add mechanism to change the number of bytes sent to the application

types/block.go

@@ -262,9 +262,8 @@ func BlockFromProto(bp *tmproto.Block) (*Block, error) {
 //-----------------------------------------------------------------------------
 
 // MaxDataBytes returns the maximum size of block's data.
-//
-// XXX: Panics on negative result.
-func MaxDataBytes(maxBytes, evidenceBytes int64, valsCount int) int64 {
+// Returns an error if the max data is negative.
+func MaxDataBytes(maxBytes, evidenceBytes int64, valsCount int) (int64, error) {
 	maxDataBytes := maxBytes -
 		MaxOverheadForBlock -
 		MaxHeaderBytes -
@@ -272,36 +271,33 @@ func MaxDataBytes(maxBytes, evidenceBytes int64, valsCount int) int64 {
 		evidenceBytes
 
 	if maxDataBytes < 0 {
-		panic(fmt.Sprintf(
+		return maxDataBytes, fmt.Errorf(
 			"Negative MaxDataBytes. Block.MaxBytes=%d is too small to accommodate header&lastCommit&evidence=%d",
 			maxBytes,
 			-(maxDataBytes - maxBytes),
-		))
+		)
 	}
-
-	return maxDataBytes
+	return maxDataBytes, nil
 }
 
 // MaxDataBytesNoEvidence returns the maximum size of block's data when
 // evidence count is unknown. MaxEvidencePerBlock will be used for the size
 // of evidence.
-//
-// XXX: Panics on negative result.
-func MaxDataBytesNoEvidence(maxBytes int64, valsCount int) int64 {
+func MaxDataBytesNoEvidence(maxBytes int64, valsCount int) (int64, error) {
 	maxDataBytes := maxBytes -
 		MaxOverheadForBlock -
 		MaxHeaderBytes -
 		MaxCommitBytes(valsCount)
 
 	if maxDataBytes < 0 {
-		panic(fmt.Sprintf(
+		return maxDataBytes, fmt.Errorf(
 			"Negative MaxDataBytesUnknownEvidence. Block.MaxBytes=%d is too small to accommodate header&lastCommit&evidence=%d",
 			maxBytes,
 			-(maxDataBytes - maxBytes),
-		))
+		)
 	}
 
-	return maxDataBytes
+	return maxDataBytes, nil
 }
 
 // MakeBlock returns a new block with an empty header, except what can be

types/block_test.go

@@ -499,7 +499,7 @@ func TestBlockMaxDataBytes(t *testing.T) {
 		maxBytes      int64
 		valsCount     int
 		evidenceBytes int64
-		panics        bool
+		errors        bool
 		result        int64
 	}{
 		0: {-10, 1, 0, true, 0},
@@ -513,15 +513,12 @@ func TestBlockMaxDataBytes(t *testing.T) {
 
 	for i, tc := range testCases {
 		tc := tc
-		if tc.panics {
-			assert.Panics(t, func() {
-				MaxDataBytes(tc.maxBytes, tc.evidenceBytes, tc.valsCount)
-			}, "#%v", i)
+		b, err := MaxDataBytes(tc.maxBytes, tc.evidenceBytes, tc.valsCount)
+		if tc.errors {
+			require.Error(t, err, "#%v", i)
 		} else {
-			assert.Equal(t,
-				tc.result,
-				MaxDataBytes(tc.maxBytes, tc.evidenceBytes, tc.valsCount),
-				"#%v", i)
+			require.NoError(t, err)
+			assert.Equal(t, tc.result, b, "#%v", i)
 		}
 	}
 }
@@ -530,7 +527,7 @@ func TestBlockMaxDataBytesNoEvidence(t *testing.T) {
 	testCases := []struct {
 		maxBytes  int64
 		valsCount int
-		panics    bool
+		errors    bool
 		result    int64
 	}{
 		0: {-10, 1, true, 0},
@@ -542,15 +539,12 @@ func TestBlockMaxDataBytesNoEvidence(t *testing.T) {
 
 	for i, tc := range testCases {
 		tc := tc
-		if tc.panics {
-			assert.Panics(t, func() {
-				MaxDataBytesNoEvidence(tc.maxBytes, tc.valsCount)
-			}, "#%v", i)
+		b, err := MaxDataBytesNoEvidence(tc.maxBytes, tc.valsCount)
+		if tc.errors {
+			assert.Error(t, err, "#%v", i)
 		} else {
-			assert.Equal(t,
-				tc.result,
-				MaxDataBytesNoEvidence(tc.maxBytes, tc.valsCount),
-				"#%v", i)
+			require.NoError(t, err)
+			assert.Equal(t, tc.result, b, "#%v", i)
 		}
 	}
 }