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reader.go
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reader.go
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package points
import (
"bufio"
"encoding/binary"
"errors"
"fmt"
"io"
"math"
"os"
"strings"
)
const MB = 1048576
func ReadPlain(r io.Reader, callback func(*Points)) error {
reader := bufio.NewReaderSize(r, MB)
for {
line, err := reader.ReadBytes('\n')
if err != nil && err != io.EOF {
return err
}
if len(line) == 0 {
break
}
if line[len(line)-1] != '\n' {
return errors.New("unfinished line in file")
}
p, err := ParseText(string(line))
if err == nil {
callback(p)
}
}
return nil
}
func ReadBinary(r io.Reader, callback func(*Points)) error {
reader := bufio.NewReaderSize(r, MB)
var p *Points
buf := make([]byte, MB)
flush := func() {
if p != nil {
callback(p)
p = nil
}
}
defer flush()
for {
flush()
l, err := binary.ReadVarint(reader)
if l > MB {
return fmt.Errorf("metric name too long: %d", l)
}
if err == io.EOF {
break
}
if err != nil {
return err
}
io.ReadAtLeast(reader, buf[:l], int(l))
cnt, _ := binary.ReadVarint(reader)
var v, t, v0, t0 int64
for i := int64(0); i < cnt; i++ {
v0, err = binary.ReadVarint(reader)
if err != nil {
return err
}
v += v0
t0, err = binary.ReadVarint(reader)
if err != nil {
return err
}
t += t0
if i == int64(0) {
p = OnePoint(string(buf[:l]), math.Float64frombits(uint64(v)), t)
} else {
p.Add(math.Float64frombits(uint64(v)), t)
}
}
}
return nil
}
func ReadFromFile(filename string, callback func(*Points)) error {
file, err := os.Open(filename)
if err != nil {
return err
}
defer file.Close()
if strings.HasSuffix(strings.ToLower(filename), ".bin") {
return ReadBinary(file, callback)
}
return ReadPlain(file, callback)
}