Fix: Block stream read process would be terminated by empty block with zero rows

clickhouse_rows.go

@@ -52,7 +52,6 @@ next:
 				r.err = err
 				return false
 			}
-			goto next
 		case block := <-r.stream:
 			if block == nil {
 				return false
@@ -63,6 +62,7 @@ next:
 			}
 			r.row, r.block = 0, block
 		}
+		goto next
 	}
 	r.row++
 	return r.row <= r.block.Rows()

clickhouse_rows_test.go

@@ -0,0 +1,116 @@
+package clickhouse
+
+import (
+	"github.com/ClickHouse/clickhouse-go/v2/lib/proto"
+	"github.com/stretchr/testify/assert"
+	"strconv"
+	"testing"
+)
+
+func TestReadWithEmptyBlock(t *testing.T) {
+	blockInitFunc := func() *proto.Block {
+		retVal := &proto.Block{
+			Packet:   0,
+			Columns:  nil,
+			Timezone: nil,
+		}
+		retVal.AddColumn("col1", ("Int64"))
+		retVal.AddColumn("col2", ("String"))
+		return retVal
+	}
+
+	testCases := map[string]struct {
+		actual   func() rows
+		expected int
+	}{
+		"none empty": {
+			func() rows {
+				firstBlock := blockInitFunc()
+				firstBlock.Append(int64(0), strconv.Itoa(0))
+				blockChan := make(chan *proto.Block)
+				go func() {
+					for i := 1; i < 10; i++ {
+						block := blockInitFunc()
+						block.Append(int64(i), strconv.Itoa(i))
+						blockChan <- block
+					}
+					close(blockChan)
+				}()
+				return rows{
+					err:       nil,
+					row:       0,
+					block:     firstBlock,
+					totals:    nil,
+					errors:    nil,
+					stream:    blockChan,
+					columns:   nil,
+					structMap: nil,
+				}
+			},
+			10,
+		},
+		"all empty": {
+			func() rows {
+				firstBlock := blockInitFunc()
+				blockChan := make(chan *proto.Block)
+				go func() {
+					for i := 1; i < 10; i++ {
+						block := blockInitFunc()
+						blockChan <- block
+					}
+					close(blockChan)
+				}()
+				return rows{
+					err:       nil,
+					row:       0,
+					block:     firstBlock,
+					totals:    nil,
+					errors:    nil,
+					stream:    blockChan,
+					columns:   nil,
+					structMap: nil,
+				}
+			},
+			0,
+		},
+		"some empty": {
+			func() rows {
+				firstBlock := blockInitFunc()
+				blockChan := make(chan *proto.Block)
+				go func() {
+					for i := 1; i < 10; i++ {
+						block := blockInitFunc()
+						if i%2 == 0 {
+							block.Append(int64(i), strconv.Itoa(i))
+						}
+						blockChan <- block
+					}
+					close(blockChan)
+				}()
+				return rows{
+					err:       nil,
+					row:       0,
+					block:     firstBlock,
+					totals:    nil,
+					errors:    nil,
+					stream:    blockChan,
+					columns:   nil,
+					structMap: nil,
+				}
+			},
+			4,
+		},
+	}
+
+	for name, testCase := range testCases {
+		t.Run(name, func(t *testing.T) {
+			actual := testCase.actual()
+
+			rowCnt := 0
+			for actual.Next() {
+				rowCnt++
+			}
+			assert.Equal(t, testCase.expected, rowCnt)
+		})
+	}
+}