cost-model/core/pkg/model/shared/shared_codecs.go

////////////////////////////////////////////////////////////////////////////////
//
//                             DO NOT MODIFY
//
//                          ┻━┻ ︵ヽ(`Д´)ﾉ︵ ┻━┻
//
//
//            This source file was automatically generated by bingen.
//
////////////////////////////////////////////////////////////////////////////////

package shared

import (
	"fmt"
	util "github.com/opencost/opencost/core/pkg/util"
	"io"
	"iter"
	"os"
	"reflect"
	"strings"
	"sync"
	"unsafe"
)

const (
	// GeneratorPackageName is the package the generator is targetting
	GeneratorPackageName string = "shared"
)

// BinaryTags represent the formatting tag used for specific optimization features
const (
	// BinaryTagStringTable is written and/or read prior to the existence of a string
	// table (where each index is encoded as a string entry in the resource
	BinaryTagStringTable string = "BGST"
)

const (
	// DefaultCodecVersion is used for any resources listed in the Default version set
	DefaultCodecVersion uint8 = 1
)

//--------------------------------------------------------------------------
//  Configuration
//--------------------------------------------------------------------------

var (
	bingenConfigLock sync.RWMutex
	bingenConfig     *BingenConfiguration = DefaultBingenConfiguration()
)

// BingenConfiguration is used to set any custom configuration in the way files are encoded
// or decoded.
type BingenConfiguration struct {
	// FileBackedStringTableEnabled enables the use of file-backed string tables for streaming
	// bingen decoding.
	FileBackedStringTableEnabled bool

	// FileBackedStringTableDir is the directory to write the string table files for reading.
	FileBackedStringTableDir string
}

// DefaultBingenConfiguration creates the default implementation of the bingen configuration
// and returns it.
func DefaultBingenConfiguration() *BingenConfiguration {
	return &BingenConfiguration{
		FileBackedStringTableEnabled: false,
		FileBackedStringTableDir:     os.TempDir(),
	}
}

// ConfigureBingen accepts a new *BingenConfiguration instance which updates the internal decoder
// and encoder behavior.
func ConfigureBingen(config *BingenConfiguration) {
	bingenConfigLock.Lock()
	defer bingenConfigLock.Unlock()

	if config == nil {
		config = DefaultBingenConfiguration()
	}
	bingenConfig = config
}

// IsBingenFileBackedStringTableEnabled accessor for file backed string table configuration
func IsBingenFileBackedStringTableEnabled() bool {
	bingenConfigLock.RLock()
	defer bingenConfigLock.RUnlock()

	return bingenConfig.FileBackedStringTableEnabled
}

// BingenFileBackedStringTableDir returns the directory configured for file backed string tables.
func BingenFileBackedStringTableDir() string {
	bingenConfigLock.RLock()
	defer bingenConfigLock.RUnlock()

	return bingenConfig.FileBackedStringTableDir
}

//--------------------------------------------------------------------------
//  Type Map
//--------------------------------------------------------------------------

// Generated type map for resolving interface implementations to
// to concrete types
var typeMap map[string]reflect.Type = map[string]reflect.Type{}

//--------------------------------------------------------------------------
//  Type Helpers
//--------------------------------------------------------------------------

// isBinaryTag returns true when the first bytes in the provided binary matches the tag
func isBinaryTag(data []byte, tag string) bool {
	if len(data) < len(tag) {
		return false
	}

	return string(data[:len(tag)]) == tag
}

// isReaderBinaryTag is used to peek the header for an io.Reader Buffer
func isReaderBinaryTag(buff *util.Buffer, tag string) bool {
	data, err := buff.Peek(len(tag))
	if err != nil && err != io.EOF {
		panic(fmt.Sprintf("called Peek() on a non buffered reader: %s", err))
	}
	if len(data) < len(tag) {
		return false
	}

	return string(data[:len(tag)]) == tag
}

// appendBytes combines a and b into a new byte array
func appendBytes(a []byte, b []byte) []byte {
	al := len(a)
	bl := len(b)
	tl := al + bl

