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|
package document
import (
"bytes"
"errors"
"fmt"
"io"
"math/rand"
"strconv"
"strings"
"sync"
"time"
// Why do we use an experimental parser? This appears to be the only JSON library that satisfies the following
// requirements:
// - Faster than the std parser
// - Supports parsing from a io.Reader
// - Supports parsing token-by-token
// - Few allocations during parsing (especially for large objects)
"github.com/go-json-experiment/json"
)
type Operation int
const (
OperationPut Operation = iota
OperationUpdate
OperationRemove
jsonArrayStart json.Kind = '['
jsonArrayEnd json.Kind = ']'
jsonObjectStart json.Kind = '{'
jsonObjectEnd json.Kind = '}'
jsonString json.Kind = '"'
)
var (
ErrMissingId = errors.New("no id specified")
fieldsPrefix = []byte(`{"fields":`)
fieldsSuffix = []byte("}")
)
func (o Operation) String() string {
switch o {
case OperationPut:
return "put"
case OperationUpdate:
return "update"
case OperationRemove:
return "remove"
}
return ""
}
// Id represents a Vespa document ID.
type Id struct {
id string
Type string
Namespace string
Number *int64
Group string
UserSpecific string
}
func (d Id) Equal(o Id) bool {
return d.Type == o.Type &&
d.Namespace == o.Namespace &&
((d.Number == nil && o.Number == nil) || *d.Number == *o.Number) &&
d.Group == o.Group &&
d.UserSpecific == o.UserSpecific
}
func (d Id) String() string { return d.id }
// ParseId parses a serialized document ID string.
func ParseId(serialized string) (Id, error) {
parts := strings.SplitN(serialized, ":", 4)
if len(parts) < 4 || parts[0] != "id" {
return Id{}, parseError(serialized)
}
namespace := parts[1]
if namespace == "" {
return Id{}, parseError(serialized)
}
docType := parts[2]
if docType == "" {
return Id{}, parseError(serialized)
}
rest := strings.SplitN(parts[3], ":", 2)
if len(rest) < 2 {
return Id{}, parseError(serialized)
}
options := rest[0]
userSpecific := rest[1]
var number *int64
group := ""
if strings.HasPrefix(options, "n=") {
n, err := strconv.ParseInt(options[2:], 10, 64)
if err != nil {
return Id{}, parseError(serialized)
}
number = &n
} else if strings.HasPrefix(options, "g=") {
group = options[2:]
if len(group) == 0 {
return Id{}, parseError(serialized)
}
} else if options != "" {
return Id{}, parseError(serialized)
}
if userSpecific == "" {
return Id{}, parseError(serialized)
}
return Id{
id: serialized,
Namespace: namespace,
Type: docType,
Number: number,
Group: group,
UserSpecific: userSpecific,
}, nil
}
// Document represents a Vespa document operation.
type Document struct {
Id Id
Condition string
Body []byte
Operation Operation
Create bool
resetFunc func()
}
func (d Document) Equal(o Document) bool {
return d.Id.Equal(o.Id) &&
d.Condition == o.Condition &&
bytes.Equal(d.Body, o.Body) &&
d.Operation == o.Operation &&
d.Create == o.Create
}
// Reset discards the body of this document.
func (d *Document) Reset() {
d.Body = nil
if d.resetFunc != nil {
d.resetFunc()
}
}
// Decoder decodes documents from a JSON structure which is either an array of objects, or objects separated by newline.
type Decoder struct {
dec *json.Decoder
buf bytes.Buffer
array bool
jsonl bool
fieldsEnd int64
documentBuffers sync.Pool
}
func (d Document) String() string {
var sb strings.Builder
sb.WriteString(d.Operation.String())
sb.WriteString(" ")
sb.WriteString(d.Id.String())
if d.Condition != "" {
sb.WriteString(", condition=")
sb.WriteString(d.Condition)
}
if d.Create {
sb.WriteString(", create=true")
}
if d.Body != nil {
sb.WriteString(", body=")
sb.WriteString(string(d.Body))
}
return sb.String()
}
func (d *Decoder) guessMode() error {
if d.array || d.jsonl {
return nil
}
kind := d.dec.PeekKind()
switch kind {
case jsonArrayStart:
if _, err := d.readNext(jsonArrayStart); err != nil {
return err
}
d.array = true
case jsonObjectStart:
d.jsonl = true
default:
return fmt.Errorf("expected %s or %s, got %s", jsonArrayStart, jsonObjectStart, kind)
}
return nil
}
func (d *Decoder) readNext(kind json.Kind) (json.Token, error) {
t, err := d.dec.ReadToken()
if err != nil {
return json.Token{}, err
}
if t.Kind() != kind {
return json.Token{}, fmt.Errorf("unexpected json kind: %q: want %q", t, kind)
}
return t, nil
}
func (d *Decoder) readString() (string, error) {
t, err := d.readNext(jsonString)
if err != nil {
