Prevent TBTC monitoring duplication

pkg/extensions/tbtc/tbtc.go

@@ -8,6 +8,8 @@ import (
 	"math"
 	"math/big"
 	"math/rand"
+	"strings"
+	"sync"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -77,7 +79,8 @@ func Initialize(
 }
 
 type tbtc struct {
-	chain chain.TBTCHandle
+	chain           chain.TBTCHandle
+	monitoringLocks sync.Map
 }
 
 func newTBTC(chain chain.TBTCHandle) *tbtc {
@@ -417,10 +420,9 @@ type backoffFn func(iteration int) time.Duration
 
 type timeoutFn func(depositAddress string) (time.Duration, error)
 
-// TODO (keep-ecdsa/pull/585#discussion_r513447505):
-//  1. Incoming events deduplication.
-//  2. Handle chain reorgs (keep-ecdsa/pull/585#discussion_r511760283)
-//  3. Resume monitoring after client restart.
+// TODO:
+//  1. Handle chain reorgs (keep-ecdsa/pull/585#discussion_r511760283 and keep-ecdsa/pull/585#discussion_r513447505)
+//  2. Resume monitoring after client restart.
 func (t *tbtc) monitorAndAct(
 	ctx context.Context,
 	monitoringName string,
@@ -437,6 +439,17 @@ func (t *tbtc) monitorAndAct(
 			return
 		}
 
+		if !t.acquireMonitoringLock(depositAddress, monitoringName) {
+			logger.Warningf(
+				"[%v] monitoring for deposit [%v] is already running; "+
+					"could not start new monitoring instance",
+				monitoringName,
+				depositAddress,
+			)
+			return
+		}
+		defer t.releaseMonitoringLock(depositAddress, monitoringName)
+
 		logger.Infof(
 			"starting [%v] monitoring for deposit [%v]",
 			monitoringName,
@@ -651,6 +664,30 @@ func (t *tbtc) pastEventsLookupStartBlock() uint64 {
 	return currentBlock - pastEventsLookbackBlocks
 }
 
+func (t *tbtc) acquireMonitoringLock(depositAddress, monitoringName string) bool {
+	_, isExistingKey := t.monitoringLocks.LoadOrStore(
+		monitoringLockKey(depositAddress, monitoringName),
+		true,
+	)
+
+	return !isExistingKey
+}
+
+func (t *tbtc) releaseMonitoringLock(depositAddress, monitoringName string) {
+	t.monitoringLocks.Delete(monitoringLockKey(depositAddress, monitoringName))
+}
+
+func monitoringLockKey(
+	depositAddress string,
+	monitoringName string,
+) string {
+	return fmt.Sprintf(
+		"%v-%v",
+		depositAddress,
+		strings.ReplaceAll(monitoringName, " ", ""),
+	)
+}
+
 // Computes the exponential backoff value for given iteration.
 // For each iteration the result value will be in range:
 // - iteration 1: [2000ms, 2100ms)

pkg/extensions/tbtc/tbtc_test.go

@@ -10,6 +10,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/keep-network/keep-common/pkg/subscription"
+
 	"github.com/keep-network/keep-ecdsa/pkg/ecdsa"
 	"github.com/keep-network/keep-ecdsa/pkg/utils/byteutils"
 
@@ -1851,6 +1853,153 @@ func TestProvideRedemptionProof_OperatorNotInSigningGroup(
 	}
 }
 
