rocksdb/table/table_reader.h
Abhishek Madan 8fe1e06ca0 Clean up FragmentedRangeTombstoneList (#4692)
Summary:
Removed `one_time_use` flag, which removed the need for some
tests, and changed all `NewRangeTombstoneIterator` methods to return
`FragmentedRangeTombstoneIterators`.

These changes also led to removing `RangeDelAggregatorV2::AddUnfragmentedTombstones`
and one of the `MemTableListVersion::AddRangeTombstoneIterators` methods.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4692

Differential Revision: D13106570

Pulled By: abhimadan

fbshipit-source-id: cbab5432d7fc2d9cdfd8d9d40361a1bffaa8f845
2018-11-28 15:29:02 -08:00

116 lines
4.7 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <memory>
#include "db/range_tombstone_fragmenter.h"
#include "rocksdb/slice_transform.h"
#include "table/internal_iterator.h"
namespace rocksdb {
class Iterator;
struct ParsedInternalKey;
class Slice;
class Arena;
struct ReadOptions;
struct TableProperties;
class GetContext;
// A Table is a sorted map from strings to strings. Tables are
// immutable and persistent. A Table may be safely accessed from
// multiple threads without external synchronization.
class TableReader {
public:
virtual ~TableReader() {}
// Returns a new iterator over the table contents.
// The result of NewIterator() is initially invalid (caller must
// call one of the Seek methods on the iterator before using it).
// arena: If not null, the arena needs to be used to allocate the Iterator.
// When destroying the iterator, the caller will not call "delete"
// but Iterator::~Iterator() directly. The destructor needs to destroy
// all the states but those allocated in arena.
// skip_filters: disables checking the bloom filters even if they exist. This
// option is effective only for block-based table format.
virtual InternalIterator* NewIterator(const ReadOptions&,
const SliceTransform* prefix_extractor,
Arena* arena = nullptr,
bool skip_filters = false,
bool for_compaction = false) = 0;
virtual FragmentedRangeTombstoneIterator* NewRangeTombstoneIterator(
const ReadOptions& /*read_options*/) {
return nullptr;
}
// Given a key, return an approximate byte offset in the file where
// the data for that key begins (or would begin if the key were
// present in the file). The returned value is in terms of file
// bytes, and so includes effects like compression of the underlying data.
// E.g., the approximate offset of the last key in the table will
// be close to the file length.
virtual uint64_t ApproximateOffsetOf(const Slice& key) = 0;
// Set up the table for Compaction. Might change some parameters with
// posix_fadvise
virtual void SetupForCompaction() = 0;
virtual std::shared_ptr<const TableProperties> GetTableProperties() const = 0;
// Prepare work that can be done before the real Get()
virtual void Prepare(const Slice& /*target*/) {}
// Report an approximation of how much memory has been used.
virtual size_t ApproximateMemoryUsage() const = 0;
// Calls get_context->SaveValue() repeatedly, starting with
// the entry found after a call to Seek(key), until it returns false.
// May not make such a call if filter policy says that key is not present.
//
// get_context->MarkKeyMayExist needs to be called when it is configured to be
// memory only and the key is not found in the block cache.
//
// readOptions is the options for the read
// key is the key to search for
// skip_filters: disables checking the bloom filters even if they exist. This
// option is effective only for block-based table format.
virtual Status Get(const ReadOptions& readOptions, const Slice& key,
GetContext* get_context,
const SliceTransform* prefix_extractor,
bool skip_filters = false) = 0;
// Prefetch data corresponding to a give range of keys
// Typically this functionality is required for table implementations that
// persists the data on a non volatile storage medium like disk/SSD
virtual Status Prefetch(const Slice* begin = nullptr,
const Slice* end = nullptr) {
(void) begin;
(void) end;
// Default implementation is NOOP.
// The child class should implement functionality when applicable
return Status::OK();
}
// convert db file to a human readable form
virtual Status DumpTable(WritableFile* /*out_file*/,
const SliceTransform* /*prefix_extractor*/) {
return Status::NotSupported("DumpTable() not supported");
}
// check whether there is corruption in this db file
virtual Status VerifyChecksum() {
return Status::NotSupported("VerifyChecksum() not supported");
}
virtual void Close() {}
};
} // namespace rocksdb