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rocksdb/db/db_impl_readonly.h

100 lines
3.4 KiB

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2012 Facebook. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#pragma once
#include "db/db_impl.h"
#include <deque>
#include <set>
#include "db/dbformat.h"
#include "db/log_writer.h"
#include "db/snapshot.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "port/port.h"
#include "util/stats_logger.h"
namespace rocksdb {
class DBImplReadOnly : public DBImpl {
public:
DBImplReadOnly(const Options& options, const std::string& dbname);
virtual ~DBImplReadOnly();
// Implementations of the DB interface
using DB::Get;
virtual Status Get(const ReadOptions& options,
const ColumnFamilyHandle& column_family, const Slice& key,
std::string* value);
[RocksDB] [MergeOperator] The new Merge Interface! Uses merge sequences. Summary: Here are the major changes to the Merge Interface. It has been expanded to handle cases where the MergeOperator is not associative. It does so by stacking up merge operations while scanning through the key history (i.e.: during Get() or Compaction), until a valid Put/Delete/end-of-history is encountered; it then applies all of the merge operations in the correct sequence starting with the base/sentinel value. I have also introduced an "AssociativeMerge" function which allows the user to take advantage of associative merge operations (such as in the case of counters). The implementation will always attempt to merge the operations/operands themselves together when they are encountered, and will resort to the "stacking" method if and only if the "associative-merge" fails. This implementation is conjectured to allow MergeOperator to handle the general case, while still providing the user with the ability to take advantage of certain efficiencies in their own merge-operator / data-structure. NOTE: This is a preliminary diff. This must still go through a lot of review, revision, and testing. Feedback welcome! Test Plan: -This is a preliminary diff. I have only just begun testing/debugging it. -I will be testing this with the existing MergeOperator use-cases and unit-tests (counters, string-append, and redis-lists) -I will be "desk-checking" and walking through the code with the help gdb. -I will find a way of stress-testing the new interface / implementation using db_bench, db_test, merge_test, and/or db_stress. -I will ensure that my tests cover all cases: Get-Memtable, Get-Immutable-Memtable, Get-from-Disk, Iterator-Range-Scan, Flush-Memtable-to-L0, Compaction-L0-L1, Compaction-Ln-L(n+1), Put/Delete found, Put/Delete not-found, end-of-history, end-of-file, etc. -A lot of feedback from the reviewers. Reviewers: haobo, dhruba, zshao, emayanke Reviewed By: haobo CC: leveldb Differential Revision: https://reviews.facebook.net/D11499
11 years ago
// TODO: Implement ReadOnly MultiGet?
using DBImpl::NewIterator;
virtual Iterator* NewIterator(const ReadOptions&);
virtual Status NewIterators(
const ReadOptions& options,
const std::vector<ColumnFamilyHandle>& column_family,
std::vector<Iterator*>* iterators) {
// TODO
return Status::NotSupported("Not supported yet.");
}
using DBImpl::Put;
virtual Status Put(const WriteOptions& options,
const ColumnFamilyHandle& column_family, const Slice& key,
const Slice& value) {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Merge;
virtual Status Merge(const WriteOptions& options,
const ColumnFamilyHandle& column_family, const Slice& key,
const Slice& value) {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Delete;
virtual Status Delete(const WriteOptions& options,
const ColumnFamilyHandle& column_family,
const Slice& key) {
return Status::NotSupported("Not supported operation in read only mode.");
}
virtual Status Write(const WriteOptions& options, WriteBatch* updates) {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::CompactRange;
virtual void CompactRange(const ColumnFamilyHandle& column_family,
const Slice* begin, const Slice* end,
bool reduce_level = false, int target_level = -1) {}
virtual Status DisableFileDeletions() {
return Status::NotSupported("Not supported operation in read only mode.");
}
virtual Status EnableFileDeletions(bool force) {
return Status::NotSupported("Not supported operation in read only mode.");
}
virtual Status GetLiveFiles(std::vector<std::string>&,
uint64_t* manifest_file_size,
bool flush_memtable = true) {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Flush;
virtual Status Flush(const FlushOptions& options,
const ColumnFamilyHandle& column_family) {
return Status::NotSupported("Not supported operation in read only mode.");
}
private:
friend class DB;
// No copying allowed
DBImplReadOnly(const DBImplReadOnly&);
void operator=(const DBImplReadOnly&);
};
}