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Make format string thread safe #2086

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merged 1 commit into from
Jul 26, 2016
Merged

Make format string thread safe #2086

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86 changes: 61 additions & 25 deletions libbeat/common/fmtstr/formatevents.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ import (
"reflect"
"strconv"
"strings"
"sync"
"time"

"github.com/elastic/beats/libbeat/common"
Expand All @@ -25,29 +26,24 @@ import (
// `%{[field.name]:default value}`.
type EventFormatString struct {
formatter StringFormatter
ctx *eventEvalContext
fields []fieldInfo
timestamp bool
}

type eventFieldEvaler struct {
ctx *eventEvalContext
index int
}

type defaultEventFieldEvaler struct {
ctx *eventEvalContext
index int
defaultValue string
}

type eventTimestampEvaler struct {
ctx *eventEvalContext
formatter *dtfmt.Formatter
}

type eventFieldCompiler struct {
ctx *eventEvalContext
keys map[string]keyInfo
timestamp bool
index int
Expand All @@ -66,13 +62,33 @@ type keyInfo struct {
type eventEvalContext struct {
keys []string
ts time.Time
buf *bytes.Buffer
}

var (
errMissingKeys = errors.New("missing keys")
errConvertString = errors.New("can not convert to string")
)

var eventCtxPool = &sync.Pool{
New: func() interface{} { return &eventEvalContext{} },
}

func newEventCtx(sz int) *eventEvalContext {
ctx := eventCtxPool.Get().(*eventEvalContext)
if ctx.keys == nil || cap(ctx.keys) < sz {
ctx.keys = make([]string, 0, sz)
} else {
ctx.keys = ctx.keys[:0]
}

return ctx
}

func releaseCtx(c *eventEvalContext) {
eventCtxPool.Put(c)
}

// MustCompileEvent copmiles an event format string into an runnable
// EventFormatString. Generates a panic if compilation fails.
func MustCompileEvent(in string) *EventFormatString {
Expand All @@ -88,7 +104,6 @@ func MustCompileEvent(in string) *EventFormatString {
func CompileEvent(in string) (*EventFormatString, error) {
ctx := &eventEvalContext{}
efComp := &eventFieldCompiler{
ctx: ctx,
keys: map[string]keyInfo{},
index: 0,
timestamp: false,
Expand All @@ -110,7 +125,6 @@ func CompileEvent(in string) (*EventFormatString, error) {
ctx.keys = make([]string, len(keys))
efs := &EventFormatString{
formatter: sf,
ctx: ctx,
fields: keys,
timestamp: efComp.timestamp,
}
Expand Down Expand Up @@ -157,24 +171,43 @@ func (fs *EventFormatString) Fields() []string {
// Run executes the format string returning a new expanded string or an error
// if execution or event field expansion fails.
func (fs *EventFormatString) Run(event common.MapStr) (string, error) {
if err := fs.collectFields(event); err != nil {
ctx := newEventCtx(len(fs.fields))
defer releaseCtx(ctx)

if ctx.buf == nil {
ctx.buf = bytes.NewBuffer(nil)
} else {
ctx.buf.Reset()
}

if err := fs.collectFields(ctx, event); err != nil {
return "", err
}
err := fs.formatter.Eval(ctx, ctx.buf)
if err != nil {
return "", err
}
return fs.formatter.Run()
return ctx.buf.String(), nil
}

// Eval executes the format string, writing the resulting string into the provided output buffer. Returns error if execution or event field expansion fails.
func (fs *EventFormatString) Eval(out *bytes.Buffer, event common.MapStr) error {
if err := fs.collectFields(event); err != nil {
ctx := newEventCtx(len(fs.fields))
defer releaseCtx(ctx)

if err := fs.collectFields(ctx, event); err != nil {
return err
}
return fs.formatter.Eval(out)
return fs.formatter.Eval(ctx, out)
}

// collectFields tries to extract and convert all required fields into an array
// of strings.
func (fs *EventFormatString) collectFields(event common.MapStr) error {
for i, fi := range fs.fields {
func (fs *EventFormatString) collectFields(
ctx *eventEvalContext,
event common.MapStr,
) error {
for _, fi := range fs.fields {
s, err := fieldString(event, fi.path)
if err != nil {
if fi.required {
Expand All @@ -183,7 +216,7 @@ func (fs *EventFormatString) collectFields(event common.MapStr) error {

s = ""
}
fs.ctx.keys[i] = s
ctx.keys = append(ctx.keys, s)
}

if fs.timestamp {
Expand All @@ -194,9 +227,9 @@ func (fs *EventFormatString) collectFields(event common.MapStr) error {

switch t := timestamp.(type) {
case common.Time:
fs.ctx.ts = time.Time(t)
ctx.ts = time.Time(t)
case time.Time:
fs.ctx.ts = t
ctx.ts = t
default:
return errors.New("unknown timestamp type")
}
Expand Down Expand Up @@ -261,10 +294,10 @@ func (e *eventFieldCompiler) compileEventField(
idx := info.index

