A fork of Gitea (see branch `mj`) adding Majority Judgment Polls 𐄷 over Issues and Merge Requests. https://git.mieuxvoter.fr
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// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package graceful
import (
"context"
"sync"
"time"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/process"
"code.gitea.io/gitea/modules/setting"
)
type state uint8
const (
stateInit state = iota
stateRunning
stateShuttingDown
stateTerminate
)
// There are three places that could inherit sockets:
//
// * HTTP or HTTPS main listener
// * HTTP redirection fallback
// * SSH
//
// If you add an additional place you must increment this number
// and add a function to call manager.InformCleanup if it's not going to be used
const numberOfServersToCreate = 4
// Manager represents the graceful server manager interface
var manager *Manager
var initOnce = sync.Once{}
// GetManager returns the Manager
func GetManager() *Manager {
InitManager(context.Background())
return manager
}
// InitManager creates the graceful manager in the provided context
func InitManager(ctx context.Context) {
initOnce.Do(func() {
manager = newGracefulManager(ctx)
// Set the process default context to the HammerContext
process.DefaultContext = manager.HammerContext()
})
}
// CallbackWithContext is combined runnable and context to watch to see if the caller has finished
type CallbackWithContext func(ctx context.Context, callback func())
// RunnableWithShutdownFns is a runnable with functions to run at shutdown and terminate
// After the callback to atShutdown is called and is complete, the main function must return.
// Similarly the callback function provided to atTerminate must return once termination is complete.
// Please note that use of the atShutdown and atTerminate callbacks will create go-routines that will wait till their respective signals
// - users must therefore be careful to only call these as necessary.
// If run is not expected to run indefinitely RunWithShutdownChan is likely to be more appropriate.
type RunnableWithShutdownFns func(atShutdown, atTerminate func(context.Context, func()))
// RunWithShutdownFns takes a function that has both atShutdown and atTerminate callbacks
// After the callback to atShutdown is called and is complete, the main function must return.
// Similarly the callback function provided to atTerminate must return once termination is complete.
// Please note that use of the atShutdown and atTerminate callbacks will create go-routines that will wait till their respective signals
// - users must therefore be careful to only call these as necessary.
// If run is not expected to run indefinitely RunWithShutdownChan is likely to be more appropriate.
func (g *Manager) RunWithShutdownFns(run RunnableWithShutdownFns) {
g.runningServerWaitGroup.Add(1)
defer g.runningServerWaitGroup.Done()
defer func() {
if err := recover(); err != nil {
log.Critical("PANIC during RunWithShutdownFns: %v\nStacktrace: %s", err, log.Stack(2))
g.doShutdown()
}
}()
run(func(ctx context.Context, atShutdown func()) {
go func() {
select {
case <-g.IsShutdown():
atShutdown()
case <-ctx.Done():
return
}
}()
}, func(ctx context.Context, atTerminate func()) {
g.RunAtTerminate(ctx, atTerminate)
})
}
// RunnableWithShutdownChan is a runnable with functions to run at shutdown and terminate.
// After the atShutdown channel is closed, the main function must return once shutdown is complete.
// (Optionally IsHammer may be waited for instead however, this should be avoided if possible.)
// The callback function provided to atTerminate must return once termination is complete.
// Please note that use of the atTerminate function will create a go-routine that will wait till terminate - users must therefore be careful to only call this as necessary.
type RunnableWithShutdownChan func(atShutdown <-chan struct{}, atTerminate CallbackWithContext)
// RunWithShutdownChan takes a function that has channel to watch for shutdown and atTerminate callbacks
// After the atShutdown channel is closed, the main function must return once shutdown is complete.
// (Optionally IsHammer may be waited for instead however, this should be avoided if possible.)
// The callback function provided to atTerminate must return once termination is complete.
// Please note that use of the atTerminate function will create a go-routine that will wait till terminate - users must therefore be careful to only call this as necessary.
func (g *Manager) RunWithShutdownChan(run RunnableWithShutdownChan) {
g.runningServerWaitGroup.Add(1)
defer g.runningServerWaitGroup.Done()
defer func() {
if err := recover(); err != nil {
log.Critical("PANIC during RunWithShutdownChan: %v\nStacktrace: %s", err, log.Stack(2))
g.doShutdown()
}
}()
run(g.IsShutdown(), func(ctx context.Context, atTerminate func()) {
g.RunAtTerminate(ctx, atTerminate)
})
}
// RunWithShutdownContext takes a function that has a context to watch for shutdown.
// After the provided context is Done(), the main function must return once shutdown is complete.