return "", err
}
return t.String(), nil
}
func (d *Decoder) readBool() (bool, error) {
t, err := d.dec.ReadToken()
if err != nil {
return false, err
}
kind := t.Kind()
if kind != 't' && kind != 'f' {
return false, fmt.Errorf("unexpected json kind: %q: want %q or %q", t, 't', 'f')
}
return t.Bool(), nil
}
func (d *Decoder) Decode() (Document, error) {
doc, err := d.decode()
if err != nil && err != io.EOF {
return doc, fmt.Errorf("invalid operation at byte offset %d: %w", d.dec.InputOffset(), err)
}
return doc, err
}
func (d *Decoder) buffer() *bytes.Buffer {
buf := d.documentBuffers.Get().(*bytes.Buffer)
buf.Reset()
return buf
}
func (d *Decoder) readField(name string, offset int64, doc *Document) error {
readId := false
switch name {
case "id", "put":
readId = true
doc.Operation = OperationPut
case "update":
readId = true
doc.Operation = OperationUpdate
case "remove":
readId = true
doc.Operation = OperationRemove
case "condition":
condition, err := d.readString()
if err != nil {
return err
}
doc.Condition = condition
case "create":
create, err := d.readBool()
if err != nil {
return err
}
doc.Create = create
case "fields":
if _, err := d.readNext(jsonObjectStart); err != nil {
return err
}
// Skip data between start of operation and start of fields
fieldsStart := d.dec.InputOffset() - 1
d.buf.Next(int(fieldsStart - offset))
depth := 1
for depth > 0 {
t, err := d.dec.ReadToken()
if err != nil {
return err
}
switch t.Kind() {
case jsonObjectStart:
depth++
case jsonObjectEnd:
depth--
}
}
d.fieldsEnd = d.dec.InputOffset()
fields := d.buf.Next(int(d.fieldsEnd - fieldsStart))
// Try to re-use buffers holding the document body. The buffer is released by document.Reset()
bodyBuf := d.buffer()
bodyBuf.Grow(len(fieldsPrefix) + len(fields) + len(fieldsSuffix))
bodyBuf.Write(fieldsPrefix)
bodyBuf.Write(fields)
bodyBuf.Write(fieldsSuffix)
doc.Body = bodyBuf.Bytes()
doc.resetFunc = func() { d.documentBuffers.Put(bodyBuf) }
}
if readId {
s, err := d.readString()
if err != nil {
return err
}
id, err := ParseId(s)
if err != nil {
return err
}
doc.Id = id
}
return nil
}
func (d *Decoder) decode() (Document, error) {
start := d.dec.InputOffset()
if err := d.guessMode(); err != nil {
return Document{}, err
}
if d.array && d.dec.PeekKind() == jsonArrayEnd {
// Reached end of the array holding document operations
if _, err := d.readNext(jsonArrayEnd); err != nil {
return Document{}, err
}
return Document{}, io.EOF
}
// Start of document operation
if _, err := d.readNext(jsonObjectStart); err != nil {
return Document{}, err
}
var doc Document
loop:
for {
switch d.dec.PeekKind() {
case jsonString:
t, err := d.dec.ReadToken()
if err != nil {
return Document{}, err
}
if err := d.readField(t.String(), start, &doc); err != nil {
return Document{}, err
}
default:
if _, err := d.readNext(jsonObjectEnd); err != nil {
return Document{}, err
}
// Drop operation from the buffer
start = max(start, d.fieldsEnd)
end := d.dec.InputOffset()
d.buf.Next(int(end - start))
break loop
}
}
if doc.Id.id == "" {
return doc, ErrMissingId
}
return doc, nil
}
func NewDecoder(r io.Reader) *Decoder {
d := &Decoder{}
d.documentBuffers.New = func() any { return &bytes.Buffer{} }
d.dec = json.NewDecoder(io.TeeReader(r, &d.buf))
return d
}
func parseError(value string) error {
return fmt.Errorf("invalid document: expected id:<namespace>:<document-type>:[n=<number>|g=<group>]:<user-specific>, got %q", value)
}
// Generator is a reader that returns synthetic documents until a given deadline.
type Generator struct {
Size int
Deadline time.Time
buf bytes.Buffer
nowFunc func() time.Time
}
func NewGenerator(size int, deadline time.Time) *Generator {
return &Generator{Size: size, Deadline: deadline, nowFunc: time.Now}
}
func randString(size int) string {
b := make([]byte, size)
for i := range b {
b[i] = byte('a' + rand.Intn('z'-'a'+1))
}
return string(b)
}
func (g *Generator) Read(p []byte) (int, error) {
if g.buf.Len() == 0 {
if !g.nowFunc().Before(g.Deadline) {
return 0, io.EOF
}
fmt.Fprintf(&g.buf, "{\"put\": \"id:test:test::%s\", \"fields\": {\"test\": \"%s\"}}\n", randString(8), randString(g.Size))
}
return g.buf.Read(p)
}
type number interface{ float64 | int64 | int }
func min[T number](x, y T) T {
if x < y {
return x
}
return y
}
func max[T number](x, y T) T {
if x > y {
return x
}
return y
}
|