open-consul/agent/consul/state/indexer.go

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package state
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"strings"
"time"
"github.com/hashicorp/consul/acl"
"github.com/hashicorp/consul/agent/structs"
)
// indexerSingle implements both memdb.Indexer and memdb.SingleIndexer. It may
// be used in a memdb.IndexSchema to specify functions that generate the index
// value for memdb.Txn operations.
//
// R represents the type used to generate the read index.
// W represents the type used to generate the write index.
type indexerSingle[R, W any] struct {
// readIndex is used by memdb for Txn.Get, Txn.First, and other operations
// that read data.
readIndex[R]
// writeIndex is used by memdb for Txn.Insert, Txn.Delete, for operations
// that write data to the index.
writeIndex[W]
}
// indexerMulti implements both memdb.Indexer and memdb.MultiIndexer. It may
// be used in a memdb.IndexSchema to specify functions that generate the index
// value for memdb.Txn operations.
//
// R represents the type used to generate the read index.
// W represents the type used to generate the write index.
type indexerMulti[R, W any] struct {
// readIndex is used by memdb for Txn.Get, Txn.First, and other operations
// that read data.
readIndex[R]
// writeIndexMulti is used by memdb for Txn.Insert, Txn.Delete, for operations
// that write data to the index.
writeIndexMulti[W]
}
// indexerSingleWithPrefix is a indexerSingle which also supports prefix queries.
//
// R represents the type used to generate the read index.
// W represents the type used to generate the write index.
// P represents the type used to generate the prefix index.
type indexerSingleWithPrefix[R, W, P any] struct {
readIndex[R]
writeIndex[W]
prefixIndex[P]
}
// readIndex implements memdb.Indexer. It exists so that a function can be used
// to provide the interface.
//
// Unlike memdb.Indexer, a readIndex function accepts only a single argument. To
// generate an index from multiple values, use a struct type with multiple fields.
type readIndex[R any] func(arg R) ([]byte, error)
func (f readIndex[R]) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("index supports only a single arg")
}
arg, ok := args[0].(R)
if !ok {
var typ R
return nil, fmt.Errorf("unexpected type %T, does not implement %T", args[0], typ)
}
return f(arg)
}
var errMissingValueForIndex = fmt.Errorf("object is missing a value for this index")
// writeIndex implements memdb.SingleIndexer. It exists so that a function
// can be used to provide this interface.
//
// Instead of a bool return value, writeIndex expects errMissingValueForIndex to
// indicate that an index could not be build for the object. It will translate
// this error into a false value to satisfy the memdb.SingleIndexer interface.
type writeIndex[W any] func(raw W) ([]byte, error)
func (f writeIndex[W]) FromObject(raw interface{}) (bool, []byte, error) {
obj, ok := raw.(W)
if !ok {
var typ W
return false, nil, fmt.Errorf("unexpected type %T, does not implement %T", raw, typ)
}
v, err := f(obj)
if errors.Is(err, errMissingValueForIndex) {
return false, nil, nil
}
return err == nil, v, err
}
// writeIndexMulti implements memdb.MultiIndexer. It exists so that a function
// can be used to provide this interface.
//
// Instead of a bool return value, writeIndexMulti expects errMissingValueForIndex to
// indicate that an index could not be build for the object. It will translate
// this error into a false value to satisfy the memdb.MultiIndexer interface.
type writeIndexMulti[W any] func(raw W) ([][]byte, error)
func (f writeIndexMulti[W]) FromObject(raw interface{}) (bool, [][]byte, error) {
obj, ok := raw.(W)
if !ok {
var typ W
return false, nil, fmt.Errorf("unexpected type %T, does not implement %T", raw, typ)
}
v, err := f(obj)
if errors.Is(err, errMissingValueForIndex) {
return false, nil, nil
}
return err == nil, v, err
}
// prefixIndex implements memdb.PrefixIndexer. It exists so that a function
// can be used to provide this interface.
type prefixIndex[P any] func(args P) ([]byte, error)
func (f prefixIndex[P]) PrefixFromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("index supports only a single arg")
}
arg, ok := args[0].(P)
if !ok {
var typ P
return nil, fmt.Errorf("unexpected type %T, does not implement %T", args[0], typ)
}
return f(arg)
}
const null = "\x00"
// indexBuilder is a buffer used to construct memdb index values.
type indexBuilder bytes.Buffer
2021-03-29 17:01:31 +00:00
func newIndexBuilder(cap int) *indexBuilder {
buff := make([]byte, 0, cap)
b := bytes.NewBuffer(buff)
return (*indexBuilder)(b)
}
// String appends the string and a null terminator to the buffer.
func (b *indexBuilder) String(v string) {
(*bytes.Buffer)(b).WriteString(v)
(*bytes.Buffer)(b).WriteString(null)
}
func (b *indexBuilder) Int64(v int64) {
const size = binary.MaxVarintLen64
// Get the value and encode it
buf := make([]byte, size)
binary.PutVarint(buf, v)
b.Raw(buf)
}
// Raw appends the bytes without a null terminator to the buffer. Raw should
// only be used when v has a fixed length, or when building the last segment of
// a prefix index.
func (b *indexBuilder) Raw(v []byte) {
(*bytes.Buffer)(b).Write(v)
}
func (b *indexBuilder) Bytes() []byte {
return (*bytes.Buffer)(b).Bytes()
}
// singleValueID is an interface that may be implemented by any type that should
// be indexed by a single ID and a structs.EnterpriseMeta to scope the ID.
type singleValueID interface {
IDValue() string
PartitionOrDefault() string
NamespaceOrDefault() string
}
type multiValueID interface {
IDValue() []string
PartitionOrDefault() string
NamespaceOrDefault() string
}
var _ singleValueID = (*structs.DirEntry)(nil)
var _ singleValueID = (*Tombstone)(nil)
var _ singleValueID = (*Query)(nil)
var _ singleValueID = (*structs.Session)(nil)
// indexFromIDValue creates an index key from any struct that implements singleValueID
func indexFromIDValueLowerCase(e singleValueID) ([]byte, error) {
v := strings.ToLower(e.IDValue())
if v == "" {
return nil, errMissingValueForIndex
}
var b indexBuilder
b.String(v)
return b.Bytes(), nil
}
// indexFromIDValue creates an index key from any struct that implements singleValueID
func indexFromMultiValueID(e multiValueID) ([]byte, error) {
var b indexBuilder
for _, v := range e.IDValue() {
if v == "" {
return nil, errMissingValueForIndex
}
b.String(strings.ToLower(v))
}
return b.Bytes(), nil
}
func (b *indexBuilder) Bool(v bool) {
b.Raw([]byte{intFromBool(v)})
}
type TimeQuery struct {
Value time.Time
acl.EnterpriseMeta
}
// NamespaceOrDefault exists because structs.EnterpriseMeta uses a pointer
// receiver for this method. Remove once that is fixed.
func (q TimeQuery) NamespaceOrDefault() string {
return q.EnterpriseMeta.NamespaceOrDefault()
}
// PartitionOrDefault exists because structs.EnterpriseMeta uses a pointer
// receiver for this method. Remove once that is fixed.
func (q TimeQuery) PartitionOrDefault() string {
return q.EnterpriseMeta.PartitionOrDefault()
}
func (b *indexBuilder) Time(t time.Time) {
val := t.Unix()
buf := make([]byte, 8)
binary.BigEndian.PutUint64(buf, uint64(val))
(*bytes.Buffer)(b).Write(buf)
}