From 7913681297b1b986b47366387e844955fac6063b Mon Sep 17 00:00:00 2001
From: Lisandro Pin <lisandro.pin@proton.ch>
Date: Wed, 29 Jan 2025 17:50:19 +0100
Subject: [PATCH] `ec.encode`: Display a warning on EC balancing if no replica
 placement settings are found. (#6487)

---
 weed/shell/command_ec_common.go               | 28 +++++++++++-------
 weed/storage/super_block/replica_placement.go |  4 +++
 .../super_block/replica_placement_test.go     | 29 +++++++++++++++++++
 3 files changed, 51 insertions(+), 10 deletions(-)

diff --git a/weed/shell/command_ec_common.go b/weed/shell/command_ec_common.go
index 0e9062d23..afbb750aa 100644
--- a/weed/shell/command_ec_common.go
+++ b/weed/shell/command_ec_common.go
@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"math/rand/v2"
+	"slices"
 	"sort"
 	"sync"
 	"time"
@@ -19,7 +20,6 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/storage/super_block"
 	"github.com/seaweedfs/seaweedfs/weed/storage/types"
 	"google.golang.org/grpc"
-	"slices"
 )
 
 type DataCenterId string
@@ -176,20 +176,28 @@ func _getDefaultReplicaPlacement(commandEnv *CommandEnv) (*super_block.ReplicaPl
 }
 
 func parseReplicaPlacementArg(commandEnv *CommandEnv, replicaStr string) (*super_block.ReplicaPlacement, error) {
+	var rp *super_block.ReplicaPlacement
+	var err error
+
 	if replicaStr != "" {
-		rp, err := super_block.NewReplicaPlacementFromString(replicaStr)
-		if err == nil {
-			fmt.Printf("using replica placement %q for EC volumes\n", rp.String())
+		rp, err = super_block.NewReplicaPlacementFromString(replicaStr)
+		if err != nil {
+			return rp, err
 		}
-		return rp, err
+		fmt.Printf("using replica placement %q for EC volumes\n", rp.String())
+	} else {
+		// No replica placement argument provided, resolve from master default settings.
+		rp, err = getDefaultReplicaPlacement(commandEnv)
+		if err != nil {
+			return rp, err
+		}
+		fmt.Printf("using master default replica placement %q for EC volumes\n", rp.String())
 	}
 
-	// No replica placement argument provided, resolve from master default settings.
-	rp, err := getDefaultReplicaPlacement(commandEnv)
-	if err == nil {
-		fmt.Printf("using master default replica placement %q for EC volumes\n", rp.String())
+	if !rp.HasReplication() {
+		fmt.Printf("WARNING: replica placement type %q is empty!", rp.String())
 	}
-	return rp, err
+	return rp, nil
 }
 
 func collectTopologyInfo(commandEnv *CommandEnv, delayBeforeCollecting time.Duration) (topoInfo *master_pb.TopologyInfo, volumeSizeLimitMb uint64, err error) {
diff --git a/weed/storage/super_block/replica_placement.go b/weed/storage/super_block/replica_placement.go
index f6d14e25b..8ec44d48c 100644
--- a/weed/storage/super_block/replica_placement.go
+++ b/weed/storage/super_block/replica_placement.go
@@ -45,6 +45,10 @@ func NewReplicaPlacementFromByte(b byte) (*ReplicaPlacement, error) {
 	return NewReplicaPlacementFromString(fmt.Sprintf("%03d", b))
 }
 
+func (rp *ReplicaPlacement) HasReplication() bool {
+	return rp.DiffDataCenterCount != 0 || rp.DiffRackCount != 0 || rp.SameRackCount != 0
+}
+
 func (a *ReplicaPlacement) Equals(b *ReplicaPlacement) bool {
 	if a == nil || b == nil {
 		return false
diff --git a/weed/storage/super_block/replica_placement_test.go b/weed/storage/super_block/replica_placement_test.go
index 7742ba548..203e3e860 100644
--- a/weed/storage/super_block/replica_placement_test.go
+++ b/weed/storage/super_block/replica_placement_test.go
@@ -12,3 +12,32 @@ func TestReplicaPlacementSerialDeserial(t *testing.T) {
 		t.Fail()
 	}
 }
+
+func TestReplicaPlacementHasReplication(t *testing.T) {
+	testCases := []struct {
+		name             string
+		replicaPlacement string
+		want             bool
+	}{
+		{"empty replica placement", "", false},
+		{"no replication", "000", false},
+		{"same rack replication", "100", true},
+		{"diff rack replication", "020", true},
+		{"DC replication", "003", true},
+		{"full replication", "155", true},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			rp, err := NewReplicaPlacementFromString(tc.replicaPlacement)
+			if err != nil {
+				t.Errorf("failed to initialize ReplicaPlacement: %v", err)
+				return
+			}
+
+			if got, want := rp.HasReplication(), tc.want; got != want {
+				t.Errorf("expected %v, got %v", want, got)
+			}
+		})
+	}
+}