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main.go
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1936 lines (1660 loc) · 41.8 KB
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package main
import (
"bytes"
"encoding/binary"
"encoding/json"
"fmt"
"os"
"path"
"strings"
"sync"
"syscall"
"unsafe"
)
// ==================== Constants and Basic Types ====================
const (
HEADER = 4
BTREE_PAGE_SIZE = 4096
BTREE_MAX_KEY_SIZE = 1000
BTREE_MAX_VAL_SIZE = 3000
FREE_LIST_HEADER = 8
FREE_LIST_CAP = (BTREE_PAGE_SIZE - FREE_LIST_HEADER) / 8
DB_SIG = "BuildYourOwnDB06"
)
const (
BNODE_NODE = 1
BNODE_LEAF = 2
)
const (
TYPE_BYTES = 1
TYPE_INT64 = 2
)
const (
MODE_UPSERT = 0
MODE_UPDATE_ONLY = 1
MODE_INSERT_ONLY = 2
)
const (
CMP_GE = +3
CMP_GT = +2
CMP_LT = -2
CMP_LE = -3
)
const (
FLAG_DELETED = 1
FLAG_UPDATED = 2
)
// ==================== Core Data Structures ====================
type BNode []byte
type LNode []byte
type Value struct {
Type uint32
I64 int64
Str []byte
}
type Record struct {
Cols []string
Vals []Value
}
type KeyRange struct {
start []byte
stop []byte
}
type UpdateReq struct {
tree *BTree
Added bool
Updated bool
Old []byte
Key []byte
Val []byte
Mode int
}
type DeleteReq struct {
tree *BTree
Deleted bool
Key []byte
}
// ==================== B+Tree Implementation ====================
func init() {
node1max := HEADER + 8 + 2 + 4 + BTREE_MAX_KEY_SIZE + BTREE_MAX_VAL_SIZE
if node1max > BTREE_PAGE_SIZE {
panic("maximum KV size exceeds page size")
}
}
func assert(condition bool) {
if !condition {
panic("assertion failed")
}
}
func (node BNode) btype() uint16 {
return binary.LittleEndian.Uint16(node[0:2])
}
func (node BNode) nkeys() uint16 {
return binary.LittleEndian.Uint16(node[2:4])
}
func (node BNode) setHeader(btype uint16, nkeys uint16) {
binary.LittleEndian.PutUint16(node[0:2], btype)
binary.LittleEndian.PutUint16(node[2:4], nkeys)
}
func (node BNode) getPtr(idx uint16) uint64 {
if idx >= node.nkeys() {
panic("index out of range")
}
pos := HEADER + 8*idx
return binary.LittleEndian.Uint64(node[pos:])
}
func (node BNode) setPtr(idx uint16, val uint64) {
if idx >= node.nkeys() {
panic("index out of range")
}
pos := HEADER + 8*idx
binary.LittleEndian.PutUint64(node[pos:], val)
}
func offsetPos(node BNode, idx uint16) uint16 {
if idx < 1 || idx > node.nkeys() {
panic("index out of range")
}
return HEADER + 8*node.nkeys() + 2*(idx-1)
}
func (node BNode) getOffset(idx uint16) uint16 {
if idx == 0 {
return 0
}
return binary.LittleEndian.Uint16(node[offsetPos(node, idx):])
}
func (node BNode) setOffset(idx uint16, offset uint16) {
if idx == 0 {
return
}
pos := offsetPos(node, idx)
binary.LittleEndian.PutUint16(node[pos:], offset)
}
func (node BNode) kvPos(idx uint16) uint16 {
if idx > node.nkeys() {
panic("index out of range")
}
return HEADER + 8*node.nkeys() + 2*node.nkeys() + node.getOffset(idx)
}
func (node BNode) getKey(idx uint16) []byte {
if idx >= node.nkeys() {
panic("index out of range")
}
pos := node.kvPos(idx)
klen := binary.LittleEndian.Uint16(node[pos:])
return node[pos+4:][:klen]
}
func (node BNode) getVal(idx uint16) []byte {
if idx >= node.nkeys() {
panic("index out of range")
}
pos := node.kvPos(idx)
klen := binary.LittleEndian.Uint16(node[pos:])
vlen := binary.LittleEndian.Uint16(node[pos+2:])
return node[pos+4+uint16(klen):][:vlen]
}
