Merge pull request #69 from oasisprotocol/feature/batch-verifier-reuse

primitives/[ed,sr]25519: BatchVerifier improvements for large batches

primitives/ed25519/batch_verify.go

@@ -332,7 +332,33 @@ func (v *BatchVerifier) Verify(rand io.Reader) (bool, []bool) {
 	return allValid, valid
 }
 
+// Reset resets a batch for reuse.
+//
+// Note: This method will reuse the existing entires slice to reduce memory
+// reallocations.  If the next batch is known to be significantly smaller
+// it may be more memory efficient to simply create a new batch.
+func (v *BatchVerifier) Reset() *BatchVerifier {
+	// Allow re-using the existing entries slice.
+	v.entries = v.entries[:0]
+
+	v.anyInvalid = false
+	v.anyCofactorless = false
+
+	return v
+}
+
 // NewBatchVerfier creates an empty BatchVerifier.
 func NewBatchVerifier() *BatchVerifier {
 	return &BatchVerifier{}
 }
+
+// NewBatchVerifierWithCapacity creates an empty BatchVerifier, with
+// preallocations done for a pre-determined batch size.
+func NewBatchVerifierWithCapacity(n int) *BatchVerifier {
+	v := NewBatchVerifier()
+	if n > 0 {
+		v.entries = make([]entry, 0, n)
+	}
+
+	return v
+}

primitives/ed25519/batch_verify_test.go

@@ -339,6 +339,53 @@ func TestBatchVerifier(t *testing.T) {
 			t.Error("batch verification should fail on an empty batch")
 		}
 	})
+	t.Run("Reset", func(t *testing.T) {
+		v := NewBatchVerifier()
+
+		// Reseting an empty batch verifier should work.
+		v.Reset()
+
+		pub, priv, err := GenerateKey(nil)
+		if err != nil {
+			t.Fatalf("failed to GenerateKey: %v", err)
+		}
+		msg := []byte("ResetTest")
+		sig := Sign(priv, msg)
+
+		for i := 0; i < 10; i++ {
+			v.Add(pub, msg, sig)
+		}
+		v.Add(pub, msg, nil)
+		v.AddWithOptions(pub, msg, nil, &Options{
+			Verify: VerifyOptionsStdLib,
+		})
+
+		v.Reset()
+		if len(v.entries) != 0 {
+			t.Fatalf("Reset did not shrink entries")
+		}
+		if cap(v.entries) == 0 {
+			// Can't check for an exact capacity since this is at the
+			// mercy of how stdlib reallocs.
+			t.Fatalf("Reset did not preserve entries backing store")
+		}
+		if v.anyInvalid != false {
+			t.Fatalf("Reset did not clear anyInvalid")
+		}
+		if v.anyCofactorless != false {
+			t.Fatalf("Reset did not clear anyCofactorless")
+		}
+	})
+	t.Run("NewWithCapacity", func(t *testing.T) {
+		v := NewBatchVerifierWithCapacity(10)
+
+		if l := len(v.entries); l != 0 {
+			t.Fatalf("unexpected v.entries length: %d", l)
+		}
+		if c := cap(v.entries); c != 10 {
+			t.Fatalf("unexpected v.entries capacity: %d", c)
+		}
+	})
 }
 
 func BenchmarkVerifyBatchOnly(b *testing.B) {

primitives/sr25519/batch_verify.go

@@ -274,7 +274,32 @@ func (v *BatchVerifier) Verify(rand io.Reader) (bool, []bool) {
 	return allValid, valid
 }
 
+// Reset resets a batch for reuse.
+//
+// Note: This method will reuse the existing entires slice to reduce memory
+// reallocations.  If the next batch is known to be significantly smaller
+// it may be more memory efficient to simply create a new batch.
+func (v *BatchVerifier) Reset() *BatchVerifier {
+	// Allow re-using the existing entries slice.
+	v.entries = v.entries[:0]
+
+	v.anyInvalid = false
+
+	return v
+}
+
 // NewBatchVerifier creates an empty BatchVerifier.
 func NewBatchVerifier() *BatchVerifier {
 	return &BatchVerifier{}
 }
+
+// NewBatchVerifierWithCapacity creates an empty BatchVerifier, with
+// preallocations done for a pre-determined batch size.
+func NewBatchVerifierWithCapacity(n int) *BatchVerifier {
+	v := NewBatchVerifier()
+	if n > 0 {
+		v.entries = make([]entry, 0, n)
+	}
+
+	return v
+}

primitives/sr25519/batch_verify_test.go

@@ -200,6 +200,55 @@ func TestBatchVerifier(t *testing.T) {
 			t.Error("batch verification should fail on an empty batch")
 		}
 	})
+	t.Run("Reset", func(t *testing.T) {
+		v := NewBatchVerifier()
+
+		// Reseting an empty batch verifier should work.
+		v.Reset()
+
+		ctx := NewSigningContext([]byte("test-batch-verify:reset"))
+		kp, err := GenerateKeyPair(nil)
+		if err != nil {
+			t.Fatalf("failed to GenerateKeyPair: %v", err)
+		}
+		pub := kp.PublicKey()
+		st := ctx.NewTranscriptBytes([]byte("ResetTest"))
+		sig, err := kp.Sign(nil, st)
+		if err != nil {
+			t.Fatalf("failed to Sign: %v", err)
+		}
+
+		for i := 0; i < 10; i++ {
+			v.Add(pub, st, sig)
+		}
+		v.Add(pub, st, &Signature{})
+		if v.anyInvalid == false {
+			t.Fatalf("Uninitialized signature did not invalidate batch")
+		}
+
+		v.Reset()
+		if len(v.entries) != 0 {
+			t.Fatalf("Reset did not shrink entries")
+		}
+		if cap(v.entries) == 0 {
+			// Can't check for an exact capacity since this is at the
+			// mercy of how stdlib reallocs.
+			t.Fatalf("Reset did not preserve entries backing store")
+		}
+		if v.anyInvalid != false {
+			t.Fatalf("Reset did not clear anyInvalid")
+		}
+	})
+	t.Run("NewWithCapacity", func(t *testing.T) {
+		v := NewBatchVerifierWithCapacity(10)
+
+		if l := len(v.entries); l != 0 {
+			t.Fatalf("unexpected v.entries length: %d", l)
+		}
+		if c := cap(v.entries); c != 10 {
+			t.Fatalf("unexpected v.entries capacity: %d", c)
+		}
+	})
 }
 
 func BenchmarkVerifyBatchOnly(b *testing.B) {