1 files changed, 475 insertions, 0 deletions
diff --git a/vendor/github.com/syndtr/goleveldb/leveldb/memdb/memdb.go b/vendor/github.com/syndtr/goleveldb/leveldb/memdb/memdb.go
new file mode 100644
index 0000000..b661c08
--- /dev/null
+++ b/vendor/github.com/syndtr/goleveldb/leveldb/memdb/memdb.go
@@ -0,0 +1,475 @@
+// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Package memdb provides in-memory key/value database implementation.
+package memdb
+
+import (
+	"math/rand"
+	"sync"
+
+	"github.com/syndtr/goleveldb/leveldb/comparer"
+	"github.com/syndtr/goleveldb/leveldb/errors"
+	"github.com/syndtr/goleveldb/leveldb/iterator"
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+// Common errors.
+var (
+	ErrNotFound     = errors.ErrNotFound
+	ErrIterReleased = errors.New("leveldb/memdb: iterator released")
+)
+
+const tMaxHeight = 12
+
+type dbIter struct {
+	util.BasicReleaser
+	p          *DB
+	slice      *util.Range
+	node       int
+	forward    bool
+	key, value []byte
+	err        error
+}
+
+func (i *dbIter) fill(checkStart, checkLimit bool) bool {
+	if i.node != 0 {
+		n := i.p.nodeData[i.node]
+		m := n + i.p.nodeData[i.node+nKey]
+		i.key = i.p.kvData[n:m]
+		if i.slice != nil {
+			switch {
+			case checkLimit && i.slice.Limit != nil && i.p.cmp.Compare(i.key, i.slice.Limit) >= 0:
+				fallthrough
+			case checkStart && i.slice.Start != nil && i.p.cmp.Compare(i.key, i.slice.Start) < 0:
+				i.node = 0
+				goto bail
+			}
+		}
+		i.value = i.p.kvData[m : m+i.p.nodeData[i.node+nVal]]
+		return true
+	}
+bail:
+	i.key = nil
+	i.value = nil
+	return false
+}
+
+func (i *dbIter) Valid() bool {
+	return i.node != 0
+}
+
+func (i *dbIter) First() bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	i.forward = true
+	i.p.mu.RLock()
+	defer i.p.mu.RUnlock()
+	if i.slice != nil && i.slice.Start != nil {
+		i.node, _ = i.p.findGE(i.slice.Start, false)
+	} else {
+		i.node = i.p.nodeData[nNext]
+	}
+	return i.fill(false, true)
+}
+
+func (i *dbIter) Last() bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	i.forward = false
+	i.p.mu.RLock()
+	defer i.p.mu.RUnlock()
+	if i.slice != nil && i.slice.Limit != nil {
+		i.node = i.p.findLT(i.slice.Limit)
+	} else {
+		i.node = i.p.findLast()
+	}
+	return i.fill(true, false)
+}
+
+func (i *dbIter) Seek(key []byte) bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	i.forward = true
+	i.p.mu.RLock()
+	defer i.p.mu.RUnlock()
+	if i.slice != nil && i.slice.Start != nil && i.p.cmp.Compare(key, i.slice.Start) < 0 {
+		key = i.slice.Start
+	}
+	i.node, _ = i.p.findGE(key, false)
+	return i.fill(false, true)
+}
+
+func (i *dbIter) Next() bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	if i.node == 0 {
+		if !i.forward {
+			return i.First()
+		}
+		return false
+	}
+	i.forward = true
+	i.p.mu.RLock()
+	defer i.p.mu.RUnlock()
+	i.node = i.p.nodeData[i.node+nNext]
+	return i.fill(false, true)
+}
+
+func (i *dbIter) Prev() bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	if i.node == 0 {
+		if i.forward {
+			return i.Last()
+		}
+		return false
+	}
+	i.forward = false
+	i.p.mu.RLock()
+	defer i.p.mu.RUnlock()
+	i.node = i.p.findLT(i.key)
+	return i.fill(true, false)
+}
+
+func (i *dbIter) Key() []byte {
+	return i.key
+}
+
+func (i *dbIter) Value() []byte {
+	return i.value
+}
+
+func (i *dbIter) Error() error { return i.err }
+
+func (i *dbIter) Release() {
+	if !i.Released() {
+		i.p = nil
+		i.node = 0
+		i.key = nil
+		i.value = nil
+		i.BasicReleaser.Release()
+	}
+}
+
+const (
+	nKV = iota
+	nKey
+	nVal
+	nHeight
+	nNext
+)
+
+// DB is an in-memory key/value database.