func (node BNode) nbytes() uint16 {
return node.kvPos(node.nkeys())
}
func nodeLookupLE(node BNode, key []byte) uint16 {
nkeys := node.nkeys()
found := uint16(0)
for i := uint16(1); i < nkeys; i++ {
cmp := bytes.Compare(node.getKey(i), key)
if cmp <= 0 {
found = i
}
if cmp >= 0 {
break
}
}
return found
}
func nodeAppendKV(new BNode, idx uint16, ptr uint64, key []byte, val []byte) {
new.setPtr(idx, ptr)
pos := new.kvPos(idx)
binary.LittleEndian.PutUint16(new[pos:], uint16(len(key)))
binary.LittleEndian.PutUint16(new[pos+2:], uint16(len(val)))
copy(new[pos+4:], key)
copy(new[pos+4+uint16(len(key)):], val)
new.setOffset(idx+1, new.getOffset(idx)+4+uint16(len(key)+len(val)))
}
func nodeAppendRange(new BNode, old BNode, dstNew uint16, srcOld uint16, n uint16) {
assert(srcOld+n <= old.nkeys())
assert(dstNew+n <= new.nkeys())
if n == 0 {
return
}
for i := uint16(0); i < n; i++ {
new.setPtr(dstNew+i, old.getPtr(srcOld+i))
}
dstBegin := new.getOffset(dstNew)
srcBegin := old.getOffset(srcOld)
for i := uint16(1); i <= n; i++ {
offset := dstBegin + old.getOffset(srcOld+i) - srcBegin
new.setOffset(dstNew+i, offset)
}
begin := old.kvPos(srcOld)
end := old.kvPos(srcOld + n)
copy(new[new.kvPos(dstNew):], old[begin:end])
}
func leafInsert(new BNode, old BNode, idx uint16, key []byte, val []byte) {
new.setHeader(BNODE_LEAF, old.nkeys()+1)
nodeAppendRange(new, old, 0, 0, idx)
nodeAppendKV(new, idx, 0, key, val)
nodeAppendRange(new, old, idx+1, idx, old.nkeys()-idx)
}
func leafUpdate(new BNode, old BNode, idx uint16, key []byte, val []byte) {
new.setHeader(BNODE_LEAF, old.nkeys())
nodeAppendRange(new, old, 0, 0, idx)
nodeAppendKV(new, idx, 0, key, val)
nodeAppendRange(new, old, idx+1, idx+1, old.nkeys()-(idx+1))
}
func nodeReplaceKidN(tree *BTree, new BNode, old BNode, idx uint16, kids ...BNode) {
inc := uint16(len(kids))
new.setHeader(BNODE_NODE, old.nkeys()+inc-1)
nodeAppendRange(new, old, 0, 0, idx)
for i, node := range kids {
nodeAppendKV(new, idx+uint16(i), tree.new(node), node.getKey(0), nil)
}
nodeAppendRange(new, old, idx+inc, idx+1, old.nkeys()-(idx+1))
}
func nodeSplit2(left BNode, right BNode, old BNode) {
nkeys := old.nkeys()
split := nkeys / 2
left.setHeader(old.btype(), split)
nodeAppendRange(left, old, 0, 0, split)
right.setHeader(old.btype(), nkeys-split)
nodeAppendRange(right, old, 0, split, nkeys-split)
}
func nodeSplit3(old BNode) (uint16, [3]BNode) {
if old.nbytes() <= BTREE_PAGE_SIZE {
old = old[:BTREE_PAGE_SIZE]
return 1, [3]BNode{old}
}
left := BNode(make([]byte, 2*BTREE_PAGE_SIZE))
right := BNode(make([]byte, BTREE_PAGE_SIZE))
nodeSplit2(left, right, old)
if left.nbytes() <= BTREE_PAGE_SIZE {
left = left[:BTREE_PAGE_SIZE]
return 2, [3]BNode{left, right}
}
leftleft := BNode(make([]byte, BTREE_PAGE_SIZE))
middle := BNode(make([]byte, BTREE_PAGE_SIZE))
nodeSplit2(leftleft, middle, left)
assert(leftleft.nbytes() <= BTREE_PAGE_SIZE)
return 3, [3]BNode{leftleft, middle, right}
}
func treeInsert(tree *BTree, node BNode, key []byte, val []byte) BNode {
new := BNode(make([]byte, 2*BTREE_PAGE_SIZE))
idx := nodeLookupLE(node, key)
switch node.btype() {
case BNODE_LEAF:
if bytes.Equal(key, node.getKey(idx)) {
leafUpdate(new, node, idx, key, val)
} else {
leafInsert(new, node, idx+1, key, val)
}
case BNODE_NODE:
nodeInsert(tree, new, node, idx, key, val)
default:
panic("bad node!")
