[#141] Fix double sidechain GAS emission on asset mint

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

cmd/neofs-ir/defaults.go

@@ -85,4 +85,7 @@ func defaultConfiguration(cfg *viper.Viper) {
 	cfg.SetDefault("netmap_cleaner.threshold", 3)
 
 	cfg.SetDefault("emit.storage.amount", 0)
+	cfg.SetDefault("emit.mint.cache_size", 1000)
+	cfg.SetDefault("emit.mint.threshold", 1)
+	cfg.SetDefault("emit.mint.value", 20000000) // 0.2 Fixed8
 }

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/alecthomas/participle v0.6.0
 	github.com/golang/protobuf v1.4.3
 	github.com/google/uuid v1.1.1
+	github.com/hashicorp/golang-lru v0.5.4
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mr-tron/base58 v1.1.3
 	github.com/multiformats/go-multiaddr v0.2.0

pkg/innerring/innerring.go

@@ -240,6 +240,9 @@ func New(ctx context.Context, log *zap.Logger, cfg *viper.Viper) (*Server, error
 		EpochState:        server,
 		ActiveState:       server,
 		Converter:         &server.precision,
+		MintEmitCacheSize: cfg.GetInt("emit.mint.cache_size"),
+		MintEmitThreshold: cfg.GetUint64("emit.mint.threshold"),
+		MintEmitValue:     util.Fixed8(cfg.GetInt64("emit.mint.value")),
 	})
 	if err != nil {
 		return nil, err

pkg/innerring/processors/neofs/process_assets.go

@@ -34,12 +34,34 @@ func (np *Processor) processDeposit(deposit *neofsEvent.Deposit) {
 		np.log.Error("can't transfer assets to balance contract", zap.Error(err))
 	}
 
-	// fixme: send gas when ^ tx accepted
-	// fixme: do not send gas to the same user twice per epoch
-	err = np.morphClient.TransferGas(deposit.To(), util.Fixed8FromInt64(2))
-	if err != nil {
-		np.log.Error("can't transfer native gas to receiver", zap.Error(err))
+	curEpoch := np.epochState.EpochCounter()
+	receiver := deposit.To()
+
+	// check if receiver already received some mint GAS emissions
+	// we should lock there even though LRU cache is already thread save
+	// we lock there because GAS transfer AND cache update must be atomic
+	np.mintEmitLock.Lock()
+	defer np.mintEmitLock.Unlock()
+
+	val, ok := np.mintEmitCache.Get(receiver.String())
+	if ok && val.(uint64)+np.mintEmitThreshold >= curEpoch {
+		np.log.Warn("double mint emission declined",
+			zap.String("receiver", receiver.String()),
+			zap.Uint64("last_emission", val.(uint64)),
+			zap.Uint64("current_epoch", curEpoch))
+
+		return
 	}
+
+	err = np.morphClient.TransferGas(receiver, np.mintEmitValue)
+	if err != nil {
+		np.log.Error("can't transfer native gas to receiver",
+			zap.String("error", err.Error()))
+
+		return
+	}
+
+	np.mintEmitCache.Add(receiver.String(), curEpoch)
 }
 
 // Process withdraw event by locking assets in balance account.

pkg/innerring/processors/neofs/processor.go

@@ -1,6 +1,9 @@
 package neofs
 
 import (
+	"sync"
+
+	lru "github.com/hashicorp/golang-lru"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neofs-node/pkg/morph/client"
 	"github.com/nspcc-dev/neofs-node/pkg/morph/event"
@@ -37,6 +40,10 @@ type (
 		epochState        EpochState
 		activeState       ActiveState
 		converter         PrecisionConverter
+		mintEmitLock      *sync.Mutex
+		mintEmitCache     *lru.Cache
+		mintEmitThreshold uint64
+		mintEmitValue     util.Fixed8
 	}
 
 	// Params of the processor constructor.
@@ -50,6 +57,9 @@ type (
 		EpochState        EpochState
 		ActiveState       ActiveState
 		Converter         PrecisionConverter
+		MintEmitCacheSize int
+		MintEmitThreshold uint64 // in epochs
+		MintEmitValue     util.Fixed8
 	}
 )
 
@@ -83,6 +93,11 @@ func New(p *Params) (*Processor, error) {
 		return nil, errors.Wrap(err, "ir/neofs: can't create worker pool")
 	}
 
+	lruCache, err := lru.New(p.MintEmitCacheSize)
+	if err != nil {
+		return nil, errors.Wrap(err, "ir/neofs: can't create LRU cache for gas emission")
+	}
+
 	return &Processor{
 		log:               p.Log,
 		pool:              pool,
@@ -93,6 +108,10 @@ func New(p *Params) (*Processor, error) {
 		epochState:        p.EpochState,
 		activeState:       p.ActiveState,
 		converter:         p.Converter,
+		mintEmitLock:      new(sync.Mutex),
+		mintEmitCache:     lruCache,
+		mintEmitThreshold: p.MintEmitThreshold,
+		mintEmitValue:     p.MintEmitValue,
 	}, nil
 }