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stream.go
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stream.go
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// Copyright ©2017 The go-hep Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package hbooksvc
import (
"fmt"
"io"
"os"
"go-hep.org/x/hep/fwk"
"go-hep.org/x/hep/rio"
)
// Mode describes the open-mode of a stream
type Mode int
const (
Read Mode = Mode(os.O_RDONLY)
Write Mode = Mode(os.O_WRONLY)
)
// Stream defines an input or output hbook stream
type Stream struct {
Name string // input|output file name
Mode Mode // read|write
}
type istream struct {
name string // stream name
fname string // file name
f io.ReadCloser
r *rio.Reader
objs []fwk.Hist
}
func (stream *istream) close() error {
defer stream.f.Close() // do not leak file descriptors
err := stream.r.Close()
if err != nil {
return err
}
err = stream.f.Close()
if err != nil {
return err
}
return err
}
func (stream *istream) read(name string, ptr interface{}) error {
var err error
seekr, ok := stream.f.(io.Seeker)
if !ok {
return fmt.Errorf("hbooksvc: input stream [%s] is not seek-able", stream.name)
}
pos, err := seekr.Seek(0, 1)
if err != nil {
return err
}
defer func() {
_, _ = seekr.Seek(pos, 0)
}()
_, err = seekr.Seek(0, 0)
if err != nil {
return err
}
r := seekr.(io.Reader)
rr, err := rio.NewReader(r)
if err != nil {
return err
}
defer rr.Close()
scan := rio.NewScanner(rr)
scan.Select([]rio.Selector{{Name: name, Unpack: true}})
if !scan.Scan() {
return scan.Err()
}
rec := scan.Record()
if rec == nil {
return fmt.Errorf("hbooksvc: could not find record [%s] in stream [%s]", name, stream.name)
}
blk := rec.Block(name)
if blk == nil {
return fmt.Errorf(
"hbooksvc: could not get block [%s] from record [%s] in stream [%s]",
name, name, stream.name,
)
}
err = blk.Read(ptr)
if err != nil {
return fmt.Errorf(
"hbooksvc: could not read data from block [%s] from record [%s] in stream [%s]: %w",
name, name, stream.name, err,
)
}
return err
}
type ostream struct {
name string // stream name
fname string // file name
f io.WriteCloser
w *rio.Writer
objs []fwk.Hist
}
func (stream *ostream) write() error {
for i := range stream.objs {
obj := stream.objs[i]
name := string(obj.Name())
rec := stream.w.Record(name)
err := rec.Connect(name, obj.Value())
if err != nil {
return fmt.Errorf(
"error writing object [%s] to stream [%s]: %w",
name, stream.name, err,
)
}
blk := rec.Block(name)
err = blk.Write(obj.Value())
if err != nil {
return fmt.Errorf(
"error writing object [%s] to stream [%s]: %w",
name, stream.name, err,
)
}
err = rec.Write()
if err != nil {
return fmt.Errorf(
"error writing object [%s] to stream [%s]: %w",
name, stream.name, err,
)
}
}
return nil
}
func (stream *ostream) close() error {
defer stream.f.Close() // do not leak file descriptors
err := stream.w.Close()
if err != nil {
return err
}
err = stream.f.Close()
if err != nil {
return err
}
return err
}