[#473] Implement EigenTrust calculations

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

pkg/services/reputation/eigentrust/calculator/calculator.go

@@ -0,0 +1,91 @@
+package eigentrustcalc
+
+import (
+	"fmt"
+
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
+	"github.com/nspcc-dev/neofs-node/pkg/util"
+)
+
+// Prm groups the required parameters of the Calculator'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 {
+	// Alpha parameter from origin EigenTrust algortihm
+	// http://ilpubs.stanford.edu:8090/562/1/2002-56.pdf Ch.5.1.
+	//
+	// Must be in range (0, 1).
+	Alpha float64
+
+	// Source of initial node trust values
+	//
+	// Must not be nil.
+	InitialTrustSource InitialTrustSource
+
+	DaughterTrustSource DaughterTrustIteratorProvider
+
+	IntermediateValueTarget IntermediateWriterProvider
+
+	FinalResultTarget IntermediateWriterProvider
+
+	WorkerPool util.WorkerPool
+}
+
+// Calculator is a processor of a single iteration of EigenTrust algorithm.
+//
+// For correct operation, the Calculator must be created
+// using the constructor (New) based on the required parameters
+// and optional components. After successful creation,
+// the Calculator is immediately ready to work through
+// API of external control of calculations and data transfer.
+type Calculator struct {
+	alpha, beta reputation.TrustValue // beta = 1 - alpha
+
+	prm Prm
+
+	opts *options
+}
+
+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 Calculator.
+//
+// Panics if at least one value of the parameters is invalid.
+//
+// The created Calculator does not require additional
+// initialization and is completely ready for work.
+func New(prm Prm, opts ...Option) *Calculator {
+	switch {
+	case prm.Alpha <= 0 || prm.Alpha >= 1:
+		panicOnPrmValue("Alpha", prm.Alpha)
+	case prm.InitialTrustSource == nil:
+		panicOnPrmValue("InitialTrustSource", prm.InitialTrustSource)
+	case prm.DaughterTrustSource == nil:
+		panicOnPrmValue("DaughterTrustSource", prm.DaughterTrustSource)
+	case prm.IntermediateValueTarget == nil:
+		panicOnPrmValue("IntermediateValueTarget", prm.IntermediateValueTarget)
+	case prm.FinalResultTarget == nil:
+		panicOnPrmValue("FinalResultTarget", prm.FinalResultTarget)
+	case prm.WorkerPool == nil:
+		panicOnPrmValue("WorkerPool", prm.WorkerPool)
+	}
+
+	o := defaultOpts()
+
+	for _, opt := range opts {
+		opt(o)
+	}
+
+	return &Calculator{
+		alpha: reputation.TrustValueFromFloat64(prm.Alpha),
+		beta:  reputation.TrustValueFromFloat64(1 - prm.Alpha),
+		prm:   prm,
+		opts:  o,
+	}
+}

