From 7a7a313426f5ebd42ba50d494bc32805e3ee94cb Mon Sep 17 00:00:00 2001
From: Pasha Sviderski <me@psviderski.name>
Date: Thu, 27 Aug 2026 12:27:54 +1000
Subject: [PATCH] feat(distlock): add gRPC Lease server that adapts a
 machine-local Store

---
 internal/distlock/server.go | 98 +++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 internal/distlock/server.go

diff --git a/internal/distlock/server.go b/internal/distlock/server.go
new file mode 100644
index 00000000..30026ea1
--- /dev/null
+++ b/internal/distlock/server.go
@@ -0,0 +1,98 @@
+package distlock
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/psviderski/uncloud/internal/machine/api/pb"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/durationpb"
+)
+
+// Server adapts a machine-local Store to the Lease gRPC service.
+type Server struct {
+	pb.UnimplementedLeaseServer
+	store Store
+}
+
+// NewServer creates a machine-local lease server.
+func NewServer(store Store) *Server {
+	return &Server{store: store}
+}
+
+// Acquire creates a lease when the resource has no unexpired lease.
+func (s *Server) Acquire(ctx context.Context, req *pb.AcquireLeaseRequest) (*pb.AcquireLeaseResponse, error) {
+	ttl, err := validateLeaseRequest(req.Resource, req.Token, req.Ttl)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, err.Error())
+	}
+
+	acquired, err := s.store.Acquire(ctx, req.Resource, req.Token, ttl)
+	if err != nil {
+		return nil, storeStatusError(ctx, "acquire lease", err)
+	}
+	return &pb.AcquireLeaseResponse{Acquired: acquired}, nil
+}
+
+// Renew extends an unexpired lease when its ownership token matches.
+func (s *Server) Renew(ctx context.Context, req *pb.RenewLeaseRequest) (*pb.RenewLeaseResponse, error) {
+	ttl, err := validateLeaseRequest(req.Resource, req.Token, req.Ttl)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, err.Error())
+	}
+
+	renewed, err := s.store.Renew(ctx, req.Resource, req.Token, ttl)
+	if err != nil {
+		return nil, storeStatusError(ctx, "renew lease", err)
+	}
+	return &pb.RenewLeaseResponse{Renewed: renewed}, nil
+}
+
+// Release removes an unexpired lease when its ownership token matches.
+func (s *Server) Release(ctx context.Context, req *pb.ReleaseLeaseRequest) (*pb.ReleaseLeaseResponse, error) {
+	if err := validateResourceToken(req.Resource, req.Token); err != nil {
+		return nil, status.Error(codes.InvalidArgument, err.Error())
+	}
+
+	released, err := s.store.Release(ctx, req.Resource, req.Token)
+	if err != nil {
+		return nil, storeStatusError(ctx, "release lease", err)
+	}
+	return &pb.ReleaseLeaseResponse{Released: released}, nil
+}
+
+func validateLeaseRequest(resource string, token []byte, ttl *durationpb.Duration) (time.Duration, error) {
+	if err := validateResourceToken(resource, token); err != nil {
+		return 0, err
+	}
+	if ttl == nil {
+		return 0, fmt.Errorf("TTL is not set")
+	}
+	if err := ttl.CheckValid(); err != nil {
+		return 0, fmt.Errorf("invalid TTL: %w", err)
+	}
+	duration := ttl.AsDuration()
+	if duration <= 0 {
+		return 0, fmt.Errorf("TTL must be positive")
+	}
+	return duration, nil
+}
+
+func validateResourceToken(resource string, token []byte) error {
+	if resource == "" {
+		return fmt.Errorf("resource is empty")
+	}
+	if len(token) == 0 {
+		return fmt.Errorf("token is empty")
+	}
+	return nil
+}
+
+func storeStatusError(ctx context.Context, operation string, err error) error {
+	if ctxErr := ctx.Err(); ctxErr != nil {
+		return status.FromContextError(ctxErr).Err()
+	}
+	return status.Error(codes.Internal, fmt.Sprintf("%s: %v", operation, err))
+}