go/core/timers/pulsar.go

// ------------------------------------------------------------------------
//   Project atila
//   Active Thing (activething.com) git.activething.com/go
//
//   File name  rkey.go
//   Created by DEV
//   Modified   05/02/2024
//
//   Copyright 2024 activething.com
// ------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------

package timers

import (
	"activething.com/go/gogo/core/contexts"
	"context"
	"sync/atomic"
	"time"





)

type (


	Pulsar 		struct {
		state  	uint32
		pulse  	int64
		err    	atomic.Value
		cancel 	contexts.Cancel
		workFn 	PulsarWorkFnc
	}


	PulsarWorkFnc 	func(ctx context.Context) error

)


func NewPulsar(pulse time.Duration, work PulsarWorkFnc) *Pulsar {
	return &Pulsar{
		state:  uint32(TimerStateCreated),
		cancel: *contexts.NewCancel(),
		pulse:  int64(pulse),
		workFn: work,
	}
}


func (p *Pulsar) State() TimerState {
	return TimerState(atomic.LoadUint32(&p.state)) }


func (p *Pulsar) Pulse() time.Duration {
	return time.Duration(atomic.LoadInt64(&p.pulse)) }


func (p *Pulsar) Err() error {
	if v := p.err.Load(); v != nil {
		return v.(error)
	}
	return nil
}


func (p *Pulsar) Start(ctx context.Context) error {
	if !atomic.CompareAndSwapUint32(&p.state,uint32(TimerStateCreated),uint32(TimerStateStarted)) {
		return G.ErrAlreadyStarted
	}
	to := atomic.LoadInt64(&p.pulse)
	if to <= 0 {
		atomic.StoreUint32(&p.state,uint32(TimerStateExpired))
		return G.ErrIntervalInvalid
	}

	cx := ctx
	if cx == nil {
		cx = context.Background()
	} else if ctx.Err() != nil {
		atomic.StoreUint32(&p.state,uint32(TimerStateCanceled))
		return context.Canceled
	}

	go func(pl *Pulsar, tk *time.Ticker, cx context.Context) {
	EXIT:
		for {
			select {
			case <-cx.Done():
				atomic.StoreUint32(&pl.state,uint32(TimerStateCanceled))
				break EXIT

			case <-pl.cancel.Done():
				break EXIT

			case <-tk.C:
				if TimerState(atomic.LoadUint32(&pl.state)) == TimerStateStarted {
					if er := pl.workFn(cx); er != nil {
						pl.err.Store(er)
						atomic.StoreUint32(&pl.state,uint32(TimerStateCanceled))
						break EXIT
					}
				}
			}
		}
		tk.Stop()
		pl.cancel.Cancel()

	}(p, time.NewTicker(time.Duration(to)), cx)

	return nil
}


func (p *Pulsar) Stop() error {
	if atomic.CompareAndSwapUint32(&p.state,uint32(TimerStateStarted), uint32(TimerStateStopped)) ||
	   atomic.CompareAndSwapUint32(&p.state,uint32(TimerStatePaused), uint32(TimerStateStopped)) {
		p.cancel.Cancel()
		return nil
	}
	return G.ErrNotStarted
}


func (p *Pulsar) Pause() error {
	if atomic.CompareAndSwapUint32(&p.state,uint32(TimerStateStarted), uint32(TimerStatePaused)) {
		return nil
	}
	return G.ErrNotStarted
}


func (p *Pulsar) Continue() error {
	if atomic.CompareAndSwapUint32(&p.state,uint32(TimerStatePaused), uint32(TimerStateStarted)) {
		return nil
	}
	return G.ErrNotPaused
}


func (p *Pulsar) Done() <-chan struct{} {
	return p.cancel.Done() }


func (p *Pulsar) Wait() {
	<-p.cancel.Done() }


/*
   ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

   I HAVE NO DESIRE TO WALK ON WATER," SAID SIDDHARTA.
   "LET THE OLD SHRAMANAS SATISFY THEMSELVES WITH SUCH SKILLS.

   SIDDHARTA
   - HERMANN HESSE -

   :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

*/