mirror of https://github.com/go-gitea/gitea
Git with a cup of tea, painless self-hosted git service
Mirror for internal git.with.parts use
https://git.with.parts
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
739 lines
12 KiB
739 lines
12 KiB
// Copyright 2013 The ql Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSES/QL-LICENSE file.
|
|
|
|
// Copyright 2015 PingCAP, Inc.
|
|
//
|
|
// 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,
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package memkv
|
|
|
|
import (
|
|
"io"
|
|
)
|
|
|
|
const (
|
|
kx = 128 //DONE benchmark tune this number if using custom key/value type(s).
|
|
kd = 64 //DONE benchmark tune this number if using custom key/value type(s).
|
|
)
|
|
|
|
type (
|
|
// cmp compares a and b. Return value is:
|
|
//
|
|
// < 0 if a < b
|
|
// 0 if a == b
|
|
// > 0 if a > b
|
|
//
|
|
cmp func(a, b []interface{}) int
|
|
|
|
d struct { // data page
|
|
c int
|
|
d [2*kd + 1]de
|
|
n *d
|
|
p *d
|
|
}
|
|
|
|
de struct { // d element
|
|
k []interface{}
|
|
v []interface{}
|
|
}
|
|
|
|
// Enumerator is the iterator for btree
|
|
Enumerator struct {
|
|
err error
|
|
hit bool
|
|
i int
|
|
k []interface{}
|
|
q *d
|
|
t *Tree
|
|
ver int64
|
|
}
|
|
|
|
// Tree is a B+tree.
|
|
Tree struct {
|
|
c int
|
|
cmp cmp
|
|
first *d
|
|
last *d
|
|
r interface{}
|
|
ver int64
|
|
}
|
|
|
|
xe struct { // x element
|
|
ch interface{}
|
|
sep *d
|
|
}
|
|
|
|
x struct { // index page
|
|
c int
|
|
x [2*kx + 2]xe
|
|
}
|
|
)
|
|
|
|
var ( // R/O zero values
|
|
zd d
|
|
zde de
|
|
zx x
|
|
zxe xe
|
|
)
|
|
|
|
func clr(q interface{}) {
|
|
switch z := q.(type) {
|
|
case *x:
|
|
for i := 0; i <= z.c; i++ { // Ch0 Sep0 ... Chn-1 Sepn-1 Chn
|
|
clr(z.x[i].ch)
|
|
}
|
|
*z = zx // GC
|
|
case *d:
|
|
*z = zd // GC
|
|
}
|
|
}
|
|
|
|
// -------------------------------------------------------------------------- x
|
|
|
|
func newX(ch0 interface{}) *x {
|
|
r := &x{}
|
|
r.x[0].ch = ch0
|
|
return r
|
|
}
|
|
|
|
func (q *x) extract(i int) {
|
|
q.c--
|
|
if i < q.c {
|
|
copy(q.x[i:], q.x[i+1:q.c+1])
|
|
q.x[q.c].ch = q.x[q.c+1].ch
|
|
q.x[q.c].sep = nil // GC
|
|
q.x[q.c+1] = zxe // GC
|
|
}
|
|
}
|
|
|
|
func (q *x) insert(i int, d *d, ch interface{}) *x {
|
|
c := q.c
|
|
if i < c {
|
|
q.x[c+1].ch = q.x[c].ch
|
|
copy(q.x[i+2:], q.x[i+1:c])
|
|
q.x[i+1].sep = q.x[i].sep
|
|
}
|
|
c++
|
|
q.c = c
|
|
q.x[i].sep = d
|
|
q.x[i+1].ch = ch
|
|
return q
|
|
}
|
|
|
|
func (q *x) siblings(i int) (l, r *d) {
|
|
if i >= 0 {
|
|
if i > 0 {
|
|
l = q.x[i-1].ch.(*d)
|
|
}
|
|
if i < q.c {
|
|
r = q.x[i+1].ch.(*d)
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// -------------------------------------------------------------------------- d
|
|
|
|
func (l *d) mvL(r *d, c int) {
|
|
copy(l.d[l.c:], r.d[:c])
|
|
copy(r.d[:], r.d[c:r.c])
|
|
l.c += c
|
|
r.c -= c
|
|
}
|
|
|
|
func (l *d) mvR(r *d, c int) {
|
|
copy(r.d[c:], r.d[:r.c])
|
|
copy(r.d[:c], l.d[l.c-c:])
|
|
r.c += c
|
|
l.c -= c
|
|
}
|
|
|
|
// ----------------------------------------------------------------------- tree
|
|
|
|
// NewTree returns a newly created, empty tree. The compare function is used
|
|
// for key collation.