}
return new
}
func nodeInsert(tree *BTree, new BNode, node BNode, idx uint16, key []byte, val []byte) {
kptr := node.getPtr(idx)
knode := tree.get(kptr)
updated := treeInsert(tree, knode, key, val)
nsplit, split := nodeSplit3(updated)
tree.del(kptr)
nodeReplaceKidN(tree, new, node, idx, split[:nsplit]...)
}
type BTree struct {
root uint64
get func(uint64) BNode
new func(BNode) uint64
del func(uint64)
}
func (tree *BTree) Insert(key []byte, val []byte) {
if tree.root == 0 {
root := BNode(make([]byte, BTREE_PAGE_SIZE))
root.setHeader(BNODE_LEAF, 2)
nodeAppendKV(root, 0, 0, nil, nil)
nodeAppendKV(root, 1, 0, key, val)
tree.root = tree.new(root)
return
}
node := tree.get(tree.root)
updated := treeInsert(tree, node, key, val)
nsplit, split := nodeSplit3(updated)
tree.del(tree.root)
if nsplit > 1 {
root := BNode(make([]byte, BTREE_PAGE_SIZE))
root.setHeader(BNODE_NODE, nsplit)
for i, knode := range split[:nsplit] {
ptr := tree.new(knode)
nodeAppendKV(root, uint16(i), ptr, knode.getKey(0), nil)
}
tree.root = tree.new(root)
} else {
tree.root = tree.new(split[0])
}
}
func (tree *BTree) Get(key []byte) ([]byte, bool) {
if tree.root == 0 {
return nil, false
}
node := tree.get(tree.root)
for node.btype() == BNODE_NODE {
idx := nodeLookupLE(node, key)
node = tree.get(node.getPtr(idx))
}
idx := nodeLookupLE(node, key)
if idx < node.nkeys() && bytes.Equal(node.getKey(idx), key) {
return node.getVal(idx), true
}
return nil, false
}
// ==================== B+Tree Deletion ====================
func leafDelete(new BNode, old BNode, idx uint16) {
new.setHeader(BNODE_LEAF, old.nkeys()-1)
nodeAppendRange(new, old, 0, 0, idx)
nodeAppendRange(new, old, idx, idx+1, old.nkeys()-(idx+1))
}
func nodeMerge(new BNode, left BNode, right BNode) {
new.setHeader(left.btype(), left.nkeys()+right.nkeys())
nodeAppendRange(new, left, 0, 0, left.nkeys())
nodeAppendRange(new, right, left.nkeys(), 0, right.nkeys())
}
func nodeReplace2Kid(new BNode, old BNode, idx uint16, ptr uint64, key []byte) {
new.setHeader(BNODE_NODE, old.nkeys()-1)
nodeAppendRange(new, old, 0, 0, idx)
nodeAppendKV(new, idx, ptr, key, nil)
nodeAppendRange(new, old, idx+1, idx+2, old.nkeys()-(idx+2))
}
func shouldMerge(tree *BTree, node BNode, idx uint16, updated BNode) (int, BNode) {
if updated.nbytes() > BTREE_PAGE_SIZE/4 {
return 0, nil
}
if idx > 0 {
sibling := tree.get(node.getPtr(idx - 1))
merged := sibling.nbytes() + updated.nbytes() - HEADER
if merged <= BTREE_PAGE_SIZE {
return -1, sibling
}
}
if idx+1 < node.nkeys() {
sibling := tree.get(node.getPtr(idx + 1))
merged := sibling.nbytes() + updated.nbytes() - HEADER
if merged <= BTREE_PAGE_SIZE {
return +1, sibling
}
}
return 0, nil
}
func treeDelete(tree *BTree, node BNode, key []byte) BNode {
new := BNode(make([]byte, BTREE_PAGE_SIZE))
idx := nodeLookupLE(node, key)
switch node.btype() {
case BNODE_LEAF:
