Add week 2 materials

materials/02-communication/grpc-practice/go-server/storage/server.go

@@ -0,0 +1,65 @@
+package storage
+
+import (
+	"context"
+	"errors"
+	storagepb "hsegrpc/proto"
+	"sync"
+	"time"
+
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+type Value struct {
+	payload   uint64
+	updatedAt time.Time
+}
+
+// toProto transforms struct into protobuf wrapper.
+func (v *Value) toProto() *storagepb.Value {
+	return &storagepb.Value{
+		Payload:   v.payload,
+		UpdatedAt: timestamppb.New(v.updatedAt),
+	}
+}
+
+type Server struct {
+	// Server must implement the Storage protobuf interface.
+	storagepb.UnimplementedStorageServer
+
+	// We use mutex to synchronize access to the value.
+	valueLocker sync.RWMutex
+	value       Value
+}
+
+func NewServer() *Server {
+	return &Server{}
+}
+
+func (s *Server) PutValue(_ context.Context, request *storagepb.PutRequest) (*storagepb.PutResponse, error) {
+	s.valueLocker.Lock()
+	defer s.valueLocker.Unlock()
+
+	// Check if the given value not empty.
+	if request.GetValue() == nil {
+		return nil, errors.New("missed value")
+	}
+
+	s.value = Value{
+		payload:   request.GetValue().GetPayload(),
+		updatedAt: time.Now(),
+	}
+
+	return &storagepb.PutResponse{
+		Value: s.value.payload,
+	}, nil
+}
+
+func (s *Server) GetValue(_ context.Context, _ *storagepb.GetRequest) (*storagepb.GetResponse, error) {
+	s.valueLocker.RLock()
+	defer s.valueLocker.RUnlock()
+
+	return &storagepb.GetResponse{
+		Value: s.value.toProto(),
+	}, nil
+}