util: added read affinity related functions and unit testcases

This commit adds util functions related to read affinity
and unit testcases for the same.

Signed-off-by: Praveen M <m.praveen@ibm.com>

internal/util/read_affinity.go

@@ -0,0 +1,76 @@
+/*
+Copyright 2023 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ConstructReadAffinityMapOption constructs a read affinity map option based on the provided crushLocationMap.
+// It appends crush location labels in the format
+// "read_from_replica=localize,crush_location=label1:value1|label2:value2|...".
+func ConstructReadAffinityMapOption(crushLocationMap map[string]string) string {
+	if len(crushLocationMap) == 0 {
+		return ""
+	}
+
+	var b strings.Builder
+	b.WriteString("read_from_replica=localize,crush_location=")
+	first := true
+	for key, val := range crushLocationMap {
+		if first {
+			b.WriteString(fmt.Sprintf("%s:%s", key, val))
+			first = false
+		} else {
+			b.WriteString(fmt.Sprintf("|%s:%s", key, val))
+		}
+	}
+
+	return b.String()
+}
+
+// GetReadAffinityMapOptions retrieves the readAffinityMapOptions from the CSI config file if it exists.
+// If not, it falls back to returning the `cliReadAffinityMapOptions` from the command line.
+// If neither of these options is available, it returns an empty string.
+func GetReadAffinityMapOptions(
+	clusterID, cliReadAffinityMapOptions string, nodeLabels map[string]string,
+) (string, error) {
+	var (
+		err                       error
+		configReadAffinityEnabled bool
+		configCrushLocationLabels string
+	)
+
+	configReadAffinityEnabled, configCrushLocationLabels, err = GetCrushLocationLabels(CsiConfigFile, clusterID)
+	if err != nil {
+		return "", err
+	}
+
+	if !configReadAffinityEnabled {
+		return "", nil
+	}
+
+	if configCrushLocationLabels == "" {
+		return cliReadAffinityMapOptions, nil
+	}
+
+	crushLocationMap := GetCrushLocationMap(configCrushLocationLabels, nodeLabels)
+	readAffinityMapOptions := ConstructReadAffinityMapOption(crushLocationMap)
+
+	return readAffinityMapOptions, nil
+}

internal/util/read_affinity_test.go

@@ -0,0 +1,68 @@
+/*
+Copyright 2023 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestReadAffinity_ConstructReadAffinityMapOption(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name             string
+		crushLocationmap map[string]string
+		wantAny          []string
+	}{
+		{
+			name:             "nil crushLocationmap",
+			crushLocationmap: nil,
+			wantAny:          []string{""},
+		},
+		{
+			name:             "empty crushLocationmap",
+			crushLocationmap: map[string]string{},
+			wantAny:          []string{""},
+		},
+		{
+			name: "single entry in crushLocationmap",
+			crushLocationmap: map[string]string{
+				"region": "east",
+			},
+			wantAny: []string{"read_from_replica=localize,crush_location=region:east"},
+		},
+		{
+			name: "multiple entries in crushLocationmap",
+			crushLocationmap: map[string]string{
+				"region": "east",
+				"zone":   "east-1",
+			},
+			wantAny: []string{
+				"read_from_replica=localize,crush_location=region:east|zone:east-1",
+				"read_from_replica=localize,crush_location=zone:east-1|region:east",
+			},
+		},
+	}
+	for _, tt := range tests {
+		currentTT := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			assert.Contains(t, currentTT.wantAny, ConstructReadAffinityMapOption(currentTT.crushLocationmap))
+		})
+	}
+}