|
|
func NewTree(cmp cmp) *Tree {
|
|
return &Tree{cmp: cmp}
|
|
}
|
|
|
|
// Clear removes all K/V pairs from the tree.
|
|
func (t *Tree) Clear() {
|
|
if t.r == nil {
|
|
return
|
|
}
|
|
|
|
clr(t.r)
|
|
t.c, t.first, t.last, t.r = 0, nil, nil, nil
|
|
t.ver++
|
|
}
|
|
|
|
func (t *Tree) cat(p *x, q, r *d, pi int) {
|
|
t.ver++
|
|
q.mvL(r, r.c)
|
|
if r.n != nil {
|
|
r.n.p = q
|
|
} else {
|
|
t.last = q
|
|
}
|
|
q.n = r.n
|
|
if p.c > 1 {
|
|
p.extract(pi)
|
|
p.x[pi].ch = q
|
|
} else {
|
|
t.r = q
|
|
}
|
|
}
|
|
|
|
func (t *Tree) catX(p, q, r *x, pi int) {
|
|
t.ver++
|
|
q.x[q.c].sep = p.x[pi].sep
|
|
copy(q.x[q.c+1:], r.x[:r.c])
|
|
q.c += r.c + 1
|
|
q.x[q.c].ch = r.x[r.c].ch
|
|
if p.c > 1 {
|
|
p.c--
|
|
pc := p.c
|
|
if pi < pc {
|
|
p.x[pi].sep = p.x[pi+1].sep
|
|
copy(p.x[pi+1:], p.x[pi+2:pc+1])
|
|
p.x[pc].ch = p.x[pc+1].ch
|
|
p.x[pc].sep = nil // GC
|
|
p.x[pc+1].ch = nil // GC
|
|
}
|
|
return
|
|
}
|
|
|
|
t.r = q
|
|
}
|
|
|
|
//Delete removes the k's KV pair, if it exists, in which case Delete returns
|
|
//true.
|
|
func (t *Tree) Delete(k []interface{}) (ok bool) {
|
|
pi := -1
|
|
var p *x
|
|
q := t.r
|
|
if q == nil {
|
|
return
|
|
}
|
|
|
|
for {
|
|
var i int
|
|
i, ok = t.find(q, k)
|
|
if ok {
|
|
switch z := q.(type) {
|
|
case *x:
|
|
dp := z.x[i].sep
|
|
switch {
|
|
case dp.c > kd:
|
|
t.extract(dp, 0)
|
|
default:
|
|
if z.c < kx && q != t.r {
|
|
t.underflowX(p, &z, pi, &i)
|
|
}
|
|
pi = i + 1
|
|
p = z
|
|
q = z.x[pi].ch
|
|
ok = false
|
|
continue
|
|
}
|
|
case *d:
|
|
t.extract(z, i)
|
|
if z.c >= kd {
|
|
return
|
|
}
|
|
|
|
if q != t.r {
|
|
t.underflow(p, z, pi)
|
|
} else if t.c == 0 {
|
|
t.Clear()
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
switch z := q.(type) {
|
|
case *x:
|
|
if z.c < kx && q != t.r {
|
|
t.underflowX(p, &z, pi, &i)
|
|
}
|
|
pi = i
|
|
p = z
|
|
q = z.x[i].ch
|
|
case *d:
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
func (t *Tree) extract(q *d, i int) { // (r []interface{}) {
|
|
t.ver++
|
|
//r = q.d[i].v // prepared for Extract
|
|
q.c--
|
|
if i < q.c {
|
|
copy(q.d[i:], q.d[i+1:q.c+1])
|
|
}
|
|
q.d[q.c] = zde // GC
|
|
t.c--
|
|
return
|
|
}
|
|
|
|
func (t *Tree) find(q interface{}, k []interface{}) (i int, ok bool) {
|
|
var mk []interface{}
|
|
l := 0
|
|
switch z := q.(type) {
|
|
case *x:
|
|
h := z.c - 1
|
|
for l <= h {
|
|
m := (l + h) >> 1
|
|
mk = z.x[m].sep.d[0].k
|
|
switch cmp := t.cmp(k, mk); {
|
|
case cmp > 0:
|
|
l = m + 1
|
|
case cmp == 0:
|
|
return m, true
|
|
default:
|
|
h = m - 1
|
|
}
|
|
}
|
|
case *d:
|
|
h := z.c - 1
|
|
for l <= h {
|
|
m := (l + h) >> 1
|
|
mk = z.d[m].k
|
|
switch cmp := t.cmp(k, mk); {
|
|
case cmp > 0:
|
|
l = m + 1
|
|
case cmp == 0:
|
|
return m, true
|
|
default:
|
|
h = m - 1
|
|
}
|
|
}
|
|
}
|
|
return l, false
|
|
}
|
|
|
|
// First returns the first item of the tree in the key collating order, or
|
|
// (nil, nil) if the tree is empty.
