72 lines
1.7 KiB
Go
72 lines
1.7 KiB
Go
package distributed
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import (
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"errors"
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"github.com/Superdanda/hade/framework"
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"github.com/Superdanda/hade/framework/contract"
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"github.com/gofrs/flock"
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"io/ioutil"
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"os"
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"path/filepath"
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"time"
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)
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type LocalDistributedService struct {
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container framework.Container //服务容器
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}
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func NewLocalDistributedService(params ...interface{}) (interface{}, error) {
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if len(params) != 1 {
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return nil, errors.New("param error")
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}
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// 有两个参数，一个是容器，一个是baseFolder
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container := params[0].(framework.Container)
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return &LocalDistributedService{container: container}, nil
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}
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// Select 为分布式选择器
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func (s LocalDistributedService) Select(serviceName string, appID string, holdTime time.Duration) (selectAppID string, err error) {
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appService := s.container.MustMake(contract.AppKey).(contract.App)
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runtimeFolder := appService.RuntimeFolder()
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lockFile := filepath.Join(runtimeFolder, "distribute_"+serviceName)
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// 使用 flock 创建文件锁
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fileLock := flock.New(lockFile)
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// 尝试加独占锁
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locked, err := fileLock.TryLock()
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if err != nil {
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return "", err
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}
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if !locked {
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// 如果未能获取锁，读取文件中的 appID
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selectAppIDByt, err := ioutil.ReadFile(lockFile)
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if err != nil {
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return "", err
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}
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return string(selectAppIDByt), nil
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}
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// 在选举有效时间内其他节点不能再抢占
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go func() {
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defer func() {
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// 释放文件锁
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_ = fileLock.Unlock()
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// 删除锁文件
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_ = os.Remove(lockFile)
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}()
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// 创建一个计时器以保持选举的有效性
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timer := time.NewTimer(holdTime)
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<-timer.C
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}()
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// 将抢占到的 appID 写入文件
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if err := os.WriteFile(lockFile, []byte(appID), 0666); err != nil {
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return "", err
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}
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return appID, nil
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}
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