+type DB struct {
+	cmp comparer.BasicComparer
+	rnd *rand.Rand
+
+	mu     sync.RWMutex
+	kvData []byte
+	// Node data:
+	// [0]         : KV offset
+	// [1]         : Key length
+	// [2]         : Value length
+	// [3]         : Height
+	// [3..height] : Next nodes
+	nodeData  []int
+	prevNode  [tMaxHeight]int
+	maxHeight int
+	n         int
+	kvSize    int
+}
+
+func (p *DB) randHeight() (h int) {
+	const branching = 4
+	h = 1
+	for h < tMaxHeight && p.rnd.Int()%branching == 0 {
+		h++
+	}
+	return
+}
+
+// Must hold RW-lock if prev == true, as it use shared prevNode slice.
+func (p *DB) findGE(key []byte, prev bool) (int, bool) {
+	node := 0
+	h := p.maxHeight - 1
+	for {
+		next := p.nodeData[node+nNext+h]
+		cmp := 1
+		if next != 0 {
+			o := p.nodeData[next]
+			cmp = p.cmp.Compare(p.kvData[o:o+p.nodeData[next+nKey]], key)
+		}
+		if cmp < 0 {
+			// Keep searching in this list
+			node = next
+		} else {
+			if prev {
+				p.prevNode[h] = node
+			} else if cmp == 0 {
+				return next, true
+			}
+			if h == 0 {
+				return next, cmp == 0
+			}
+			h--
+		}
+	}
+}
+
+func (p *DB) findLT(key []byte) int {
+	node := 0
+	h := p.maxHeight - 1
+	for {
+		next := p.nodeData[node+nNext+h]
+		o := p.nodeData[next]
+		if next == 0 || p.cmp.Compare(p.kvData[o:o+p.nodeData[next+nKey]], key) >= 0 {
+			if h == 0 {
+				break
+			}
+			h--
+		} else {
+			node = next
+		}
+	}
+	return node
+}
+
+func (p *DB) findLast() int {
+	node := 0
+	h := p.maxHeight - 1
+	for {
+		next := p.nodeData[node+nNext+h]
+		if next == 0 {
+			if h == 0 {
+				break
+			}
+			h--
+		} else {
+			node = next
+		}
+	}
+	return node
+}
+
+// Put sets the value for the given key. It overwrites any previous value
+// for that key; a DB is not a multi-map.
+//
+// It is safe to modify the contents of the arguments after Put returns.
+func (p *DB) Put(key []byte, value []byte) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	if node, exact := p.findGE(key, true); exact {
+		kvOffset := len(p.kvData)
+		p.kvData = append(p.kvData, key...)
+		p.kvData = append(p.kvData, value...)
+		p.nodeData[node] = kvOffset
+		m := p.nodeData[node+nVal]
+		p.nodeData[node+nVal] = len(value)
+		p.kvSize += len(value) - m
+		return nil
+	}
+
+	h := p.randHeight()
+	if h > p.maxHeight {
+		for i := p.maxHeight; i < h; i++ {
+			p.prevNode[i] = 0
+		}
+		p.maxHeight = h
+	}
+
+	kvOffset := len(p.kvData)
+	p.kvData = append(p.kvData, key...)
+	p.kvData = append(p.kvData, value...)
+	// Node
+	node := len(p.nodeData)
+	p.nodeData = append(p.nodeData, kvOffset, len(key), len(value), h)
+	for i, n := range p.prevNode[:h] {
+		m := n + nNext + i
+		p.nodeData = append(p.nodeData, p.nodeData[m])
+		p.nodeData[m] = node
+	}
+
+	p.kvSize += len(key) + len(value)
+	p.n++
+	return nil
+}
+
+// Delete deletes the value for the given key. It returns ErrNotFound if
+// the DB does not contain the key.
+//
+// It is safe to modify the contents of the arguments after Delete returns.
+func (p *DB) Delete(key []byte) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	node, exact := p.findGE(key, true)
+	if !exact {
+		return ErrNotFound
+	}
+
+	h := p.nodeData[node+nHeight]
+	for i, n := range p.prevNode[:h] {
+		m := n + nNext + i
+		p.nodeData[m] = p.nodeData[p.nodeData[m]+nNext+i]
+	}
+
+	p.kvSize -= p.nodeData[node+nKey] + p.nodeData[node+nVal]
+	p.n--
+	return nil
+}
+
+// Contains returns true if the given key are in the DB.
+//
+// It is safe to modify the contents of the arguments after Contains returns.
