Measure FPC number of currently active conflicts

plugins/metrics/fpc.go

 package metrics
+
+import (
+	"sync/atomic"
+
+	"github.com/iotaledger/goshimmer/packages/vote"
+)
+
+var activeConflicts uint64
+
+func processRoundStats(stats vote.RoundStats) {
+	// get the number of active conflicts
+	numActive := (uint64)(len(stats.ActiveVoteContexts))
+	atomic.StoreUint64(&activeConflicts, numActive)
+}
+
+// ActiveConflicts returns the number of currently active conflicts.
+func ActiveConflicts() uint64 {
+	return atomic.LoadUint64(&activeConflicts)
+}

plugins/metrics/fpc_test.go

 package metrics
+
+import (
+	"testing"
+
+	"github.com/magiconair/properties/assert"
+)
+
+func TestActiveConflicts(t *testing.T) {
+	// initialized to 0
+	assert.Equal(t, ActiveConflicts(), (uint64)(0))
+
+}

plugins/metrics/plugin.go

@@ -6,11 +6,11 @@ import (
 	"github.com/iotaledger/goshimmer/dapps/valuetransfers"
 	"github.com/iotaledger/goshimmer/dapps/valuetransfers/packages/payload"
 	valuetangle "github.com/iotaledger/goshimmer/dapps/valuetransfers/packages/tangle"
-
 	"github.com/iotaledger/goshimmer/packages/binary/messagelayer/message"
 	"github.com/iotaledger/goshimmer/packages/binary/messagelayer/tangle"
 	"github.com/iotaledger/goshimmer/packages/metrics"
 	"github.com/iotaledger/goshimmer/packages/shutdown"
+	"github.com/iotaledger/goshimmer/packages/vote"
 	"github.com/iotaledger/goshimmer/plugins/messagelayer"
 	"github.com/iotaledger/hive.go/daemon"
 	"github.com/iotaledger/hive.go/events"
@@ -48,6 +48,11 @@ func configure(_ *node.Plugin) {
 		increaseReceivedTPSCounter()
 	}))
 
+	// FPC round executed
+	valuetransfers.Voter().Events().RoundExecuted.Attach(events.NewClosure(func(roundStats vote.RoundStats) {
+		processRoundStats(roundStats)
+	}))
+
 	//// Events coming from metrics package ////
 
 	metrics.Events().FPCInboundBytes.Attach(events.NewClosure(func(amountBytes uint64) {