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