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Copy pathkeys.go
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598 lines (516 loc) · 16.1 KB
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/*
* Copyright 2016-2018 Dgraph Labs, Inc. and Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package x
import (
"encoding/binary"
"math"
"strings"
"github.com/pkg/errors"
"github.com/dgraph-io/dgraph/protos/pb"
)
const (
// TODO(pawan) - Make this 2 bytes long. Right now ParsedKey has byteType and
// bytePrefix. Change it so that it just has one field which has all the information.
// ByteData indicates the key stores data.
ByteData = byte(0x00)
// ByteIndex indicates the key stores an index.
ByteIndex = byte(0x02)
// ByteReverse indicates the key stores a reverse index.
ByteReverse = byte(0x04)
// ByteCount indicates the key stores a count index.
ByteCount = byte(0x08)
// ByteCountRev indicates the key stores a reverse count index.
ByteCountRev = ByteCount | ByteReverse
// DefaultPrefix is the prefix used for data, index and reverse keys so that relative
// order of data doesn't change keys of same attributes are located together.
DefaultPrefix = byte(0x00)
byteSchema = byte(0x01)
byteType = byte(0x02)
// ByteSplit is a constant to specify a given key corresponds to a posting list split
// into multiple parts.
ByteSplit = byte(0x01)
// ByteUnused is a constant to specify keys which need to be discarded.
ByteUnused = byte(0xff)
)
func writeAttr(buf []byte, attr string) []byte {
AssertTrue(len(attr) < math.MaxUint16)
binary.BigEndian.PutUint16(buf[:2], uint16(len(attr)))
rest := buf[2:]
AssertTrue(len(attr) == copy(rest, attr))
return rest[len(attr):]
}
// genKey creates the key and writes the initial bytes (type byte, length of attribute,
// and the attribute itself). It leaves the rest of the key empty for further processing
// if necessary.
func generateKey(typeByte byte, attr string, totalLen int) []byte {
AssertTrue(totalLen >= 1+2+len(attr))
buf := make([]byte, totalLen)
buf[0] = typeByte
rest := buf[1:]
writeAttr(rest, attr)
return buf
}
// SchemaKey returns schema key for given attribute. Schema keys are stored
// separately with unique prefix, since we need to iterate over all schema keys.
// The structure of a schema key is as follows:
//
// byte 0: key type prefix (set to byteSchema)
// byte 1-2: length of attr
// next len(attr) bytes: value of attr
func SchemaKey(attr string) []byte {
return generateKey(byteSchema, attr, 1+2+len(attr))
}
// TypeKey returns type key for given type name. Type keys are stored separately
// with a unique prefix, since we need to iterate over all type keys.
// The structure of a type key is as follows:
//
// byte 0: key type prefix (set to byteType)
// byte 1-2: length of typeName
// next len(attr) bytes: value of attr (the type name)
func TypeKey(attr string) []byte {
return generateKey(byteType, attr, 1+2+len(attr))
}
// DataKey generates a data key with the given attribute and UID.
// The structure of a data key is as follows:
//
// byte 0: key type prefix (set to DefaultPrefix)
// byte 1-2: length of attr
// next len(attr) bytes: value of attr
// next byte: data type prefix (set to ByteData)
// next byte: byte to determine if this key corresponds to a list that has been split
// into multiple parts
// next eight bytes: value of uid
// next eight bytes (optional): if the key corresponds to a split list, the startUid of
// the split stored in this key.
func DataKey(attr string, uid uint64) []byte {
prefixLen := 1 + 2 + len(attr)
totalLen := prefixLen + 1 + 1 + 8
buf := generateKey(DefaultPrefix, attr, totalLen)
rest := buf[prefixLen:]
rest[0] = ByteData
// By default, this key does not correspond to a part of a split key.
rest = rest[1:]
rest[0] = 0
rest = rest[1:]
binary.BigEndian.PutUint64(rest, uid)
return buf
}
// ReverseKey generates a reverse key with the given attribute and UID.
// The structure of a reverse key is as follows:
//
// byte 0: key type prefix (set to DefaultPrefix)
// byte 1-2: length of attr
// next len(attr) bytes: value of attr
// next byte: data type prefix (set to ByteReverse)
// next byte: byte to determine if this key corresponds to a list that has been split
// into multiple parts
// next eight bytes: value of uid
// next eight bytes (optional): if the key corresponds to a split list, the startUid of
// the split stored in this key.
func ReverseKey(attr string, uid uint64) []byte {
prefixLen := 1 + 2 + len(attr)
totalLen := prefixLen + 1 + 1 + 8
buf := generateKey(DefaultPrefix, attr, totalLen)
rest := buf[prefixLen:]
rest[0] = ByteReverse
// By default, this key does not correspond to a part of a split key.
rest = rest[1:]
rest[0] = 0
rest = rest[1:]
binary.BigEndian.PutUint64(rest, uid)
return buf
}
// IndexKey generates a index key with the given attribute and term.
