// WithProcessClosed returns a context.Context that is cancelled
// after Process p is Closed. It is the equivalent of:
//
// func WithProcessClosed(ctx context.Context, p goprocess.Process) context.Context {
// ctx, cancel := context.WithCancel(ctx)
// go func() {
// <-p.Closed()
// cancel()
// }()
// return ctx
// }
//
func WithProcessClosed(ctx context.Context, p goprocess.Process) context.Context {
ctx, cancel := context.WithCancel(ctx)
go func() {
<-p.Closed()
cancel()
}()
return ctx
}
func (d *datastore) runQuery(worker goprocess.Process, qrb *dsq.ResultBuilder) {
var rnge *util.Range
if qrb.Query.Prefix != "" {
rnge = util.BytesPrefix([]byte(qrb.Query.Prefix))
}
i := d.DB.NewIterator(rnge, nil)
defer i.Release()
// advance iterator for offset
if qrb.Query.Offset > 0 {
for j := 0; j < qrb.Query.Offset; j++ {
i.Next()
}
}
// iterate, and handle limit, too
for sent := 0; i.Next(); sent++ {
// end early if we hit the limit
if qrb.Query.Limit > 0 && sent >= qrb.Query.Limit {
break
}
k := ds.NewKey(string(i.Key())).String()
e := dsq.Entry{Key: k}
if !qrb.Query.KeysOnly {
buf := make([]byte, len(i.Value()))
copy(buf, i.Value())
e.Value = buf
}
select {
case qrb.Output <- dsq.Result{Entry: e}: // we sent it out
case <-worker.Closing(): // client told us to end early.
break
}
}
if err := i.Error(); err != nil {
select {
case qrb.Output <- dsq.Result{Error: err}: // client read our error
case <-worker.Closing(): // client told us to end.
return
}
}
}
// WaitForContext makes p WaitFor ctx. When Closing, p waits for
// ctx.Done(), before being Closed(). It is simply:
//
// p.WaitFor(goprocess.WithContext(ctx))
//
func WaitForContext(ctx context.Context, p goprocess.Process) {
p.WaitFor(WithContext(ctx))
}