156 lines
3.8 KiB
Go
156 lines
3.8 KiB
Go
package common
|
|
|
|
import (
|
|
"container/heap"
|
|
"math"
|
|
"time"
|
|
|
|
"sync/atomic"
|
|
|
|
"github.com/benbjohnson/clock"
|
|
)
|
|
|
|
// A callable is a function that is called and return an (optional) next scheduled time
|
|
type callable func() time.Time
|
|
|
|
type schedCall struct {
|
|
t time.Time
|
|
c callable
|
|
}
|
|
|
|
func (sc *schedCall) FromNow(now time.Time) time.Duration {
|
|
if sc.t.After(now) {
|
|
return time.Duration(sc.t.Sub(now).Nanoseconds())
|
|
}
|
|
return time.Duration(0)
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
|
|
// A min-heap of scheduled callables
|
|
type schedCallsHeap []*schedCall
|
|
|
|
func (ch *schedCallsHeap) Len() int { return len(*ch) }
|
|
func (ch *schedCallsHeap) Less(i, j int) bool { return (*ch)[i].t.Before((*ch)[j].t) }
|
|
func (ch *schedCallsHeap) Swap(i, j int) {
|
|
(*ch)[i], (*ch)[j] = (*ch)[j], (*ch)[i]
|
|
}
|
|
|
|
func (ch *schedCallsHeap) Push(x interface{}) {
|
|
// Push and Pop use pointer receivers because they modify the slice's length,
|
|
// not just its contents.
|
|
entry := x.(*schedCall)
|
|
*ch = append(*ch, entry)
|
|
}
|
|
|
|
func (ch *schedCallsHeap) Pop() interface{} {
|
|
old := *ch
|
|
n := len(old)
|
|
item := old[n-1]
|
|
*ch = old[0 : n-1]
|
|
return item
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
|
|
// SchedQueue is queue of scheduled callables
|
|
type SchedQueue struct {
|
|
clock clock.Clock
|
|
callablesH schedCallsHeap
|
|
schedChan chan *schedCall
|
|
closeChan chan bool
|
|
counter uint64 // number of calls invoked so far (used for stats). Note: it will wrap.
|
|
}
|
|
|
|
// NewSchedQueue creates a new scheduled queue
|
|
func NewSchedQueue(clock clock.Clock) *SchedQueue {
|
|
cq := SchedQueue{
|
|
clock: clock,
|
|
schedChan: make(chan *schedCall),
|
|
closeChan: make(chan bool),
|
|
}
|
|
heap.Init(&cq.callablesH)
|
|
return &cq
|
|
}
|
|
|
|
// Start starts the scheduled queue
|
|
func (cq *SchedQueue) Start() {
|
|
go func() {
|
|
defer func() { Debug.Printf("[sched-q] Quitting (%d calls pending)", len(cq.callablesH)) }()
|
|
|
|
var now time.Time
|
|
timer := cq.clock.Timer(time.Duration(math.MaxInt64))
|
|
|
|
for {
|
|
// Wait until an insertion, until the next callable or until we are Stop()ed
|
|
select {
|
|
case ce := <-cq.schedChan:
|
|
heap.Push(&cq.callablesH, ce)
|
|
now = cq.clock.Now()
|
|
case <-cq.closeChan:
|
|
return
|
|
case now = <-timer.C:
|
|
}
|
|
|
|
timer.Stop()
|
|
durationUntilNext := cq.durationUntilNext(now)
|
|
for durationUntilNext == 0 {
|
|
sched := heap.Pop(&cq.callablesH).(*schedCall)
|
|
|
|
atomic.AddUint64(&cq.counter, 1)
|
|
schedNextTime := sched.c()
|
|
|
|
if !schedNextTime.IsZero() {
|
|
sched.t = schedNextTime
|
|
heap.Push(&cq.callablesH, sched) // TODO: use a Fix() instead of Pop()&Push()
|
|
}
|
|
|
|
now = cq.clock.Now()
|
|
durationUntilNext = cq.durationUntilNext(now)
|
|
}
|
|
|
|
timer = cq.clock.Timer(durationUntilNext)
|
|
}
|
|
}()
|
|
}
|
|
|
|
// Stop stops the scheduled queue
|
|
func (cq *SchedQueue) Stop() {
|
|
Debug.Printf("[sched-q] Stopping...")
|
|
cq.closeChan <- true
|
|
}
|
|
|
|
// Add schedules a call.
|
|
// The callable should not modify the scheduled queue in any way.
|
|
func (cq *SchedQueue) Add(c callable, t time.Time) {
|
|
Debug.Printf("[sched-q] Adding call at %s", t)
|
|
ce := schedCall{c: c, t: t}
|
|
cq.schedChan <- &ce
|
|
}
|
|
|
|
// Counter returns the number of calls invoked in the queued
|
|
// Note: the result will wrap over time.
|
|
func (cq *SchedQueue) Count() uint64 {
|
|
return atomic.LoadUint64(&cq.counter)
|
|
}
|
|
|
|
func (cq *SchedQueue) durationUntilNext(now time.Time) time.Duration {
|
|
if len(cq.callablesH) > 0 {
|
|
firstSched := cq.callablesH[0]
|
|
return firstSched.FromNow(now)
|
|
}
|
|
return time.Duration(math.MaxInt64)
|
|
}
|
|
|
|
// ensure that the background goroutine has executed any pending callbacks
|
|
func (cq *SchedQueue) Flush() {
|
|
ch := make(chan struct{})
|
|
flushFunc := func() time.Time {
|
|
atomic.AddUint64(&cq.counter, ^uint64(0)) // decrement so nobody sees this
|
|
close(ch)
|
|
return time.Time{}
|
|
}
|
|
cq.schedChan <- &schedCall{c: flushFunc, t: time.Time{}}
|
|
<-ch
|
|
}
|