+func (p *DB) Contains(key []byte) bool {
+	p.mu.RLock()
+	_, exact := p.findGE(key, false)
+	p.mu.RUnlock()
+	return exact
+}
+
+// Get gets the value for the given key. It returns error.ErrNotFound if the
+// DB does not contain the key.
+//
+// The caller should not modify the contents of the returned slice, but
+// it is safe to modify the contents of the argument after Get returns.
+func (p *DB) Get(key []byte) (value []byte, err error) {
+	p.mu.RLock()
+	if node, exact := p.findGE(key, false); exact {
+		o := p.nodeData[node] + p.nodeData[node+nKey]
+		value = p.kvData[o : o+p.nodeData[node+nVal]]
+	} else {
+		err = ErrNotFound
+	}
+	p.mu.RUnlock()
+	return
+}
+
+// Find finds key/value pair whose key is greater than or equal to the
+// given key. It returns ErrNotFound if the table doesn't contain
+// such pair.
+//
+// The caller should not modify the contents of the returned slice, but
+// it is safe to modify the contents of the argument after Find returns.
+func (p *DB) Find(key []byte) (rkey, value []byte, err error) {
+	p.mu.RLock()
+	if node, _ := p.findGE(key, false); node != 0 {
+		n := p.nodeData[node]
+		m := n + p.nodeData[node+nKey]
+		rkey = p.kvData[n:m]
+		value = p.kvData[m : m+p.nodeData[node+nVal]]
+	} else {
+		err = ErrNotFound
+	}
+	p.mu.RUnlock()
+	return
+}
+
+// NewIterator returns an iterator of the DB.
+// The returned iterator is not safe for concurrent use, but it is safe to use
+// multiple iterators concurrently, with each in a dedicated goroutine.
+// It is also safe to use an iterator concurrently with modifying its
+// underlying DB. However, the resultant key/value pairs are not guaranteed
+// to be a consistent snapshot of the DB at a particular point in time.
+//
+// Slice allows slicing the iterator to only contains keys in the given
+// range. A nil Range.Start is treated as a key before all keys in the
+// DB. And a nil Range.Limit is treated as a key after all keys in
+// the DB.
+//
+// The iterator must be released after use, by calling Release method.
+//
+// Also read Iterator documentation of the leveldb/iterator package.
+func (p *DB) NewIterator(slice *util.Range) iterator.Iterator {
+	return &dbIter{p: p, slice: slice}
+}
+
+// Capacity returns keys/values buffer capacity.
+func (p *DB) Capacity() int {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return cap(p.kvData)
+}
+
+// Size returns sum of keys and values length. Note that deleted
+// key/value will not be accounted for, but it will still consume
+// the buffer, since the buffer is append only.
+func (p *DB) Size() int {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return p.kvSize
+}
+
+// Free returns keys/values free buffer before need to grow.
+func (p *DB) Free() int {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return cap(p.kvData) - len(p.kvData)
+}
+
+// Len returns the number of entries in the DB.
+func (p *DB) Len() int {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return p.n
+}
+
+// Reset resets the DB to initial empty state. Allows reuse the buffer.
+func (p *DB) Reset() {
+	p.mu.Lock()
+	p.rnd = rand.New(rand.NewSource(0xdeadbeef))
+	p.maxHeight = 1
+	p.n = 0
+	p.kvSize = 0
+	p.kvData = p.kvData[:0]
+	p.nodeData = p.nodeData[:nNext+tMaxHeight]
+	p.nodeData[nKV] = 0
+	p.nodeData[nKey] = 0
+	p.nodeData[nVal] = 0
+	p.nodeData[nHeight] = tMaxHeight
+	for n := 0; n < tMaxHeight; n++ {
+		p.nodeData[nNext+n] = 0
+		p.prevNode[n] = 0
+	}
+	p.mu.Unlock()
+}
+
+// New creates a new initialized in-memory key/value DB. The capacity
+// is the initial key/value buffer capacity. The capacity is advisory,
+// not enforced.
+//
+// This DB is append-only, deleting an entry would remove entry node but not
+// reclaim KV buffer.
+//
+// The returned DB instance is safe for concurrent use.
+func New(cmp comparer.BasicComparer, capacity int) *DB {
+	p := &DB{
+		cmp:       cmp,
+		rnd:       rand.New(rand.NewSource(0xdeadbeef)),
+		maxHeight: 1,
+		kvData:    make([]byte, 0, capacity),
+		nodeData:  make([]int, 4+tMaxHeight),
+	}
+	p.nodeData[nHeight] = tMaxHeight
+	return p
+}