github.com/cockroachdb/pebble@v0.0.0-20231214172447-ab4952c5f87b/internal/arenaskl/flush_iterator.go (about)

     1  /*
     2   * Copyright 2017 Dgraph Labs, Inc. and Contributors
     3   * Modifications copyright (C) 2017 Andy Kimball and Contributors
     4   *
     5   * Licensed under the Apache License, Version 2.0 (the "License");
     6   * you may not use this file except in compliance with the License.
     7   * You may obtain a copy of the License at
     8   *
     9   *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  
    18  package arenaskl
    19  
    20  import "github.com/cockroachdb/pebble/internal/base"
    21  
    22  // flushIterator is an iterator over the skiplist object. Use Skiplist.NewFlushIter
    23  // to construct an iterator. The current state of the iterator can be cloned by
    24  // simply value copying the struct.
    25  type flushIterator struct {
    26  	Iterator
    27  	bytesIterated *uint64
    28  }
    29  
    30  // flushIterator implements the base.InternalIterator interface.
    31  var _ base.InternalIterator = (*flushIterator)(nil)
    32  
    33  func (it *flushIterator) String() string {
    34  	return "memtable"
    35  }
    36  
    37  func (it *flushIterator) SeekGE(
    38  	key []byte, flags base.SeekGEFlags,
    39  ) (*base.InternalKey, base.LazyValue) {
    40  	panic("pebble: SeekGE unimplemented")
    41  }
    42  
    43  func (it *flushIterator) SeekPrefixGE(
    44  	prefix, key []byte, flags base.SeekGEFlags,
    45  ) (*base.InternalKey, base.LazyValue) {
    46  	panic("pebble: SeekPrefixGE unimplemented")
    47  }
    48  
    49  func (it *flushIterator) SeekLT(
    50  	key []byte, flags base.SeekLTFlags,
    51  ) (*base.InternalKey, base.LazyValue) {
    52  	panic("pebble: SeekLT unimplemented")
    53  }
    54  
    55  // First seeks position at the first entry in list. Returns the key and value
    56  // if the iterator is pointing at a valid entry, and (nil, nil) otherwise. Note
    57  // that First only checks the upper bound. It is up to the caller to ensure
    58  // that key is greater than or equal to the lower bound.
    59  func (it *flushIterator) First() (*base.InternalKey, base.LazyValue) {
    60  	key, val := it.Iterator.First()
    61  	if key == nil {
    62  		return nil, base.LazyValue{}
    63  	}
    64  	*it.bytesIterated += uint64(it.nd.allocSize)
    65  	return key, val
    66  }
    67  
    68  // Next advances to the next position. Returns the key and value if the
    69  // iterator is pointing at a valid entry, and (nil, nil) otherwise.
    70  // Note: flushIterator.Next mirrors the implementation of Iterator.Next
    71  // due to performance. Keep the two in sync.
    72  func (it *flushIterator) Next() (*base.InternalKey, base.LazyValue) {
    73  	it.nd = it.list.getNext(it.nd, 0)
    74  	if it.nd == it.list.tail {
    75  		return nil, base.LazyValue{}
    76  	}
    77  	it.decodeKey()
    78  	*it.bytesIterated += uint64(it.nd.allocSize)
    79  	return &it.key, base.MakeInPlaceValue(it.value())
    80  }
    81  
    82  func (it *flushIterator) NextPrefix(succKey []byte) (*base.InternalKey, base.LazyValue) {
    83  	panic("pebble: NextPrefix unimplemented")
    84  }
    85  
    86  func (it *flushIterator) Prev() (*base.InternalKey, base.LazyValue) {
    87  	panic("pebble: Prev unimplemented")
    88  }