pkg/services/reputation/eigentrust/calculator/calls.go

@@ -0,0 +1,270 @@
+package eigentrustcalc
+
+import (
+	"context"
+	"encoding/hex"
+
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation/eigentrust"
+	"go.uber.org/zap"
+)
+
+type CalculatePrm struct {
+	last bool
+
+	ei eigentrust.EpochIteration
+}
+
+func (p *CalculatePrm) SetEpochIteration(ei eigentrust.EpochIteration) {
+	p.ei = ei
+}
+
+type iterContext struct {
+	context.Context
+	eigentrust.EpochIteration
+}
+
+func (c *Calculator) Calculate(prm CalculatePrm) {
+	ctx := iterContext{
+		Context:        context.Background(),
+		EpochIteration: prm.ei,
+	}
+
+	iter := ctx.I()
+
+	if iter == 0 {
+		c.sendInitialValues(ctx)
+		return
+	}
+
+	// decrement iteration number to select the values collected
+	// on the previous stage
+	ctx.SetI(iter - 1)
+
+	consumersIter, err := c.prm.DaughterTrustSource.InitConsumersIterator(ctx)
+	if err != nil {
+		c.opts.log.Debug("consumers trust iterator's init failure",
+			zap.String("error", err.Error()),
+		)
+
+		return
+	}
+
+	// continue with initial iteration number
+	ctx.SetI(iter)
+
+	err = consumersIter.Iterate(func(daughter reputation.PeerID, iter TrustIterator) error {
+		err := c.prm.WorkerPool.Submit(func() {
+			c.iterateDaughter(iterDaughterPrm{
+				lastIter:      prm.last,
+				ctx:           ctx,
+				id:            daughter,
+				consumersIter: iter,
+			})
+		})
+		if err != nil {
+			c.opts.log.Debug("worker pool submit failure",
+				zap.String("error", err.Error()),
+			)
+		}
+
+		// don't stop trying
+		return nil
+	})
+	if err != nil {
+		c.opts.log.Debug("iterate daughters failed",
+			zap.String("error", err.Error()),
+		)
+	}
+}
+
+type iterDaughterPrm struct {
+	lastIter bool
+
+	ctx Context
+
+	id reputation.PeerID
+
+	consumersIter TrustIterator
+}
+
+func (c *Calculator) iterateDaughter(p iterDaughterPrm) {
+	initTrust, err := c.prm.InitialTrustSource.InitialTrust(p.id)
+	if err != nil {
+		c.opts.log.Debug("get initial trust failure",
+			zap.String("daughter", hex.EncodeToString(p.id.Bytes())),
+			zap.String("error", err.Error()),
+		)
+
+		return
+	}
+
+	daughterIter, err := c.prm.DaughterTrustSource.InitDaughterIterator(p.ctx, p.id)
+	if err != nil {
+		c.opts.log.Debug("daughter trust iterator's init failure",
+			zap.String("error", err.Error()),
+		)
+
+		return
+	}
+
+	sum := reputation.TrustZero
+
+	err = p.consumersIter.Iterate(func(trust reputation.Trust) error {
+		if !p.lastIter {
+			select {
+			case <-p.ctx.Done():
+				return p.ctx.Err()
+			default:
+			}
+		}
+
+		sum.Add(trust.Value())
+		return nil
+	})
+	if err != nil {
+		c.opts.log.Debug("iterate over daughter's trusts failure",
+			zap.String("error", err.Error()),
+		)
+
+		return
+	}
+
+	// Alpha * Pd
+	initTrust.Mul(c.alpha)
+
+	sum.Mul(c.beta)
+	sum.Add(initTrust)
+
+	var intermediateTrust eigentrust.IterationTrust
+
+	intermediateTrust.SetEpoch(p.ctx.Epoch())
+	intermediateTrust.SetTrustingPeer(p.id)
+	intermediateTrust.SetI(p.ctx.I())
+
+	if p.lastIter {