|
|
func (t *Tree) First() (k []interface{}, v []interface{}) {
|
|
if q := t.first; q != nil {
|
|
q := &q.d[0]
|
|
k, v = q.k, q.v
|
|
}
|
|
return
|
|
}
|
|
|
|
// Get returns the value associated with k and true if it exists. Otherwise Get
|
|
// returns (nil, false).
|
|
func (t *Tree) Get(k []interface{}) (v []interface{}, ok bool) {
|
|
q := t.r
|
|
if q == nil {
|
|
return
|
|
}
|
|
|
|
for {
|
|
var i int
|
|
if i, ok = t.find(q, k); ok {
|
|
switch z := q.(type) {
|
|
case *x:
|
|
return z.x[i].sep.d[0].v, true
|
|
case *d:
|
|
return z.d[i].v, true
|
|
}
|
|
}
|
|
switch z := q.(type) {
|
|
case *x:
|
|
q = z.x[i].ch
|
|
default:
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
func (t *Tree) insert(q *d, i int, k []interface{}, v []interface{}) *d {
|
|
t.ver++
|
|
c := q.c
|
|
if i < c {
|
|
copy(q.d[i+1:], q.d[i:c])
|
|
}
|
|
c++
|
|
q.c = c
|
|
q.d[i].k, q.d[i].v = k, v
|
|
t.c++
|
|
return q
|
|
}
|
|
|
|
// Last returns the last item of the tree in the key collating order, or (nil,
|
|
// nil) if the tree is empty.
|
|
func (t *Tree) Last() (k []interface{}, v []interface{}) {
|
|
if q := t.last; q != nil {
|
|
q := &q.d[q.c-1]
|
|
k, v = q.k, q.v
|
|
}
|
|
return
|
|
}
|
|
|
|
// Len returns the number of items in the tree.
|
|
func (t *Tree) Len() int {
|
|
return t.c
|
|
}
|
|
|
|
func (t *Tree) overflow(p *x, q *d, pi, i int, k []interface{}, v []interface{}) {
|
|
t.ver++
|
|
l, r := p.siblings(pi)
|
|
|
|
if l != nil && l.c < 2*kd {
|
|
l.mvL(q, 1)
|
|
t.insert(q, i-1, k, v)
|
|
return
|
|
}
|
|
|
|
if r != nil && r.c < 2*kd {
|
|
if i < 2*kd {
|
|
q.mvR(r, 1)
|
|
t.insert(q, i, k, v)
|
|
} else {
|
|
t.insert(r, 0, k, v)
|
|
}
|
|
return
|
|
}
|
|
|
|
t.split(p, q, pi, i, k, v)
|
|
}
|
|
|
|
// Seek returns an Enumerator positioned on a an item such that k >= item's
|
|
// key. ok reports if k == item.key The Enumerator's position is possibly
|
|
// after the last item in the tree.
|
|
func (t *Tree) Seek(k []interface{}) (e *Enumerator, ok bool) {
|
|
q := t.r
|
|
if q == nil {
|
|
e = &Enumerator{nil, false, 0, k, nil, t, t.ver}
|
|
return
|
|
}
|
|
|
|
for {
|
|
var i int
|
|
if i, ok = t.find(q, k); ok {
|
|
switch z := q.(type) {
|
|
case *x:
|
|
e = &Enumerator{nil, ok, 0, k, z.x[i].sep, t, t.ver}
|
|
return
|
|
case *d:
|
|
e = &Enumerator{nil, ok, i, k, z, t, t.ver}
|
|
return
|
|
}
|
|
}
|
|
switch z := q.(type) {
|
|
case *x:
|
|
q = z.x[i].ch
|
|
case *d:
|
|
e = &Enumerator{nil, ok, i, k, z, t, t.ver}
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
// SeekFirst returns an Enumerator positioned on the first KV pair in the tree,
|
|
// if any. For an empty tree, err == io.EOF is returned and e will be nil.
