377 lines
8.4 KiB
Go
377 lines
8.4 KiB
Go
package kafka
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import (
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"bufio"
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"errors"
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"fmt"
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"io"
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"reflect"
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)
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type readable interface {
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readFrom(*bufio.Reader, int) (int, error)
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}
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var errShortRead = errors.New("not enough bytes available to load the response")
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func peekRead(r *bufio.Reader, sz int, n int, f func([]byte)) (int, error) {
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if n > sz {
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return sz, errShortRead
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}
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b, err := r.Peek(n)
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if err != nil {
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return sz, err
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}
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f(b)
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return discardN(r, sz, n)
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}
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func readInt8(r *bufio.Reader, sz int, v *int8) (int, error) {
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return peekRead(r, sz, 1, func(b []byte) { *v = makeInt8(b) })
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}
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func readInt16(r *bufio.Reader, sz int, v *int16) (int, error) {
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return peekRead(r, sz, 2, func(b []byte) { *v = makeInt16(b) })
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}
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func readInt32(r *bufio.Reader, sz int, v *int32) (int, error) {
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return peekRead(r, sz, 4, func(b []byte) { *v = makeInt32(b) })
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}
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func readInt64(r *bufio.Reader, sz int, v *int64) (int, error) {
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return peekRead(r, sz, 8, func(b []byte) { *v = makeInt64(b) })
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}
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func readBool(r *bufio.Reader, sz int, v *bool) (int, error) {
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return peekRead(r, sz, 1, func(b []byte) { *v = b[0] != 0 })
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}
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func readString(r *bufio.Reader, sz int, v *string) (int, error) {
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return readStringWith(r, sz, func(r *bufio.Reader, sz int, n int) (remain int, err error) {
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*v, remain, err = readNewString(r, sz, n)
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return
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})
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}
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func readStringWith(r *bufio.Reader, sz int, cb func(*bufio.Reader, int, int) (int, error)) (int, error) {
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var err error
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var len int16
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if sz, err = readInt16(r, sz, &len); err != nil {
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return sz, err
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}
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n := int(len)
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if n > sz {
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return sz, errShortRead
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}
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return cb(r, sz, n)
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}
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func readNewString(r *bufio.Reader, sz int, n int) (string, int, error) {
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b, sz, err := readNewBytes(r, sz, n)
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return string(b), sz, err
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}
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func readBytes(r *bufio.Reader, sz int, v *[]byte) (int, error) {
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return readBytesWith(r, sz, func(r *bufio.Reader, sz int, n int) (remain int, err error) {
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*v, remain, err = readNewBytes(r, sz, n)
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return
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})
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}
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func readBytesWith(r *bufio.Reader, sz int, cb func(*bufio.Reader, int, int) (int, error)) (int, error) {
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var err error
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var len int32
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if sz, err = readInt32(r, sz, &len); err != nil {
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return sz, err
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}
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n := int(len)
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if n > sz {
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return sz, errShortRead
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}
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return cb(r, sz, n)
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}
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func readNewBytes(r *bufio.Reader, sz int, n int) ([]byte, int, error) {
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var err error
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var b []byte
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if n > 0 {
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b = make([]byte, n)
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n, err = io.ReadFull(r, b)
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b = b[:n]
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sz -= n
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}
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return b, sz, err
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}
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func readArrayWith(r *bufio.Reader, sz int, cb func(*bufio.Reader, int) (int, error)) (int, error) {
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var err error
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var len int32
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if sz, err = readInt32(r, sz, &len); err != nil {
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return sz, err
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}
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for n := int(len); n > 0; n-- {
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if sz, err = cb(r, sz); err != nil {
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break
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}
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}
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return sz, err
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}
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func readStringArray(r *bufio.Reader, sz int, v *[]string) (remain int, err error) {
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var content []string
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fn := func(r *bufio.Reader, size int) (fnRemain int, fnErr error) {
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var value string
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if fnRemain, fnErr = readString(r, size, &value); fnErr != nil {
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return
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}
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content = append(content, value)
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return
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}
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if remain, err = readArrayWith(r, sz, fn); err != nil {
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return
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}
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*v = content
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return
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}
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func readMapStringInt32(r *bufio.Reader, sz int, v *map[string][]int32) (remain int, err error) {
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var len int32
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if remain, err = readInt32(r, sz, &len); err != nil {
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return
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}
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content := make(map[string][]int32, len)
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for i := 0; i < int(len); i++ {
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var key string
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var values []int32
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if remain, err = readString(r, remain, &key); err != nil {
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return
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}
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fn := func(r *bufio.Reader, size int) (fnRemain int, fnErr error) {
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var value int32
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if fnRemain, fnErr = readInt32(r, size, &value); fnErr != nil {
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return
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}
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values = append(values, value)
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return
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}
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if remain, err = readArrayWith(r, remain, fn); err != nil {
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return
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}
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content[key] = values
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}
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*v = content
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return
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}
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func read(r *bufio.Reader, sz int, a interface{}) (int, error) {
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switch v := a.(type) {
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case *int8:
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return readInt8(r, sz, v)
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case *int16:
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return readInt16(r, sz, v)
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case *int32:
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return readInt32(r, sz, v)
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case *int64:
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return readInt64(r, sz, v)
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case *bool:
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return readBool(r, sz, v)
