forked from mirrors/gotosocial
97 lines
2.2 KiB
Go
97 lines
2.2 KiB
Go
package nowish
|
|
|
|
import (
|
|
"sync/atomic"
|
|
"time"
|
|
)
|
|
|
|
// Timeout provides a reusable structure for enforcing timeouts with a cancel
|
|
type Timeout struct {
|
|
noCopy noCopy //nolint noCopy because a copy will mess with atomics
|
|
|
|
tk *time.Ticker // tk is the underlying timeout-timer
|
|
ch chan struct{} // ch is the cancel propagation channel
|
|
st timeoutState // st stores the current timeout state (and protects concurrent use)
|
|
}
|
|
|
|
// NewTimeout returns a new Timeout instance
|
|
func NewTimeout() Timeout {
|
|
tk := time.NewTicker(time.Minute)
|
|
tk.Stop() // don't keep it running
|
|
return Timeout{
|
|
tk: tk,
|
|
ch: make(chan struct{}),
|
|
}
|
|
}
|
|
|
|
// Start starts the timer with supplied timeout. If timeout is reached before
|
|
// cancel then supplied timeout hook will be called. Error may be called if
|
|
// Timeout is already running when this function is called
|
|
func (t *Timeout) Start(d time.Duration, hook func()) {
|
|
// Attempt to acquire start
|
|
if !t.st.start() {
|
|
panic("nowish: timeout already started")
|
|
}
|
|
|
|
// Start the ticker
|
|
t.tk.Reset(d)
|
|
|
|
go func() {
|
|
cancelled := false
|
|
|
|
select {
|
|
// Timeout reached
|
|
case <-t.tk.C:
|
|
if !t.st.stop() {
|
|
// cancel was called in the nick of time
|
|
<-t.ch
|
|
cancelled = true
|
|
}
|
|
|
|
// Cancel called
|
|
case <-t.ch:
|
|
cancelled = true
|
|
}
|
|
|
|
// Stop ticker
|
|
t.tk.Stop()
|
|
|
|
// If timed out call hook
|
|
if !cancelled {
|
|
hook()
|
|
}
|
|
|
|
// Finally, reset state
|
|
t.st.reset()
|
|
}()
|
|
}
|
|
|
|
// Cancel cancels the currently running timer. If a cancel is achieved, then
|
|
// this function will return after the timeout goroutine is finished
|
|
func (t *Timeout) Cancel() {
|
|
// Attempt to acquire stop
|
|
if !t.st.stop() {
|
|
return
|
|
}
|
|
|
|
// Send a cancel signal
|
|
t.ch <- struct{}{}
|
|
}
|
|
|
|
// timeoutState provides a thread-safe timeout state mechanism
|
|
type timeoutState uint32
|
|
|
|
// start attempts to start the state, must be already reset, returns success
|
|
func (t *timeoutState) start() bool {
|
|
return atomic.CompareAndSwapUint32((*uint32)(t), 0, 1)
|
|
}
|
|
|
|
// stop attempts to stop the state, must already be started, returns success
|
|
func (t *timeoutState) stop() bool {
|
|
return atomic.CompareAndSwapUint32((*uint32)(t), 1, 2)
|
|
}
|
|
|
|
// reset is fairly self explanatory
|
|
func (t *timeoutState) reset() {
|
|
atomic.StoreUint32((*uint32)(t), 0)
|
|
}
|