if len(ops) == 0 {
return &eventFieldEvaler{e.ctx, idx}, nil
return &eventFieldEvaler{idx}, nil
}

return &defaultEventFieldEvaler{e.ctx, idx, defaultValue}, nil
return &defaultEventFieldEvaler{idx, defaultValue}, nil
}

func (e *eventFieldCompiler) compileTimestamp(
Expand All @@ -281,34 +314,37 @@ func (e *eventFieldCompiler) compileTimestamp(
}

e.timestamp = true
return &eventTimestampEvaler{e.ctx, formatter}, nil
return &eventTimestampEvaler{formatter}, nil
}

func (e *eventFieldEvaler) Eval(out *bytes.Buffer) error {
func (e *eventFieldEvaler) Eval(c interface{}, out *bytes.Buffer) error {
type stringer interface {
String() string
}

s := e.ctx.keys[e.index]
ctx := c.(*eventEvalContext)
s := ctx.keys[e.index]
_, err := out.WriteString(s)
return err
}

func (e *defaultEventFieldEvaler) Eval(out *bytes.Buffer) error {
func (e *defaultEventFieldEvaler) Eval(c interface{}, out *bytes.Buffer) error {
type stringer interface {
String() string
}

s := e.ctx.keys[e.index]
ctx := c.(*eventEvalContext)
s := ctx.keys[e.index]
if s == "" {
s = e.defaultValue
}
_, err := out.WriteString(s)
return err
}

func (e *eventTimestampEvaler) Eval(out *bytes.Buffer) error {
_, err := e.formatter.Write(out, e.ctx.ts)
func (e *eventTimestampEvaler) Eval(c interface{}, out *bytes.Buffer) error {
ctx := c.(*eventEvalContext)
_, err := e.formatter.Write(out, ctx.ts)
return err
}

Expand Down
24 changes: 11 additions & 13 deletions libbeat/common/fmtstr/formatstring.go
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ import (
type FormatEvaler interface {
// Eval will execute the format and writes the results into
// the provided output buffer. Returns error on failure.
Eval(out *bytes.Buffer) error
Eval(ctx interface{}, out *bytes.Buffer) error
}

// StringFormatter interface extends FormatEvaler adding support for querying
Expand All @@ -20,7 +20,7 @@ type StringFormatter interface {
FormatEvaler

// Run execute the formatter returning the generated string.
Run() (string, error)
Run(ctx interface{}) (string, error)

// IsConst returns true, if execution of formatter will always return the
// same constant string.
Expand All @@ -42,7 +42,6 @@ type constStringFormatter struct {
}

type execStringFormatter struct {
buf *bytes.Buffer
evalers []FormatEvaler
}

Expand Down Expand Up @@ -145,7 +144,6 @@ func compile(ctx *compileCtx, in string) (StringFormatter, error) {
// create executable string formatter
fmt := execStringFormatter{
evalers: evalers,
buf: bytes.NewBuffer(nil),
}
return fmt, nil
}
Expand Down Expand Up @@ -184,34 +182,34 @@ func optimize(in []FormatEvaler) []FormatEvaler {
return out
}

func (f constStringFormatter) Eval(out *bytes.Buffer) error {
func (f constStringFormatter) Eval(_ interface{}, out *bytes.Buffer) error {
_, err := out.WriteString(f.s)
return err
}

func (f constStringFormatter) Run() (string, error) {
func (f constStringFormatter) Run(_ interface{}) (string, error) {
return f.s, nil
}

func (f constStringFormatter) IsConst() bool {
return true
}

func (f execStringFormatter) Eval(out *bytes.Buffer) error {
func (f execStringFormatter) Eval(ctx interface{}, out *bytes.Buffer) error {
for _, evaler := range f.evalers {
if err := evaler.Eval(out); err != nil {
if err := evaler.Eval(ctx, out); err != nil {
return err
}
}
return nil
}

func (f execStringFormatter) Run() (string, error) {
f.buf.Reset()
if err := f.Eval(f.buf); err != nil {
func (f execStringFormatter) Run(ctx interface{}) (string, error) {
buf := bytes.NewBuffer(nil)
if err := f.Eval(ctx, buf); err != nil {
return "", err
}
return f.buf.String(), nil
return buf.String(), nil
}

func (f execStringFormatter) IsConst() bool {
Expand All @@ -224,7 +222,7 @@ func (e StringElement) compile(ctx *compileCtx) (FormatEvaler, error) {

// Eval write the string elements constant string value into
// output buffer.
func (e StringElement) Eval(out *bytes.Buffer) error {
func (e StringElement) Eval(_ interface{}, out *bytes.Buffer) error {
_, err := out.WriteString(e.s)
return err
}
Expand Down
2 changes: 1 addition & 1 deletion libbeat/common/fmtstr/formatstring_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -123,7 +123,7 @@ func TestFormatString(t *testing.T) {
}

// run string formatter
actual, err := sf.Run()
actual, err := sf.Run(nil)

// test validation
if test.dyn == nil {
Expand Down