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case *string:
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return readString(r, sz, v)
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case *[]byte:
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return readBytes(r, sz, v)
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}
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switch v := reflect.ValueOf(a).Elem(); v.Kind() {
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case reflect.Struct:
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return readStruct(r, sz, v)
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case reflect.Slice:
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return readSlice(r, sz, v)
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default:
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panic(fmt.Sprintf("unsupported type: %T", a))
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}
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}
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func readAll(r *bufio.Reader, sz int, ptrs ...interface{}) (int, error) {
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var err error
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for _, ptr := range ptrs {
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if sz, err = readPtr(r, sz, ptr); err != nil {
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break
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}
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}
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return sz, err
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}
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func readPtr(r *bufio.Reader, sz int, ptr interface{}) (int, error) {
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switch v := ptr.(type) {
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case *int8:
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return readInt8(r, sz, v)
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case *int16:
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return readInt16(r, sz, v)
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case *int32:
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return readInt32(r, sz, v)
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case *int64:
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return readInt64(r, sz, v)
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case *string:
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return readString(r, sz, v)
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case *[]byte:
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return readBytes(r, sz, v)
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case readable:
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return v.readFrom(r, sz)
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default:
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panic(fmt.Sprintf("unsupported type: %T", v))
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}
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}
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func readStruct(r *bufio.Reader, sz int, v reflect.Value) (int, error) {
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var err error
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for i, n := 0, v.NumField(); i != n; i++ {
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if sz, err = read(r, sz, v.Field(i).Addr().Interface()); err != nil {
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return sz, err
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}
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}
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return sz, nil
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}
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func readSlice(r *bufio.Reader, sz int, v reflect.Value) (int, error) {
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var err error
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var len int32
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if sz, err = readInt32(r, sz, &len); err != nil {
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return sz, err
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}
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if n := int(len); n < 0 {
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v.Set(reflect.Zero(v.Type()))
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} else {
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v.Set(reflect.MakeSlice(v.Type(), n, n))
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for i := 0; i != n; i++ {
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if sz, err = read(r, sz, v.Index(i).Addr().Interface()); err != nil {
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return sz, err
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}
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}
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}
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return sz, nil
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}
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func readFetchResponseHeader(r *bufio.Reader, size int) (throttle int32, watermark int64, remain int, err error) {
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var n int32
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var p struct {
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Partition int32
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ErrorCode int16
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HighwaterMarkOffset int64
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MessageSetSize int32
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}
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if remain, err = readInt32(r, size, &throttle); err != nil {
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return
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}
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if remain, err = readInt32(r, remain, &n); err != nil {
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return
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}
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// This error should never trigger, unless there's a bug in the kafka client
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// or server.
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if n != 1 {
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err = fmt.Errorf("1 kafka topic was expected in the fetch response but the client received %d", n)
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return
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}
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// We ignore the topic name because we've requests messages for a single
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// topic, unless there's a bug in the kafka server we will have received
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// the name of the topic that we requested.
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if remain, err = discardString(r, remain); err != nil {
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return
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}
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if remain, err = readInt32(r, remain, &n); err != nil {
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return
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}
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// This error should never trigger, unless there's a bug in the kafka client
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// or server.
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if n != 1 {
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err = fmt.Errorf("1 kafka partition was expected in the fetch response but the client received %d", n)
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return
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}
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if remain, err = read(r, remain, &p); err != nil {
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return
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}
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if p.ErrorCode != 0 {
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err = Error(p.ErrorCode)
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return
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}
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// This error should never trigger, unless there's a bug in the kafka client
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// or server.
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if remain != int(p.MessageSetSize) {
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err = fmt.Errorf("the size of the message set in a fetch response doesn't match the number of remaining bytes (message set size = %d, remaining bytes = %d)", p.MessageSetSize, remain)
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return
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}
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watermark = p.HighwaterMarkOffset
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return
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}
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func readMessageHeader(r *bufio.Reader, sz int) (offset int64, attributes int8, timestamp int64, remain int, err error) {
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var version int8
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if remain, err = readInt64(r, sz, &offset); err != nil {
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return
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}
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// On discarding the message size and CRC:
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// ---------------------------------------
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//
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// - Not sure why kafka gives the message size here, we already have the
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// number of remaining bytes in the response and kafka should only truncate
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// the trailing message.
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//
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// - TCP is already taking care of ensuring data integrity, no need to
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// waste resources doing it a second time so we just skip the message CRC.
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//
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if remain, err = discardN(r, remain, 8); err != nil {
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return
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}
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if remain, err = readInt8(r, remain, &version); err != nil {
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return
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}
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if remain, err = readInt8(r, remain, &attributes); err != nil {
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return
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}
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switch version {
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case 0:
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case 1:
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remain, err = readInt64(r, remain, ×tamp)
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default:
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err = fmt.Errorf("unsupported message version %d found in fetch response", version)
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}
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return
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}
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