	// allocate a new byte array for the combined
	// use native copy for speedy byte copying
	result := make([]byte, tl)
	copy(result, a)
	copy(result[al:], b)

	return result
}

// typeToString determines the basic properties of the type, the qualifier, package path, and
// type name, and returns the qualified type
func typeToString(f interface{}) string {
	qual := ""
	t := reflect.TypeOf(f)
	if t.Kind() == reflect.Ptr {
		t = t.Elem()
		qual = "*"
	}

	return fmt.Sprintf("%s%s.%s", qual, t.PkgPath(), t.Name())
}

// resolveType uses the name of a type and returns the package, base type name, and whether
// or not it's a pointer.
func resolveType(t string) (pkg string, name string, isPtr bool) {
	isPtr = t[:1] == "*"
	if isPtr {
		t = t[1:]
	}

	slashIndex := strings.LastIndex(t, "/")
	if slashIndex >= 0 {
		t = t[slashIndex+1:]
	}
	parts := strings.Split(t, ".")
	if parts[0] == GeneratorPackageName {
		parts[0] = ""
	}

	pkg = parts[0]
	name = parts[1]
	return
}

//--------------------------------------------------------------------------
//  Stream Helpers
//--------------------------------------------------------------------------

// StreamFactoryFunc is an alias for a func that creates a BingenStream implementation.
type StreamFactoryFunc func(io.Reader) BingenStream

// Generated streamable factory map for finding the specific new stream methods
// by T type
var streamFactoryMap map[reflect.Type]StreamFactoryFunc = map[reflect.Type]StreamFactoryFunc{}

// NewStreamFor accepts an io.Reader, and returns a new BingenStream for the generic T
// type provided _if_ it is a registered bingen type that is annotated as 'streamable'. See
// the streamFactoryMap for generated type listings.
func NewStreamFor[T any](reader io.Reader) (BingenStream, error) {
	typeKey := reflect.TypeFor[T]()

	factory, ok := streamFactoryMap[typeKey]
	if !ok {
		return nil, fmt.Errorf("the type: %s is not a registered bingen streamable type", typeKey.Name())
	}

	return factory(reader), nil
}

// BingenStream is the stream interface for all streamable types
type BingenStream interface {
	// Stream returns the iterator which will stream each field of the target type and
	// return the field info as well as the value.
	Stream() iter.Seq2[BingenFieldInfo, *BingenValue]

	// Close will close any dynamic io.Reader used to stream in the fields
	Close()

	// Error returns an error if one occurred during the process of streaming the type's fields.
	// This can be checked after iterating through the Stream().
	Error() error
}

// BingenValue contains the value of a field as well as any index/key associated with that value.
type BingenValue struct {
	Value any
	Index any
}

// IsNil is just a method accessor way to check to see if the value returned was nil
func (bv *BingenValue) IsNil() bool {
	return bv == nil
}

// creates a single BingenValue instance without a key or index
func singleV(value any) *BingenValue {
	return &BingenValue{
		Value: value,
	}
}

// creates a pair of key/index and value.
func pairV(index any, value any) *BingenValue {
	return &BingenValue{
		Value: value,
		Index: index,
	}
}

// BingenFieldInfo contains the type of the field being streamed as well as the name of the field.
type BingenFieldInfo struct {
	Type reflect.Type
	Name string
}

//--------------------------------------------------------------------------
//  String Table Writer
//--------------------------------------------------------------------------

// StringTableWriter maps strings to specific indices for encoding
type StringTableWriter struct {
	l       sync.Mutex
	indices map[string]int
	next    int
}

// NewStringTableWriter Creates a new StringTableWriter instance with provided contents
func NewStringTableWriter(contents ...string) *StringTableWriter {
	st := &StringTableWriter{
		indices: make(map[string]int, len(contents)),
		next:    len(contents),
	}

	for i, entry := range contents {
		st.indices[entry] = i
	}

	return st
}

// AddOrGet atomically retrieves a string entry's index if it exist. Otherwise, it will
// add the entry and return the index.
func (st *StringTableWriter) AddOrGet(s string) int {
	st.l.Lock()
	defer st.l.Unlock()

	if ind, ok := st.indices[s]; ok {
		return ind
	}

	current := st.next
	st.next++

	st.indices[s] = current
	return current
}

// ToSlice Converts the contents to a string array for encoding.
func (st *StringTableWriter) ToSlice() []string {
	st.l.Lock()
	defer st.l.Unlock()

	if st.next == 0 {
		return []string{}
	}

	sl := make([]string, st.next)
	for s, i := range st.indices {
		sl[i] = s
	}
	return sl
}

