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// Package idleshut provides a lifecycle and idletime management tool.
package idleshut
import (
"sync"
"time"
)
// Config contains the options for creating a new process.
type Config struct {
// Start, if non-nil, is called by Process.Start. If an error is returned,
// starting the process is aborted.
Start func() error
// Stop, if non-nil, is called by Process.Stop. If an error is returned,
// stopping the process is aborted.
Stop func() error
// If TickDuration is non-zero, the process will count ticks where
// the process is active or idle. Process are kept active by the user
// calling the Process.Touch() method. When the process has been idle for
// more than MaxIdleTicks, it will be stopped. If ticking is enabled,
// TickError must be set or operations will result in a panic.
TickDuration time.Duration
TickError func(error)
// Tick is called by Process for every iteration of Tick. If
// an error is returned, it is sent to TickError. Additionally,
// IdleTick and ActiveTick are called for idle and active ticks
// respectively.
Tick func() error
IdleTick func() error
ActiveTick func() error
// MaxIdleTicks, if nonzero and ticking is configured, will cause
// the process to stop once the maximum number of ticks has been
// reached.
MaxIdleTicks uint
}
func (cfg Config) validate() {
allSet := cfg.TickError == nil && cfg.TickDuration == 0
noneSet := cfg.TickError != nil && cfg.TickDuration != 0
if !allSet && !noneSet {
panic("idleshut: Config.IdleTick, config.IdleProcessError, and config.Tick must all be set or all be unset")
}
}
// New returns a new Process with the given configuration.
func New(cfg Config) *Process {
cfg.validate()
return &Process{cfg: cfg}
}
// Process is a lifecycle and idle process monitor.
type Process struct {
cfg Config
mtx sync.Mutex
started time.Time
stopped time.Time
running bool
touched bool
idleTicks uint
currentGeneration uint
}
// Touch resets the idle timer to zero.
func (p *Process) Touch() bool {
p.mtx.Lock()
defer p.mtx.Unlock()
p.idleTicks = 0
p.touched = true
return p.running
}
// Start initiates the process.
func (p *Process) Start() error {
p.mtx.Lock()
defer p.mtx.Unlock()
if !p.running {
var err error
if p.cfg.Start != nil {
err = p.cfg.Start()
}
if err != nil {
return err
}
p.running = true
p.started = time.Now()
p.currentGeneration++
go p.startTicker()
}
return nil
}
// Running returns true if the process is currently running.
func (p *Process) Running() bool {
p.mtx.Lock()
defer p.mtx.Unlock()
return p.running
}
func (p *Process) generation() uint {
p.mtx.Lock()
defer p.mtx.Unlock()
return p.currentGeneration
}
func (p *Process) startTicker() {
if p.cfg.TickDuration == 0 {
return
}
startingGen := p.generation()
tk := time.NewTicker(p.cfg.TickDuration)
for {
<-tk.C
// if we stopped running, or we started again and thus the geneneration has advanced, return
if !p.Running() || p.generation() != startingGen {
return
}
func() {
p.mtx.Lock()
defer p.mtx.Unlock()
if p.cfg.Tick != nil {
p.idleProcessError(p.cfg.Tick())
}
if p.touched {
p.idleTicks = 0
p.touched = false //reset
if p.cfg.ActiveTick != nil {
p.idleProcessError(p.cfg.ActiveTick())
}
} else {
p.idleTicks++
if p.cfg.IdleTick != nil {
p.idleProcessError(p.cfg.IdleTick())
}
if p.idleTicks >= p.cfg.MaxIdleTicks {
p.idleProcessError(p.stopWithLock())
}
}
}()
}
}
func (p *Process) idleProcessError(err error) {
if err != nil && p.cfg.TickError != nil {
go p.cfg.TickError(err)
}
}
// Stop halts the process.
func (p *Process) Stop() error {
p.mtx.Lock()
defer p.mtx.Unlock()
if p.running {
return p.stopWithLock()
}
return nil
}
func (p *Process) stopWithLock() error {
var err error
if p.cfg.Stop != nil {
err = p.cfg.Stop()
}
if err != nil {
return err
}
p.idleTicks = 0
p.running = false
p.stopped = time.Now()
return nil
}