From 9f68305c2e88b1aea294ac3e75b75038151534e1 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <e.stratonikov@yadro.com>
Date: Mon, 19 Feb 2024 17:03:25 +0300
Subject: [PATCH] Revert "[#972] pilorama: Remove removeDuplicatesInPlace()"

This reverts commit 45fd4e4ff16dd63d60afe816c41ee71e1a16db28.

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
---
 pkg/local_object_storage/pilorama/batch.go    | 15 +++-
 .../pilorama/batch_test.go                    | 70 +++++++++++++++++++
 2 files changed, 83 insertions(+), 2 deletions(-)
 create mode 100644 pkg/local_object_storage/pilorama/batch_test.go

diff --git a/pkg/local_object_storage/pilorama/batch.go b/pkg/local_object_storage/pilorama/batch.go
index 520c6dfb4..c65488b74 100644
--- a/pkg/local_object_storage/pilorama/batch.go
+++ b/pkg/local_object_storage/pilorama/batch.go
@@ -2,7 +2,6 @@ package pilorama
 
 import (
 	"encoding/binary"
-	"slices"
 	"sort"
 	"sync"
 	"time"
@@ -51,7 +50,7 @@ func (b *batch) run() {
 		sort.Slice(b.operations, func(i, j int) bool {
 			return b.operations[i].Time < b.operations[j].Time
 		})
-		b.operations = slices.CompactFunc(b.operations, func(x, y *Move) bool { return x.Time == y.Time })
+		b.operations = removeDuplicatesInPlace(b.operations)
 
 		// Our main use-case is addition of new items. In this case,
 		// we do not need to perform undo()/redo(), just do().
@@ -116,3 +115,15 @@ func (b *batch) run() {
 		b.results[i] <- err
 	}
 }
+
+func removeDuplicatesInPlace(a []*Move) []*Move {
+	equalCount := 0
+	for i := 1; i < len(a); i++ {
+		if a[i].Time == a[i-1].Time {
+			equalCount++
+		} else {
+			a[i-equalCount] = a[i]
+		}
+	}
+	return a[:len(a)-equalCount]
+}
diff --git a/pkg/local_object_storage/pilorama/batch_test.go b/pkg/local_object_storage/pilorama/batch_test.go
new file mode 100644
index 000000000..931fce18c
--- /dev/null
+++ b/pkg/local_object_storage/pilorama/batch_test.go
@@ -0,0 +1,70 @@
+package pilorama
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_removeDuplicatesInPlace(t *testing.T) {
+	testCases := []struct {
+		before []int
+		after  []int
+	}{
+		{
+			before: []int{},
+			after:  []int{},
+		},
+		{
+			before: []int{1},
+			after:  []int{1},
+		},
+		{
+			before: []int{1, 2},
+			after:  []int{1, 2},
+		},
+		{
+			before: []int{1, 2, 3},
+			after:  []int{1, 2, 3},
+		},
+		{
+			before: []int{1, 1, 2},
+			after:  []int{1, 2},
+		},
+		{
+			before: []int{1, 2, 2},
+			after:  []int{1, 2},
+		},
+		{
+			before: []int{1, 2, 2, 3},
+			after:  []int{1, 2, 3},
+		},
+		{
+			before: []int{1, 1, 1},
+			after:  []int{1},
+		},
+		{
+			before: []int{1, 1, 2, 2},
+			after:  []int{1, 2},
+		},
+		{
+			before: []int{1, 1, 1, 2, 3, 3, 3},
+			after:  []int{1, 2, 3},
+		},
+	}
+
+	for _, tc := range testCases {
+		ops := make([]*Move, len(tc.before))
+		for i := range ops {
+			ops[i] = &Move{Meta: Meta{Time: Timestamp(tc.before[i])}}
+		}
+
+		expected := make([]*Move, len(tc.after))
+		for i := range expected {
+			expected[i] = &Move{Meta: Meta{Time: Timestamp(tc.after[i])}}
+		}
+
+		actual := removeDuplicatesInPlace(ops)
+		require.Equal(t, expected, actual, "%d", tc.before)
+	}
+}