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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,220 @@ | ||
| package orchestrator | ||
|
|
||
| import ( | ||
| "container/heap" | ||
| "context" | ||
| "sync" | ||
| "time" | ||
|
|
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| v1 "github.com/garethgeorge/backrest/gen/go/v1" | ||
| ) | ||
|
|
||
| var taskQueueDefaultPollInterval = 3 * time.Minute | ||
|
|
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| type taskQueue struct { | ||
| dequeueMu sync.Mutex | ||
| mu sync.Mutex | ||
| heap scheduledTaskHeapByTime | ||
| notify chan struct{} | ||
| ready scheduledTaskHeapByPriorityThenTime | ||
| pollInterval time.Duration | ||
|
|
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| Now func() time.Time | ||
| } | ||
|
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| func newTaskQueue(now func() time.Time) taskQueue { | ||
| return taskQueue{ | ||
| heap: scheduledTaskHeapByTime{}, | ||
| ready: scheduledTaskHeapByPriorityThenTime{}, | ||
| pollInterval: taskQueueDefaultPollInterval, | ||
| Now: now, | ||
| } | ||
| } | ||
|
|
||
| func (t *taskQueue) curTime() time.Time { | ||
| if t.Now != nil { | ||
| return t.Now() | ||
| } | ||
| return time.Now() | ||
| } | ||
|
|
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| func (t *taskQueue) Push(tasks ...scheduledTask) { | ||
| t.mu.Lock() | ||
| defer t.mu.Unlock() | ||
|
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||
| for _, task := range tasks { | ||
| task := task | ||
| if task.task == nil { | ||
| panic("task cannot be nil") | ||
| } | ||
| heap.Push(&t.heap, &task) | ||
| } | ||
|
|
||
| if t.notify != nil { | ||
| t.notify <- struct{}{} | ||
| } | ||
| } | ||
|
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| func (t *taskQueue) Reset() []*scheduledTask { | ||
| t.mu.Lock() | ||
| defer t.mu.Unlock() | ||
|
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| oldTasks := t.heap.tasks | ||
| oldTasks = append(oldTasks, t.ready.tasks...) | ||
| t.heap.tasks = nil | ||
| t.ready.tasks = nil | ||
|
|
||
| if t.notify != nil { | ||
| t.notify <- struct{}{} | ||
| } | ||
| return oldTasks | ||
| } | ||
|
|
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| func (t *taskQueue) Dequeue(ctx context.Context) *scheduledTask { | ||
| t.dequeueMu.Lock() | ||
| defer t.dequeueMu.Unlock() | ||
|
|
||
| t.mu.Lock() | ||
| defer t.mu.Unlock() | ||
| t.notify = make(chan struct{}, 10) | ||
| defer func() { | ||
| close(t.notify) | ||
| t.notify = nil | ||
| }() | ||
|
|
||
| for { | ||
| first, ok := t.heap.Peek().(*scheduledTask) | ||
| if !ok { // no tasks in heap. | ||
| if t.ready.Len() > 0 { | ||
| return heap.Pop(&t.ready).(*scheduledTask) | ||
| } | ||
| t.mu.Unlock() | ||
| select { | ||
| case <-ctx.Done(): | ||
| t.mu.Lock() | ||
| return nil | ||
| case <-t.notify: | ||
| } | ||
| t.mu.Lock() | ||
| continue | ||
| } | ||
|
|
||
| now := t.curTime() | ||
|
|
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| // if there's a task in the ready queue AND the first task isn't ready yet then immediately return the ready task. | ||
| ready, ok := t.ready.Peek().(*scheduledTask) | ||
| if ok && now.Before(first.runAt) { | ||
| heap.Pop(&t.ready) | ||
| return ready | ||
| } | ||
|
|
||
| t.mu.Unlock() | ||
| d := first.runAt.Sub(now) | ||
| if t.pollInterval > 0 && d > t.pollInterval { | ||
| // A poll interval may be set to work around clock changes | ||
| // e.g. when a laptop wakes from sleep or the system clock is adjusted. | ||
| d = t.pollInterval | ||
| } | ||
| timer := time.NewTimer(d) | ||
|
|
||
| select { | ||
| case <-timer.C: | ||
| t.mu.Lock() | ||
| if t.heap.Len() == 0 { | ||
| break | ||
| } | ||
|
|
||
| for { | ||
| first, ok := t.heap.Peek().(*scheduledTask) | ||
| if !ok { | ||
| break | ||
| } | ||
| if first.runAt.After(t.curTime()) { | ||
| // task is not yet ready to run | ||
| break | ||
| } | ||
| heap.Pop(&t.heap) // remove the task from the heap | ||
| heap.Push(&t.ready, first) | ||
| } | ||
|
|
||
| if t.ready.Len() == 0 { | ||
| break | ||
| } | ||
| return heap.Pop(&t.ready).(*scheduledTask) | ||
| case <-t.notify: // new task was added, loop again to ensure we have the earliest task. | ||
| t.mu.Lock() | ||
| if !timer.Stop() { | ||
| <-timer.C | ||
| } | ||
| case <-ctx.Done(): | ||
| t.mu.Lock() | ||
| if !timer.Stop() { | ||
| <-timer.C | ||
| } | ||
| return nil | ||
| } | ||
| } | ||
| } | ||
|
|
||
| type scheduledTask struct { | ||
| task Task | ||
| runAt time.Time | ||
| priority int | ||
| callbacks []func(error) | ||
| config *v1.Config | ||
| } | ||
|
|
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| type scheduledTaskHeap struct { | ||
| tasks []*scheduledTask | ||
| comparator func(i, j *scheduledTask) bool | ||
| } | ||
|
|
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| func (h *scheduledTaskHeap) Len() int { | ||
| return len(h.tasks) | ||
| } | ||
|
|
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| func (h *scheduledTaskHeap) Swap(i, j int) { | ||
| h.tasks[i], h.tasks[j] = h.tasks[j], h.tasks[i] | ||
| } | ||
|
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| func (h *scheduledTaskHeap) Push(x interface{}) { | ||
| h.tasks = append(h.tasks, x.(*scheduledTask)) | ||
| } | ||
|
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| func (h *scheduledTaskHeap) Pop() interface{} { | ||
| old := h.tasks | ||
| n := len(old) | ||
| x := old[n-1] | ||
| h.tasks = old[0 : n-1] | ||
| return x | ||
| } | ||
|
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| func (h *scheduledTaskHeap) Peek() interface{} { | ||
| if len(h.tasks) == 0 { | ||
| return nil | ||
| } | ||
| return h.tasks[0] | ||
| } | ||
|
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| type scheduledTaskHeapByTime struct { | ||
| scheduledTaskHeap | ||
| } | ||
|
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| var _ heap.Interface = &scheduledTaskHeapByTime{} | ||
|
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| func (h *scheduledTaskHeapByTime) Less(i, j int) bool { | ||
| return h.tasks[i].runAt.Before(h.tasks[j].runAt) | ||
| } | ||
|
|
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| type scheduledTaskHeapByPriorityThenTime struct { | ||
| scheduledTaskHeap | ||
| } | ||
|
|
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| var _ heap.Interface = &scheduledTaskHeapByPriorityThenTime{} | ||
|
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| func (h *scheduledTaskHeapByPriorityThenTime) Less(i, j int) bool { | ||
| if h.tasks[i].priority != h.tasks[j].priority { | ||
| return h.tasks[i].priority > h.tasks[j].priority | ||
| } | ||
| return h.tasks[i].runAt.Before(h.tasks[j].runAt) | ||
| } |