Merge pull request #316 from onflow/fxamacker/change-array-get-to-return-value

Change `Array.Get()` to return `Value` instead of `Storable`

Author: fxamacker

array.go

@@ -1995,9 +1995,18 @@ func NewArrayWithRootID(storage SlabStorage, rootID StorageID) (*Array, error) {
 	}, nil
 }
 
-func (a *Array) Get(i uint64) (Storable, error) {
-	// Don't need to wrap error as external error because err is already categorized by ArraySlab.Get().
-	return a.root.Get(a.Storage, i)
+func (a *Array) Get(i uint64) (Value, error) {
+	storable, err := a.root.Get(a.Storage, i)
+	if err != nil {
+		// Don't need to wrap error as external error because err is already categorized by ArraySlab.Get().
+		return nil, err
+	}
+	v, err := storable.StoredValue(a.Storage)
+	if err != nil {
+		// Wrap err as external error (if needed) because err is returned by Storable interface.
+		return nil, wrapErrorfAsExternalErrorIfNeeded(err, "failed to get storable's stored value")
+	}
+	return v, nil
 }
 
 func (a *Array) Set(index uint64, value Value) (Storable, error) {

array_bench_test.go

@@ -25,7 +25,8 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-var noop Storable
+var noopValue Value
+var noopStorable Storable
 
 func BenchmarkArrayGet100x(b *testing.B) {
 	benchmarks := []struct {
@@ -223,18 +224,18 @@ func benchmarkArrayGet(b *testing.B, initialArraySize, numberOfOps int) {
 
 	array := setupArray(b, r, storage, initialArraySize)
 
-	var storable Storable
+	var value Value
 
 	b.StartTimer()
 
 	for i := 0; i < b.N; i++ {
 		for i := 0; i < numberOfOps; i++ {
 			index := r.Intn(int(array.Count()))
-			storable, _ = array.Get(uint64(index))
+			value, _ = array.Get(uint64(index))
 		}
 	}
 
-	noop = storable
+	noopValue = value
 }
 
 func benchmarkArrayInsert(b *testing.B, initialArraySize, numberOfOps int) {
@@ -307,7 +308,7 @@ func benchmarkArrayRemoveAll(b *testing.B, initialArraySize int) {
 		}
 	}
 
-	noop = storable
+	noopStorable = storable
 }
 
 func benchmarkArrayPopIterate(b *testing.B, initialArraySize int) {
@@ -336,7 +337,7 @@ func benchmarkArrayPopIterate(b *testing.B, initialArraySize int) {
 		}
 	}
 
-	noop = storable
+	noopStorable = storable
 }
 
 func benchmarkNewArrayFromAppend(b *testing.B, initialArraySize int) {

array_test.go

@@ -57,10 +57,7 @@ func verifyArray(
 
 	// Verify array elements
 	for i, v := range values {
-		s, err := array.Get(uint64(i))
-		require.NoError(t, err)
-
-		e, err := s.StoredValue(array.Storage)
+		e, err := array.Get(uint64(i))
 		require.NoError(t, err)
 
 		valueEqual(t, typeInfoComparator, v, e)
@@ -153,8 +150,8 @@ func TestArrayAppendAndGet(t *testing.T) {
 		require.NoError(t, err)
 	}
 
-	storable, err := array.Get(array.Count())
-	require.Nil(t, storable)
+	e, err := array.Get(array.Count())
+	require.Nil(t, e)
 	require.Equal(t, 1, errorCategorizationCount(err))
 
 	var userError *UserError

cmd/stress/array.go

@@ -417,14 +417,10 @@ func checkArrayDataLoss(array *atree.Array, values []atree.Value) error {
 
 	// Check every element
 	for i, v := range values {
-		storable, err := array.Get(uint64(i))
+		convertedValue, err := array.Get(uint64(i))
 		if err != nil {
 			return fmt.Errorf("failed to get element at %d: %w", i, err)
 		}
-		convertedValue, err := storable.StoredValue(array.Storage)
-		if err != nil {
-			return fmt.Errorf("failed to convert storable to value at %d: %w", i, err)
-		}
 		err = valueEqual(v, convertedValue)
 		if err != nil {
 			return fmt.Errorf("failed to compare %s and %s: %w", v, convertedValue, err)