/
dataset.go
86 lines (70 loc) · 1.61 KB
/
dataset.go
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package tsdb
import (
"errors"
"time"
"github.com/gsdocker/gsconfig"
"github.com/gsdocker/gserrors"
)
// Errors
var (
ErrOp = errors.New("unsupport operation")
)
type _DataSet struct {
storage Storage // storage
cached *_Cached // cached
miniVersion uint64 // mini version of this dataset
cursor uint64 // current read cursor
Q chan *DBValue // dataset queue
closed chan bool // closed flag
}
func (datasource *_DataSource) makeDataSet(storage Storage, cached *_Cached, miniVersion uint64) DataSet {
dataset := &_DataSet{
storage: storage,
cached: cached,
miniVersion: miniVersion,
cursor: miniVersion,
Q: make(chan *DBValue),
closed: make(chan bool),
}
go dataset.readLoop()
return dataset
}
func (dataset *_DataSet) readLoop() {
timeout := gsconfig.Seconds("tsdb.dataset.sleep", 2)
timer := time.NewTimer(timeout)
for {
val, ok := dataset.cached.Get(dataset.cursor)
if !ok {
val, ok = dataset.storage.Read(dataset.cursor)
if !ok {
timer.Reset(timeout)
select {
case <-timer.C:
continue
case <-dataset.closed:
return
}
}
}
select {
case dataset.Q <- val:
case <-dataset.closed:
return
}
}
}
func (dataset *_DataSet) MiniVersion() uint64 {
return dataset.miniVersion
}
func (dataset *_DataSet) Next() (data []byte, version uint64) {
select {
case val := <-dataset.Q:
return val.Content, val.ID
case <-dataset.closed:
gserrors.Panicf(ErrOp, "call Next on closed dataset")
return nil, 0
}
}
func (dataset *_DataSet) Close() {
close(dataset.closed)
}