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multisyncer.go
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/
multisyncer.go
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//
// Copyright 2015, Sander van Harmelen
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
package multisyncer
type syncer chan cmdData
type cmdData struct {
action cmdAction
token interface{}
done chan struct{}
}
type cmdAction int
const (
lock cmdAction = iota
unlock
)
// MultiSyncer synchronizes access based on a given token
type MultiSyncer interface {
Lock(interface{})
Unlock(interface{})
}
// New returns a new MultiSyncer
func New() MultiSyncer {
s := make(syncer)
go s.run()
return s
}
func (s syncer) run() {
store := make(map[interface{}]chan struct{})
for cmd := range s {
l, ok := store[cmd.token]
if !ok && cmd.action == lock {
l = make(chan struct{}, 1)
store[cmd.token] = l
}
go func(cmd cmdData) {
switch cmd.action {
case lock:
l <- struct{}{}
case unlock:
if ok {
<-l
}
}
cmd.done <- struct{}{}
}(cmd)
}
}
// Lock implements the MultiSyncer interface
func (s syncer) Lock(token interface{}) {
done := make(chan struct{})
s <- cmdData{action: lock, token: token, done: done}
<-done
}
// Unlock implements the MultiSyncer interface
func (s syncer) Unlock(token interface{}) {
done := make(chan struct{})
s <- cmdData{action: unlock, token: token, done: done}
<-done
}