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dex/vendor/github.com/jonboulle/clockwork/clockwork.go

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2017-01-10 04:21:47 +05:30
package clockwork
import (
"sync"
"time"
)
// Clock provides an interface that packages can use instead of directly
// using the time module, so that chronology-related behavior can be tested
type Clock interface {
After(d time.Duration) <-chan time.Time
Sleep(d time.Duration)
Now() time.Time
}
// FakeClock provides an interface for a clock which can be
// manually advanced through time
type FakeClock interface {
Clock
// Advance advances the FakeClock to a new point in time, ensuring any existing
// sleepers are notified appropriately before returning
Advance(d time.Duration)
// BlockUntil will block until the FakeClock has the given number of
// sleepers (callers of Sleep or After)
BlockUntil(n int)
}
// NewRealClock returns a Clock which simply delegates calls to the actual time
// package; it should be used by packages in production.
func NewRealClock() Clock {
return &realClock{}
}
// NewFakeClock returns a FakeClock implementation which can be
// manually advanced through time for testing. The initial time of the
// FakeClock will be an arbitrary non-zero time.
func NewFakeClock() FakeClock {
// use a fixture that does not fulfill Time.IsZero()
return NewFakeClockAt(time.Date(1984, time.April, 4, 0, 0, 0, 0, time.UTC))
}
// NewFakeClockAt returns a FakeClock initialised at the given time.Time.
func NewFakeClockAt(t time.Time) FakeClock {
return &fakeClock{
time: t,
}
}
type realClock struct{}
func (rc *realClock) After(d time.Duration) <-chan time.Time {
return time.After(d)
}
func (rc *realClock) Sleep(d time.Duration) {
time.Sleep(d)
}
func (rc *realClock) Now() time.Time {
return time.Now()
}
type fakeClock struct {
sleepers []*sleeper
blockers []*blocker
time time.Time
l sync.RWMutex
}
// sleeper represents a caller of After or Sleep
type sleeper struct {
until time.Time
done chan time.Time
}
// blocker represents a caller of BlockUntil
type blocker struct {
count int
ch chan struct{}
}
// After mimics time.After; it waits for the given duration to elapse on the
// fakeClock, then sends the current time on the returned channel.
func (fc *fakeClock) After(d time.Duration) <-chan time.Time {
fc.l.Lock()
defer fc.l.Unlock()
now := fc.time
done := make(chan time.Time, 1)
if d.Nanoseconds() == 0 {
// special case - trigger immediately
done <- now
} else {
// otherwise, add to the set of sleepers
s := &sleeper{
until: now.Add(d),
done: done,
}
fc.sleepers = append(fc.sleepers, s)
// and notify any blockers
fc.blockers = notifyBlockers(fc.blockers, len(fc.sleepers))
}
return done
}
// notifyBlockers notifies all the blockers waiting until the
// given number of sleepers are waiting on the fakeClock. It
// returns an updated slice of blockers (i.e. those still waiting)
func notifyBlockers(blockers []*blocker, count int) (newBlockers []*blocker) {
for _, b := range blockers {
if b.count == count {
close(b.ch)
} else {
newBlockers = append(newBlockers, b)
}
}
return
}
// Sleep blocks until the given duration has passed on the fakeClock
func (fc *fakeClock) Sleep(d time.Duration) {
<-fc.After(d)
}
// Time returns the current time of the fakeClock
func (fc *fakeClock) Now() time.Time {
fc.l.RLock()
t := fc.time
fc.l.RUnlock()
return t
}
// Advance advances fakeClock to a new point in time, ensuring channels from any
// previous invocations of After are notified appropriately before returning
func (fc *fakeClock) Advance(d time.Duration) {
fc.l.Lock()
defer fc.l.Unlock()
end := fc.time.Add(d)
var newSleepers []*sleeper
for _, s := range fc.sleepers {
if end.Sub(s.until) >= 0 {
s.done <- end
} else {
newSleepers = append(newSleepers, s)
}
}
fc.sleepers = newSleepers
fc.blockers = notifyBlockers(fc.blockers, len(fc.sleepers))
fc.time = end
}
// BlockUntil will block until the fakeClock has the given number of sleepers
// (callers of Sleep or After)
func (fc *fakeClock) BlockUntil(n int) {
fc.l.Lock()
// Fast path: current number of sleepers is what we're looking for
if len(fc.sleepers) == n {
fc.l.Unlock()
return
}
// Otherwise, set up a new blocker
b := &blocker{
count: n,
ch: make(chan struct{}),
}
fc.blockers = append(fc.blockers, b)
fc.l.Unlock()
<-b.ch
}