[#428] reputation: Implement local trust storage

Implement in-memory `Storage` which is going to be used to submit the
results of interactions with network members. `Storage` also provides an
iterator interface, so the component can be used in `Controller`.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/services/reputation/local/storage/storage.go

@@ -0,0 +1,43 @@
+package truststorage
+
+import (
+	"sync"
+)
+
+// Prm groups the required parameters of the Storage's constructor.
+//
+// All values must comply with the requirements imposed on them.
+// Passing incorrect parameter values will result in constructor
+// failure (error or panic depending on the implementation).
+//
+// The component is not parameterizable at the moment.
+type Prm struct{}
+
+// Storage represents in-memory storage of
+// local reputation values.
+//
+// Storage provides access to normalized local trust
+// values through iterator interface.
+//
+// For correct operation, Storage must be created
+// using the constructor (New) based on the required parameters
+// and optional components. After successful creation,
+// Storage is immediately ready to work through API.
+type Storage struct {
+	prm Prm
+
+	mtx sync.RWMutex
+
+	mItems map[uint64]*EpochTrustValueStorage
+}
+
+// New creates a new instance of the Storage.
+//
+// The created Storage does not require additional
+// initialization and is completely ready for work.
+func New(prm Prm) *Storage {
+	return &Storage{
+		prm:    prm,
+		mItems: make(map[uint64]*EpochTrustValueStorage),
+	}
+}