open-consul/vendor/github.com/hashicorp/go-memdb/index.go

570 lines
15 KiB
Go

package memdb
import (
"encoding/binary"
"encoding/hex"
"fmt"
"reflect"
"strings"
)
// Indexer is an interface used for defining indexes
type Indexer interface {
// ExactFromArgs is used to build an exact index lookup
// based on arguments
FromArgs(args ...interface{}) ([]byte, error)
}
// SingleIndexer is an interface used for defining indexes
// generating a single entry per object
type SingleIndexer interface {
// FromObject is used to extract an index value from an
// object or to indicate that the index value is missing.
FromObject(raw interface{}) (bool, []byte, error)
}
// MultiIndexer is an interface used for defining indexes
// generating multiple entries per object
type MultiIndexer interface {
// FromObject is used to extract index values from an
// object or to indicate that the index value is missing.
FromObject(raw interface{}) (bool, [][]byte, error)
}
// PrefixIndexer can optionally be implemented for any
// indexes that support prefix based iteration. This may
// not apply to all indexes.
type PrefixIndexer interface {
// PrefixFromArgs returns a prefix that should be used
// for scanning based on the arguments
PrefixFromArgs(args ...interface{}) ([]byte, error)
}
// StringFieldIndex is used to extract a field from an object
// using reflection and builds an index on that field.
type StringFieldIndex struct {
Field string
Lowercase bool
}
func (s *StringFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(s.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", s.Field, obj)
}
val := fv.String()
if val == "" {
return false, nil, nil
}
if s.Lowercase {
val = strings.ToLower(val)
}
// Add the null character as a terminator
val += "\x00"
return true, []byte(val), nil
}
func (s *StringFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
arg, ok := args[0].(string)
if !ok {
return nil, fmt.Errorf("argument must be a string: %#v", args[0])
}
if s.Lowercase {
arg = strings.ToLower(arg)
}
// Add the null character as a terminator
arg += "\x00"
return []byte(arg), nil
}
func (s *StringFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
val, err := s.FromArgs(args...)
if err != nil {
return nil, err
}
// Strip the null terminator, the rest is a prefix
n := len(val)
if n > 0 {
return val[:n-1], nil
}
return val, nil
}
// StringSliceFieldIndex is used to extract a field from an object
// using reflection and builds an index on that field.
type StringSliceFieldIndex struct {
Field string
Lowercase bool
}
func (s *StringSliceFieldIndex) FromObject(obj interface{}) (bool, [][]byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(s.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", s.Field, obj)
}
if fv.Kind() != reflect.Slice || fv.Type().Elem().Kind() != reflect.String {
return false, nil, fmt.Errorf("field '%s' is not a string slice", s.Field)
}
length := fv.Len()
vals := make([][]byte, 0, length)
for i := 0; i < fv.Len(); i++ {
val := fv.Index(i).String()
if val == "" {
continue
}
if s.Lowercase {
val = strings.ToLower(val)
}
// Add the null character as a terminator
val += "\x00"
vals = append(vals, []byte(val))
}
if len(vals) == 0 {
return false, nil, nil
}
return true, vals, nil
}
func (s *StringSliceFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
arg, ok := args[0].(string)
if !ok {
return nil, fmt.Errorf("argument must be a string: %#v", args[0])
}
if s.Lowercase {
arg = strings.ToLower(arg)
}
// Add the null character as a terminator
arg += "\x00"
return []byte(arg), nil
}
func (s *StringSliceFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
val, err := s.FromArgs(args...)
if err != nil {
return nil, err
}
// Strip the null terminator, the rest is a prefix
n := len(val)
if n > 0 {
return val[:n-1], nil
}
return val, nil
}
// StringMapFieldIndex is used to extract a field of type map[string]string
// from an object using reflection and builds an index on that field.
