accounting: clear finished transfer in stats-reset

In order to reduce memory usage `stats-reset` also
clears finished transfers.

Fixes #3734

docs/content/rc.md

@@ -521,8 +521,8 @@ The value for "eta" is null if an eta cannot be determined.
 
 ### core/stats-reset: Reset stats. {#core/stats-reset}
 
-This clears counters and errors for all stats or specific stats group if group
-is provided.
+This clears counters, errors and finished transfers for all stats or specific
+stats group if group is provided.
 
 Parameters
 

fs/accounting/stats.go

@@ -627,6 +627,20 @@ func (s *StatsInfo) RemoveTransfer(transfer *Transfer) {
 	s.mu.Unlock()
 }
 
+// PruneAllTransfers removes all finished transfers.
+func (s *StatsInfo) PruneAllTransfers() {
+	s.mu.Lock()
+	for i := 0; i < len(s.startedTransfers); i++ {
+		tr := s.startedTransfers[i]
+		if tr.IsDone() {
+			s.removeTransfer(tr, i)
+			// i'th element is removed, recover iterator to not skip next element.
+			i--
+		}
+	}
+	s.mu.Unlock()
+}
+
 // PruneTransfers makes sure there aren't too many old transfers by removing
 // single finished transfer.
 func (s *StatsInfo) PruneTransfers() {

fs/accounting/stats_groups.go

@@ -59,8 +59,10 @@ func resetStats(ctx context.Context, in rc.Params) (rc.Params, error) {
 	}
 
 	if group != "" {
-		groups.get(group).ResetCounters()
-		groups.get(group).ResetErrors()
+		stats := groups.get(group)
+		stats.ResetCounters()
+		stats.ResetErrors()
+		stats.PruneAllTransfers()
 	} else {
 		groups.clear()
 	}
@@ -190,8 +192,8 @@ Returns the following values:
 		Fn:    resetStats,
 		Title: "Reset stats.",
 		Help: `
-This clears counters and errors for all stats or specific stats group if group
-is provided.
+This clears counters, errors and finished transfers for all stats or specific 
+stats group if group is provided.
 
 Parameters
 
@@ -333,6 +335,7 @@ func (sg *statsGroups) clear() {
 	for _, stats := range sg.m {
 		stats.ResetErrors()
 		stats.ResetCounters()
+		stats.PruneAllTransfers()
 	}
 
 	sg.m = make(map[string]*StatsInfo)

fs/accounting/stats_test.go

@@ -431,3 +431,25 @@ func TestPruneTransfers(t *testing.T) {
 		})
 	}
 }
+
+func TestPruneAllTransfers(t *testing.T) {
+	const transfers = 10
+
+	s := NewStats()
+	for i := int64(1); i <= int64(transfers); i++ {
+		s.AddTransfer(&Transfer{
+			startedAt:   time.Unix(i, 0),
+			completedAt: time.Unix(i+1, 0),
+		})
+	}
+
+	s.mu.Lock()
+	assert.Equal(t, transfers, len(s.startedTransfers))
+	s.mu.Unlock()
+
+	s.PruneAllTransfers()
+
+	s.mu.Lock()
+	assert.Empty(t, s.startedTransfers)
+	s.mu.Unlock()
+}