accounting: add NewCheckingTransferNoHistory constructor

This creates a checking transfer which is shown in the progress
display while it is running but is not kept in the completed
transfers history, so it never appears in core/transferred and is not
retained in memory after it finishes.

This is for repeated bookkeeping operations (eg directory modtime
updates) which would otherwise crowd file transfers out of the
history.

fs/accounting/stats.go

@@ -798,6 +798,20 @@ func (s *StatsInfo) NewCheckingTransfer(obj fs.DirEntry, what string) *Transfer
 	return tr
 }
 
+// NewCheckingTransferNoHistory adds a checking transfer to the stats,
+// from the object, which is shown while it is running but is not kept
+// in the completed transfers history (so never appears in
+// core/transferred).
+//
+// Use this for repeated bookkeeping operations (eg directory modtime
+// updates) which would otherwise crowd file transfers out of the
+// history.
+func (s *StatsInfo) NewCheckingTransferNoHistory(obj fs.DirEntry, what string) *Transfer {
+	tr := newCheckingTransferNoHistory(s, obj, what)
+	s.checking.add(tr)
+	return tr
+}
+
 // DoneChecking removes a check from the stats
 func (s *StatsInfo) DoneChecking(remote string) {
 	s.checking.del(remote)
@@ -831,7 +845,7 @@ func (s *StatsInfo) NewTransfer(obj fs.DirEntry, dstFs fs.Fs) *Transfer {
 
 // NewTransferRemoteSize adds a transfer to the stats based on remote and size.
 func (s *StatsInfo) NewTransferRemoteSize(remote string, size int64, srcFs, dstFs fs.Fs) *Transfer {
-	tr := newTransferRemoteSize(s, remote, size, false, "", srcFs, dstFs)
+	tr := newTransferRemoteSize(s, remote, size, false, "", srcFs, dstFs, false)
 	s.transferring.add(tr)
 	s.startAverageLoop()
 	return tr

fs/accounting/transfer.go

@@ -71,15 +71,23 @@ type Transfer struct {
 
 // newCheckingTransfer instantiates new checking of the object.
 func newCheckingTransfer(stats *StatsInfo, obj fs.DirEntry, what string) *Transfer {
-	return newTransferRemoteSize(stats, obj.Remote(), obj.Size(), true, what, nil, nil)
+	return newTransferRemoteSize(stats, obj.Remote(), obj.Size(), true, what, nil, nil, false)
+}
+
+// newCheckingTransferNoHistory instantiates new checking of the
+// object which is not kept in the completed transfers history.
+func newCheckingTransferNoHistory(stats *StatsInfo, obj fs.DirEntry, what string) *Transfer {
+	return newTransferRemoteSize(stats, obj.Remote(), obj.Size(), true, what, nil, nil, true)
 }
 
 // newTransfer instantiates new transfer.
 func newTransfer(stats *StatsInfo, obj fs.DirEntry, srcFs, dstFs fs.Fs) *Transfer {
-	return newTransferRemoteSize(stats, obj.Remote(), obj.Size(), false, "", srcFs, dstFs)
+	return newTransferRemoteSize(stats, obj.Remote(), obj.Size(), false, "", srcFs, dstFs, false)
 }
 
-func newTransferRemoteSize(stats *StatsInfo, remote string, size int64, checking bool, what string, srcFs, dstFs fs.Fs) *Transfer {
+// If noHistory is set the transfer is not kept in the completed
+// transfers history after it is done.
+func newTransferRemoteSize(stats *StatsInfo, remote string, size int64, checking bool, what string, srcFs, dstFs fs.Fs, noHistory bool) *Transfer {
 	tr := &Transfer{
 		stats:     stats,
 		remote:    remote,
@@ -90,7 +98,9 @@ func newTransferRemoteSize(stats *StatsInfo, remote string, size int64, checking
 		srcFs:     srcFs,
 		dstFs:     dstFs,
 	}
-	stats.AddTransfer(tr)
+	if !noHistory {
+		stats.AddTransfer(tr)
+	}
 	return tr
 }
 

fs/accounting/transfer_test.go

@@ -87,6 +87,25 @@ func TestTransfer(t *testing.T) {
 		}, out)
 	})
 
+	t.Run("NoHistory", func(t *testing.T) {
+		s := NewStats(ctx)
+
+		// A normal checking transfer is kept in the history
+		tr := s.NewCheckingTransfer(o, "checking")
+		tr.Done(ctx, nil)
+		assert.Equal(t, 1, len(s.Transferred()))
+
+		// A no history checking transfer is shown while running but
+		// is not kept in the history
+		tr = s.NewCheckingTransferNoHistory(o, "setting modtime")
+		assert.Equal(t, 1, s.checking.count())
+		assert.Equal(t, 1, len(s.Transferred()))
+		tr.Done(ctx, nil)
+		assert.Equal(t, 0, s.checking.count())
+		assert.Equal(t, 1, len(s.Transferred()))
+		assert.Equal(t, int64(2), s.GetChecks())
+	})
+
 	t.Run("Snapshot checking transfer", func(t *testing.T) {
 		ctr := newCheckingTransfer(s, o, "checking")
 		snap := ctr.Snapshot()