From 74ec71446f873c771476218e56ad220450cc40b4 Mon Sep 17 00:00:00 2001
From: Pavel Karpy <p.karpy@yadro.com>
Date: Tue, 20 Dec 2022 16:15:15 +0300
Subject: [PATCH] [#2167] shard: Do not use write-cache by default in `Head`

Both `meta` and `write-cache` are expected to have a fast underlying disk,
so it does not seem like an optimisation. Moreover, `write-cache`'s `Head`
is a `Get` with payload cutting, it _must_ use more memory for no reason
(`meta` was created for such requests). Also, `write-cache` does not allow
performing any "meta" relations checks (such as locking, tombstoning).

Signed-off-by: Pavel Karpy <p.karpy@yadro.com>
---
 CHANGELOG.md                           |  1 +
 pkg/local_object_storage/shard/head.go | 19 -------------------
 2 files changed, 1 insertion(+), 19 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 932e3116c..7bee2e25b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ Changelog for NeoFS Node
 - Tree service now synchronizes with container nodes in a random order (#2127)
 - Pilorama no longer tries to apply already applied operations (#2161)
 - Use `sync.Pool` in Object.PUT service (#2139)
+- Shard uses metabase for `HEAD` requests by default, not write-cache (#2167)
 
 ### Fixed
 - Open FSTree in sync mode by default (#1992)
diff --git a/pkg/local_object_storage/shard/head.go b/pkg/local_object_storage/shard/head.go
index 3136e99ce..0e51da737 100644
--- a/pkg/local_object_storage/shard/head.go
+++ b/pkg/local_object_storage/shard/head.go
@@ -1,8 +1,6 @@
 package shard
 
 import (
-	"fmt"
-
 	meta "github.com/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
 	objectSDK "github.com/TrueCloudLab/frostfs-sdk-go/object"
 	oid "github.com/TrueCloudLab/frostfs-sdk-go/object/id"
@@ -46,23 +44,6 @@ func (r HeadRes) Object() *objectSDK.Object {
 // Returns an error of type apistatus.ObjectAlreadyRemoved if the requested object has been marked as removed in shard.
 // Returns the object.ErrObjectIsExpired if the object is presented but already expired.
 func (s *Shard) Head(prm HeadPrm) (HeadRes, error) {
-	// object can be saved in write-cache (if enabled) or in metabase
-
-	if s.hasWriteCache() {
-		// try to read header from write-cache
-		header, err := s.writeCache.Head(prm.addr)
-		if err == nil {
-			return HeadRes{
-				obj: header,
-			}, nil
-		} else if !IsErrNotFound(err) {
-			// in this case we think that object is presented in write-cache, but corrupted
-			return HeadRes{}, fmt.Errorf("could not read header from write-cache: %w", err)
-		}
-
-		// otherwise object seems to be flushed to metabase
-	}
-
 	var obj *objectSDK.Object
 	var err error
 	if s.GetMode().NoMetabase() {