mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-04 22:20:53 +01:00
160 lines
3.5 KiB
Go
160 lines
3.5 KiB
Go
package runners
|
|
|
|
import (
|
|
"context"
|
|
"sync"
|
|
)
|
|
|
|
// Service provides a means of tracking a single long-running service, provided protected state
|
|
// changes and preventing multiple instances running. Also providing service state information.
|
|
type Service struct {
|
|
state uint32 // 0=stopped, 1=running, 2=stopping
|
|
wait sync.Mutex // wait is the mutex used as a single-entity wait-group, i.e. just a "wait" :p
|
|
cncl context.CancelFunc // cncl is the cancel function set for the current context
|
|
ctx context.Context // ctx is the current context for running function (or nil if not running)
|
|
mu sync.Mutex // mu protects state changes
|
|
}
|
|
|
|
// Run will run the supplied function until completion, use given context to propagate cancel.
|
|
// Immediately returns false if the Service is already running, and true after completed run.
|
|
func (svc *Service) Run(fn func(context.Context)) bool {
|
|
// Attempt to start the svc
|
|
ctx, ok := svc.doStart()
|
|
if !ok {
|
|
return false
|
|
}
|
|
|
|
defer func() {
|
|
// unlock single wait
|
|
svc.wait.Unlock()
|
|
|
|
// ensure stopped
|
|
svc.Stop()
|
|
}()
|
|
|
|
// Run user func
|
|
if fn != nil {
|
|
fn(ctx)
|
|
}
|
|
return true
|
|
}
|
|
|
|
// Stop will attempt to stop the service, cancelling the running function's context. Immediately
|
|
// returns false if not running, and true only after Service is fully stopped.
|
|
func (svc *Service) Stop() bool {
|
|
// Attempt to stop the svc
|
|
cncl, ok := svc.doStop()
|
|
if !ok {
|
|
return false
|
|
}
|
|
|
|
defer func() {
|
|
// Get svc lock
|
|
svc.mu.Lock()
|
|
|
|
// Wait until stopped
|
|
svc.wait.Lock()
|
|
svc.wait.Unlock()
|
|
|
|
// Reset the svc
|
|
svc.ctx = nil
|
|
svc.cncl = nil
|
|
svc.state = 0
|
|
svc.mu.Unlock()
|
|
}()
|
|
|
|
cncl() // cancel ctx
|
|
return true
|
|
}
|
|
|
|
// doStart will safely set Service state to started, returning a ptr to this context insance.
|
|
func (svc *Service) doStart() (context.Context, bool) {
|
|
// Protect startup
|
|
svc.mu.Lock()
|
|
|
|
if svc.state != 0 /* not stopped */ {
|
|
svc.mu.Unlock()
|
|
return nil, false
|
|
}
|
|
|
|
// state started
|
|
svc.state = 1
|
|
|
|
// Take our own ptr
|
|
var ctx context.Context
|
|
|
|
if svc.ctx == nil {
|
|
// Context required allocating
|
|
svc.ctx, svc.cncl = ContextWithCancel()
|
|
}
|
|
|
|
// Start the waiter
|
|
svc.wait.Lock()
|
|
|
|
// Set our ptr + unlock
|
|
ctx = svc.ctx
|
|
svc.mu.Unlock()
|
|
|
|
return ctx, true
|
|
}
|
|
|
|
// doStop will safely set Service state to stopping, returning a ptr to this cancelfunc instance.
|
|
func (svc *Service) doStop() (context.CancelFunc, bool) {
|
|
// Protect stop
|
|
svc.mu.Lock()
|
|
|
|
if svc.state != 1 /* not started */ {
|
|
svc.mu.Unlock()
|
|
return nil, false
|
|
}
|
|
|
|
// state stopping
|
|
svc.state = 2
|
|
|
|
// Take our own ptr
|
|
// and unlock state
|
|
cncl := svc.cncl
|
|
svc.mu.Unlock()
|
|
|
|
return cncl, true
|
|
}
|
|
|
|
// Running returns if Service is running (i.e. state NOT stopped / stopping).
|
|
func (svc *Service) Running() bool {
|
|
svc.mu.Lock()
|
|
state := svc.state
|
|
svc.mu.Unlock()
|
|
return (state == 1)
|
|
}
|
|
|
|
// Done returns a channel that's closed when Service.Stop() is called. It is
|
|
// the same channel provided to the currently running service function.
|
|
func (svc *Service) Done() <-chan struct{} {
|
|
var done <-chan struct{}
|
|
|
|
svc.mu.Lock()
|
|
switch svc.state {
|
|
// stopped
|
|
// (here we create a new context so that the
|
|
// returned 'done' channel here will still
|
|
// be valid for when Service is next started)
|
|
case 0:
|
|
if svc.ctx == nil {
|
|
// need to allocate new context
|
|
svc.ctx, svc.cncl = ContextWithCancel()
|
|
}
|
|
done = svc.ctx.Done()
|
|
|
|
// started
|
|
case 1:
|
|
done = svc.ctx.Done()
|
|
|
|
// stopping
|
|
case 2:
|
|
done = svc.ctx.Done()
|
|
}
|
|
svc.mu.Unlock()
|
|
|
|
return done
|
|
}
|