From 22acd84019a0eaf678952167f163ef27ecee157f Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@victoriametrics.com>
Date: Thu, 29 Feb 2024 17:24:34 +0200
Subject: [PATCH] lib/storage: use unsafe.Slice instead of deprecated
 reflect.SliceHeader

---
 lib/storage/index_db.go | 25 +++++--------------------
 1 file changed, 5 insertions(+), 20 deletions(-)

diff --git a/lib/storage/index_db.go b/lib/storage/index_db.go
index a710eba4a8..dab52f186f 100644
--- a/lib/storage/index_db.go
+++ b/lib/storage/index_db.go
@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"io"
 	"path/filepath"
-	"reflect"
 	"sort"
 	"strconv"
 	"sync"
@@ -415,14 +414,7 @@ func marshalMetricIDs(dst []byte, metricIDs []uint64) []byte {
 	// Compress metricIDs, so they occupy less space in the cache.
 	//
 	// The srcBuf is a []byte cast of metricIDs.
-	var srcBuf []byte
-	if len(metricIDs) > 0 {
-		sh := (*reflect.SliceHeader)(unsafe.Pointer(&srcBuf))
-		sh.Data = uintptr(unsafe.Pointer(&metricIDs[0]))
-		sh.Cap = 8 * len(metricIDs)
-		sh.Len = 8 * len(metricIDs)
-	}
-
+	srcBuf := unsafe.Slice((*byte)(unsafe.Pointer(unsafe.SliceData(metricIDs))), 8*len(metricIDs))
 	dst = encoding.CompressZSTDLevel(dst, srcBuf, 1)
 	return dst
 }
@@ -431,13 +423,8 @@ func mustUnmarshalMetricIDs(dst []uint64, src []byte) []uint64 {
 	// Decompress src into dstBuf.
 	//
 	// dstBuf is a []byte cast of dst.
-	var dstBuf []byte
-	if len(dst) > 0 {
-		sh := (*reflect.SliceHeader)(unsafe.Pointer(&dstBuf))
-		sh.Data = uintptr(unsafe.Pointer(&dst[0]))
-		sh.Cap = 8 * cap(dst)
-		sh.Len = 8 * len(dst)
-	}
+	dstBuf := unsafe.Slice((*byte)(unsafe.Pointer(unsafe.SliceData(dst))), 8*cap(dst))
+	dstBuf = dstBuf[:8*len(dst)]
 	dstBufLen := len(dstBuf)
 	var err error
 	dstBuf, err = encoding.DecompressZSTD(dstBuf, src)
@@ -453,10 +440,8 @@ func mustUnmarshalMetricIDs(dst []uint64, src []byte) []uint64 {
 	}
 
 	// Convert dstBuf back to dst
-	sh := (*reflect.SliceHeader)(unsafe.Pointer(&dst))
-	sh.Data = uintptr(unsafe.Pointer(&dstBuf[0]))
-	sh.Cap = cap(dstBuf) / 8
-	sh.Len = len(dstBuf) / 8
+	dst = unsafe.Slice((*uint64)(unsafe.Pointer(unsafe.SliceData(dstBuf))), cap(dstBuf)/8)
+	dst = dst[:len(dstBuf)/8]
 
 	return dst
 }