+		finalWriter, err := c.prm.FinalResultTarget.InitIntermediateWriter(p.ctx)
+		if err != nil {
+			c.opts.log.Debug("init intermediate writer failure",
+				zap.String("error", err.Error()),
+			)
+
+			return
+		}
+
+		intermediateTrust.SetValue(sum)
+
+		err = finalWriter.WriteIntermediateTrust(intermediateTrust)
+		if err != nil {
+			c.opts.log.Debug("write final result failure",
+				zap.String("error", err.Error()),
+			)
+
+			return
+		}
+	} else {
+		intermediateWriter, err := c.prm.IntermediateValueTarget.InitIntermediateWriter(p.ctx)
+		if err != nil {
+			c.opts.log.Debug("init intermediate writer failure",
+				zap.String("error", err.Error()),
+			)
+
+			return
+		}
+
+		err = daughterIter.Iterate(func(trust reputation.Trust) error {
+			select {
+			case <-p.ctx.Done():
+				return p.ctx.Err()
+			default:
+			}
+
+			val := trust.Value()
+			val.Mul(sum)
+
+			trust.SetValue(val)
+
+			intermediateTrust.SetPeer(trust.Peer())
+			intermediateTrust.SetValue(val)
+
+			err := intermediateWriter.WriteIntermediateTrust(intermediateTrust)
+			if err != nil {
+				c.opts.log.Debug("write intermediate value failure",
+					zap.String("error", err.Error()),
+				)
+			}
+
+			return nil
+		})
+		if err != nil {
+			c.opts.log.Debug("iterate daughter trusts failure",
+				zap.String("error", err.Error()),
+			)
+		}
+	}
+}
+
+func (c *Calculator) sendInitialValues(ctx Context) {
+	daughterIter, err := c.prm.DaughterTrustSource.InitAllDaughtersIterator(ctx)
+	if err != nil {
+		c.opts.log.Debug("all daughters trust iterator's init failure",
+			zap.String("error", err.Error()),
+		)
+
+		return
+	}
+
+	intermediateWriter, err := c.prm.IntermediateValueTarget.InitIntermediateWriter(ctx)
+	if err != nil {
+		c.opts.log.Debug("init intermediate writer failure",
+			zap.String("error", err.Error()),
+		)
+
+		return
+	}
+
+	var intermediateTrust eigentrust.IterationTrust
+
+	intermediateTrust.SetEpoch(ctx.Epoch())
+	intermediateTrust.SetI(ctx.I())
+
+	err = daughterIter.Iterate(func(daughter reputation.PeerID, iterator TrustIterator) error {
+		intermediateTrust.SetTrustingPeer(daughter)
+
+		return iterator.Iterate(func(trust reputation.Trust) error {
+			trusted := trust.Peer()
+
+			initTrust, err := c.prm.InitialTrustSource.InitialTrust(trusted)
+			if err != nil {
+				c.opts.log.Debug("get initial trust failure",
+					zap.String("peer", hex.EncodeToString(trusted.Bytes())),
+					zap.String("error", err.Error()),
+				)
+
+				// don't stop on single failure
+				return nil
+			}
+
+			intermediateTrust.SetPeer(trusted)
+
+			initTrust.Mul(trust.Value())
+			intermediateTrust.SetValue(initTrust)
+
+			err = intermediateWriter.WriteIntermediateTrust(intermediateTrust)
+			if err != nil {
+				c.opts.log.Debug("write intermediate value failure",
+					zap.String("error", err.Error()),
+				)
+
+				// don't stop on single failure
+			}
+
+			return nil
+		})
+	})
+	if err != nil {
+		c.opts.log.Debug("iterate over all daughters failure",
+			zap.String("error", err.Error()),
+		)
+	}
+}