type StringMapFieldIndex struct {
Field string
Lowercase bool
}
var MapType = reflect.MapOf(reflect.TypeOf(""), reflect.TypeOf("")).Kind()
func (s *StringMapFieldIndex) FromObject(obj interface{}) (bool, [][]byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(s.Field)
if !fv.IsValid() {
return false, nil, fmt.Errorf("field '%s' for %#v is invalid", s.Field, obj)
}
if fv.Kind() != MapType {
return false, nil, fmt.Errorf("field '%s' is not a map[string]string", s.Field)
}
length := fv.Len()
vals := make([][]byte, 0, length)
for _, key := range fv.MapKeys() {
k := key.String()
if k == "" {
continue
}
val := fv.MapIndex(key).String()
if s.Lowercase {
k = strings.ToLower(k)
val = strings.ToLower(val)
}
// Add the null character as a terminator
k += "\x00" + val + "\x00"
vals = append(vals, []byte(k))
}
if len(vals) == 0 {
return false, nil, nil
}
return true, vals, nil
}
func (s *StringMapFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) > 2 || len(args) == 0 {
return nil, fmt.Errorf("must provide one or two arguments")
}
key, ok := args[0].(string)
if !ok {
return nil, fmt.Errorf("argument must be a string: %#v", args[0])
}
if s.Lowercase {
key = strings.ToLower(key)
}
// Add the null character as a terminator
key += "\x00"
if len(args) == 2 {
val, ok := args[1].(string)
if !ok {
return nil, fmt.Errorf("argument must be a string: %#v", args[1])
}
if s.Lowercase {
val = strings.ToLower(val)
}
// Add the null character as a terminator
key += val + "\x00"
}
return []byte(key), nil
}
// UintFieldIndex is used to extract a uint field from an object using
// reflection and builds an index on that field.
type UintFieldIndex struct {
Field string
}
func (u *UintFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(u.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", u.Field, obj)
}
// Check the type
k := fv.Kind()
size, ok := IsUintType(k)
if !ok {
return false, nil, fmt.Errorf("field %q is of type %v; want a uint", u.Field, k)
}
// Get the value and encode it
val := fv.Uint()
buf := make([]byte, size)
binary.PutUvarint(buf, val)
return true, buf, nil
}
func (u *UintFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
v := reflect.ValueOf(args[0])
if !v.IsValid() {
return nil, fmt.Errorf("%#v is invalid", args[0])
}
k := v.Kind()
size, ok := IsUintType(k)
if !ok {
return nil, fmt.Errorf("arg is of type %v; want a uint", k)
}
val := v.Uint()
buf := make([]byte, size)
binary.PutUvarint(buf, val)
return buf, nil
}
// IsUintType returns whether the passed type is a type of uint and the number
// of bytes needed to encode the type.
func IsUintType(k reflect.Kind) (size int, okay bool) {
switch k {
case reflect.Uint:
return binary.MaxVarintLen64, true
case reflect.Uint8:
return 2, true
case reflect.Uint16:
return binary.MaxVarintLen16, true
case reflect.Uint32:
return binary.MaxVarintLen32, true
case reflect.Uint64:
return binary.MaxVarintLen64, true
default:
return 0, false
}
}
// UUIDFieldIndex is used to extract a field from an object
// using reflection and builds an index on that field by treating
// it as a UUID. This is an optimization to using a StringFieldIndex
// as the UUID can be more compactly represented in byte form.
type UUIDFieldIndex struct {
Field string
}
func (u *UUIDFieldIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(u.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", u.Field, obj)
}
val := fv.String()
if val == "" {
return false, nil, nil
}
buf, err := u.parseString(val, true)
return true, buf, err
}
func (u *UUIDFieldIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
switch arg := args[0].(type) {
case string:
return u.parseString(arg, true)
case []byte:
if len(arg) != 16 {
return nil, fmt.Errorf("byte slice must be 16 characters")
}
return arg, nil
default:
return nil,
fmt.Errorf("argument must be a string or byte slice: %#v", args[0])
}
}
func (u *UUIDFieldIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
switch arg := args[0].(type) {
case string:
return u.parseString(arg, false)
case []byte:
return arg, nil
default:
return nil,
fmt.Errorf("argument must be a string or byte slice: %#v", args[0])
}
}
// parseString parses a UUID from the string. If enforceLength is false, it will
// parse a partial UUID. An error is returned if the input, stripped of hyphens,
// is not even length.
func (u *UUIDFieldIndex) parseString(s string, enforceLength bool) ([]byte, error) {
// Verify the length
l := len(s)
if enforceLength && l != 36 {
return nil, fmt.Errorf("UUID must be 36 characters")
} else if l > 36 {
return nil, fmt.Errorf("Invalid UUID length. UUID have 36 characters; got %d", l)
}
hyphens := strings.Count(s, "-")
if hyphens > 4 {
return nil, fmt.Errorf(`UUID should have maximum of 4 "-"; got %d`, hyphens)
}
// The sanitized length is the length of the original string without the "-".
sanitized := strings.Replace(s, "-", "", -1)
sanitizedLength := len(sanitized)
if sanitizedLength%2 != 0 {
return nil, fmt.Errorf("Input (without hyphens) must be even length")
}
dec, err := hex.DecodeString(sanitized)
if err != nil {
return nil, fmt.Errorf("Invalid UUID: %v", err)
}
return dec, nil
}
// FieldSetIndex is used to extract a field from an object using reflection and
// builds an index on whether the field is set by comparing it against its
// type's nil value.