// The structure of an index key is as follows:
//
// byte 0: key type prefix (set to DefaultPrefix)
// byte 1-2: length of attr
// next len(attr) bytes: value of attr
// next byte: data type prefix (set to ByteIndex)
// next byte: byte to determine if this key corresponds to a list that has been split
// into multiple parts
// next len(term) bytes: value of term
// next eight bytes (optional): if the key corresponds to a split list, the startUid of
// the split stored in this key.
func IndexKey(attr, term string) []byte {
prefixLen := 1 + 2 + len(attr)
totalLen := prefixLen + 1 + 1 + len(term)
buf := generateKey(DefaultPrefix, attr, totalLen)
rest := buf[prefixLen:]
rest[0] = ByteIndex
// By default, this key does not correspond to a part of a split key.
rest = rest[1:]
rest[0] = 0
rest = rest[1:]
AssertTrue(len(term) == copy(rest, term))
return buf
}
// CountKey generates a count key with the given attribute and uid.
// The structure of a count key is as follows:
//
// byte 0: key type prefix (set to DefaultPrefix)
// byte 1-2: length of attr
// next len(attr) bytes: value of attr
// next byte: data type prefix (set to ByteCount or ByteCountRev)
// next byte: byte to determine if this key corresponds to a list that has been split
// into multiple parts. Since count indexes only store one number, this value will
// always be zero.
// next four bytes: value of count.
func CountKey(attr string, count uint32, reverse bool) []byte {
prefixLen := 1 + 2 + len(attr)
totalLen := prefixLen + 1 + 1 + 4
buf := generateKey(DefaultPrefix, attr, totalLen)
rest := buf[prefixLen:]
if reverse {
rest[0] = ByteCountRev
} else {
rest[0] = ByteCount
}
// By default, this key does not correspond to a part of a split key.
rest = rest[1:]
rest[0] = 0
rest = rest[1:]
binary.BigEndian.PutUint32(rest, count)
return buf
}
// ParsedKey represents a key that has been parsed into its multiple attributes.
type ParsedKey struct {
byteType byte
Attr string
Uid uint64
HasStartUid bool
StartUid uint64
Term string
Count uint32
bytePrefix byte
}
// IsData returns whether the key is a data key.
func (p ParsedKey) IsData() bool {
return p.bytePrefix == DefaultPrefix && p.byteType == ByteData
}
// IsReverse returns whether the key is a reverse key.
func (p ParsedKey) IsReverse() bool {
return p.bytePrefix == DefaultPrefix && p.byteType == ByteReverse
}
// IsCountOrCountRev returns whether the key is a count or a count rev key.
func (p ParsedKey) IsCountOrCountRev() bool {
return p.IsCount() || p.IsCountRev()
}
// IsCount returns whether the key is a count key.
func (p ParsedKey) IsCount() bool {
return p.bytePrefix == DefaultPrefix && p.byteType == ByteCount
}
// IsCountRev returns whether the key is a count rev key.
func (p ParsedKey) IsCountRev() bool {
return p.bytePrefix == DefaultPrefix && p.byteType == ByteCountRev
}
// IsIndex returns whether the key is an index key.
func (p ParsedKey) IsIndex() bool {
return p.bytePrefix == DefaultPrefix && p.byteType == ByteIndex
}
// IsSchema returns whether the key is a schema key.
func (p ParsedKey) IsSchema() bool {
return p.bytePrefix == byteSchema
}
// IsType returns whether the key is a type key.
func (p ParsedKey) IsType() bool {
return p.bytePrefix == byteType
}
// IsOfType checks whether the key is of the given type.
func (p ParsedKey) IsOfType(typ byte) bool {
switch typ {
case ByteCount, ByteCountRev:
return p.IsCountOrCountRev()
case ByteReverse:
return p.IsReverse()
case ByteIndex:
return p.IsIndex()
case ByteData:
return p.IsData()
default:
}
return false
}
// SkipPredicate returns the first key after the keys corresponding to the predicate
// of this key. Useful when iterating in the reverse order.