|
|
func (t *Tree) SeekFirst() (e *Enumerator, err error) {
|
|
q := t.first
|
|
if q == nil {
|
|
return nil, io.EOF
|
|
}
|
|
|
|
return &Enumerator{nil, true, 0, q.d[0].k, q, t, t.ver}, nil
|
|
}
|
|
|
|
// SeekLast returns an Enumerator positioned on the last KV pair in the tree,
|
|
// if any. For an empty tree, err == io.EOF is returned and e will be nil.
|
|
func (t *Tree) SeekLast() (e *Enumerator, err error) {
|
|
q := t.last
|
|
if q == nil {
|
|
return nil, io.EOF
|
|
}
|
|
|
|
return &Enumerator{nil, true, q.c - 1, q.d[q.c-1].k, q, t, t.ver}, nil
|
|
}
|
|
|
|
// Set sets the value associated with k.
|
|
func (t *Tree) Set(k []interface{}, v []interface{}) {
|
|
pi := -1
|
|
var p *x
|
|
q := t.r
|
|
if q != nil {
|
|
for {
|
|
i, ok := t.find(q, k)
|
|
if ok {
|
|
switch z := q.(type) {
|
|
case *x:
|
|
z.x[i].sep.d[0].v = v
|
|
case *d:
|
|
z.d[i].v = v
|
|
}
|
|
return
|
|
}
|
|
|
|
switch z := q.(type) {
|
|
case *x:
|
|
if z.c > 2*kx {
|
|
t.splitX(p, &z, pi, &i)
|
|
}
|
|
pi = i
|
|
p = z
|
|
q = z.x[i].ch
|
|
case *d:
|
|
switch {
|
|
case z.c < 2*kd:
|
|
t.insert(z, i, k, v)
|
|
default:
|
|
t.overflow(p, z, pi, i, k, v)
|
|
}
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
z := t.insert(&d{}, 0, k, v)
|
|
t.r, t.first, t.last = z, z, z
|
|
return
|
|
}
|
|
|
|
func (t *Tree) split(p *x, q *d, pi, i int, k []interface{}, v []interface{}) {
|
|
t.ver++
|
|
r := &d{}
|
|
if q.n != nil {
|
|
r.n = q.n
|
|
r.n.p = r
|
|
} else {
|
|
t.last = r
|
|
}
|
|
q.n = r
|
|
r.p = q
|
|
|
|
copy(r.d[:], q.d[kd:2*kd])
|
|
for i := range q.d[kd:] {
|
|
q.d[kd+i] = zde
|
|
}
|
|
q.c = kd
|
|
r.c = kd
|
|
if pi >= 0 {
|
|
p.insert(pi, r, r)
|
|
} else {
|
|
t.r = newX(q).insert(0, r, r)
|
|
}
|
|
if i > kd {
|
|
t.insert(r, i-kd, k, v)
|
|
return
|
|
}
|
|
|
|
t.insert(q, i, k, v)
|
|
}
|
|
|
|
func (t *Tree) splitX(p *x, pp **x, pi int, i *int) {
|
|
t.ver++
|
|
q := *pp
|
|
r := &x{}
|
|
copy(r.x[:], q.x[kx+1:])
|
|
q.c = kx
|
|
r.c = kx
|
|
if pi >= 0 {
|
|
p.insert(pi, q.x[kx].sep, r)
|
|
} else {
|
|
t.r = newX(q).insert(0, q.x[kx].sep, r)
|
|
}
|
|
q.x[kx].sep = nil
|
|
for i := range q.x[kx+1:] {
|
|
q.x[kx+i+1] = zxe
|
|
}
|
|
if *i > kx {
|
|
*pp = r
|
|
*i -= kx + 1
|
|
}
|
|
}
|
|
|
|
func (t *Tree) underflow(p *x, q *d, pi int) {
|
|
t.ver++
|
|
l, r := p.siblings(pi)
|
|
|
|
if l != nil && l.c+q.c >= 2*kd {
|
|
l.mvR(q, 1)
|
|
} else if r != nil && q.c+r.c >= 2*kd {
|
|
q.mvL(r, 1)
|
|
r.d[r.c] = zde // GC
|
|
} else if l != nil {
|
|
t.cat(p, l, q, pi-1)
|
|
} else {
|
|
t.cat(p, q, r, pi)
|
|
}
|
|
}
|
|
|
|
func (t *Tree) underflowX(p *x, pp **x, pi int, i *int) {
|
|
t.ver++
|
|
var l, r *x
|
|
q := *pp
|
|
|
|
if pi >= 0 {
|
|
if pi > 0 {
|
|
l = p.x[pi-1].ch.(*x)
|
|
}
|
|
if pi < p.c {
|
|
r = p.x[pi+1].ch.(*x)