type FieldSetIndex struct {
Field string
}
func (f *FieldSetIndex) FromObject(obj interface{}) (bool, []byte, error) {
v := reflect.ValueOf(obj)
v = reflect.Indirect(v) // Dereference the pointer if any
fv := v.FieldByName(f.Field)
if !fv.IsValid() {
return false, nil,
fmt.Errorf("field '%s' for %#v is invalid", f.Field, obj)
}
if fv.Interface() == reflect.Zero(fv.Type()).Interface() {
return true, []byte{0}, nil
}
return true, []byte{1}, nil
}
func (f *FieldSetIndex) FromArgs(args ...interface{}) ([]byte, error) {
return fromBoolArgs(args)
}
// ConditionalIndex builds an index based on a condition specified by a passed
// user function. This function may examine the passed object and return a
// boolean to encapsulate an arbitrarily complex conditional.
type ConditionalIndex struct {
Conditional ConditionalIndexFunc
}
// ConditionalIndexFunc is the required function interface for a
// ConditionalIndex.
type ConditionalIndexFunc func(obj interface{}) (bool, error)
func (c *ConditionalIndex) FromObject(obj interface{}) (bool, []byte, error) {
// Call the user's function
res, err := c.Conditional(obj)
if err != nil {
return false, nil, fmt.Errorf("ConditionalIndexFunc(%#v) failed: %v", obj, err)
}
if res {
return true, []byte{1}, nil
}
return true, []byte{0}, nil
}
func (c *ConditionalIndex) FromArgs(args ...interface{}) ([]byte, error) {
return fromBoolArgs(args)
}
// fromBoolArgs is a helper that expects only a single boolean argument and
// returns a single length byte array containing either a one or zero depending
// on whether the passed input is true or false respectively.
func fromBoolArgs(args []interface{}) ([]byte, error) {
if len(args) != 1 {
return nil, fmt.Errorf("must provide only a single argument")
}
if val, ok := args[0].(bool); !ok {
return nil, fmt.Errorf("argument must be a boolean type: %#v", args[0])
} else if val {
return []byte{1}, nil
}
return []byte{0}, nil
}
// CompoundIndex is used to build an index using multiple sub-indexes
// Prefix based iteration is supported as long as the appropriate prefix
// of indexers support it. All sub-indexers are only assumed to expect
// a single argument.
type CompoundIndex struct {
Indexes []Indexer
// AllowMissing results in an index based on only the indexers
// that return data. If true, you may end up with 2/3 columns
// indexed which might be useful for an index scan. Otherwise,
// the CompoundIndex requires all indexers to be satisfied.
AllowMissing bool
}
func (c *CompoundIndex) FromObject(raw interface{}) (bool, []byte, error) {
var out []byte
for i, idxRaw := range c.Indexes {
idx, ok := idxRaw.(SingleIndexer)
if !ok {
return false, nil, fmt.Errorf("sub-index %d error: %s", i, "sub-index must be a SingleIndexer")
}
ok, val, err := idx.FromObject(raw)
if err != nil {
return false, nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
if !ok {
if c.AllowMissing {
break
} else {
return false, nil, nil
}
}
out = append(out, val...)
}
return true, out, nil
}
func (c *CompoundIndex) FromArgs(args ...interface{}) ([]byte, error) {
if len(args) != len(c.Indexes) {
return nil, fmt.Errorf("less arguments than index fields")
}
var out []byte
for i, arg := range args {
val, err := c.Indexes[i].FromArgs(arg)
if err != nil {
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
out = append(out, val...)
}
return out, nil
}
func (c *CompoundIndex) PrefixFromArgs(args ...interface{}) ([]byte, error) {
if len(args) > len(c.Indexes) {
return nil, fmt.Errorf("more arguments than index fields")
}
var out []byte
for i, arg := range args {
if i+1 < len(args) {
val, err := c.Indexes[i].FromArgs(arg)
if err != nil {
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
out = append(out, val...)
} else {
prefixIndexer, ok := c.Indexes[i].(PrefixIndexer)
if !ok {
return nil, fmt.Errorf("sub-index %d does not support prefix scanning", i)
}
val, err := prefixIndexer.PrefixFromArgs(arg)
if err != nil {
return nil, fmt.Errorf("sub-index %d error: %v", i, err)
}
out = append(out, val...)
}
}
return out, nil
}