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vendor/github.com/syndtr/goleveldb/leveldb/iterator/array_iter.go

@@ -0,0 +1,184 @@
+// Copyright (c) 2014, 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 iterator
+
+import (
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+// BasicArray is the interface that wraps basic Len and Search method.
+type BasicArray interface {
+	// Len returns length of the array.
+	Len() int
+
+	// Search finds smallest index that point to a key that is greater
+	// than or equal to the given key.
+	Search(key []byte) int
+}
+
+// Array is the interface that wraps BasicArray and basic Index method.
+type Array interface {
+	BasicArray
+
+	// Index returns key/value pair with index of i.
+	Index(i int) (key, value []byte)
+}
+
+// Array is the interface that wraps BasicArray and basic Get method.
+type ArrayIndexer interface {
+	BasicArray
+
+	// Get returns a new data iterator with index of i.
+	Get(i int) Iterator
+}
+
+type basicArrayIterator struct {
+	util.BasicReleaser
+	array BasicArray
+	pos   int
+	err   error
+}
+
+func (i *basicArrayIterator) Valid() bool {
+	return i.pos >= 0 && i.pos < i.array.Len() && !i.Released()
+}
+
+func (i *basicArrayIterator) First() bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	if i.array.Len() == 0 {
+		i.pos = -1
+		return false
+	}
+	i.pos = 0
+	return true
+}
+
+func (i *basicArrayIterator) Last() bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	n := i.array.Len()
+	if n == 0 {
+		i.pos = 0
+		return false
+	}
+	i.pos = n - 1
+	return true
+}
+
+func (i *basicArrayIterator) Seek(key []byte) bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	n := i.array.Len()
+	if n == 0 {
+		i.pos = 0
+		return false
+	}
+	i.pos = i.array.Search(key)
+	if i.pos >= n {
+		return false
+	}
+	return true
+}
+
+func (i *basicArrayIterator) Next() bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	i.pos++
+	if n := i.array.Len(); i.pos >= n {
+		i.pos = n
+		return false
+	}
+	return true
+}
+
+func (i *basicArrayIterator) Prev() bool {
+	if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	i.pos--
+	if i.pos < 0 {
+		i.pos = -1
+		return false
+	}
+	return true
+}
+
+func (i *basicArrayIterator) Error() error { return i.err }
+
+type arrayIterator struct {
+	basicArrayIterator
+	array      Array
+	pos        int
+	key, value []byte
+}
+
+func (i *arrayIterator) updateKV() {
+	if i.pos == i.basicArrayIterator.pos {
+		return
+	}
+	i.pos = i.basicArrayIterator.pos
+	if i.Valid() {
+		i.key, i.value = i.array.Index(i.pos)
+	} else {
+		i.key = nil
+		i.value = nil
+	}
+}
+
+func (i *arrayIterator) Key() []byte {
+	i.updateKV()
+	return i.key
+}
+
+func (i *arrayIterator) Value() []byte {
+	i.updateKV()
+	return i.value
+}
+
+type arrayIteratorIndexer struct {
+	basicArrayIterator
+	array ArrayIndexer
+}
+
+func (i *arrayIteratorIndexer) Get() Iterator {
+	if i.Valid() {
+		return i.array.Get(i.basicArrayIterator.pos)
+	}
+	return nil
+}
+
+// NewArrayIterator returns an iterator from the given array.
+func NewArrayIterator(array Array) Iterator {
+	return &arrayIterator{
+		basicArrayIterator: basicArrayIterator{array: array, pos: -1},
+		array:              array,
+		pos:                -1,
+	}
+}
+
+// NewArrayIndexer returns an index iterator from the given array.
+func NewArrayIndexer(array ArrayIndexer) IteratorIndexer {
+	return &arrayIteratorIndexer{
+		basicArrayIterator: basicArrayIterator{array: array, pos: -1},
+		array:              array,
+	}
+}

vendor/github.com/syndtr/goleveldb/leveldb/iterator/array_iter_test.go

@@ -0,0 +1,30 @@
+// Copyright (c) 2014, 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 iterator_test
+
+import (
+	. "github.com/onsi/ginkgo"
+
+	. "github.com/syndtr/goleveldb/leveldb/iterator"
+	"github.com/syndtr/goleveldb/leveldb/testutil"
+)
+
+var _ = testutil.Defer(func() {
+	Describe("Array iterator", func() {
+		It("Should iterates and seeks correctly", func() {
+			// Build key/value.
+			kv := testutil.KeyValue_Generate(nil, 70, 1, 5, 3, 3)
+
+			// Test the iterator.
+			t := testutil.IteratorTesting{
+				KeyValue: kv.Clone(),
+				Iter:     NewArrayIterator(kv),
+			}
+			testutil.DoIteratorTesting(&t)
+		})
+	})
+})

