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package logformat
import (
"errors"
"fmt"
"os"
"reflect"
"strings"
"time"
"github.com/mimecast/dtail/internal/io/logger"
"github.com/mimecast/dtail/internal/mapr"
)
// Parser is used to parse the mapreduce information from the server log files.
type Parser struct {
hostname string
logFormatName string
makeFieldsFunc reflect.Value
makeFieldsReceiver reflect.Value
timeZoneName string
timeZoneOffset string
}
// NewParser returns a new log parser.
func NewParser(logFormatName string, query *mapr.Query) (*Parser, error) {
hostname, err := os.Hostname()
if err != nil {
return nil, err
}
now := time.Now()
zone, offset := now.Zone()
p := Parser{
hostname: hostname,
timeZoneName: zone,
timeZoneOffset: fmt.Sprintf("%d", offset),
}
err = p.reflectLogFormat(logFormatName)
if err != nil {
return nil, err
}
return &p, nil
}
// The aim of this is that everyone can plug in their own mapr log format
// parsing method to DTail. Just add a method MakeFieldsMODULENAME to type
// Parser. Whereas MODULENAME must be a upeprcase string.
func (p *Parser) reflectLogFormat(logFormatName string) error {
methodName := fmt.Sprintf("MakeFields%s", strings.ToUpper(logFormatName))
rt := reflect.TypeOf(p)
method, ok := rt.MethodByName(methodName)
if !ok {
return errors.New("No such mapr log format module: " + methodName)
}
p.makeFieldsFunc = method.Func
p.makeFieldsReceiver = reflect.ValueOf(p)
return nil
}
// MakeFields is for returning the fields from a given log line.
func (p *Parser) MakeFields(maprLine string) (fields map[string]string, err error) {
inputValues := []reflect.Value{p.makeFieldsReceiver, reflect.ValueOf(maprLine)}
returnValues := p.makeFieldsFunc.Call(inputValues)
errInterface := returnValues[1].Interface()
if errInterface == nil {
fields, err = returnValues[0].Interface().(map[string]string), nil
logger.Trace("parser.MakeFields", fields, err)
return
}
fields, err = returnValues[0].Interface().(map[string]string), errInterface.(error)
logger.Trace("parser.MakeFields", fields, err)
return
}
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