pkg/services/reputation/eigentrust/calculator/deps.go

@@ -0,0 +1,47 @@
+package eigentrustcalc
+
+import (
+	"context"
+
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation/eigentrust"
+)
+
+type Context interface {
+	context.Context
+
+	// Must return epoch number to select the values
+	// for global trust calculation.
+	Epoch() uint64
+
+	// Must return the sequence number of the iteration.
+	I() uint32
+}
+
+type InitialTrustSource interface {
+	InitialTrust(reputation.PeerID) (reputation.TrustValue, error)
+}
+
+type TrustIterator interface {
+	Iterate(reputation.TrustHandler) error
+}
+
+type PeerTrustsHandler func(reputation.PeerID, TrustIterator) error
+
+type PeerTrustsIterator interface {
+	Iterate(PeerTrustsHandler) error
+}
+
+type DaughterTrustIteratorProvider interface {
+	InitDaughterIterator(Context, reputation.PeerID) (TrustIterator, error)
+	InitAllDaughtersIterator(Context) (PeerTrustsIterator, error)
+	InitConsumersIterator(Context) (PeerTrustsIterator, error)
+}
+
+type IntermediateWriter interface {
+	WriteIntermediateTrust(eigentrust.IterationTrust) error
+}
+
+type IntermediateWriterProvider interface {
+	InitIntermediateWriter(Context) (IntermediateWriter, error)
+}