vendor/github.com/syndtr/goleveldb/leveldb/iterator/indexed_iter.go

@@ -0,0 +1,242 @@
+// 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 iterator
+
+import (
+	"github.com/syndtr/goleveldb/leveldb/errors"
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+// IteratorIndexer is the interface that wraps CommonIterator and basic Get
+// method. IteratorIndexer provides index for indexed iterator.
+type IteratorIndexer interface {
+	CommonIterator
+
+	// Get returns a new data iterator for the current position, or nil if
+	// done.
+	Get() Iterator
+}
+
+type indexedIterator struct {
+	util.BasicReleaser
+	index  IteratorIndexer
+	strict bool
+
+	data   Iterator
+	err    error
+	errf   func(err error)
+	closed bool
+}
+
+func (i *indexedIterator) setData() {
+	if i.data != nil {
+		i.data.Release()
+	}
+	i.data = i.index.Get()
+}
+
+func (i *indexedIterator) clearData() {
+	if i.data != nil {
+		i.data.Release()
+	}
+	i.data = nil
+}
+
+func (i *indexedIterator) indexErr() {
+	if err := i.index.Error(); err != nil {
+		if i.errf != nil {
+			i.errf(err)
+		}
+		i.err = err
+	}
+}
+
+func (i *indexedIterator) dataErr() bool {
+	if err := i.data.Error(); err != nil {
+		if i.errf != nil {
+			i.errf(err)
+		}
+		if i.strict || !errors.IsCorrupted(err) {
+			i.err = err
+			return true
+		}
+	}
+	return false
+}
+
+func (i *indexedIterator) Valid() bool {
+	return i.data != nil && i.data.Valid()
+}
+
+func (i *indexedIterator) First() bool {
+	if i.err != nil {
+		return false
+	} else if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	if !i.index.First() {
+		i.indexErr()
+		i.clearData()
+		return false
+	}
+	i.setData()
+	return i.Next()
+}
+
+func (i *indexedIterator) Last() bool {
+	if i.err != nil {
+		return false
+	} else if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	if !i.index.Last() {
+		i.indexErr()
+		i.clearData()
+		return false
+	}
+	i.setData()
+	if !i.data.Last() {
+		if i.dataErr() {
+			return false
+		}
+		i.clearData()
+		return i.Prev()
+	}
+	return true
+}
+
+func (i *indexedIterator) Seek(key []byte) bool {
+	if i.err != nil {
+		return false
+	} else if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	if !i.index.Seek(key) {
+		i.indexErr()
+		i.clearData()
+		return false
+	}
+	i.setData()
+	if !i.data.Seek(key) {
+		if i.dataErr() {
+			return false
+		}
+		i.clearData()
+		return i.Next()
+	}
+	return true
+}
+
+func (i *indexedIterator) Next() bool {
+	if i.err != nil {
+		return false
+	} else if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	switch {
+	case i.data != nil && !i.data.Next():
+		if i.dataErr() {
+			return false
+		}
+		i.clearData()
+		fallthrough
+	case i.data == nil:
+		if !i.index.Next() {
+			i.indexErr()
+			return false
+		}
+		i.setData()
+		return i.Next()
+	}
+	return true
+}
+
+func (i *indexedIterator) Prev() bool {
+	if i.err != nil {
+		return false
+	} else if i.Released() {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	switch {
+	case i.data != nil && !i.data.Prev():
+		if i.dataErr() {
+			return false
+		}
+		i.clearData()
+		fallthrough
+	case i.data == nil:
+		if !i.index.Prev() {
+			i.indexErr()
+			return false
+		}
+		i.setData()
+		if !i.data.Last() {
+			if i.dataErr() {
+				return false
+			}
+			i.clearData()
+			return i.Prev()
+		}
+	}
+	return true
+}
+
+func (i *indexedIterator) Key() []byte {
+	if i.data == nil {
+		return nil
+	}
+	return i.data.Key()
+}
+
+func (i *indexedIterator) Value() []byte {
+	if i.data == nil {
+		return nil
+	}
+	return i.data.Value()
+}
+
+func (i *indexedIterator) Release() {
+	i.clearData()
+	i.index.Release()
+	i.BasicReleaser.Release()
+}
+
+func (i *indexedIterator) Error() error {
+	if i.err != nil {
+		return i.err
+	}
+	if err := i.index.Error(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (i *indexedIterator) SetErrorCallback(f func(err error)) {
+	i.errf = f
+}
+
+// NewIndexedIterator returns an 'indexed iterator'. An index is iterator
+// that returns another iterator, a 'data iterator'. A 'data iterator' is the
+// iterator that contains actual key/value pairs.
+//
+// If strict is true the any 'corruption errors' (i.e errors.IsCorrupted(err) == true)
+// won't be ignored and will halt 'indexed iterator', otherwise the iterator will
+// continue to the next 'data iterator'. Corruption on 'index iterator' will not be
+// ignored and will halt the iterator.
+func NewIndexedIterator(index IteratorIndexer, strict bool) Iterator {
+	return &indexedIterator{index: index, strict: strict}
+}

