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decode.go
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decode.go
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package decoders
import (
"sync"
"github.com/inconshreveable/log15"
"github.com/stephane-martin/skewer/conf"
"github.com/stephane-martin/skewer/decoders/base"
"github.com/stephane-martin/skewer/javascript"
"github.com/stephane-martin/skewer/model"
"github.com/stephane-martin/skewer/utils"
"github.com/stephane-martin/skewer/utils/eerrors"
"github.com/zond/gotomic"
"golang.org/x/text/encoding/unicode"
)
type BaseParser func([]byte) ([]*model.SyslogMessage, error)
var parsers = map[base.Format](func([]byte) ([]*model.SyslogMessage, error)){
base.RFC5424: p5424,
base.RFC3164: p3164,
base.JSON: pJSON,
base.RsyslogJSON: pRsyslogJSON,
base.GELF: pGELF,
base.InfluxDB: pInflux,
base.Protobuf: pProtobuf,
base.Collectd: pCollectd,
base.LTSV: pLTSV,
base.W3C: nil,
}
type Parser interface {
Parse(m []byte) ([]*model.SyslogMessage, error)
Release()
}
// nativeParser is a decoder implemented as golang function
type nativeParser struct {
baseParser func([]byte) ([]*model.SyslogMessage, error)
}
func (p *nativeParser) Release() {}
func (p *nativeParser) Parse(m []byte) ([]*model.SyslogMessage, error) {
return p.baseParser(m)
}
// jsParser is a decoder implemented as a JS function
type jsParser struct {
baseParser func([]byte) ([]*model.SyslogMessage, error)
jsEnv *javascript.Environment
parsersEnv *ParsersEnv
}
func (p *jsParser) Release() {
p.parsersEnv.jsEnvsPool.Put(p.jsEnv)
}
func (p *jsParser) Parse(m []byte) ([]*model.SyslogMessage, error) {
return p.baseParser(m)
}
// ParsersEnv encapsulates JS and Golang parsers.
type ParsersEnv struct {
sync.Mutex
parserCache *gotomic.Hash
jsFuncs map[string]string
jsEnvsPool *sync.Pool
logger log15.Logger
}
func NewParsersEnv(config []conf.ParserConfig, logger log15.Logger) *ParsersEnv {
env := ParsersEnv{
jsFuncs: make(map[string]string, len(config)),
logger: logger,
parserCache: gotomic.NewHash(),
}
for _, c := range config {
env.jsFuncs[c.Name] = c.Func
}
env.jsEnvsPool = &sync.Pool{New: env.newJSEnv}
return &env
}
func (e *ParsersEnv) newJSEnv() interface{} {
jsEnv := javascript.NewParsersEnvironment(e.logger)
var jsFuncName, jsFuncBody string
var err error
for jsFuncName, jsFuncBody = range e.jsFuncs {
err = jsEnv.AddParser(jsFuncName, jsFuncBody)
if err != nil {
e.logger.Warn("Error initializing parser", "name", jsFuncName, "error", err)
}
}
return jsEnv
}
func (e *ParsersEnv) getJSEnv() *javascript.Environment {
return e.jsEnvsPool.Get().(*javascript.Environment)
}
func (e *ParsersEnv) Parse(c *conf.DecoderBaseConfig, m []byte) ([]*model.SyslogMessage, error) {
if len(m) == 0 {
return nil, nil
}
if c == nil {
return nil, eerrors.Fatal(eerrors.New("Decoder config is NIL"))
}
parser, err := e.getParser(c)
if parser == nil || err != nil {
return nil, DecodingError(eerrors.Wrapf(err, "Unknown decoder: %s", c.Format))
}
syslogMsgs, err := parser.Parse(m)
parser.Release()
if err != nil {
return nil, DecodingError(eerrors.Wrap(err, "Parsing error"))
}
return syslogMsgs, nil
}
func (e *ParsersEnv) getParser(c *conf.DecoderBaseConfig) (p Parser, err error) {
frmt := base.ParseFormat(c.Format)
if frmt == -1 {
// look for a JS function
return e.getJSParser(c.Format)
}
// casual parser
return e.getNonJSParser(frmt, c)
}
func (e *ParsersEnv) getJSParser(funcName string) (*jsParser, error) {
if _, ok := e.jsFuncs[funcName]; !ok {
return nil, DecodingError(eerrors.Errorf("Unknown decoder: '%s'", funcName))
}
jsEnv := e.getJSEnv()
baseParser, err := jsEnv.GetParser(funcName)
if err != nil {
return nil, err
}
return &jsParser{
baseParser: baseParser,
jsEnv: jsEnv,
parsersEnv: e,
}, nil
}
func (e *ParsersEnv) getNonJSParser(frmt base.Format, c *conf.DecoderBaseConfig) (*nativeParser, error) {
// some parsers may be heavy to build, so we cache them
var p func([]byte) ([]*model.SyslogMessage, error)
if thing, have := e.parserCache.Get(c); have {
// fast path: we have already built such a parser
return &nativeParser{baseParser: thing.(func([]byte) ([]*model.SyslogMessage, error))}, nil
}
// slow path
e.Lock()
defer e.Unlock()
if frmt == base.W3C {
// W3C parsed is parametrized
if len(c.W3CFields) == 0 {
return nil, DecodingError(eerrors.New("No fields specified for W3C Extended Log Format decoder"))
}
p = W3CDecoder(c.W3CFields)
} else {
p = parsers[frmt]
}
// add a decoding step to deal with charsets
p = parserWithEncoding(frmt, c.Charset, p)
// now the parser has been built. cache it so that we don't have to build it again later.
// we assume that the parser func is "pure" and "thread-safe".
e.parserCache.Put(c, p)
return &nativeParser{baseParser: p}, nil
}
func parserWithEncoding(frmt base.Format, charset string, p func([]byte) ([]*model.SyslogMessage, error)) func([]byte) ([]*model.SyslogMessage, error) {
switch frmt {
case base.RFC3164, base.RFC5424, base.W3C:
return func(m []byte) ([]*model.SyslogMessage, error) {
var err error
m, err = utils.SelectDecoder(charset).Bytes(m)
if err != nil {
return nil, InvalidCharsetError(err)
}
return p(m)
}
case base.JSON, base.RsyslogJSON, base.GELF, base.InfluxDB, -1:
return func(m []byte) ([]*model.SyslogMessage, error) {
var err error
m, err = unicode.UTF8.NewDecoder().Bytes(m)
if err != nil {
return nil, InvalidCharsetError(err)
}
return p(m)
}
case base.Protobuf, base.Collectd:
return p
default:
return p
}
}