/*}: Add GetPdataHash method for pdata storage

2 files changed, 60 insertions, 9 deletions

diff --git a/pkg/api/api0/api0testutil/storage.go b/pkg/api/api0/api0testutil/storage.go
index f88c27c..be3bd4a 100644
--- a/pkg/api/api0/api0testutil/storage.go
+++ b/pkg/api/api0/api0testutil/storage.go
@@ -25,6 +25,18 @@ func TestPdataStorage(t *testing.T, s api0.PdataStorage) {
 		pdata1SHA := sha256.Sum256(pdata1)
 		pdata2SHA := sha256.Sum256(pdata2)
 
+		t.Run("HashForNonexistentUser1", func(t *testing.T) {
+			hash, exists, err := s.GetPdataHash(user1)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if exists {
+				t.Fatalf("exists should be false")
+			}
+			if hash != zeroSHA {
+				t.Fatalf("should not return hash")
+			}
+		})
 		t.Run("GetForNonexistentUser1", func(t *testing.T) {
 			for _, tc := range []struct {
 				Name string
@@ -52,6 +64,18 @@ func TestPdataStorage(t *testing.T, s api0.PdataStorage) {
 				t.Fatalf("unexpected error: %v", err)
 			}
 		})
+		t.Run("HashForExistingUser1Pdata1", func(t *testing.T) {
+			hash, exists, err := s.GetPdataHash(user1)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if !exists {
+				t.Fatalf("exists should be true")
+			}
+			if hash != pdata1SHA {
+				t.Fatalf("should return correct hash")
+			}
+		})
 		t.Run("GetForExistingUser1", func(t *testing.T) {
 			for _, tc := range []struct {
 				Name string
@@ -92,6 +116,18 @@ func TestPdataStorage(t *testing.T, s api0.PdataStorage) {
 				t.Fatalf("unexpected error: %v", err)
 			}
 		})
+		t.Run("HashForExistingUser1Pdata2", func(t *testing.T) {
+			hash, exists, err := s.GetPdataHash(user1)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if !exists {
+				t.Fatalf("exists should be true")
+			}
+			if hash != pdata2SHA {
+				t.Fatalf("should return correct hash")
+			}
+		})
 		t.Run("GetForExistingUser2", func(t *testing.T) {
 			for _, tc := range []struct {
 				Name string
@@ -170,36 +206,48 @@ func TestPdataStorage(t *testing.T, s api0.PdataStorage) {
 				}
 				randSched()
 
-				if buf, exists, err := s.GetPdataCached(uid, data1sha); err != nil || !exists || buf != nil {
+				if hash, exists, err := s.GetPdataHash(uid); err != nil || !exists || hash != data1sha {
 					fail.Store(4)
 					return
 				}
 				randSched()
 
-				if buf, exists, err := s.GetPdataCached(uid, data2sha); err != nil || !exists || !bytes.Equal(buf, data1) {
+				if buf, exists, err := s.GetPdataCached(uid, data1sha); err != nil || !exists || buf != nil {
 					fail.Store(5)
 					return
 				}
 				randSched()
 
-				if err := s.SetPdata(uid, data2); err != nil {
+				if buf, exists, err := s.GetPdataCached(uid, data2sha); err != nil || !exists || !bytes.Equal(buf, data1) {
 					fail.Store(6)
 					return
 				}
 				randSched()
 
-				if buf, exists, err := s.GetPdataCached(uid, data2sha); err != nil || !exists || buf != nil {
+				if err := s.SetPdata(uid, data2); err != nil {
 					fail.Store(7)
 					return
 				}
 				randSched()
 
-				if buf, exists, err := s.GetPdataCached(uid, data1sha); err != nil || !exists || !bytes.Equal(buf, data2) {
+				if hash, exists, err := s.GetPdataHash(uid); err != nil || !exists || hash != data2sha {
 					fail.Store(8)
 					return
 				}
 				randSched()
 
+				if buf, exists, err := s.GetPdataCached(uid, data2sha); err != nil || !exists || buf != nil {
+					fail.Store(9)
+					return
+				}
+				randSched()
+
+				if buf, exists, err := s.GetPdataCached(uid, data1sha); err != nil || !exists || !bytes.Equal(buf, data2) {
+					fail.Store(10)
+					return
+				}
+				randSched()
+
 			}(uid)
 		}
 		if wg.Wait(); fail.Load() != 0 {
diff --git a/pkg/api/api0/storage.go b/pkg/api/api0/storage.go
index cf7b078..a17e8da 100644
--- a/pkg/api/api0/storage.go
+++ b/pkg/api/api0/storage.go
@@ -6,11 +6,14 @@ import "crypto/sha256"
 // on the contents of the stored blobs (including validity). It may compress the
 // stored data. It must be safe for concurrent use.
 type PdataStorage interface {
+	// GetPdataHash gets the current pdata hash for uid. If there is not any
+	// pdata for uid, exists is false. If another error occurs, err is non-nil.
+	GetPdataHash(uid uint64) (hash [sha256.Size]byte, exists bool, err error)
+
 	// GetPdataCached gets the pdata for uid. If there is not any pdata for uid,
-	// ok is false. If the provided hash is nonzero and the current pdata
-	// matches, buf is nil. If another error occurs, buf is nil, ok is false,
-	// and err is non-nil.
-	GetPdataCached(uid uint64, sha256 [sha256.Size]byte) (buf []byte, exists bool, err error)
+	// exists is false. If the provided hash is nonzero and the current pdata
+	// matches, buf is nil. If another error occurs, err is non-nil.
+	GetPdataCached(uid uint64, sha [sha256.Size]byte) (buf []byte, exists bool, err error)
 
 	// SetPdata sets the raw pdata for uid.
 	SetPdata(uid uint64, buf []byte) (err error)