Serge Bazanski | de0330a | 2020-07-30 20:48:48 +0200 | [diff] [blame] | 1 | package main |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "time" |
| 6 | |
| 7 | "github.com/golang/glog" |
| 8 | ) |
| 9 | |
| 10 | type lockCtrl struct { |
| 11 | getCurrent *lockCtrlGetCurrent |
| 12 | take *lockCtrlTake |
| 13 | release *lockCtrlRelease |
| 14 | subscribe *lockCtrlSubscribe |
| 15 | bump *lockCtrlBump |
| 16 | } |
| 17 | |
| 18 | type lockCtrlGetCurrent struct { |
| 19 | res chan *lockResCurrent |
| 20 | } |
| 21 | |
| 22 | type lockCtrlTake struct { |
| 23 | note string |
| 24 | addr string |
| 25 | prev string |
| 26 | res chan bool |
| 27 | } |
| 28 | |
| 29 | type lockCtrlRelease struct { |
| 30 | addr string |
| 31 | force bool |
| 32 | res chan struct{} |
| 33 | } |
| 34 | |
| 35 | type lockCtrlSubscribe struct { |
| 36 | subscriber chan *lockUpdate |
| 37 | } |
| 38 | |
| 39 | type lockCtrlBump struct { |
| 40 | addr string |
| 41 | } |
| 42 | |
| 43 | type lockResCurrent struct { |
| 44 | note string |
| 45 | addr string |
| 46 | deadline time.Time |
| 47 | } |
| 48 | |
| 49 | type lockUpdate struct { |
| 50 | note string |
| 51 | addr string |
| 52 | } |
| 53 | |
radex | 81da4e5 | 2020-08-27 23:56:29 +0200 | [diff] [blame] | 54 | func (s *service) runLocker(ctx context.Context, ctrlC chan *lockCtrl, ownershipDuration time.Duration) { |
Serge Bazanski | de0330a | 2020-07-30 20:48:48 +0200 | [diff] [blame] | 55 | glog.Infof("Locker starting...") |
| 56 | |
| 57 | var curNote string |
| 58 | var curAddr string |
| 59 | var curDeadline time.Time |
| 60 | var subscribers []chan *lockUpdate |
| 61 | |
| 62 | notify := func() { |
| 63 | for _, sub := range subscribers { |
| 64 | go func() { |
| 65 | sub <- &lockUpdate{ |
| 66 | note: curNote, |
| 67 | addr: curAddr, |
| 68 | } |
| 69 | }() |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | t := time.NewTicker(5 * time.Second) |
| 74 | defer t.Stop() |
| 75 | |
| 76 | for { |
| 77 | select { |
| 78 | case <-ctx.Done(): |
| 79 | err := ctx.Err() |
| 80 | glog.Errorf("Locker stoppped: %v", err) |
| 81 | return |
| 82 | case <-t.C: |
| 83 | if curAddr != "" && time.Now().After(curDeadline) { |
| 84 | glog.Infof("Expiring lock") |
| 85 | curAddr = "" |
| 86 | curNote = "" |
| 87 | notify() |
| 88 | } |
| 89 | case ctrl := <-ctrlC: |
| 90 | switch { |
| 91 | case ctrl.take != nil: |
| 92 | won := false |
| 93 | if curAddr == ctrl.take.prev { |
| 94 | won = true |
| 95 | curNote = ctrl.take.note |
| 96 | curAddr = ctrl.take.addr |
radex | 81da4e5 | 2020-08-27 23:56:29 +0200 | [diff] [blame] | 97 | curDeadline = time.Now().Add(ownershipDuration) |
Serge Bazanski | de0330a | 2020-07-30 20:48:48 +0200 | [diff] [blame] | 98 | notify() |
| 99 | glog.Infof("Lock taken by %q %q", curNote, curAddr) |
| 100 | } |
| 101 | go func() { |
| 102 | ctrl.take.res <- won |
| 103 | }() |
| 104 | case ctrl.release != nil: |
| 105 | if curAddr == ctrl.release.addr || ctrl.release.force { |
| 106 | curAddr = "" |
| 107 | curNote = "" |
| 108 | notify() |
| 109 | glog.Infof("Lock relased") |
| 110 | } |
| 111 | go func() { |
| 112 | ctrl.release.res <- struct{}{} |
| 113 | }() |
| 114 | case ctrl.getCurrent != nil: |
| 115 | go func() { |
| 116 | ctrl.getCurrent.res <- &lockResCurrent{ |
| 117 | note: curNote, |
| 118 | addr: curAddr, |
| 119 | deadline: curDeadline, |
| 120 | } |
| 121 | }() |
| 122 | case ctrl.bump != nil: |
| 123 | if curAddr != "" { |
radex | 81da4e5 | 2020-08-27 23:56:29 +0200 | [diff] [blame] | 124 | curDeadline = time.Now().Add(ownershipDuration) |
Serge Bazanski | de0330a | 2020-07-30 20:48:48 +0200 | [diff] [blame] | 125 | } |
| 126 | case ctrl.subscribe != nil: |
| 127 | subscribers = append(subscribers, ctrl.subscribe.subscriber) |
| 128 | } |
| 129 | } |
| 130 | } |
| 131 | } |