vendor/github.com/syndtr/goleveldb/leveldb/iterator/indexed_iter_test.go

@@ -0,0 +1,83 @@
+// Copyright (c) 2014, 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 iterator_test
+
+import (
+	"sort"
+
+	. "github.com/onsi/ginkgo"
+
+	"github.com/syndtr/goleveldb/leveldb/comparer"
+	. "github.com/syndtr/goleveldb/leveldb/iterator"
+	"github.com/syndtr/goleveldb/leveldb/testutil"
+)
+
+type keyValue struct {
+	key []byte
+	testutil.KeyValue
+}
+
+type keyValueIndex []keyValue
+
+func (x keyValueIndex) Search(key []byte) int {
+	return sort.Search(x.Len(), func(i int) bool {
+		return comparer.DefaultComparer.Compare(x[i].key, key) >= 0
+	})
+}
+
+func (x keyValueIndex) Len() int                        { return len(x) }
+func (x keyValueIndex) Index(i int) (key, value []byte) { return x[i].key, nil }
+func (x keyValueIndex) Get(i int) Iterator              { return NewArrayIterator(x[i]) }
+
+var _ = testutil.Defer(func() {
+	Describe("Indexed iterator", func() {
+		Test := func(n ...int) func() {
+			if len(n) == 0 {
+				rnd := testutil.NewRand()
+				n = make([]int, rnd.Intn(17)+3)
+				for i := range n {
+					n[i] = rnd.Intn(19) + 1
+				}
+			}
+
+			return func() {
+				It("Should iterates and seeks correctly", func(done Done) {
+					// Build key/value.
+					index := make(keyValueIndex, len(n))
+					sum := 0
+					for _, x := range n {
+						sum += x
+					}
+					kv := testutil.KeyValue_Generate(nil, sum, 1, 10, 4, 4)
+					for i, j := 0, 0; i < len(n); i++ {
+						for x := n[i]; x > 0; x-- {
+							key, value := kv.Index(j)
+							index[i].key = key
+							index[i].Put(key, value)
+							j++
+						}
+					}
+
+					// Test the iterator.
+					t := testutil.IteratorTesting{
+						KeyValue: kv.Clone(),
+						Iter:     NewIndexedIterator(NewArrayIndexer(index), true),
+					}
+					testutil.DoIteratorTesting(&t)
+					done <- true
+				}, 1.5)
+			}
+		}
+
+		Describe("with 100 keys", Test(100))
+		Describe("with 50-50 keys", Test(50, 50))
+		Describe("with 50-1 keys", Test(50, 1))
+		Describe("with 50-1-50 keys", Test(50, 1, 50))
+		Describe("with 1-50 keys", Test(1, 50))
+		Describe("with random N-keys", Test())
+	})
+})