+func TestMonitorAndActDeduplication(t *testing.T) {
+	ctx, cancelCtx := context.WithCancel(context.Background())
+	defer cancelCtx()
+
+	tbtcChain := local.NewTBTCLocalChain(ctx)
+	tbtc := newTBTC(tbtcChain)
+
+	monitoringName := "monitoring"
+
+	shouldMonitorFn := func(depositAddress string) bool {
+		return true
+	}
+
+	monitoringStartFn := func(
+		handler depositEventHandler,
+	) (subscription.EventSubscription, error) {
+		for i := 0; i < 5; i++ {
+			handler("deposit") // simulate multiple start events
+		}
+
+		return subscription.NewEventSubscription(func() {}), nil
+	}
+
+	monitoringStopFn := func(
+		handler depositEventHandler,
+	) (subscription.EventSubscription, error) {
+		return subscription.NewEventSubscription(func() {}), nil
+	}
+
+	keepClosedFn := func(depositAddress string) (chan struct{}, func(), error) {
+		return make(chan struct{}), func() {}, nil
+	}
+
+	actCounter := 0
+	actFn := func(depositAddress string) error {
+		actCounter++
+		return nil
+	}
+
+	timeoutFn := func(depositAddress string) (duration time.Duration, e error) {
+		return timeout, nil
+	}
+
+	monitoringSubscription, err := tbtc.monitorAndAct(
+		ctx,
+		monitoringName,
+		shouldMonitorFn,
+		monitoringStartFn,
+		monitoringStopFn,
+		keepClosedFn,
+		actFn,
+		constantBackoff,
+		timeoutFn,
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer monitoringSubscription.Unsubscribe()
+
+	// wait a bit longer than the monitoring timeout
+	// to make sure the potential transaction completes
+	time.Sleep(2 * timeout)
+
+	expectedActCounter := 1
+	if actCounter != expectedActCounter {
+		t.Errorf(
+			"unexpected number of action invocations\n"+
+				"expected: [%v]\n"+
+				"actual:   [%v]",
+			expectedActCounter,
+			actCounter,
+		)
+	}
+}
+
+func TestAcquireMonitoringLock(t *testing.T) {
+	ctx, cancelCtx := context.WithCancel(context.Background())
+	defer cancelCtx()
+
+	tbtcChain := local.NewTBTCLocalChain(ctx)
+	tbtc := newTBTC(tbtcChain)
+
+	if !tbtc.acquireMonitoringLock("0xAA", "monitoring one") {
+		t.Errorf("monitoring wasn't started before; should be locked successfully")
+	}
+
+	if !tbtc.acquireMonitoringLock("0xBB", "monitoring one") {
+		t.Errorf("monitoring wasn't started before; should be locked successfully")
+	}
+
+	if !tbtc.acquireMonitoringLock("0xAA", "monitoring two") {
+		t.Errorf("monitoring wasn't started before; should be locked successfully")
+	}
+
+	if !tbtc.acquireMonitoringLock("0xBB", "monitoring two") {
+		t.Errorf("monitoring wasn't started before; should be locked successfully")
+	}
+}
+
+func TestAcquireMonitoringLock_Duplicate(t *testing.T) {
+	ctx, cancelCtx := context.WithCancel(context.Background())
+	defer cancelCtx()
+
+	tbtcChain := local.NewTBTCLocalChain(ctx)
+	tbtc := newTBTC(tbtcChain)
+
+	if !tbtc.acquireMonitoringLock("0xAA", "monitoring one") {
+		t.Errorf("monitoring wasn't started before; should be locked successfully")
+	}
+
+	if tbtc.acquireMonitoringLock("0xAA", "monitoring one") {
+		t.Errorf("monitoring was started before; lock attempt should be rejected")
+	}
+}
+
+func TestReleaseMonitoringLock(t *testing.T) {
+	ctx, cancelCtx := context.WithCancel(context.Background())
+	defer cancelCtx()
+
+	tbtcChain := local.NewTBTCLocalChain(ctx)
+	tbtc := newTBTC(tbtcChain)
+
+	if !tbtc.acquireMonitoringLock("0xAA", "monitoring one") {
+		t.Errorf("monitoring wasn't started before; should be locked successfully")
+	}
+
+	tbtc.releaseMonitoringLock("0xAA", "monitoring one")
+
+	if !tbtc.acquireMonitoringLock("0xAA", "monitoring one") {
+		t.Errorf("monitoring lock has been released; should be locked successfully")
+	}
+}
+
+func TestReleaseMonitoringLock_WhenEmpty(t *testing.T) {
+	ctx, cancelCtx := context.WithCancel(context.Background())
+	defer cancelCtx()
+
+	tbtcChain := local.NewTBTCLocalChain(ctx)
+	tbtc := newTBTC(tbtcChain)
+
+	tbtc.releaseMonitoringLock("0xAA", "monitoring one")
+
+	if !tbtc.acquireMonitoringLock("0xAA", "monitoring one") {
+		t.Errorf("monitoring wasn't started before; should be locked successfully")
+	}
+}
+
 func submitKeepPublicKey(
 	depositAddress string,
 	tbtcChain *local.TBTCLocalChain,