mirror of
https://github.com/seaweedfs/seaweedfs.git
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108 lines
2.9 KiB
Go
108 lines
2.9 KiB
Go
package weed_server
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import (
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"context"
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"fmt"
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"math/rand"
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"time"
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"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
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)
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/*
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How exclusive lock works?
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-----------
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Shell
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------
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When shell lock,
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* lease an admin token (lockTime, token)
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* start a goroutine to renew the admin token periodically
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For later volume operations, send (lockTime, token) to volume servers for exclusive access
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* need to pause renewal a few seconds, to prevent race condition
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When shell unlock
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* stop the renewal goroutine
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* sends a release lock request
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Master
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------
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Master maintains:
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* randomNumber
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* lastLockTime
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When master receives the lease/renew request from shell
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If lastLockTime still fresh {
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if is a renew and token is valid {
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// for renew
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generate the randomNumber => token
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return
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}
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refuse
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return
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} else {
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// for fresh lease request
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generate the randomNumber => token
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return
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}
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When master receives the release lock request from shell
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set the lastLockTime to zero
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When master receives the verfication request from volume servers
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return secret+lockTime == token && lockTime == lastLockTime
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Volume
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------
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When receives (lockTime, token), ask the master whether this is valid
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*/
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const (
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LockDuration = 10 * time.Second
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)
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func (ms *MasterServer) LeaseAdminToken(ctx context.Context, req *master_pb.LeaseAdminTokenRequest) (*master_pb.LeaseAdminTokenResponse, error) {
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resp := &master_pb.LeaseAdminTokenResponse{}
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if ms.adminAccessLockTime.Add(LockDuration).After(time.Now()) {
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if req.PreviousToken != 0 && ms.isValidToken(time.Unix(0, req.PreviousLockTime), req.PreviousToken) {
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// for renew
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ts, token := ms.generateToken()
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resp.Token, resp.LockTsNs = token, ts.UnixNano()
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return resp, nil
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}
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// refuse since still locked
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return resp, fmt.Errorf("already locked")
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}
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// for fresh lease request
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ts, token := ms.generateToken()
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resp.Token, resp.LockTsNs = token, ts.UnixNano()
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return resp, nil
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}
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func (ms *MasterServer) isValidToken(ts time.Time, token int64) bool {
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return ms.adminAccessLockTime.Equal(ts) && ms.adminAccessSecret == token
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}
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func (ms *MasterServer) generateToken() (ts time.Time, token int64) {
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ms.adminAccessLockTime = time.Now()
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ms.adminAccessSecret = rand.Int63()
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return ms.adminAccessLockTime, ms.adminAccessSecret
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}
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func (ms *MasterServer) ReleaseAdminToken(ctx context.Context, req *master_pb.ReleaseAdminTokenRequest) (*master_pb.ReleaseAdminTokenResponse, error) {
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resp := &master_pb.ReleaseAdminTokenResponse{}
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if ms.isValidToken(time.Unix(0, req.PreviousLockTime), req.PreviousToken) {
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ms.adminAccessSecret = 0
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}
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return resp, nil
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}
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func (ms *MasterServer) VerifyAdminToken(ctx context.Context, req *master_pb.VerifyAdminTokenRequest) (*master_pb.VerifyAdminTokenResponse, error) {
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resp := &master_pb.VerifyAdminTokenResponse{}
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if ms.isValidToken(time.Unix(0, req.LockTime), req.Token) {
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resp.IsValid = true
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}
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return resp, nil
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}
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