Refactor EntityStore interface to multiple interfaces of specific type

runner/storage.go

@@ -0,0 +1,74 @@
+package runner
+
+import (
+	"sync"
+)
+
+// Storage is an interface for storing runners.
+type Storage interface {
+	// Add adds an runner to the storage.
+	// It overwrites the old runner if one with the same id was already stored.
+	Add(Runner)
+
+	// Get returns a runner from the storage.
+	// Iff the runner does not exist in the storage, ok will be false.
+	Get(id string) (r Runner, ok bool)
+
+	// Delete deletes the runner with the passed id from the storage. It does nothing if no runner with the id is present in the store.
+	Delete(id string)
+
+	// Length returns the number of currently stored runners in the storage.
+	Length() int
+
+	// Sample returns and removes an arbitrary runner from the storage.
+	// ok is true iff a runner was returned.
+	Sample() (r Runner, ok bool)
+}
+
+// localRunnerStorage stores runner objects in the local application memory.
+// ToDo: Create implementation that use some persistent storage like a database
+type localRunnerStorage struct {
+	sync.RWMutex
+	runners map[string]Runner
+}
+
+// NewLocalRunnerStorage responds with a Storage implementation.
+// This implementation stores the data thread-safe in the local application memory
+func NewLocalRunnerStorage() *localRunnerStorage {
+	return &localRunnerStorage{
+		runners: make(map[string]Runner),
+	}
+}
+
+func (s *localRunnerStorage) Add(r Runner) {
+	s.Lock()
+	defer s.Unlock()
+	s.runners[r.Id()] = r
+}
+
+func (s *localRunnerStorage) Get(id string) (r Runner, ok bool) {
+	s.RLock()
+	defer s.RUnlock()
+	r, ok = s.runners[id]
+	return
+}
+
+func (s *localRunnerStorage) Delete(id string) {
+	s.Lock()
+	defer s.Unlock()
+	delete(s.runners, id)
+}
+
+func (s *localRunnerStorage) Sample() (Runner, bool) {
+	s.Lock()
+	defer s.Unlock()
+	for _, runner := range s.runners {
+		delete(s.runners, runner.Id())
+		return runner, true
+	}
+	return nil, false
+}
+
+func (s *localRunnerStorage) Length() int {
+	return len(s.runners)
+}