mirror of
https://github.com/ChronosX88/go-gun.git
synced 2024-11-08 20:21:01 +00:00
162 lines
3.7 KiB
Go
162 lines
3.7 KiB
Go
package gun
|
|
|
|
import (
|
|
"context"
|
|
"sync"
|
|
)
|
|
|
|
type Scoped struct {
|
|
gun *Gun
|
|
parentID string
|
|
field string
|
|
|
|
valueChansToListeners map[<-chan *ValueFetch]*messageIDListener
|
|
valueChansToListenersLock sync.Mutex
|
|
}
|
|
|
|
type messageIDListener struct {
|
|
id string
|
|
values chan *ValueFetch
|
|
receivedMessages chan *ReceivedMessage
|
|
}
|
|
|
|
func newScoped(gun *Gun, parentID string, field string) *Scoped {
|
|
return &Scoped{
|
|
gun: gun,
|
|
parentID: parentID,
|
|
field: field,
|
|
}
|
|
}
|
|
|
|
type ValueFetch struct {
|
|
// This can be a context error on cancelation
|
|
Err error
|
|
Field string
|
|
// Nil if there is an error
|
|
Value *StatefulValue
|
|
// Nil when local and sometimes on error
|
|
Peer Peer
|
|
}
|
|
|
|
type Ack struct {
|
|
Err error
|
|
Ok bool
|
|
Peer Peer
|
|
}
|
|
|
|
func (s *Scoped) Val(ctx context.Context) *ValueFetch {
|
|
// Try local before remote
|
|
if v := s.ValLocal(ctx); v != nil {
|
|
return v
|
|
}
|
|
return s.ValRemote(ctx)
|
|
}
|
|
|
|
func (s *Scoped) ValLocal(ctx context.Context) *ValueFetch {
|
|
var v ValueFetch
|
|
if v.Value, v.Err = s.gun.storage.Get(ctx, s.parentID, s.field); v.Err == ErrStorageNotFound {
|
|
return nil
|
|
}
|
|
return &v
|
|
}
|
|
|
|
func (s *Scoped) ValRemote(ctx context.Context) *ValueFetch {
|
|
ch := s.OnRemote(ctx)
|
|
defer s.Off(ch)
|
|
return <-ch
|
|
}
|
|
|
|
func (s *Scoped) On(ctx context.Context) <-chan *ValueFetch {
|
|
ch := make(chan *ValueFetch, 1)
|
|
if v := s.ValLocal(ctx); v != nil {
|
|
ch <- v
|
|
}
|
|
go s.onRemote(ctx, ch)
|
|
return ch
|
|
}
|
|
|
|
func (s *Scoped) OnRemote(ctx context.Context) <-chan *ValueFetch {
|
|
ch := make(chan *ValueFetch, 1)
|
|
go s.onRemote(ctx, ch)
|
|
return ch
|
|
}
|
|
|
|
func (s *Scoped) onRemote(ctx context.Context, ch chan *ValueFetch) {
|
|
// Create get request
|
|
req := &Message{
|
|
ID: randString(9),
|
|
Get: &MessageGetRequest{ID: s.parentID, Field: s.field},
|
|
}
|
|
// Make a chan to listen for received messages and link it to
|
|
// the given one so we can turn it "off". Off will close this
|
|
// chan.
|
|
msgCh := make(chan *ReceivedMessage)
|
|
s.valueChansToListenersLock.Lock()
|
|
s.valueChansToListeners[ch] = &messageIDListener{req.ID, ch, msgCh}
|
|
s.valueChansToListenersLock.Unlock()
|
|
// Listen for responses to this get
|
|
s.gun.RegisterMessageIDPutListener(req.ID, msgCh)
|
|
// TODO: only for children: s.gun.RegisterValueIDPutListener(s.id, msgCh)
|
|
// Handle received messages turning them to value fetches
|
|
go func() {
|
|
for {
|
|
select {
|
|
case <-ctx.Done():
|
|
ch <- &ValueFetch{Err: ctx.Err(), Field: s.field}
|
|
s.Off(ch)
|
|
return
|
|
case msg, ok := <-msgCh:
|
|
if !ok {
|
|
return
|
|
}
|
|
// We asked for a single field, should only get that field
|
|
if n := msg.Put[s.parentID]; n != nil && n.Values[s.field] != nil {
|
|
// TODO: conflict resolution
|
|
// TODO: dedupe
|
|
// TODO: store and cache
|
|
safeValueFetchSend(ch, &ValueFetch{
|
|
Field: s.field,
|
|
Value: &StatefulValue{n.Values[s.field], n.State[s.field]},
|
|
Peer: msg.Peer,
|
|
})
|
|
}
|
|
}
|
|
}
|
|
}()
|
|
// Send async, sending back errors
|
|
go func() {
|
|
for peerErr := range s.gun.Send(ctx, req) {
|
|
safeValueFetchSend(ch, &ValueFetch{
|
|
Err: peerErr.Err,
|
|
Field: s.field,
|
|
Peer: peerErr.Peer,
|
|
})
|
|
}
|
|
}()
|
|
}
|
|
|
|
func (s *Scoped) Off(ch <-chan *ValueFetch) bool {
|
|
s.valueChansToListenersLock.Lock()
|
|
l := s.valueChansToListeners[ch]
|
|
delete(s.valueChansToListeners, ch)
|
|
s.valueChansToListenersLock.Unlock()
|
|
if l != nil {
|
|
// Unregister the chan
|
|
s.gun.UnregisterMessageIDPutListener(l.id)
|
|
// Close the message chan and the value chan
|
|
close(l.receivedMessages)
|
|
close(l.values)
|
|
}
|
|
return l != nil
|
|
}
|
|
|
|
func (s *Scoped) Scoped(ctx context.Context, key string, children ...string) *Scoped {
|
|
panic("TODO")
|
|
}
|
|
|
|
func safeValueFetchSend(ch chan<- *ValueFetch, f *ValueFetch) {
|
|
// Due to the fact that we may send on a closed channel here, we ignore the panic
|
|
defer func() { recover() }()
|
|
ch <- f
|
|
}
|