pkg/services/reputation/eigentrust/calculator/opts.go

@@ -0,0 +1,30 @@
+package eigentrustcalc
+
+import (
+	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
+	"go.uber.org/zap"
+)
+
+// Option sets an optional parameter of Controller.
+type Option func(*options)
+
+type options struct {
+	log *logger.Logger
+}
+
+func defaultOpts() *options {
+	return &options{
+		log: zap.L(),
+	}
+}
+
+// WithLogger returns option to specify logging component.
+//
+// Ignores nil values.
+func WithLogger(l *logger.Logger) Option {
+	return func(o *options) {
+		if l != nil {
+			o.log = l
+		}
+	}
+}

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

@@ -0,0 +1,69 @@
+package eigentrustctrl
+
+import (
+	"context"
+
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation/eigentrust"
+	"go.uber.org/zap"
+)
+
+// ContinuePrm groups the required parameters of Continue operation.
+type ContinuePrm struct {
+	epoch uint64
+}
+
+type iterContext struct {
+	context.Context
+
+	eigentrust.EpochIteration
+
+	last bool
+}
+
+func (x iterContext) Last() bool {
+	return x.last
+}
+
+type iterContextCancel struct {
+	iterContext
+
+	cancel context.CancelFunc
+}
+
+// Continue moves the global reputation calculator to the next iteration.
+func (c *Controller) Continue(prm ContinuePrm) {
+	c.mtx.Lock()
+
+	{
+		iterCtx, ok := c.mCtx[prm.epoch]
+		if !ok {
+			iterCtx := new(iterContextCancel)
+			c.mCtx[prm.epoch] = iterCtx
+
+			iterCtx.Context, iterCtx.cancel = context.WithCancel(context.Background())
+		} else {
+			iterCtx.cancel()
+		}
+
+		iterCtx.last = iterCtx.I() == c.prm.IterationNumber
+
+		err := c.prm.WorkerPool.Submit(func() {
+			c.prm.DaughtersTrustCalculator.Calculate(iterCtx.iterContext)
+		})
+		if err != nil {
+			c.opts.log.Debug("iteration submit failure",
+				zap.String("error", err.Error()),
+			)
+		}
+
+		if iterCtx.last {
+			delete(c.mCtx, prm.epoch)
+			// In this case and worker pool failure we can mark epoch
+			// number as already processed, but in any case it grows up
+			// during normal operation of the system. Also, such information
+			// will only live while the application is alive.
+		}
+	}
+
+	c.mtx.Unlock()
+}

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),
+	}
+}

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

@@ -0,0 +1,35 @@
+package eigentrustctrl
+
+import (
+	"context"
+)
+
+// IterationContext is a context of the i-th
+// stage of iterative EigenTrust algorithm.
+type IterationContext interface {
+	context.Context
+
+	// Must return epoch number to select the values
+	// for global trust calculation.
+	Epoch() uint64
+
+	// Must return the sequence number of the iteration.
+	I() uint32
+
+	// Must return true if I() is the last iteration.
+	Last() bool
+}
+
+// DaughtersTrustCalculator is an interface of entity
+// responsible for calculating the global trust of
+// daughter nodes in terms of EigenTrust algorithm.
+type DaughtersTrustCalculator interface {
+	// Must perform the iteration step of the loop
+	// for computing the global trust of all daughter
+	// nodes and sending intermediate values
+	// according to EigenTrust description
+	// http://ilpubs.stanford.edu:8090/562/1/2002-56.pdf Ch.5.1.
+	//
+	// Execution should be interrupted if ctx.Last().
+	Calculate(ctx IterationContext)
+}