vendor/github.com/syndtr/goleveldb/leveldb/iterator/iter.go

@@ -0,0 +1,131 @@
+// 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 iterator provides interface and implementation to traverse over
+// contents of a database.
+package iterator
+
+import (
+	"errors"
+
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+var (
+	ErrIterReleased = errors.New("leveldb/iterator: iterator released")
+)
+
+// IteratorSeeker is the interface that wraps the 'seeks method'.
+type IteratorSeeker interface {
+	// First moves the iterator to the first key/value pair. If the iterator
+	// only contains one key/value pair then First and Last whould moves
+	// to the same key/value pair.
+	// It returns whether such pair exist.
+	First() bool
+
+	// Last moves the iterator to the last key/value pair. If the iterator
+	// only contains one key/value pair then First and Last whould moves
+	// to the same key/value pair.
+	// It returns whether such pair exist.
+	Last() bool
+
+	// Seek moves the iterator to the first key/value pair whose key is greater
+	// than or equal to the given key.
+	// It returns whether such pair exist.
+	//
+	// It is safe to modify the contents of the argument after Seek returns.
+	Seek(key []byte) bool
+
+	// Next moves the iterator to the next key/value pair.
+	// It returns whether the iterator is exhausted.
+	Next() bool
+
+	// Prev moves the iterator to the previous key/value pair.
+	// It returns whether the iterator is exhausted.
+	Prev() bool
+}
+
+// CommonIterator is the interface that wraps common interator methods.
+type CommonIterator interface {
+	IteratorSeeker
+
+	// util.Releaser is the interface that wraps basic Release method.
+	// When called Release will releases any resources associated with the
+	// iterator.
+	util.Releaser
+
+	// util.ReleaseSetter is the interface that wraps the basic SetReleaser
+	// method.
+	util.ReleaseSetter
+
+	// TODO: Remove this when ready.
+	Valid() bool
+
+	// Error returns any accumulated error. Exhausting all the key/value pairs
+	// is not considered to be an error.
+	Error() error
+}
+
+// Iterator iterates over a DB's key/value pairs in key order.
+//
+// When encouter an error any 'seeks method' will return false and will
+// yield no key/value pairs. The error can be queried by calling the Error
+// method. Calling Release is still necessary.
+//
+// An iterator must be released after use, but it is not necessary to read
+// an iterator until exhaustion.
+// Also, an iterator is not necessarily goroutine-safe, but it is safe to use
+// multiple iterators concurrently, with each in a dedicated goroutine.
+type Iterator interface {
+	CommonIterator
+
+	// Key returns the key of the current key/value pair, or nil if done.
+	// The caller should not modify the contents of the returned slice, and
+	// its contents may change on the next call to any 'seeks method'.
+	Key() []byte
+
+	// Value returns the key of the current key/value pair, or nil if done.
+	// The caller should not modify the contents of the returned slice, and
+	// its contents may change on the next call to any 'seeks method'.
+	Value() []byte
+}
+
+// ErrorCallbackSetter is the interface that wraps basic SetErrorCallback
+// method.
+//
+// ErrorCallbackSetter implemented by indexed and merged iterator.
+type ErrorCallbackSetter interface {
+	// SetErrorCallback allows set an error callback of the coresponding
+	// iterator. Use nil to clear the callback.
+	SetErrorCallback(f func(err error))
+}
+
+type emptyIterator struct {
+	util.BasicReleaser
+	err error
+}
+
+func (i *emptyIterator) rErr() {
+	if i.err == nil && i.Released() {
+		i.err = ErrIterReleased
+	}
+}
+
+func (*emptyIterator) Valid() bool            { return false }
+func (i *emptyIterator) First() bool          { i.rErr(); return false }
+func (i *emptyIterator) Last() bool           { i.rErr(); return false }
+func (i *emptyIterator) Seek(key []byte) bool { i.rErr(); return false }
+func (i *emptyIterator) Next() bool           { i.rErr(); return false }
+func (i *emptyIterator) Prev() bool           { i.rErr(); return false }
+func (*emptyIterator) Key() []byte            { return nil }
+func (*emptyIterator) Value() []byte          { return nil }
+func (i *emptyIterator) Error() error         { return i.err }
+
+// NewEmptyIterator creates an empty iterator. The err parameter can be
+// nil, but if not nil the given err will be returned by Error method.
+func NewEmptyIterator(err error) Iterator {
+	return &emptyIterator{err: err}
+}

vendor/github.com/syndtr/goleveldb/leveldb/iterator/iter_suite_test.go

@@ -0,0 +1,11 @@
+package iterator_test
+
+import (
+	"testing"
+
+	"github.com/syndtr/goleveldb/leveldb/testutil"
+)
+
+func TestIterator(t *testing.T) {
+	testutil.RunSuite(t, "Iterator Suite")
+}