// ToBytes Converts the contents to a binary encoded representation
func (st *StringTableWriter) ToBytes() []byte {
	buff := util.NewBuffer()
	buff.WriteBytes([]byte(BinaryTagStringTable)) // bingen table header

	strs := st.ToSlice()

	buff.WriteInt(len(strs)) // table length
	for _, s := range strs {
		buff.WriteString(s)
	}

	return buff.Bytes()
}

//--------------------------------------------------------------------------
//  String Table Reader
//--------------------------------------------------------------------------

// StringTableReader is the interface used to read the string table from the decoding.
type StringTableReader interface {
	// At returns the string entry at a specific index, or panics on out of bounds.
	At(index int) string

	// Len returns the total number of strings loaded in the string table.
	Len() int

	// Close will clear the loaded table, and drop any external resources used.
	Close() error
}

// SliceStringTableReader is a basic pre-loaded []string that provides index-based access.
// The cost of this implementation is holding all strings in memory, which provides faster
// lookup performance for memory usage.
type SliceStringTableReader struct {
	table []string
}

// NewSliceStringTableReaderFrom creates a new SliceStringTableReader instance loading
// data directly from the buffer. The buffer's position should start at the table length.
func NewSliceStringTableReaderFrom(buffer *util.Buffer) StringTableReader {
	// table length
	tl := buffer.ReadInt()

	var table []string
	if tl > 0 {
		table = make([]string, tl)
		for i := range tl {
			table[i] = buffer.ReadString()
		}
	}

	return &SliceStringTableReader{
		table: table,
	}
}

// At returns the string entry at a specific index, or panics on out of bounds.
func (sstr *SliceStringTableReader) At(index int) string {
	if index < 0 || index >= len(sstr.table) {
		panic(fmt.Errorf("%s: string table index out of bounds: %d", GeneratorPackageName, index))
	}

	return sstr.table[index]
}

// Len returns the total number of strings loaded in the string table.
func (sstr *SliceStringTableReader) Len() int {
	if sstr == nil {
		return 0
	}

	return len(sstr.table)
}

// Close for the slice tables just nils out the slice and returns
func (sstr *SliceStringTableReader) Close() error {
	sstr.table = nil
	return nil
}

// fileStringRef maps a bingen string-table index to a payload stored in a temp file.
type fileStringRef struct {
	off    int64
	length int
}

// FileStringTableReader leverages a local file to write string table data for lookup. On
// memory focused systems, this allows a slower parse with a significant decrease in memory
// usage. This implementation is often pair with streaming readers for high throughput with
// reduced memory usage.
type FileStringTableReader struct {
	f    *os.File
	refs []fileStringRef
}

// NewFileStringTableFromBuffer reads exactly tl length-prefixed (uint16) string payloads from buffer
// and appends each payload to a new temp file. It does not retain full strings in memory.
func NewFileStringTableReaderFrom(buffer *util.Buffer, dir string) StringTableReader {
	// helper func to cast a string in-place to a byte slice.
	// NOTE: Return value is READ-ONLY. DO NOT MODIFY!
	byteSliceFor := func(s string) []byte {
		return unsafe.Slice(unsafe.StringData(s), len(s))
	}

	err := os.MkdirAll(dir, 0755)
	if err != nil {
		panic(fmt.Errorf("%s: failed to create string table directory: %w", GeneratorPackageName, err))
	}

	f, err := os.CreateTemp(dir, fmt.Sprintf("%s-bgst-*", GeneratorPackageName))
	if err != nil {
		panic(fmt.Errorf("%s: failed to create string table file: %w", GeneratorPackageName, err))
	}

	var writeErr error
	defer func() {
		if writeErr != nil {
			_ = f.Close()
		}
	}()

	// table length
	tl := buffer.ReadInt()

	var refs []fileStringRef
	if tl > 0 {
		refs = make([]fileStringRef, tl)

		for i := range tl {
			payload := byteSliceFor(buffer.ReadString())

			var off int64
			if len(payload) > 0 {
				off, err = f.Seek(0, io.SeekEnd)
				if err != nil {
					writeErr = fmt.Errorf("%s: failed to seek string table file: %w", GeneratorPackageName, err)
					panic(writeErr)
				}
				if _, err := f.Write(payload); err != nil {
					writeErr = fmt.Errorf("%s: failed to write string table entry %d: %w", GeneratorPackageName, i, err)
					panic(writeErr)
				}
			}

