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rocksdb/db/db_impl_readonly.h

125 lines
4.6 KiB

// 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).
#pragma once
#ifndef ROCKSDB_LITE
#include "db/db_impl.h"
#include <vector>
#include <string>
namespace rocksdb {
class DBImplReadOnly : public DBImpl {
public:
DBImplReadOnly(const DBOptions& options, const std::string& dbname);
virtual ~DBImplReadOnly();
// Implementations of the DB interface
using DB::Get;
virtual Status Get(const ReadOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
PinnableSlice* value) override;
[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?
[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
using DBImpl::NewIterator;
virtual Iterator* NewIterator(const ReadOptions&,
ColumnFamilyHandle* column_family) override;
virtual Status NewIterators(
const ReadOptions& options,
const std::vector<ColumnFamilyHandle*>& column_families,
std::vector<Iterator*>* iterators) override;
using DBImpl::Put;
virtual Status Put(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice& /*key*/, const Slice& /*value*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Merge;
virtual Status Merge(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice& /*key*/, const Slice& /*value*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Delete;
virtual Status Delete(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice& /*key*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
Support for SingleDelete() Summary: This patch fixes #7460559. It introduces SingleDelete as a new database operation. This operation can be used to delete keys that were never overwritten (no put following another put of the same key). If an overwritten key is single deleted the behavior is undefined. Single deletion of a non-existent key has no effect but multiple consecutive single deletions are not allowed (see limitations). In contrast to the conventional Delete() operation, the deletion entry is removed along with the value when the two are lined up in a compaction. Note: The semantics are similar to @igor's prototype that allowed to have this behavior on the granularity of a column family ( https://reviews.facebook.net/D42093 ). This new patch, however, is more aggressive when it comes to removing tombstones: It removes the SingleDelete together with the value whenever there is no snapshot between them while the older patch only did this when the sequence number of the deletion was older than the earliest snapshot. Most of the complex additions are in the Compaction Iterator, all other changes should be relatively straightforward. The patch also includes basic support for single deletions in db_stress and db_bench. Limitations: - Not compatible with cuckoo hash tables - Single deletions cannot be used in combination with merges and normal deletions on the same key (other keys are not affected by this) - Consecutive single deletions are currently not allowed (and older version of this patch supported this so it could be resurrected if needed) Test Plan: make all check Reviewers: yhchiang, sdong, rven, anthony, yoshinorim, igor Reviewed By: igor Subscribers: maykov, dhruba, leveldb Differential Revision: https://reviews.facebook.net/D43179
9 years ago
using DBImpl::SingleDelete;
virtual Status SingleDelete(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice& /*key*/) override {
Support for SingleDelete() Summary: This patch fixes #7460559. It introduces SingleDelete as a new database operation. This operation can be used to delete keys that were never overwritten (no put following another put of the same key). If an overwritten key is single deleted the behavior is undefined. Single deletion of a non-existent key has no effect but multiple consecutive single deletions are not allowed (see limitations). In contrast to the conventional Delete() operation, the deletion entry is removed along with the value when the two are lined up in a compaction. Note: The semantics are similar to @igor's prototype that allowed to have this behavior on the granularity of a column family ( https://reviews.facebook.net/D42093 ). This new patch, however, is more aggressive when it comes to removing tombstones: It removes the SingleDelete together with the value whenever there is no snapshot between them while the older patch only did this when the sequence number of the deletion was older than the earliest snapshot. Most of the complex additions are in the Compaction Iterator, all other changes should be relatively straightforward. The patch also includes basic support for single deletions in db_stress and db_bench. Limitations: - Not compatible with cuckoo hash tables - Single deletions cannot be used in combination with merges and normal deletions on the same key (other keys are not affected by this) - Consecutive single deletions are currently not allowed (and older version of this patch supported this so it could be resurrected if needed) Test Plan: make all check Reviewers: yhchiang, sdong, rven, anthony, yoshinorim, igor Reviewed By: igor Subscribers: maykov, dhruba, leveldb Differential Revision: https://reviews.facebook.net/D43179
9 years ago
return Status::NotSupported("Not supported operation in read only mode.");
}
virtual Status Write(const WriteOptions& /*options*/,
WriteBatch* /*updates*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::CompactRange;
virtual Status CompactRange(const CompactRangeOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice* /*begin*/,
const Slice* /*end*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::CompactFiles;
virtual Status CompactFiles(
const CompactionOptions& /*compact_options*/,
ColumnFamilyHandle* /*column_family*/,
const std::vector<std::string>& /*input_file_names*/,
const int /*output_level*/, const int /*output_path_id*/ = -1) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
virtual Status DisableFileDeletions() override {
return Status::NotSupported("Not supported operation in read only mode.");
}
virtual Status EnableFileDeletions(bool /*force*/) override {
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) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::Flush;
virtual Status Flush(const FlushOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DBImpl::SyncWAL;
virtual Status SyncWAL() override {
return Status::NotSupported("Not supported operation in read only mode.");
}
using DB::IngestExternalFile;
virtual Status IngestExternalFile(
ColumnFamilyHandle* /*column_family*/,
const std::vector<std::string>& /*external_files*/,
const IngestExternalFileOptions& /*ingestion_options*/) override {
return Status::NotSupported("Not supported operation in read only mode.");
}
private:
friend class DB;
// No copying allowed
DBImplReadOnly(const DBImplReadOnly&);
void operator=(const DBImplReadOnly&);
};
}
#endif // !ROCKSDB_LITE