VOL-4019: Initial commit with grpc nbi, sbi, etcd, kafka and hw management rpcs.

Change-Id: I78feaf7da284028fc61f42c5e0c5f56e72fe9e78
diff --git a/pkg/db/operations.go b/pkg/db/operations.go
new file mode 100644
index 0000000..ea63050
--- /dev/null
+++ b/pkg/db/operations.go
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2020-present Open Networking Foundation
+ *
+ * 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 db holds utils for datastore implementation
+package db
+
+import (
+	"context"
+	"errors"
+
+	"github.com/opencord/voltha-lib-go/v4/pkg/log"
+)
+
+// Read function reads key value pair from db/kvstore
+func Read(ctx context.Context, key string) (string, error) {
+	if kvClient != nil {
+		logger.Debugw(ctx, "Reading-key-value-pair-from-kv-store", log.Fields{"key": key})
+		kvPair, err := kvClient.client.Get(ctx, key)
+		if err != nil {
+			return "", err
+		}
+		if kvPair == nil {
+			return "", errors.New("key not found")
+		}
+		return string(kvPair.Value.([]byte)), nil
+
+	}
+	logger.Errorw(ctx, "Reading-key-value-pair-in kv-store-failed-because-kvstore-not-initialised", log.Fields{"key": key})
+	return "", errors.New("kvstore not initialised")
+}
+
+// ReadAll function reads all key value pair from db/kvstore
+func ReadAll(ctx context.Context, keyPrefix string) (map[string]string, error) {
+	keyValues := make(map[string]string)
+	if kvClient != nil {
+		logger.Debugw(ctx, "Reading-all-key-value-pairs-from-kv-store", log.Fields{"key-prefix": keyPrefix})
+		kvPairs, err := kvClient.client.List(ctx, keyPrefix)
+		if err != nil {
+			return keyValues, err
+		}
+		if kvPairs == nil {
+			return keyValues, errors.New("key not found")
+		}
+
+		for key, kvPair := range kvPairs {
+			keyValues[key] = string(kvPair.Value.([]byte))
+		}
+		return keyValues, nil
+	}
+	logger.Errorw(ctx, "Reading-all-key-value-pair-in-kv-store-failed-because-kvstore-not-initialised", log.Fields{"key-prefix": keyPrefix})
+	return keyValues, errors.New("kvstore not initialised")
+}
+
+// Del function deletes key value pair from db/kvstore
+func Del(ctx context.Context, key string) error {
+	if kvClient != nil {
+		logger.Debugw(ctx, "Deleting-key-value-pair-from-kv-store", log.Fields{"key": key})
+		return kvClient.client.Delete(ctx, key)
+	}
+	logger.Errorw(ctx, "Deleting-key-value-pair-in-kv-store-failed-because-kvstore-not-initialised", log.Fields{"key": key})
+	return errors.New("kvstore not initialised")
+}
+
+// DelAll function deletes all key value pair from db/kvstore with provided key prefix
+func DelAll(ctx context.Context, keyPrefix string) error {
+	if kvClient != nil {
+		logger.Debugw(ctx, "Deleting-all-key-value-pair-from-kv-store-with-prefix", log.Fields{"key-prefix": keyPrefix})
+		return kvClient.client.DeleteWithPrefix(ctx, keyPrefix)
+	}
+	logger.Errorw(ctx, "Deleting-all-key-value-pair-in-kv-store-with-prefix-failed-because-kvstore-not-initialised", log.Fields{"key-prefix": keyPrefix})
+	return errors.New("kvstore not initialised")
+}
+
+// Put function stores key value pair in db/kvstore
+func Put(ctx context.Context, key string, val string) error {
+	if kvClient != nil {
+		logger.Debugw(ctx, "Storing-key-value-pair-in-kv-store", log.Fields{"key": key, "value": val})
+		return kvClient.client.Put(ctx, key, val)
+	}
+	logger.Errorw(ctx, "Storing-key-value-pair-in-kv-store-failed-because-kvstore-not-initialised", log.Fields{"key": key, "value": val})
+	return errors.New("kvstore not initialised")
+}