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

@@ -0,0 +1,30 @@
+package eigentrustctrl
+
+import (
+	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
+	"go.uber.org/zap"
+)
+
+// Option sets an optional parameter of Controller.
+type Option func(*options)
+
+type options struct {
+	log *logger.Logger
+}
+
+func defaultOpts() *options {
+	return &options{
+		log: zap.L(),
+	}
+}
+
+// WithLogger returns option to specify logging component.
+//
+// Ignores nil values.
+func WithLogger(l *logger.Logger) Option {
+	return func(o *options) {
+		if l != nil {
+			o.log = l
+		}
+	}
+}

pkg/services/reputation/eigentrust/iteration.go

@@ -0,0 +1,31 @@
+package eigentrust
+
+import (
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
+)
+
+type EpochIteration struct {
+	e uint64
+	i uint32
+}
+
+func (x EpochIteration) Epoch() uint64 {
+	return x.e
+}
+
+func (x *EpochIteration) SetEpoch(e uint64) {
+	x.e = e
+}
+
+func (x EpochIteration) I() uint32 {
+	return x.i
+}
+
+func (x *EpochIteration) SetI(i uint32) {
+	x.i = i
+}
+
+type IterationTrust struct {
+	EpochIteration
+	reputation.Trust
+}

pkg/services/reputation/eigentrust/storage/consumers/calls.go

@@ -0,0 +1,189 @@
+package consumerstorage
+
+import (
+	"sync"
+
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation/eigentrust"
+)
+
+// Put saves intermediate trust of the consumer to daughter peer.
+func (x *Storage) Put(trust eigentrust.IterationTrust) {
+	var s *iterationConsumersStorage
+
+	x.mtx.Lock()
+
+	{
+		epoch := trust.Epoch()
+
+		s = x.mItems[epoch]
+		if s == nil {
+			s = &iterationConsumersStorage{
+				mItems: make(map[uint32]*ConsumersStorage, 1),
+			}
+
+			x.mItems[epoch] = s
+		}
+	}
+
+	x.mtx.Unlock()
+
+	s.put(trust)
+}
+
+// Consumers returns the storage of trusts of the consumers of the daugher peers
+// for particular iteration of EigenTrust calculation for particular epoch.
+//
+// Returns false if there is no data for the epoch and iter.
+func (x *Storage) Consumers(epoch uint64, iter uint32) (*ConsumersStorage, bool) {
+	var (
+		s  *iterationConsumersStorage
+		ok bool
+	)
+
+	x.mtx.Lock()
+
+	{
+		s, ok = x.mItems[epoch]
+	}
+
+	x.mtx.Unlock()
+
+	if !ok {
+		return nil, false
+	}
+
+	return s.consumers(iter)
+}
+
+// maps iteration numbers of EigenTrust algorithm to repositories
+// of the trusts of the consumers of the daughter peers.
+type iterationConsumersStorage struct {
+	mtx sync.RWMutex
+
+	mItems map[uint32]*ConsumersStorage
+}
+
+func (x *iterationConsumersStorage) put(trust eigentrust.IterationTrust) {
+	var s *ConsumersStorage
+
+	x.mtx.Lock()
+
+	{
+		iter := trust.I()
+
+		s = x.mItems[iter]
+		if s == nil {
+			s = &ConsumersStorage{
+				mItems: make(map[reputation.PeerID]*ConsumersTrusts, 1),
+			}
+
+			x.mItems[iter] = s
+		}
+	}
+
+	x.mtx.Unlock()
+
+	s.put(trust)
+}
+
+func (x *iterationConsumersStorage) consumers(iter uint32) (s *ConsumersStorage, ok bool) {
+	x.mtx.Lock()
+
+	{
+		s, ok = x.mItems[iter]
+	}
+
+	x.mtx.Unlock()
+
+	return
+}
+
+// ConsumersStorage represents in-memory storage of intermediate trusts
+// of the peer consumers.
+//
+// Maps daughter peers to repositories of the trusts of their consumers.
+type ConsumersStorage struct {
+	mtx sync.RWMutex
+
+	mItems map[reputation.PeerID]*ConsumersTrusts
+}
+
+func (x *ConsumersStorage) put(trust eigentrust.IterationTrust) {
+	var s *ConsumersTrusts
+
+	x.mtx.Lock()
+
+	{
+		daughter := trust.Peer()
+
+		s = x.mItems[daughter]
+		if s == nil {
+			s = &ConsumersTrusts{
+				mItems: make(map[reputation.PeerID]reputation.Trust, 1),
+			}
+
+			x.mItems[daughter] = s
+		}
+	}
+
+	x.mtx.Unlock()
+
+	s.put(trust)
+}
+
+// Iterate passes IDs of the daughter peers with the trusts of their consumers to h.
+//
+// Returns errors from h directly.
+func (x *ConsumersStorage) Iterate(h func(trusted reputation.PeerID, consumerTrusts *ConsumersTrusts) error) (err error) {
+	x.mtx.RLock()
+
+	{
+		for trusted, trusts := range x.mItems {
+			if err = h(trusted, trusts); err != nil {
+				break
+			}
+		}
+	}
+
+	x.mtx.RUnlock()
+
+	return
+}
+
+// ConsumersTrusts represents in-memory storage of the trusts
+// of the consumer peers to some other peer.
+type ConsumersTrusts struct {
+	mtx sync.RWMutex
+
+	mItems map[reputation.PeerID]reputation.Trust
+}
+
+func (x *ConsumersTrusts) put(trust eigentrust.IterationTrust) {
+	x.mtx.Lock()
+
+	{
+		x.mItems[trust.TrustingPeer()] = trust.Trust
+	}
+
+	x.mtx.Unlock()
+}
+
+// Iterate passes all stored trusts to h.
+//
+// Returns errors from h directly.
+func (x *ConsumersTrusts) Iterate(h reputation.TrustHandler) (err error) {
+	x.mtx.RLock()
+
+	{
+		for _, trust := range x.mItems {
+			if err = h(trust); err != nil {
+				break
+			}
+		}
+	}
+
+	x.mtx.RUnlock()
+
+	return
+}

