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package backend
import (
"context"
"sync"
"github.com/ProtonMail/gluon/async"
"github.com/ProtonMail/gluon/connector"
"github.com/ProtonMail/gluon/imap"
"github.com/ProtonMail/gluon/logging"
)
// updateInjector allows anyone to publish custom imap updates alongside the updates that are generated from the
// Connector.
type updateInjector struct {
// updatesCh is the channel that delivers API updates to the mailserver.
updatesCh chan imap.Update
// forwardWG is used to ensure we wait until the forward() goroutine has finished executing.
forwardWG sync.WaitGroup
forwardQuitCh chan struct{}
}
// newUpdateInjector creates a new updateInjector.
//
// nolint:contextcheck
func newUpdateInjector(connector connector.Connector, userID string, panicHandler async.PanicHandler) *updateInjector {
injector := &updateInjector{
updatesCh: make(chan imap.Update),
forwardQuitCh: make(chan struct{}),
}
injector.forwardWG.Add(1)
async.GoAnnotated(context.Background(), panicHandler, func(ctx context.Context) {
injector.forward(ctx, connector.GetUpdates())
}, logging.Labels{
"Action": "Forwarding updates",
"UserID": userID,
})
return injector
}
// GetUpdates returns a channel on which updates from the server are sent.
func (u *updateInjector) GetUpdates() <-chan imap.Update {
return u.updatesCh
}
func (u *updateInjector) Close(ctx context.Context) error {
close(u.forwardQuitCh)
u.forwardWG.Wait()
return nil
}
// forward pulls updates off the stream and forwards them to the outgoing update channel.
func (u *updateInjector) forward(ctx context.Context, updateCh <-chan imap.Update) {
defer func() {
close(u.updatesCh)
u.forwardWG.Done()
}()
for {
select {
case <-ctx.Done():
return
case update, ok := <-updateCh:
if !ok {
return
}
u.send(ctx, update)
case <-u.forwardQuitCh:
return
}
}
}
// send the update on the updates channel, optionally blocking until it has been processed.
func (u *updateInjector) send(ctx context.Context, update imap.Update) {
select {
case <-u.forwardQuitCh:
return
case u.updatesCh <- update:
case <-ctx.Done():
return
}
}
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