if bytes.Equal(key, node.getKey(idx)) {
leafDelete(new, node, idx)
} else {
return nil
}
case BNODE_NODE:
return nodeDelete(tree, node, idx, key)
default:
panic("bad node!")
}
return new
}
func nodeDelete(tree *BTree, node BNode, idx uint16, key []byte) BNode {
kptr := node.getPtr(idx)
updated := treeDelete(tree, tree.get(kptr), key)
if updated == nil {
return nil
}
tree.del(kptr)
new := BNode(make([]byte, BTREE_PAGE_SIZE))
mergeDir, sibling := shouldMerge(tree, node, idx, updated)
switch {
case mergeDir < 0:
merged := BNode(make([]byte, BTREE_PAGE_SIZE))
nodeMerge(merged, sibling, updated)
tree.del(node.getPtr(idx - 1))
nodeReplace2Kid(new, node, idx-1, tree.new(merged), merged.getKey(0))
case mergeDir > 0:
merged := BNode(make([]byte, BTREE_PAGE_SIZE))
nodeMerge(merged, updated, sibling)
tree.del(node.getPtr(idx + 1))
nodeReplace2Kid(new, node, idx, tree.new(merged), merged.getKey(0))
case updated.nkeys() == 0:
if node.nkeys() == 1 && idx == 0 {
new.setHeader(BNODE_NODE, 0)
} else {
nodeReplaceKidN(tree, new, node, idx, updated)
}
default:
nodeReplaceKidN(tree, new, node, idx, updated)
}
return new
}
func (tree *BTree) Delete(key []byte) bool {
if tree.root == 0 {
return false
}
updated := treeDelete(tree, tree.get(tree.root), key)
if updated == nil {
return false
}
tree.del(tree.root)
if updated.nkeys() == 0 {
tree.root = 0
} else {
tree.root = tree.new(updated)
}
return true
}
// ==================== Free List Implementation ====================
func (node LNode) getNext() uint64 {
return binary.LittleEndian.Uint64(node[0:8])
}
func (node LNode) setNext(next uint64) {
binary.LittleEndian.PutUint64(node[0:8], next)
}
func (node LNode) getPtr(idx int) uint64 {
pos := FREE_LIST_HEADER + 8*idx
return binary.LittleEndian.Uint64(node[pos:])
}
func (node LNode) setPtr(idx int, ptr uint64) {
pos := FREE_LIST_HEADER + 8*idx
binary.LittleEndian.PutUint64(node[pos:], ptr)
}
type FreeList struct {
get func(uint64) BNode
new func(BNode) uint64
set func(uint64) BNode
headPage uint64
headSeq uint64
tailPage uint64
tailSeq uint64
maxSeq uint64
maxVer uint64
curVer uint64
}
func seq2idx(seq uint64) int {
return int(seq % FREE_LIST_CAP)
}
func (fl *FreeList) SetMaxSeq() {
fl.maxSeq = fl.tailSeq
}
func flPop(fl *FreeList) (ptr uint64, head uint64) {
if fl.headSeq >= fl.maxSeq {
return 0, 0
}
node := LNode(fl.get(fl.headPage))
ptr = node.getPtr(seq2idx(fl.headSeq))
fl.headSeq++
if seq2idx(fl.headSeq) == 0 {
head, fl.headPage = fl.headPage, node.getNext()
assert(fl.headPage != 0)
}
return
}
func (fl *FreeList) PopHead() uint64 {
ptr, head := flPop(fl)
if head != 0 {
fl.PushTail(head)
}
return ptr
}
func (fl *FreeList) PushTail(ptr uint64) {
node := LNode(fl.set(fl.tailPage))
node.setPtr(seq2idx(fl.tailSeq), ptr)
fl.tailSeq++
if seq2idx(fl.tailSeq) == 0 {
next, head := flPop(fl)
if next == 0 {