pkg/services/reputation/eigentrust/storage/consumers/storage.go

@@ -0,0 +1,40 @@
+package consumerstorage
+
+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 that of the trusts
+// of the consumer peers.
+//
+// It maps epoch numbers to the repositories of intermediate
+// trusts of the consumers of the daughter peers.
+//
+// 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 {
+	mtx sync.RWMutex
+
+	mItems map[uint64]*iterationConsumersStorage
+}
+
+// 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) *Storage {
+	return &Storage{
+		mItems: make(map[uint64]*iterationConsumersStorage),
+	}
+}

pkg/services/reputation/eigentrust/storage/daughters/calls.go

@@ -0,0 +1,134 @@
+package daughters
+
+import (
+	"sync"
+
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
+)
+
+// Put saves daughter peer's trust to its provider for the epoch.
+func (x *Storage) Put(epoch uint64, trust reputation.Trust) {
+	var s *daughterStorage
+
+	x.mtx.Lock()
+
+	{
+		s = x.mItems[epoch]
+		if s == nil {
+			s = &daughterStorage{
+				mItems: make(map[reputation.PeerID]*DaughterTrusts, 1),
+			}
+
+			x.mItems[epoch] = s
+		}
+	}
+
+	x.mtx.Unlock()
+
+	s.put(trust)
+}
+
+// DaughterTrusts returns daughter trusts for the epoch.
+//
+// Returns false if there is no data for the epoch and daughter.
+func (x *Storage) DaughterTrusts(epoch uint64, daughter reputation.PeerID) (*DaughterTrusts, bool) {
+	var (
+		s  *daughterStorage
+		ok bool
+	)
+
+	x.mtx.RLock()
+
+	{
+		s, ok = x.mItems[epoch]
+	}
+
+	x.mtx.RUnlock()
+
+	if !ok {
+		return nil, false
+	}
+
+	return s.daughterTrusts(daughter)
+}
+
+// maps IDs of daughter peers to repositories of the local trusts to their providers.
+type daughterStorage struct {
+	mtx sync.RWMutex
+
+	mItems map[reputation.PeerID]*DaughterTrusts
+}
+
+func (x *daughterStorage) put(trust reputation.Trust) {
+	var dt *DaughterTrusts
+
+	x.mtx.Lock()
+
+	{
+		trusting := trust.TrustingPeer()
+
+		dt = x.mItems[trusting]
+		if dt == nil {
+			dt = &DaughterTrusts{
+				mItems: make(map[reputation.PeerID]reputation.Trust, 1),
+			}
+
+			x.mItems[trusting] = dt
+		}
+	}
+
+	x.mtx.Unlock()
+
+	dt.put(trust)
+}
+
+func (x *daughterStorage) daughterTrusts(id reputation.PeerID) (dt *DaughterTrusts, ok bool) {
+	x.mtx.RLock()
+
+	{
+		dt, ok = x.mItems[id]
+	}
+
+	x.mtx.RUnlock()
+
+	return
+}
+
+// DaughterTrusts represents in-memory storage of local trusts
+// of the daughter peer to its providers.
+//
+// Maps IDs of daughter's providers to the local trusts to them.
+type DaughterTrusts struct {
+	mtx sync.RWMutex
+
+	mItems map[reputation.PeerID]reputation.Trust
+}
+
+func (x *DaughterTrusts) put(trust reputation.Trust) {
+	x.mtx.Lock()
+
+	{
+		x.mItems[trust.Peer()] = trust
+	}
+
+	x.mtx.Unlock()
+}
+
+// Iterate passes all stored trusts to h.
+//
+// Returns errors from h directly.
+func (x *DaughterTrusts) Iterate(h reputation.TrustHandler) (err error) {
+	x.mtx.RLock()
+
+	{
+		for _, trust := range x.mItems {
+			if err = h(trust); err != nil {
+				break
+			}
+		}
+	}
+
+	x.mtx.RUnlock()
+
+	return
+}

pkg/services/reputation/eigentrust/storage/daughters/storage.go

@@ -0,0 +1,38 @@
+package daughters
+
+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 trust
+// values of the daughter peers.
+//
+// It maps epoch numbers to the repositories of local trusts
+// of the daughter peers.
+//
+// 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 {
+	mtx sync.RWMutex
+
+	mItems map[uint64]*daughterStorage
+}
+
+// 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) *Storage {
+	return &Storage{
+		mItems: make(map[uint64]*daughterStorage),
+	}
+}

pkg/services/reputation/trust.go

@@ -7,8 +7,13 @@ import (
 // TrustValue represents the numeric value of the node's trust.
 type TrustValue float64
 
-// TrustOne is a trust value equal to one.
-const TrustOne = TrustValue(1)
+const (
+	// TrustOne is a trust value equal to one.
+	TrustOne = TrustValue(1)
+
+	// TrustZero is a trust value equal to zero.
+	TrustZero = TrustValue(0)
+)
 
 // TrustValueFromFloat64 converts float64 to TrustValue.
 func TrustValueFromFloat64(v float64) TrustValue {
@@ -39,6 +44,11 @@ func (v TrustValue) Div(v2 TrustValue) TrustValue {
 	return v / v2
 }
 
+// Mul multiplies v by v2.
+func (v *TrustValue) Mul(v2 TrustValue) {
+	*v *= v2
+}
+
 // IsZero returns true if v equal to zero.
 func (v TrustValue) IsZero() bool {
 	return v == 0
@@ -46,7 +56,7 @@ func (v TrustValue) IsZero() bool {
 
 // Trust represents peer's trust (reputation).
 type Trust struct {
-	peer PeerID
+	trusting, peer PeerID
 
 	val TrustValue
 }
@@ -78,3 +88,13 @@ func (t Trust) Peer() PeerID {
 func (t *Trust) SetPeer(id PeerID) {
 	t.peer = id
 }
+
+// TrustingPeer returns trusting peer ID.
+func (t Trust) TrustingPeer() PeerID {
+	return t.trusting
+}
+
+// SetTrustingPeer sets trusting peer ID.
+func (t *Trust) SetTrustingPeer(id PeerID) {
+	t.trusting = id
+}