syncthing/internal/model/deviceactivity.go

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// Copyright (C) 2014 The Syncthing Authors.
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//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// This program 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 General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. If not, see <http://www.gnu.org/licenses/>.
package model
import (
"sync"
"github.com/syncthing/syncthing/internal/protocol"
)
// 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),
}
}
func (m *deviceActivity) leastBusy(availability []protocol.DeviceID) protocol.DeviceID {
m.mut.Lock()
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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()
}