func (p ParsedKey) SkipPredicate() []byte {
buf := make([]byte, 1+2+len(p.Attr)+1)
buf[0] = p.bytePrefix
rest := buf[1:]
k := writeAttr(rest, p.Attr)
AssertTrue(len(k) == 1)
k[0] = 0xFF
return buf
}
// SkipSchema returns the first key after all the schema keys.
func (p ParsedKey) SkipSchema() []byte {
var buf [1]byte
buf[0] = byteSchema + 1
return buf[:]
}
// SkipType returns the first key after all the type keys.
func (p ParsedKey) SkipType() []byte {
var buf [1]byte
buf[0] = byteType + 1
return buf[:]
}
// DataPrefix returns the prefix for data keys.
func (p ParsedKey) DataPrefix() []byte {
buf := make([]byte, 1+2+len(p.Attr)+1+1)
buf[0] = p.bytePrefix
rest := buf[1:]
k := writeAttr(rest, p.Attr)
AssertTrue(len(k) == 2)
k[0] = ByteData
k[1] = 0
return buf
}
// IndexPrefix returns the prefix for index keys.
func (p ParsedKey) IndexPrefix() []byte {
buf := make([]byte, 1+2+len(p.Attr)+1+1)
buf[0] = p.bytePrefix
rest := buf[1:]
k := writeAttr(rest, p.Attr)
AssertTrue(len(k) == 2)
k[0] = ByteIndex
k[1] = 0
return buf
}
// ReversePrefix returns the prefix for index keys.
func (p ParsedKey) ReversePrefix() []byte {
buf := make([]byte, 1+2+len(p.Attr)+1+1)
buf[0] = p.bytePrefix
rest := buf[1:]
k := writeAttr(rest, p.Attr)
AssertTrue(len(k) == 2)
k[0] = ByteReverse
k[1] = 0
return buf
}
// CountPrefix returns the prefix for count keys.
func (p ParsedKey) CountPrefix(reverse bool) []byte {
buf := make([]byte, 1+2+len(p.Attr)+1+1)
buf[0] = p.bytePrefix
rest := buf[1:]
k := writeAttr(rest, p.Attr)
AssertTrue(len(k) == 2)
if reverse {
k[0] = ByteCountRev
} else {
k[0] = ByteCount
}
k[1] = 0
return buf
}
// ToBackupKey returns the key in the format used for writing backups.
func (p ParsedKey) ToBackupKey() *pb.BackupKey {
key := pb.BackupKey{}
key.Attr = p.Attr
key.Uid = p.Uid
key.StartUid = p.StartUid
key.Term = p.Term
key.Count = p.Count
switch {
case p.IsData():
key.Type = pb.BackupKey_DATA
case p.IsIndex():
key.Type = pb.BackupKey_INDEX
case p.IsReverse():
key.Type = pb.BackupKey_REVERSE
case p.IsCount():
key.Type = pb.BackupKey_COUNT
case p.IsCountRev():
key.Type = pb.BackupKey_COUNT_REV
case p.IsSchema():
key.Type = pb.BackupKey_SCHEMA
case p.IsType():
key.Type = pb.BackupKey_TYPE
}
return &key
}
// FromBackupKey takes a key in the format used for backups and converts it to a key.
func FromBackupKey(backupKey *pb.BackupKey) []byte {
if backupKey == nil {
return nil
}
var key []byte
switch backupKey.Type {
case pb.BackupKey_DATA:
key = DataKey(backupKey.Attr, backupKey.Uid)
case pb.BackupKey_INDEX:
key = IndexKey(backupKey.Attr, backupKey.Term)
case pb.BackupKey_REVERSE:
key = ReverseKey(backupKey.Attr, backupKey.Uid)
case pb.BackupKey_COUNT:
key = CountKey(backupKey.Attr, backupKey.Count, false)
case pb.BackupKey_COUNT_REV:
key = CountKey(backupKey.Attr, backupKey.Count, true)
case pb.BackupKey_SCHEMA:
key = SchemaKey(backupKey.Attr)
case pb.BackupKey_TYPE:
key = TypeKey(backupKey.Attr)
}
if backupKey.StartUid > 0 {
var err error
key, err = GetSplitKey(key, backupKey.StartUid)
Check(err)
}
return key
}
// SchemaPrefix returns the prefix for Schema keys.
func SchemaPrefix() []byte {
var buf [1]byte
buf[0] = byteSchema
return buf[:]
}
// TypePrefix returns the prefix for Schema keys.
func TypePrefix() []byte {
var buf [1]byte
buf[0] = byteType
return buf[:]
}
// PredicatePrefix returns the prefix for all keys belonging to this predicate except schema key.
