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203 lines
5.0 KiB
203 lines
5.0 KiB
// Package idleshut provides a lifecycle and idletime management tool.
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//
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// Copyright 2017 Stephen Searles
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//
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// Redistribution and use in source and binary forms, with or without modification,
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// are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation and/or
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// other materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors
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// may be used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
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// TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package idleshut
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import (
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"sync"
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"time"
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)
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// Config are the options for creating a new process
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type Config struct {
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// Start is called by Process.Start. If an error is returned,
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// starting the process is aborted.
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Start func() error
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// Stop is called by Process.Stop. If an error is returned,
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// stopping the process is aborted.
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Stop func() error
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// IdleTick is called by Process for every iteration of Tick. If
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// an error is returned, it is sent to IdleProcessError. IdleTick
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// and IdleProcessError must both be set or unset; mixed set-edness
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// will result in a panic.
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IdleTick func() error
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IdleProcessError func(error)
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Tick time.Duration
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// MaxIdleTicks, if nonzero and ticking is configured, will cause
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// the process to stop once the maximum number of ticks has been
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// reached.
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MaxIdleTicks uint
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}
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func (cfg Config) validate() {
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allSet := cfg.IdleTick == nil && cfg.IdleProcessError == nil && cfg.Tick == 0
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noneSet := cfg.IdleTick != nil && cfg.IdleProcessError != nil && cfg.Tick != 0
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if !allSet && !noneSet {
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panic("idleshut: Config.IdleTick, config.IdleProcessError, and config.Tick must all be set or all be unset")
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}
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}
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// New returns a new Process with the given configuration.
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func New(cfg Config) *Process {
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cfg.validate()
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return &Process{cfg: cfg}
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}
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// Process is a lifecycle and idle process monitor.
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type Process struct {
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cfg Config
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mtx sync.Mutex
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started time.Time
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stopped time.Time
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running bool
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touched bool
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idleTicks uint
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currentGeneration uint
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}
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// Touch resets the idle timer to zero.
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func (p *Process) Touch() bool {
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p.mtx.Lock()
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defer p.mtx.Unlock()
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p.idleTicks = 0
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p.touched = true
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return p.running
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}
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// Start initiates the process.
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func (p *Process) Start() error {
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p.mtx.Lock()
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defer p.mtx.Unlock()
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if !p.running {
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var err error
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if p.cfg.Start != nil {
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err = p.cfg.Start()
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}
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if err != nil {
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return err
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}
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p.running = true
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p.started = time.Now()
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p.currentGeneration++
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go p.startTicker()
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}
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return nil
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}
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// Running returns true if the process is currently running.
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func (p *Process) Running() bool {
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p.mtx.Lock()
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defer p.mtx.Unlock()
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return p.running
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}
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func (p *Process) generation() uint {
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p.mtx.Lock()
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defer p.mtx.Unlock()
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return p.currentGeneration
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}
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func (p *Process) startTicker() {
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if p.cfg.Tick == 0 || p.cfg.IdleTick == nil {
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return
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}
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startingGen := p.generation()
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tk := time.NewTicker(p.cfg.Tick)
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for {
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<-tk.C
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// if we stopped running, or we started again and thus the geneneration has advanced, return
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if !p.Running() || p.generation() != startingGen {
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return
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}
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func() {
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p.mtx.Lock()
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defer p.mtx.Unlock()
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if p.touched {
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p.idleTicks = 0
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p.touched = false //reset
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} else {
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p.idleTicks++
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if p.cfg.IdleTick != nil {
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p.idleProcessError(p.cfg.IdleTick())
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}
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if p.idleTicks >= p.cfg.MaxIdleTicks {
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p.idleProcessError(p.stopWithLock())
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}
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}
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}()
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}
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}
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func (p *Process) idleProcessError(err error) {
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if err != nil && p.cfg.IdleProcessError != nil {
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go p.cfg.IdleProcessError(err)
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}
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}
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// Stop halts the process.
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func (p *Process) Stop() error {
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p.mtx.Lock()
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defer p.mtx.Unlock()
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if p.running {
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return p.stopWithLock()
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}
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return nil
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}
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func (p *Process) stopWithLock() error {
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var err error
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if p.cfg.Stop != nil {
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err = p.cfg.Stop()
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}
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if err != nil {
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return err
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}
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p.idleTicks = 0
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p.running = false
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p.stopped = time.Now()
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return nil
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}
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