From 717c554fb07ff28f186aff1514c991bcfa1fc019 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Wed, 29 Jul 2020 11:51:37 +0300
Subject: [PATCH] app/vmselect/promql: remove rollupFuncArg.realPrevValue
 handling, since the corner case in `increase()` is handled in another way now

See e00cfc854df22fc64ad41dffcbacb44c32ba2060 for the approach used now.
---
 app/vmselect/promql/rollup.go      | 28 +++-------------------------
 app/vmselect/promql/rollup_test.go |  9 ++++-----
 2 files changed, 7 insertions(+), 30 deletions(-)

diff --git a/app/vmselect/promql/rollup.go b/app/vmselect/promql/rollup.go
index ba1d0588f3..0cfc4bec26 100644
--- a/app/vmselect/promql/rollup.go
+++ b/app/vmselect/promql/rollup.go
@@ -28,8 +28,8 @@ var rollupFuncs = map[string]newRollupFunc{
 	"deriv_fast":         newRollupFuncOneArg(rollupDerivFast),
 	"holt_winters":       newRollupHoltWinters,
 	"idelta":             newRollupFuncOneArg(rollupIdelta),
-	"increase":           newRollupFuncOneArg(rollupIncrease), // + rollupFuncsRemoveCounterResets
-	"irate":              newRollupFuncOneArg(rollupIderiv),   // + rollupFuncsRemoveCounterResets
+	"increase":           newRollupFuncOneArg(rollupDelta),  // + rollupFuncsRemoveCounterResets
+	"irate":              newRollupFuncOneArg(rollupIderiv), // + rollupFuncsRemoveCounterResets
 	"predict_linear":     newRollupPredictLinear,
 	"rate":               newRollupFuncOneArg(rollupDerivFast), // + rollupFuncsRemoveCounterResets
 	"resets":             newRollupFuncOneArg(rollupResets),
@@ -94,7 +94,7 @@ var rollupAggrFuncs = map[string]rollupFunc{
 	"deriv":            rollupDerivSlow,
 	"deriv_fast":       rollupDerivFast,
 	"idelta":           rollupIdelta,
-	"increase":         rollupIncrease,  // + rollupFuncsRemoveCounterResets
+	"increase":         rollupDelta,     // + rollupFuncsRemoveCounterResets
 	"irate":            rollupIderiv,    // + rollupFuncsRemoveCounterResets
 	"rate":             rollupDerivFast, // + rollupFuncsRemoveCounterResets
 	"resets":           rollupResets,
@@ -327,10 +327,6 @@ type rollupFuncArg struct {
 	idx           int
 	step          int64
 
-	// Real previous value even if it is located too far from the current window.
-	// It matches prevValue if prevValue is not nan.
-	realPrevValue float64
-
 	tsm *timeseriesMap
 }
 
@@ -342,7 +338,6 @@ func (rfa *rollupFuncArg) reset() {
 	rfa.currTimestamp = 0
 	rfa.idx = 0
 	rfa.step = 0
-	rfa.realPrevValue = nan
 	rfa.tsm = nil
 }
 
@@ -487,7 +482,6 @@ func (rc *rollupConfig) doInternal(dstValues []float64, tsm *timeseriesMap, valu
 	rfa := getRollupFuncArg()
 	rfa.idx = 0
 	rfa.step = rc.Step
-	rfa.realPrevValue = nan
 	rfa.tsm = tsm
 
 	i := 0
@@ -514,11 +508,6 @@ func (rc *rollupConfig) doInternal(dstValues []float64, tsm *timeseriesMap, valu
 		rfa.values = values[i:j]
 		rfa.timestamps = timestamps[i:j]
 		rfa.currTimestamp = tEnd
-		if i > 0 {
-			rfa.realPrevValue = values[i-1]
-		} else {
-			rfa.realPrevValue = nan
-		}
 		value := rc.Func(rfa)
 		rfa.idx++
 		dstValues = append(dstValues, value)
@@ -1205,14 +1194,6 @@ func rollupStdvar(rfa *rollupFuncArg) float64 {
 }
 
 func rollupDelta(rfa *rollupFuncArg) float64 {
-	return rollupDeltaInternal(rfa, false)
-}
-
-func rollupIncrease(rfa *rollupFuncArg) float64 {
-	return rollupDeltaInternal(rfa, true)
-}
-
-func rollupDeltaInternal(rfa *rollupFuncArg, canUseRealPrevValue bool) float64 {
 	// There is no need in handling NaNs here, since they must be cleaned up
 	// before calling rollup funcs.
 	values := rfa.values
@@ -1236,9 +1217,6 @@ func rollupDeltaInternal(rfa *rollupFuncArg, canUseRealPrevValue bool) float64 {
 		}
 		if math.Abs(values[0]) < 10*(math.Abs(d)+1) {
 			prevValue = 0
-			if canUseRealPrevValue && !math.IsNaN(rfa.realPrevValue) {
-				prevValue = rfa.realPrevValue
-			}
 		} else {
 			prevValue = values[0]
 			values = values[1:]
diff --git a/app/vmselect/promql/rollup_test.go b/app/vmselect/promql/rollup_test.go
index 9b63706154..7a467413b9 100644
--- a/app/vmselect/promql/rollup_test.go
+++ b/app/vmselect/promql/rollup_test.go
@@ -1040,15 +1040,14 @@ func testRowsEqual(t *testing.T, values []float64, timestamps []int64, valuesExp
 	}
 }
 
-func TestRollupIncrease(t *testing.T) {
+func TestRollupDelta(t *testing.T) {
 	f := func(prevValue float64, values []float64, resultExpected float64) {
 		t.Helper()
 		rfa := &rollupFuncArg{
-			prevValue:     prevValue,
-			realPrevValue: prevValue,
-			values:        values,
+			prevValue: prevValue,
+			values:    values,
 		}
-		result := rollupIncrease(rfa)
+		result := rollupDelta(rfa)
 		if math.IsNaN(result) {
 			if !math.IsNaN(resultExpected) {
 				t.Fatalf("unexpected result; got %v; want %v", result, resultExpected)