diff options
Diffstat (limited to 'vendor/github.com/syndtr/goleveldb/leveldb/iterator/merged_iter.go')
-rw-r--r-- | vendor/github.com/syndtr/goleveldb/leveldb/iterator/merged_iter.go | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/vendor/github.com/syndtr/goleveldb/leveldb/iterator/merged_iter.go b/vendor/github.com/syndtr/goleveldb/leveldb/iterator/merged_iter.go new file mode 100644 index 000000000..1a7e29df8 --- /dev/null +++ b/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)), + } +} |