next = fl.new(make([]byte, BTREE_PAGE_SIZE))
}
LNode(fl.set(fl.tailPage)).setNext(next)
fl.tailPage = next
if head != 0 {
LNode(fl.set(fl.tailPage)).setPtr(0, head)
fl.tailSeq++
}
}
}
// ==================== KV Store Implementation ====================
type KV struct {
Path string
fd int
tree BTree
free FreeList
mmap struct {
total int
chunks [][]byte
}
page struct {
flushed uint64
nappend uint64
updates map[uint64][]byte
}
version uint64
ongoing []uint64
history []CommittedTX
mutex sync.Mutex
failed bool
}
type CommittedTX struct {
version uint64
writes []KeyRange
}
func createFileSync(file string) (int, error) {
// Create the directory if it doesn't exist
dir := path.Dir(file)
if err := os.MkdirAll(dir, 0755); err != nil {
return -1, fmt.Errorf("create directory: %w", err)
}
// Create the file with proper sync flags
f, err := os.OpenFile(file, os.O_RDWR|os.O_CREATE|os.O_SYNC, 0644)
if err != nil {
return -1, fmt.Errorf("create file: %w", err)
}
// Get the file descriptor
fd := int(f.Fd())
// Sync the directory entry
if dirfd, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0); err == nil {
syscall.Fsync(dirfd)
syscall.Close(dirfd)
}
return fd, nil
}
func (db *KV) pageReadFile(ptr uint64) BNode {
start := uint64(0)
for _, chunk := range db.mmap.chunks {
end := start + uint64(len(chunk))/BTREE_PAGE_SIZE
if ptr < end {
offset := BTREE_PAGE_SIZE * (ptr - start)
return BNode(chunk[offset : offset+BTREE_PAGE_SIZE])
}
start = end
}
panic("bad ptr")
}
func (db *KV) pageRead(ptr uint64) BNode {
if node, ok := db.page.updates[ptr]; ok {
return BNode(node)
}
return db.pageReadFile(ptr)
}
func (db *KV) pageAppend(node BNode) uint64 {
ptr := db.page.flushed + db.page.nappend
db.page.nappend++
db.page.updates[ptr] = node
return ptr
}
func (db *KV) pageAlloc(node BNode) uint64 {
if ptr := db.free.PopHead(); ptr != 0 {
db.page.updates[ptr] = node
return ptr
}
return db.pageAppend(node)
}
func (db *KV) pageWrite(ptr uint64) BNode {
if node, ok := db.page.updates[ptr]; ok {
return BNode(node)
}
node := make([]byte, BTREE_PAGE_SIZE)
copy(node, db.pageReadFile(ptr))
db.page.updates[ptr] = node
return BNode(node)
}
func extendMmap(db *KV, size int) error {
if size <= db.mmap.total {
return nil
}
alloc := db.mmap.total
if alloc == 0 {
alloc = 64 << 20
}
for db.mmap.total+alloc < size {
alloc *= 2
}
chunk, err := syscall.Mmap(db.fd, int64(db.mmap.total), alloc, syscall.PROT_READ, syscall.MAP_SHARED)
if err != nil {
return fmt.Errorf("mmap: %w", err)
}
db.mmap.total += alloc
db.mmap.chunks = append(db.mmap.chunks, chunk)
return nil
}
func writePages(db *KV) error {
// Calculate size including ALL updates, not just appended ones
maxPage := db.page.flushed + db.page.nappend - 1
for ptr := range db.page.updates {
if ptr > maxPage {
maxPage = ptr
}
}
size := int(maxPage+1) * BTREE_PAGE_SIZE
if err := extendMmap(db, size); err != nil {
