mv internal lib

lib/model/deviceactivity.go

@@ -0,0 +1,53 @@
+// Copyright (C) 2014 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package model
+
+import (
+	"github.com/syncthing/protocol"
+	"github.com/syncthing/syncthing/lib/sync"
+)
+
+// deviceActivity tracks the number of outstanding requests per device and can
+// answer which device is least busy. It is safe for use from multiple
+// goroutines.
+type deviceActivity struct {
+	act map[protocol.DeviceID]int
+	mut sync.Mutex
+}
+
+func newDeviceActivity() *deviceActivity {
+	return &deviceActivity{
+		act: make(map[protocol.DeviceID]int),
+		mut: sync.NewMutex(),
+	}
+}
+
+func (m *deviceActivity) leastBusy(availability []protocol.DeviceID) protocol.DeviceID {
+	m.mut.Lock()
+	low := 2<<30 - 1
+	var selected protocol.DeviceID
+	for _, device := range availability {
+		if usage := m.act[device]; usage < low {
+			low = usage
+			selected = device
+		}
+	}
+	m.mut.Unlock()
+	return selected
+}
+
+func (m *deviceActivity) using(device protocol.DeviceID) {
+	m.mut.Lock()
+	m.act[device]++
+	m.mut.Unlock()
+}
+
+func (m *deviceActivity) done(device protocol.DeviceID) {
+	m.mut.Lock()
+	m.act[device]--
+	m.mut.Unlock()
+}