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moby--moby/libnetwork/networkdb/watch.go

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package networkdb
import "github.com/docker/go-events"
type opType uint8
const (
opCreate opType = 1 + iota
opUpdate
opDelete
)
type event struct {
Table string
NetworkID string
Key string
Value []byte
}
// CreateEvent generates a table entry create event to the watchers
type CreateEvent event
// UpdateEvent generates a table entry update event to the watchers
type UpdateEvent event
// DeleteEvent generates a table entry delete event to the watchers
type DeleteEvent event
// Watch creates a watcher with filters for a particular table or
// network or key or any combination of the tuple. If any of the
// filter is an empty string it acts as a wildcard for that
// field. Watch returns a channel of events, where the events will be
// sent.
func (nDB *NetworkDB) Watch(tname, nid, key string) (chan events.Event, func()) {
var matcher events.Matcher
if tname != "" || nid != "" || key != "" {
matcher = events.MatcherFunc(func(ev events.Event) bool {
var evt event
switch ev := ev.(type) {
case CreateEvent:
evt = event(ev)
case UpdateEvent:
evt = event(ev)
case DeleteEvent:
evt = event(ev)
}
if tname != "" && evt.Table != tname {
return false
}
if nid != "" && evt.NetworkID != nid {
return false
}
if key != "" && evt.Key != key {
return false
}
return true
})
}
ch := events.NewChannel(0)
sink := events.Sink(events.NewQueue(ch))
if matcher != nil {
sink = events.NewFilter(sink, matcher)
}
nDB.broadcaster.Add(sink)
return ch.C, func() {
nDB.broadcaster.Remove(sink)
ch.Close()
sink.Close()
}
}
func makeEvent(op opType, tname, nid, key string, value []byte) events.Event {
ev := event{
Table: tname,
NetworkID: nid,
Key: key,
Value: value,
}
switch op {
case opCreate:
return CreateEvent(ev)
case opUpdate:
return UpdateEvent(ev)
case opDelete:
return DeleteEvent(ev)
}
return nil
}