Merge pull request #17610 from influxdata/fix-cursor-buffer-read

fix(storage): Fix query cursor read that caused cursor truncation.

storage/reads/array_cursor.gen.go

@@ -55,8 +55,6 @@ func (c *floatArrayFilterCursor) Next() *cursors.FloatArray {
 
 	if c.tmp.Len() > 0 {
 		a = c.tmp
-		c.tmp.Timestamps = nil
-		c.tmp.Values = nil
 	} else {
 		a = c.FloatArrayCursor.Next()
 	}
@@ -76,6 +74,12 @@ LOOP:
 				}
 			}
 		}
+
+		// Clear bufferred timestamps & values if we make it through a cursor.
+		// The break above will skip this if a cursor is partially read.
+		c.tmp.Timestamps = nil
+		c.tmp.Values = nil
+
 		a = c.FloatArrayCursor.Next()
 	}
 
@@ -271,8 +275,6 @@ func (c *integerArrayFilterCursor) Next() *cursors.IntegerArray {
 
 	if c.tmp.Len() > 0 {
 		a = c.tmp
-		c.tmp.Timestamps = nil
-		c.tmp.Values = nil
 	} else {
 		a = c.IntegerArrayCursor.Next()
 	}
@@ -292,6 +294,12 @@ LOOP:
 				}
 			}
 		}
+
+		// Clear bufferred timestamps & values if we make it through a cursor.
+		// The break above will skip this if a cursor is partially read.
+		c.tmp.Timestamps = nil
+		c.tmp.Values = nil
+
 		a = c.IntegerArrayCursor.Next()
 	}
 
@@ -487,8 +495,6 @@ func (c *unsignedArrayFilterCursor) Next() *cursors.UnsignedArray {
 
 	if c.tmp.Len() > 0 {
 		a = c.tmp
-		c.tmp.Timestamps = nil
-		c.tmp.Values = nil
 	} else {
 		a = c.UnsignedArrayCursor.Next()
 	}
@@ -508,6 +514,12 @@ LOOP:
 				}
 			}
 		}
+
+		// Clear bufferred timestamps & values if we make it through a cursor.
+		// The break above will skip this if a cursor is partially read.
+		c.tmp.Timestamps = nil
+		c.tmp.Values = nil
+
 		a = c.UnsignedArrayCursor.Next()
 	}
 
@@ -703,8 +715,6 @@ func (c *stringArrayFilterCursor) Next() *cursors.StringArray {
 
 	if c.tmp.Len() > 0 {
 		a = c.tmp
-		c.tmp.Timestamps = nil
-		c.tmp.Values = nil
 	} else {
 		a = c.StringArrayCursor.Next()
 	}
@@ -724,6 +734,12 @@ LOOP:
 				}
 			}
 		}
+
+		// Clear bufferred timestamps & values if we make it through a cursor.
+		// The break above will skip this if a cursor is partially read.
+		c.tmp.Timestamps = nil
+		c.tmp.Values = nil
+
 		a = c.StringArrayCursor.Next()
 	}
 
@@ -879,8 +895,6 @@ func (c *booleanArrayFilterCursor) Next() *cursors.BooleanArray {
 
 	if c.tmp.Len() > 0 {
 		a = c.tmp
-		c.tmp.Timestamps = nil
-		c.tmp.Values = nil
 	} else {
 		a = c.BooleanArrayCursor.Next()
 	}
@@ -900,6 +914,12 @@ LOOP:
 				}
 			}
 		}
+
+		// Clear bufferred timestamps & values if we make it through a cursor.
+		// The break above will skip this if a cursor is partially read.
+		c.tmp.Timestamps = nil
+		c.tmp.Values = nil
+
 		a = c.BooleanArrayCursor.Next()
 	}
 

storage/reads/array_cursor.gen.go.tmpl

@@ -54,8 +54,6 @@ func (c *{{$type}}) Next() {{$arrayType}} {
 
 	if c.tmp.Len() > 0 {
 		a = c.tmp
-		c.tmp.Timestamps = nil
-		c.tmp.Values = nil
 	} else {
 		a = c.{{.Name}}ArrayCursor.Next()
 	}
@@ -75,6 +73,12 @@ LOOP:
 				}
 			}
 		}
+		
+		// Clear bufferred timestamps & values if we make it through a cursor.
+		// The break above will skip this if a cursor is partially read.
+		c.tmp.Timestamps = nil
+		c.tmp.Values = nil
+		
 		a = c.{{.Name}}ArrayCursor.Next()
 	}
 

storage/reads/array_cursor_test.go

@@ -0,0 +1,58 @@
+package reads
+
+import (
+	"testing"
+
+	"github.com/influxdata/influxdb/v2/tsdb/cursors"
+)
+
+func TestIntegerFilterArrayCursor(t *testing.T) {
+	var i int
+	expr := MockExpression{
+		EvalBoolFunc: func(v Valuer) bool {
+			i++
+			return i%2 == 0
+		},
+	}
+
+	var resultN int
+	ac := MockIntegerArrayCursor{
+		CloseFunc: func() {},
+		ErrFunc:   func() error { return nil },
+		StatsFunc: func() cursors.CursorStats { return cursors.CursorStats{} },
+		NextFunc: func() *cursors.IntegerArray {
+			resultN++
+			if resultN == 4 {
+				return cursors.NewIntegerArrayLen(0)
+			}
+			return cursors.NewIntegerArrayLen(900)
+		},
+	}
+
+	c := newIntegerFilterArrayCursor(&expr)
+	c.reset(&ac)
+
+	if got, want := len(c.Next().Timestamps), 1000; got != want {
+		t.Fatalf("len(Next())=%d, want %d", got, want)
+	} else if got, want := len(c.Next().Timestamps), 350; got != want {
+		t.Fatalf("len(Next())=%d, want %d", got, want)
+	}
+}
+
+type MockIntegerArrayCursor struct {
+	CloseFunc func()
+	ErrFunc   func() error
+	StatsFunc func() cursors.CursorStats
+	NextFunc  func() *cursors.IntegerArray
+}
+
+func (c *MockIntegerArrayCursor) Close()                      { c.CloseFunc() }
+func (c *MockIntegerArrayCursor) Err() error                  { return c.ErrFunc() }
+func (c *MockIntegerArrayCursor) Stats() cursors.CursorStats  { return c.StatsFunc() }
+func (c *MockIntegerArrayCursor) Next() *cursors.IntegerArray { return c.NextFunc() }
+
+type MockExpression struct {
+	EvalBoolFunc func(v Valuer) bool
+}
+
+func (e *MockExpression) EvalBool(v Valuer) bool { return e.EvalBoolFunc(v) }