func PredicatePrefix(predicate string) []byte {
buf := make([]byte, 1+2+len(predicate))
buf[0] = DefaultPrefix
k := writeAttr(buf[1:], predicate)
AssertTrue(len(k) == 0)
return buf
}
// GetSplitKey takes a key baseKey and generates the key of the list split that starts at startUid.
func GetSplitKey(baseKey []byte, startUid uint64) ([]byte, error) {
keyCopy := make([]byte, len(baseKey)+8)
copy(keyCopy, baseKey)
p, err := Parse(baseKey)
if err != nil {
return nil, err
}
index := 1 + 2 + len(p.Attr) + 1
if index >= len(keyCopy) {
panic("Cannot write to key. Key is too small")
}
keyCopy[index] = ByteSplit
binary.BigEndian.PutUint64(keyCopy[len(baseKey):], startUid)
return keyCopy, nil
}
// Parse would parse the key. ParsedKey does not reuse the key slice, so the key slice can change
// without affecting the contents of ParsedKey.
func Parse(key []byte) (ParsedKey, error) {
var p ParsedKey
p.bytePrefix = key[0]
if p.bytePrefix == ByteUnused {
return p, nil
}
sz := int(binary.BigEndian.Uint16(key[1:3]))
k := key[3:]
p.Attr = string(k[:sz])
k = k[sz:]
switch p.bytePrefix {
case byteSchema, byteType:
return p, nil
default:
}
p.byteType = k[0]
k = k[1:]
p.HasStartUid = k[0] == ByteSplit
k = k[1:]
switch p.byteType {
case ByteData, ByteReverse:
if len(k) < 8 {
return p, errors.Errorf("uid length < 8 for key: %q, parsed key: %+v", key, p)
}
p.Uid = binary.BigEndian.Uint64(k)
if !p.HasStartUid {
break
}
if len(k) < 16 {
return p, errors.Errorf("StartUid length < 8 for key: %q, parsed key: %+v", key, p)
}
k = k[8:]
p.StartUid = binary.BigEndian.Uint64(k)
case ByteIndex:
if !p.HasStartUid {
p.Term = string(k)
break
}
if len(k) < 8 {
return p, errors.Errorf("StartUid length < 8 for key: %q, parsed key: %+v", key, p)
}
term := k[:len(k)-8]
startUid := k[len(k)-8:]
p.Term = string(term)
p.StartUid = binary.BigEndian.Uint64(startUid)
case ByteCount, ByteCountRev:
if len(k) < 4 {
return p, errors.Errorf("count length < 4 for key: %q, parsed key: %+v", key, p)
}
p.Count = binary.BigEndian.Uint32(k)
if !p.HasStartUid {
break
}
if len(k) < 12 {
return p, errors.Errorf("StartUid length < 8 for key: %q, parsed key: %+v", key, p)
}
k = k[4:]
p.StartUid = binary.BigEndian.Uint64(k)
default:
// Some other data type.
return p, errors.Errorf("Invalid data type")
}
return p, nil
}
var reservedPredicateMap = map[string]struct{}{
"dgraph.type": {},
}
var aclPredicateMap = map[string]struct{}{
"dgraph.xid": {},
"dgraph.password": {},
"dgraph.user.group": {},
"dgraph.group.acl": {},
}
// internalPredicateMap stores a set of Dgraph's internal predicate. An internal
// predicate is a predicate that has a special meaning in Dgraph and its query
// language and should not be allowed as a user-defined predicate.
var internalPredicateMap = map[string]struct{}{
"uid": {},
}
// IsReservedPredicate returns true if the predicate is in the reserved predicate list.
func IsReservedPredicate(pred string) bool {
_, ok := reservedPredicateMap[strings.ToLower(pred)]
return ok || IsAclPredicate(pred)
}
// IsAclPredicate returns true if the predicate is in the list of reserved
// predicates for the ACL feature.
func IsAclPredicate(pred string) bool {
_, ok := aclPredicateMap[strings.ToLower(pred)]
return ok
}
// ReservedPredicates returns the complete list of reserved predicates.
func ReservedPredicates() []string {
var preds []string
for pred := range reservedPredicateMap {
preds = append(preds, pred)
}
for pred := range aclPredicateMap {
preds = append(preds, pred)
}
return preds
}
// IsInternalPredicate returns true if the predicate is in the internal predicate list.
func IsInternalPredicate(pred string) bool {
_, ok := internalPredicateMap[strings.ToLower(pred)]
return ok
}