les: duplicate downloader and fetcher to allow progressive refactoring

les/downloader/modes.go

@@ -0,0 +1,81 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package downloader
+
+import "fmt"
+
+// SyncMode represents the synchronisation mode of the downloader.
+// It is a uint32 as it is used with atomic operations.
+type SyncMode uint32
+
+const (
+	FullSync  SyncMode = iota // Synchronise the entire blockchain history from full blocks
+	FastSync                  // Quickly download the headers, full sync only at the chain
+	SnapSync                  // Download the chain and the state via compact snapshots
+	LightSync                 // Download only the headers and terminate afterwards
+)
+
+func (mode SyncMode) IsValid() bool {
+	return mode >= FullSync && mode <= LightSync
+}
+
+// String implements the stringer interface.
+func (mode SyncMode) String() string {
+	switch mode {
+	case FullSync:
+		return "full"
+	case FastSync:
+		return "fast"
+	case SnapSync:
+		return "snap"
+	case LightSync:
+		return "light"
+	default:
+		return "unknown"
+	}
+}
+
+func (mode SyncMode) MarshalText() ([]byte, error) {
+	switch mode {
+	case FullSync:
+		return []byte("full"), nil
+	case FastSync:
+		return []byte("fast"), nil
+	case SnapSync:
+		return []byte("snap"), nil
+	case LightSync:
+		return []byte("light"), nil
+	default:
+		return nil, fmt.Errorf("unknown sync mode %d", mode)
+	}
+}
+
+func (mode *SyncMode) UnmarshalText(text []byte) error {
+	switch string(text) {
+	case "full":
+		*mode = FullSync
+	case "fast":
+		*mode = FastSync
+	case "snap":
+		*mode = SnapSync
+	case "light":
+		*mode = LightSync
+	default:
+		return fmt.Errorf(`unknown sync mode %q, want "full", "fast" or "light"`, text)
+	}
+	return nil
+}