return err
}
// Write ALL updated pages, not just the newly appended ones
buffers := make([][]byte, 0, len(db.page.updates))
offsets := make([]int64, 0, len(db.page.updates))
for ptr, data := range db.page.updates {
buffers = append(buffers, data)
offsets = append(offsets, int64(ptr*BTREE_PAGE_SIZE))
}
// Write each page at its correct offset
for i, data := range buffers {
if _, err := syscall.Pwrite(db.fd, data, offsets[i]); err != nil {
return err
}
}
db.page.flushed += db.page.nappend
db.page.nappend = 0
return nil
}
func saveMeta(db *KV) []byte {
var data [64]byte
copy(data[:16], []byte(DB_SIG))
binary.LittleEndian.PutUint64(data[16:], db.tree.root)
binary.LittleEndian.PutUint64(data[24:], db.page.flushed)
binary.LittleEndian.PutUint64(data[32:], db.free.headPage)
binary.LittleEndian.PutUint64(data[40:], db.free.headSeq)
binary.LittleEndian.PutUint64(data[48:], db.free.tailPage)
binary.LittleEndian.PutUint64(data[56:], db.free.tailSeq)
return data[:]
}
func loadMeta(db *KV, data []byte) {
if len(data) < 64 {
panic("corrupted meta page")
}
if string(data[:16]) != DB_SIG {
panic("invalid database file")
}
db.tree.root = binary.LittleEndian.Uint64(data[16:])
db.page.flushed = binary.LittleEndian.Uint64(data[24:])
db.free.headPage = binary.LittleEndian.Uint64(data[32:])
db.free.headSeq = binary.LittleEndian.Uint64(data[40:])
db.free.tailPage = binary.LittleEndian.Uint64(data[48:])
db.free.tailSeq = binary.LittleEndian.Uint64(data[56:])
}
func updateRoot(db *KV) error {
if _, err := syscall.Pwrite(db.fd, saveMeta(db), 0); err != nil {
return fmt.Errorf("write meta page: %w", err)
}
return nil
}
func updateFile(db *KV) error {
if err := writePages(db); err != nil {
return err
}
if err := syscall.Fsync(db.fd); err != nil {
return err
}
if err := updateRoot(db); err != nil {
return err
}
return syscall.Fsync(db.fd)
}
func updateOrRevert(db *KV, meta []byte) error {
if db.failed {
if _, err := syscall.Pwrite(db.fd, meta, 0); err != nil {
return err
}
if err := syscall.Fsync(db.fd); err != nil {
return err
}
db.failed = false
}
err := updateFile(db)
if err != nil {
db.failed = true
loadMeta(db, meta)
db.page.nappend = 0
db.page.updates = make(map[uint64][]byte)
}
return err
}
func (db *KV) Open() error {
db.page.updates = make(map[uint64][]byte)
db.free.maxSeq = db.free.tailSeq
db.tree.get = db.pageRead
db.tree.new = db.pageAlloc
db.tree.del = db.free.PushTail
db.free.get = db.pageRead
db.free.new = db.pageAppend
db.free.set = db.pageWrite
fd, err := createFileSync(db.Path)
if err != nil {
return err
}
db.fd = fd
info, err := os.Stat(db.Path)
if err != nil {
return err
}
if info.Size() == 0 {
db.page.flushed = 2
db.free.headPage = 1
db.free.tailPage = 1
} else {
if err := extendMmap(db, int(info.Size())); err != nil {
return err
}
loadMeta(db, db.mmap.chunks[0])
}
return nil
}
func (db *KV) Close() error {
