[#473] Implement EigenTrust calculations

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

pkg/services/reputation/eigentrust/controller/controller.go

@@ -0,0 +1,85 @@
+package eigentrustctrl
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/nspcc-dev/neofs-node/pkg/util"
+)
+
+// Prm groups the required parameters of the Controller'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).
+type Prm struct {
+	// Number of iterations
+	IterationNumber uint32
+
+	// Component of computing iteration of EigenTrust algorithm.
+	//
+	// Must not be nil.
+	DaughtersTrustCalculator DaughtersTrustCalculator
+
+	// Routine execution pool for single epoch iteration.
+	WorkerPool util.WorkerPool
+}
+
+// Controller represents EigenTrust algorithm transient controller.
+//
+// Controller's main goal is to separate the two main stages of
+// the calculation:
+//  1.reporting local values to manager nodes
+//  2.calculating global trusts of child nodes
+//
+// Calculation stages are controlled based on external signals
+// that come from the application through the Controller's API.
+//
+// For correct operation, the controller must be created
+// using the constructor (New) based on the required parameters
+// and optional components. After successful creation,
+// the constructor is immediately ready to work through
+// API of external control of calculations and data transfer.
+type Controller struct {
+	prm Prm
+
+	opts *options
+
+	mtx  sync.Mutex
+	mCtx map[uint64]*iterContextCancel
+}
+
+const invalidPrmValFmt = "invalid parameter %s (%T):%v"
+
+func panicOnPrmValue(n string, v interface{}) {
+	panic(fmt.Sprintf(invalidPrmValFmt, n, v, v))
+}
+
+// New creates a new instance of the Controller.
+//
+// Panics if at least one value of the parameters is invalid.
+//
+// The created Controller does not require additional
+// initialization and is completely ready for work.
+func New(prm Prm, opts ...Option) *Controller {
+	switch {
+	case prm.IterationNumber == 0:
+		panicOnPrmValue("IterationNumber", prm.IterationNumber)
+	case prm.WorkerPool == nil:
+		panicOnPrmValue("WorkerPool", prm.WorkerPool)
+	case prm.DaughtersTrustCalculator == nil:
+		panicOnPrmValue("DaughtersTrustCalculator", prm.DaughtersTrustCalculator)
+	}
+
+	o := defaultOpts()
+
+	for _, opt := range opts {
+		opt(o)
+	}
+
+	return &Controller{
+		prm:  prm,
+		opts: o,
+		mCtx: make(map[uint64]*iterContextCancel),
+	}
+}