|
|
}
|
|
}
|
|
|
|
if l != nil && l.c > kx {
|
|
q.x[q.c+1].ch = q.x[q.c].ch
|
|
copy(q.x[1:], q.x[:q.c])
|
|
q.x[0].ch = l.x[l.c].ch
|
|
q.x[0].sep = p.x[pi-1].sep
|
|
q.c++
|
|
*i++
|
|
l.c--
|
|
p.x[pi-1].sep = l.x[l.c].sep
|
|
return
|
|
}
|
|
|
|
if r != nil && r.c > kx {
|
|
q.x[q.c].sep = p.x[pi].sep
|
|
q.c++
|
|
q.x[q.c].ch = r.x[0].ch
|
|
p.x[pi].sep = r.x[0].sep
|
|
copy(r.x[:], r.x[1:r.c])
|
|
r.c--
|
|
rc := r.c
|
|
r.x[rc].ch = r.x[rc+1].ch
|
|
r.x[rc].sep = nil
|
|
r.x[rc+1].ch = nil
|
|
return
|
|
}
|
|
|
|
if l != nil {
|
|
*i += l.c + 1
|
|
t.catX(p, l, q, pi-1)
|
|
*pp = l
|
|
return
|
|
}
|
|
|
|
t.catX(p, q, r, pi)
|
|
}
|
|
|
|
// ----------------------------------------------------------------- Enumerator
|
|
|
|
// Next returns the currently enumerated item, if it exists and moves to the
|
|
// next item in the key collation order. If there is no item to return, err ==
|
|
// io.EOF is returned.
|
|
func (e *Enumerator) Next() (k []interface{}, v []interface{}, err error) {
|
|
if err = e.err; err != nil {
|
|
return
|
|
}
|
|
|
|
if e.ver != e.t.ver {
|
|
f, hit := e.t.Seek(e.k)
|
|
if !e.hit && hit {
|
|
if err = f.next(); err != nil {
|
|
return
|
|
}
|
|
}
|
|
|
|
*e = *f
|
|
}
|
|
if e.q == nil {
|
|
e.err, err = io.EOF, io.EOF
|
|
return
|
|
}
|
|
|
|
if e.i >= e.q.c {
|
|
if err = e.next(); err != nil {
|
|
return
|
|
}
|
|
}
|
|
|
|
i := e.q.d[e.i]
|
|
k, v = i.k, i.v
|
|
e.k, e.hit = k, false
|
|
e.next()
|
|
return
|
|
}
|
|
|
|
func (e *Enumerator) next() error {
|
|
if e.q == nil {
|
|
e.err = io.EOF
|
|
return io.EOF
|
|
}
|
|
|
|
switch {
|
|
case e.i < e.q.c-1:
|
|
e.i++
|
|
default:
|
|
if e.q, e.i = e.q.n, 0; e.q == nil {
|
|
e.err = io.EOF
|
|
}
|
|
}
|
|
return e.err
|
|
}
|
|
|
|
// Prev returns the currently enumerated item, if it exists and moves to the
|
|
// previous item in the key collation order. If there is no item to return, err
|
|
// == io.EOF is returned.
|
|
func (e *Enumerator) Prev() (k []interface{}, v []interface{}, err error) {
|
|
if err = e.err; err != nil {
|
|
return
|
|
}
|
|
|
|
if e.ver != e.t.ver {
|
|
f, hit := e.t.Seek(e.k)
|
|
if !e.hit && hit {
|
|
if err = f.prev(); err != nil {
|
|
return
|
|
}
|
|
}
|
|
|
|
*e = *f
|
|
}
|
|
if e.q == nil {
|
|
e.err, err = io.EOF, io.EOF
|
|
return
|
|
}
|
|
|
|
if e.i >= e.q.c {
|
|
if err = e.next(); err != nil {
|
|
return
|
|
}
|
|
}
|
|
|
|
i := e.q.d[e.i]
|
|
k, v = i.k, i.v
|
|
e.k, e.hit = k, false
|
|
e.prev()
|
|
return
|
|
}
|
|
|
|
func (e *Enumerator) prev() error {
|
|
if e.q == nil {
|
|
e.err = io.EOF
|
|
return io.EOF
|
|
}
|
|
|
|
switch {
|
|
case e.i > 0:
|
|
e.i--
|
|
default:
|
|
if e.q = e.q.p; e.q == nil {
|
|
e.err = io.EOF
|
|
break
|
|
}
|
|
|
|
e.i = e.q.c - 1
|
|
}
|
|
return e.err
|
|
}
|
|
|