for _, chunk := range db.mmap.chunks {
if err := syscall.Munmap(chunk); err != nil {
return err
}
}
return syscall.Close(db.fd)
}
func (db *KV) Get(key []byte) ([]byte, bool) {
return db.tree.Get(key)
}
func (db *KV) Set(key []byte, val []byte) error {
meta := saveMeta(db)
db.tree.Insert(key, val)
return updateOrRevert(db, meta)
}
func (db *KV) Del(key []byte) (bool, error) {
meta := saveMeta(db)
deleted := db.tree.Delete(key)
err := updateOrRevert(db, meta)
return deleted, err
}
// ==================== Table System ====================
type TableDef struct {
Name string
Types []uint32
Cols []string
PKeys int
Prefix uint32
Indexes [][]string
Prefixes []uint32
}
type DB struct {
Path string
kv KV
}
var TDEF_TABLE = &TableDef{
Prefix: 2,
Name: "@table",
Types: []uint32{TYPE_BYTES, TYPE_BYTES},
Cols: []string{"name", "def"},
PKeys: 1,
}
var TDEF_META = &TableDef{
Prefix: 1,
Name: "@meta",
Types: []uint32{TYPE_BYTES, TYPE_BYTES},
Cols: []string{"key", "val"},
PKeys: 1,
}
func (rec *Record) AddStr(col string, val []byte) *Record {
rec.Cols = append(rec.Cols, col)
rec.Vals = append(rec.Vals, Value{Type: TYPE_BYTES, Str: val})
return rec
}
func (rec *Record) AddInt64(col string, val int64) *Record {
rec.Cols = append(rec.Cols, col)
rec.Vals = append(rec.Vals, Value{Type: TYPE_INT64, I64: val})
return rec
}
func (rec *Record) Get(col string) *Value {
for i, c := range rec.Cols {
if c == col {
return &rec.Vals[i]
}
}
return nil
}
func encodeKey(out []byte, prefix uint32, vals []Value) []byte {
var buf [4]byte
binary.BigEndian.PutUint32(buf[:], prefix)
out = append(out, buf[:]...)
for _, v := range vals {
out = append(out, byte(v.Type))
switch v.Type {
case TYPE_INT64:
var num [8]byte
u := uint64(v.I64) + (1 << 63)
binary.BigEndian.PutUint64(num[:], u)
out = append(out, num[:]...)
case TYPE_BYTES:
out = appendEscapedString(out, v.Str)
out = append(out, 0)
default:
panic("unknown type")
}
}
return out
}
func appendEscapedString(out []byte, str []byte) []byte {
for _, b := range str {
switch b {
case 0:
out = append(out, 1, 1)
case 1:
out = append(out, 1, 2)
default:
out = append(out, b)
}
}
return out
}
func decodeValues(in []byte, out []Value) {
pos := 0
for i := range out {
if pos >= len(in) {
break
}
typ := in[pos]
pos++
switch typ {
case TYPE_INT64:
if pos+8 > len(in) {
panic("corrupted data")
}
u := binary.BigEndian.Uint64(in[pos:])
out[i].I64 = int64(u - (1 << 63))
out[i].Type = TYPE_INT64
pos += 8
case TYPE_BYTES:
str, n := readEscapedString(in[pos:])
out[i].Str = str
out[i].Type = TYPE_BYTES
pos += n + 1
default:
panic("unknown type")
}
}
}
func readEscapedString(in []byte) ([]byte, int) {
var out []byte
i := 0
for i < len(in) && in[i] != 0 {
if in[i] == 1 {
if i+1 >= len(in) {
panic("corrupted string")
}
switch in[i+1] {
case 1:
out = append(out, 0)
case 2:
out = append(out, 1)
}
i += 2