// (Optionally the HammerContext may be obtained and waited for however, this should be avoided if possible.)
func (g *Manager) RunWithShutdownContext(run func(context.Context)) {
g.runningServerWaitGroup.Add(1)
defer g.runningServerWaitGroup.Done()
defer func() {
if err := recover(); err != nil {
log.Critical("PANIC during RunWithShutdownContext: %v\nStacktrace: %s", err, log.Stack(2))
g.doShutdown()
}
}()
run(g.ShutdownContext())
}
// RunAtTerminate adds to the terminate wait group and creates a go-routine to run the provided function at termination
func (g *Manager) RunAtTerminate(ctx context.Context, terminate func()) {
g.terminateWaitGroup.Add(1)
go func() {
defer g.terminateWaitGroup.Done()
defer func() {
if err := recover(); err != nil {
log.Critical("PANIC during RunAtTerminate: %v\nStacktrace: %s", err, log.Stack(2))
}
}()
select {
case <-g.IsTerminate():
terminate()
case <-ctx.Done():
}
}()
}
// RunAtShutdown creates a go-routine to run the provided function at shutdown
func (g *Manager) RunAtShutdown(ctx context.Context, shutdown func()) {
go func() {
defer func() {
if err := recover(); err != nil {
log.Critical("PANIC during RunAtShutdown: %v\nStacktrace: %s", err, log.Stack(2))
}
}()
select {
case <-g.IsShutdown():
shutdown()
case <-ctx.Done():
}
}()
}
// RunAtHammer creates a go-routine to run the provided function at shutdown
func (g *Manager) RunAtHammer(ctx context.Context, hammer func()) {
go func() {
defer func() {
if err := recover(); err != nil {
log.Critical("PANIC during RunAtHammer: %v\nStacktrace: %s", err, log.Stack(2))
}
}()
select {
case <-g.IsHammer():
hammer()
case <-ctx.Done():
}
}()
}
func (g *Manager) doShutdown() {
if !g.setStateTransition(stateRunning, stateShuttingDown) {
return
}
g.lock.Lock()
close(g.shutdown)
g.lock.Unlock()
if setting.GracefulHammerTime >= 0 {
go g.doHammerTime(setting.GracefulHammerTime)
}
go func() {
g.WaitForServers()
// Mop up any remaining unclosed events.
g.doHammerTime(0)
<-time.After(1 * time.Second)
g.doTerminate()
g.WaitForTerminate()
g.lock.Lock()
close(g.done)
g.lock.Unlock()
}()
}
func (g *Manager) doHammerTime(d time.Duration) {
time.Sleep(d)
g.lock.Lock()
select {
case <-g.hammer:
default:
log.Warn("Setting Hammer condition")
close(g.hammer)
}
g.lock.Unlock()
}
func (g *Manager) doTerminate() {
if !g.setStateTransition(stateShuttingDown, stateTerminate) {
return
}
g.lock.Lock()
select {
case <-g.terminate:
default:
log.Warn("Terminating")
close(g.terminate)
}
g.lock.Unlock()
}
// IsChild returns if the current process is a child of previous Gitea process
func (g *Manager) IsChild() bool {
return g.isChild
}
// IsShutdown returns a channel which will be closed at shutdown.
// The order of closure is IsShutdown, IsHammer (potentially), IsTerminate
func (g *Manager) IsShutdown() <-chan struct{} {
return g.shutdown
}
// IsHammer returns a channel which will be closed at hammer
// The order of closure is IsShutdown, IsHammer (potentially), IsTerminate
// Servers running within the running server wait group should respond to IsHammer
// if not shutdown already
func (g *Manager) IsHammer() <-chan struct{} {
return g.hammer
}
// IsTerminate returns a channel which will be closed at terminate
// The order of closure is IsShutdown, IsHammer (potentially), IsTerminate
// IsTerminate will only close once all running servers have stopped
func (g *Manager) IsTerminate() <-chan struct{} {
return g.terminate
}
// ServerDone declares a running server done and subtracts one from the
// running server wait group. Users probably do not want to call this
// and should use one of the RunWithShutdown* functions
func (g *Manager) ServerDone() {
g.runningServerWaitGroup.Done()
}
// WaitForServers waits for all running servers to finish. Users should probably
// instead use AtTerminate or IsTerminate
func (g *Manager) WaitForServers() {
g.runningServerWaitGroup.Wait()
}
// WaitForTerminate waits for all terminating actions to finish.
// Only the main go-routine should use this
func (g *Manager) WaitForTerminate() {
g.terminateWaitGroup.Wait()
}
func (g *Manager) getState() state {
g.lock.RLock()
defer g.lock.RUnlock()
return g.state
}
func (g *Manager) setStateTransition(old, new state) bool {
if old != g.getState() {
return false
}
g.lock.Lock()
if g.state != old {
g.lock.Unlock()
return false
}
g.state = new
g.lock.Unlock()
return true
}
func (g *Manager) setState(st state) {
g.lock.Lock()
defer g.lock.Unlock()
g.state = st
}
// InformCleanup tells the cleanup wait group that we have either taken a listener
// or will not be taking a listener
func (g *Manager) InformCleanup() {
g.createServerWaitGroup.Done()
}
// Done allows the manager to be viewed as a context.Context, it returns a channel that is closed when the server is finished terminating
func (g *Manager) Done() <-chan struct{} {
return g.done
}
// Err allows the manager to be viewed as a context.Context done at Terminate, it returns ErrTerminate
func (g *Manager) Err() error {
select {
case <-g.Done():
return ErrTerminate
default:
return nil
}
}
// Value allows the manager to be viewed as a context.Context done at Terminate, it has no values
func (g *Manager) Value(key interface{}) interface{} {
return nil
}
// Deadline returns nil as there is no fixed Deadline for the manager, it allows the manager to be viewed as a context.Context
func (g *Manager) Deadline() (deadline time.Time, ok bool) {
return
}