vendor/github.com/syndtr/goleveldb/leveldb/iterator/merged_iter.go

@@ -0,0 +1,304 @@
+// 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 iterator
+
+import (
+	"github.com/syndtr/goleveldb/leveldb/comparer"
+	"github.com/syndtr/goleveldb/leveldb/errors"
+	"github.com/syndtr/goleveldb/leveldb/util"
+)
+
+type dir int
+
+const (
+	dirReleased dir = iota - 1
+	dirSOI
+	dirEOI
+	dirBackward
+	dirForward
+)
+
+type mergedIterator struct {
+	cmp    comparer.Comparer
+	iters  []Iterator
+	strict bool
+
+	keys     [][]byte
+	index    int
+	dir      dir
+	err      error
+	errf     func(err error)
+	releaser util.Releaser
+}
+
+func assertKey(key []byte) []byte {
+	if key == nil {
+		panic("leveldb/iterator: nil key")
+	}
+	return key
+}
+
+func (i *mergedIterator) iterErr(iter Iterator) bool {
+	if err := iter.Error(); err != nil {
+		if i.errf != nil {
+			i.errf(err)
+		}
+		if i.strict || !errors.IsCorrupted(err) {
+			i.err = err
+			return true
+		}
+	}
+	return false
+}
+
+func (i *mergedIterator) Valid() bool {
+	return i.err == nil && i.dir > dirEOI
+}
+
+func (i *mergedIterator) First() bool {
+	if i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	for x, iter := range i.iters {
+		switch {
+		case iter.First():
+			i.keys[x] = assertKey(iter.Key())
+		case i.iterErr(iter):
+			return false
+		default:
+			i.keys[x] = nil
+		}
+	}
+	i.dir = dirSOI
+	return i.next()
+}
+
+func (i *mergedIterator) Last() bool {
+	if i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	for x, iter := range i.iters {
+		switch {
+		case iter.Last():
+			i.keys[x] = assertKey(iter.Key())
+		case i.iterErr(iter):
+			return false
+		default:
+			i.keys[x] = nil
+		}
+	}
+	i.dir = dirEOI
+	return i.prev()
+}
+
+func (i *mergedIterator) Seek(key []byte) bool {
+	if i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	for x, iter := range i.iters {
+		switch {
+		case iter.Seek(key):
+			i.keys[x] = assertKey(iter.Key())
+		case i.iterErr(iter):
+			return false
+		default:
+			i.keys[x] = nil
+		}
+	}
+	i.dir = dirSOI
+	return i.next()
+}
+
+func (i *mergedIterator) next() bool {
+	var key []byte
+	if i.dir == dirForward {
+		key = i.keys[i.index]
+	}
+	for x, tkey := range i.keys {
+		if tkey != nil && (key == nil || i.cmp.Compare(tkey, key) < 0) {
+			key = tkey
+			i.index = x
+		}
+	}
+	if key == nil {
+		i.dir = dirEOI
+		return false
+	}
+	i.dir = dirForward
+	return true
+}
+
+func (i *mergedIterator) Next() bool {
+	if i.dir == dirEOI || i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	switch i.dir {
+	case dirSOI:
+		return i.First()
+	case dirBackward:
+		key := append([]byte{}, i.keys[i.index]...)
+		if !i.Seek(key) {
+			return false
+		}
+		return i.Next()
+	}
+
+	x := i.index
+	iter := i.iters[x]
+	switch {
+	case iter.Next():
+		i.keys[x] = assertKey(iter.Key())
+	case i.iterErr(iter):
+		return false
+	default:
+		i.keys[x] = nil
+	}
+	return i.next()
+}
+
+func (i *mergedIterator) prev() bool {
+	var key []byte
+	if i.dir == dirBackward {
+		key = i.keys[i.index]
+	}
+	for x, tkey := range i.keys {
+		if tkey != nil && (key == nil || i.cmp.Compare(tkey, key) > 0) {
+			key = tkey
+			i.index = x
+		}
+	}
+	if key == nil {
+		i.dir = dirSOI
+		return false
+	}
+	i.dir = dirBackward
+	return true
+}
+
+func (i *mergedIterator) Prev() bool {
+	if i.dir == dirSOI || i.err != nil {
+		return false
+	} else if i.dir == dirReleased {
+		i.err = ErrIterReleased
+		return false
+	}
+
+	switch i.dir {
+	case dirEOI:
+		return i.Last()
+	case dirForward:
+		key := append([]byte{}, i.keys[i.index]...)
+		for x, iter := range i.iters {
+			if x == i.index {
+				continue
+			}
+			seek := iter.Seek(key)
+			switch {
+			case seek && iter.Prev(), !seek && iter.Last():
+				i.keys[x] = assertKey(iter.Key())
+			case i.iterErr(iter):
+				return false
+			default:
+				i.keys[x] = nil
+			}
+		}
+	}
+
+	x := i.index
+	iter := i.iters[x]
+	switch {
+	case iter.Prev():
+		i.keys[x] = assertKey(iter.Key())
+	case i.iterErr(iter):
+		return false
+	default:
+		i.keys[x] = nil
+	}
+	return i.prev()
+}
+
+func (i *mergedIterator) Key() []byte {
+	if i.err != nil || i.dir <= dirEOI {
+		return nil
+	}
+	return i.keys[i.index]
+}
+
+func (i *mergedIterator) Value() []byte {
+	if i.err != nil || i.dir <= dirEOI {
+		return nil
+	}
+	return i.iters[i.index].Value()
+}
+
+func (i *mergedIterator) Release() {
+	if i.dir != dirReleased {
+		i.dir = dirReleased
+		for _, iter := range i.iters {
+			iter.Release()
+		}
+		i.iters = nil
+		i.keys = nil
+		if i.releaser != nil {
+			i.releaser.Release()
+			i.releaser = nil
+		}
+	}
+}
+
+func (i *mergedIterator) SetReleaser(releaser util.Releaser) {
+	if i.dir == dirReleased {
+		panic(util.ErrReleased)
+	}
+	if i.releaser != nil && releaser != nil {
+		panic(util.ErrHasReleaser)
+	}
+	i.releaser = releaser
+}
+
+func (i *mergedIterator) Error() error {
+	return i.err
+}
+
+func (i *mergedIterator) SetErrorCallback(f func(err error)) {
+	i.errf = f
+}
+
+// NewMergedIterator returns an iterator that merges its input. Walking the
+// resultant iterator will return all key/value pairs of all input iterators
+// in strictly increasing key order, as defined by cmp.
+// The input's key ranges may overlap, but there are assumed to be no duplicate
+// keys: if iters[i] contains a key k then iters[j] will not contain that key k.
+// None of the iters may be nil.
+//
+// If strict is true the any 'corruption errors' (i.e errors.IsCorrupted(err) == true)
+// won't be ignored and will halt 'merged iterator', otherwise the iterator will
+// continue to the next 'input iterator'.
+func NewMergedIterator(iters []Iterator, cmp comparer.Comparer, strict bool) Iterator {
+	return &mergedIterator{
+		iters:  iters,
+		cmp:    cmp,
+		strict: strict,
+		keys:   make([][]byte, len(iters)),
+	}
+}