			refs[i] = fileStringRef{
				off:    off,
				length: len(payload),
			}
		}
	}

	return &FileStringTableReader{
		f:    f,
		refs: refs,
	}
}

// At returns the string from the internal file using the reference's offset and length.
func (fstr *FileStringTableReader) At(index int) string {
	if fstr == nil || fstr.f == nil {
		panic(fmt.Errorf("%s: failed to read file string table data", GeneratorPackageName))
	}
	if index < 0 || index >= len(fstr.refs) {
		panic(fmt.Errorf("%s: string table index out of bounds: %d", GeneratorPackageName, index))
	}

	ref := fstr.refs[index]
	if ref.length == 0 {
		return ""
	}

	b := make([]byte, ref.length)
	_, err := fstr.f.ReadAt(b, ref.off)
	if err != nil {
		return ""
	}

	// cast the allocated bytes to a string in-place, as we
	// were the ones that allocated the bytes
	return unsafe.String(unsafe.SliceData(b), len(b))
}

// Len returns the total number of strings loaded in the string table.
func (fstr *FileStringTableReader) Len() int {
	if fstr == nil {
		return 0
	}

	return len(fstr.refs)
}

// Close for the file string table reader closes the file and deletes it.
func (fstr *FileStringTableReader) Close() error {
	if fstr == nil || fstr.f == nil {
		return nil
	}

	path := fstr.f.Name()
	err := fstr.f.Close()
	fstr.f = nil
	fstr.refs = nil

	if path != "" {
		_ = os.Remove(path)
	}

	return err
}

//--------------------------------------------------------------------------
//  Codec Context
//--------------------------------------------------------------------------

// EncodingContext is a context object passed to the encoders to ensure reuse of buffer
// and table data
type EncodingContext struct {
	Buffer *util.Buffer
	Table  *StringTableWriter
}

// IsStringTable returns true if the table is available
func (ec *EncodingContext) IsStringTable() bool {
	return ec.Table != nil
}

// DecodingContext is a context object passed to the decoders to ensure parent objects
// reuse as much data as possible
type DecodingContext struct {
	Buffer *util.Buffer
	Table  StringTableReader
}

// NewDecodingContextFromBytes creates a new DecodingContext instance using an byte slice
func NewDecodingContextFromBytes(data []byte) *DecodingContext {
	var table StringTableReader

	buff := util.NewBufferFromBytes(data)

	// string table header validation
	if isBinaryTag(data, BinaryTagStringTable) {
		buff.ReadBytes(len(BinaryTagStringTable)) // strip tag length

		// always use a slice string table with a byte array since the
		// data is already in memory
		table = NewSliceStringTableReaderFrom(buff)
	}

	return &DecodingContext{
		Buffer: buff,
		Table:  table,
	}
}

// NewDecodingContextFromReader creates a new DecodingContext instance using an io.Reader
// implementation
func NewDecodingContextFromReader(reader io.Reader) *DecodingContext {
	var table StringTableReader

	buff := util.NewBufferFromReader(reader)

	if isReaderBinaryTag(buff, BinaryTagStringTable) {
		buff.ReadBytes(len(BinaryTagStringTable)) // strip tag length

		// create correct string table implementation
		if IsBingenFileBackedStringTableEnabled() {
			table = NewFileStringTableReaderFrom(buff, BingenFileBackedStringTableDir())
		} else {
			table = NewSliceStringTableReaderFrom(buff)
		}
	}

	return &DecodingContext{
		Buffer: buff,
		Table:  table,
	}
}

// IsStringTable returns true if the table is available
func (dc *DecodingContext) IsStringTable() bool {
	return dc.Table != nil && dc.Table.Len() > 0
}

// Close will ensure that any string table resources and buffer resources are
// cleaned up.
func (dc *DecodingContext) Close() {
	if dc.Table != nil {
		_ = dc.Table.Close()
		dc.Table = nil
	}
}

//--------------------------------------------------------------------------
//  Binary Codec
//--------------------------------------------------------------------------

// BinEncoder is an encoding interface which defines a context based marshal contract.
type BinEncoder interface {
	MarshalBinaryWithContext(*EncodingContext) error
}

// BinDecoder is a decoding interface which defines a context based unmarshal contract.
type BinDecoder interface {
	UnmarshalBinaryWithContext(*DecodingContext) error
}