add healthcheck service

internal/store/memory/store.go

@@ -0,0 +1,40 @@
+package memory
+
+import (
+	"context"
+	"sync"
+
+	"git.loyso.art/frx/devsim/internal/entities"
+)
+
+type store struct {
+	stats map[entities.DeviceID]entities.DeviceStatistics
+	mu    sync.Mutex
+}
+
+func NewStore() *store {
+	return &store{
+		stats: make(map[entities.DeviceID]entities.DeviceStatistics),
+	}
+}
+
+func (s *store) List(ctx context.Context) ([]entities.DeviceStatistics, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	out := make([]entities.DeviceStatistics, 0, len(s.stats))
+	for _, s := range s.stats {
+		out = append(out, s)
+	}
+
+	return out, nil
+}
+
+func (s *store) Upsert(ctx context.Context, stats entities.DeviceStatistics) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.stats[stats.ID] = stats
+
+	return nil
+}