vendor/github.com/syndtr/goleveldb/leveldb/iterator/merged_iter_test.go

@@ -0,0 +1,60 @@
+// Copyright (c) 2014, 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 iterator_test
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"github.com/syndtr/goleveldb/leveldb/comparer"
+	. "github.com/syndtr/goleveldb/leveldb/iterator"
+	"github.com/syndtr/goleveldb/leveldb/testutil"
+)
+
+var _ = testutil.Defer(func() {
+	Describe("Merged iterator", func() {
+		Test := func(filled int, empty int) func() {
+			return func() {
+				It("Should iterates and seeks correctly", func(done Done) {
+					rnd := testutil.NewRand()
+
+					// Build key/value.
+					filledKV := make([]testutil.KeyValue, filled)
+					kv := testutil.KeyValue_Generate(nil, 100, 1, 10, 4, 4)
+					kv.Iterate(func(i int, key, value []byte) {
+						filledKV[rnd.Intn(filled)].Put(key, value)
+					})
+
+					// Create itearators.
+					iters := make([]Iterator, filled+empty)
+					for i := range iters {
+						if empty == 0 || (rnd.Int()%2 == 0 && filled > 0) {
+							filled--
+							Expect(filledKV[filled].Len()).ShouldNot(BeZero())
+							iters[i] = NewArrayIterator(filledKV[filled])
+						} else {
+							empty--
+							iters[i] = NewEmptyIterator(nil)
+						}
+					}
+
+					// Test the iterator.
+					t := testutil.IteratorTesting{
+						KeyValue: kv.Clone(),
+						Iter:     NewMergedIterator(iters, comparer.DefaultComparer, true),
+					}
+					testutil.DoIteratorTesting(&t)
+					done <- true
+				}, 1.5)
+			}
+		}
+
+		Describe("with three, all filled iterators", Test(3, 0))
+		Describe("with one filled, one empty iterators", Test(1, 1))
+		Describe("with one filled, two empty iterators", Test(1, 2))
+	})
+})