rocksdb/db/blob/blob_file_meta.h

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Add blob files to VersionStorageInfo/VersionBuilder (#6597) Summary: The patch adds a couple of classes to represent metadata about blob files: `SharedBlobFileMetaData` contains the information elements that are immutable (once the blob file is closed), e.g. blob file number, total number and size of blob files, checksum method/value, while `BlobFileMetaData` contains attributes that can vary across versions like the amount of garbage in the file. There is a single `SharedBlobFileMetaData` for each blob file, which is jointly owned by the `BlobFileMetaData` objects that point to it; `BlobFileMetaData` objects, in turn, are owned by `Version`s and can also be shared if the (immutable _and_ mutable) state of the blob file is the same in two versions. In addition, the patch adds the blob file metadata to `VersionStorageInfo`, and extends `VersionBuilder` so that it can apply blob file related `VersionEdit`s (i.e. those containing `BlobFileAddition`s and/or `BlobFileGarbage`), and save blob file metadata to a new `VersionStorageInfo`. Consistency checks are also extended to ensure that table files point to blob files that are part of the `Version`, and that all blob files that are part of any given `Version` have at least some _non_-garbage data in them. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6597 Test Plan: `make check` Reviewed By: riversand963 Differential Revision: D20656803 Pulled By: ltamasi fbshipit-source-id: f1f74d135045b3b42d0146f03ee576ef0a4bfd80
2020-03-27 02:48:55 +01:00
// 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
#include "rocksdb/rocksdb_namespace.h"
#include <cassert>
#include <iosfwd>
#include <memory>
#include <string>
namespace ROCKSDB_NAMESPACE {
// SharedBlobFileMetaData represents the immutable part of blob files' metadata,
// like the blob file number, total number and size of blobs, or checksum
// method and value. There is supposed to be one object of this class per blob
// file (shared across all versions that include the blob file in question);
// hence, the type is neither copyable nor movable. A blob file can be marked
// obsolete when the corresponding SharedBlobFileMetaData object is destroyed.
class SharedBlobFileMetaData {
public:
SharedBlobFileMetaData(uint64_t blob_file_number, uint64_t total_blob_count,
uint64_t total_blob_bytes, std::string checksum_method,
std::string checksum_value)
: blob_file_number_(blob_file_number),
total_blob_count_(total_blob_count),
total_blob_bytes_(total_blob_bytes),
checksum_method_(std::move(checksum_method)),
checksum_value_(std::move(checksum_value)) {
assert(checksum_method_.empty() == checksum_value_.empty());
}
~SharedBlobFileMetaData();
SharedBlobFileMetaData(const SharedBlobFileMetaData&) = delete;
SharedBlobFileMetaData& operator=(const SharedBlobFileMetaData&) = delete;
uint64_t GetBlobFileNumber() const { return blob_file_number_; }
uint64_t GetTotalBlobCount() const { return total_blob_count_; }
uint64_t GetTotalBlobBytes() const { return total_blob_bytes_; }
const std::string& GetChecksumMethod() const { return checksum_method_; }
const std::string& GetChecksumValue() const { return checksum_value_; }
std::string DebugString() const;
private:
uint64_t blob_file_number_;
uint64_t total_blob_count_;
uint64_t total_blob_bytes_;
std::string checksum_method_;
std::string checksum_value_;
};
std::ostream& operator<<(std::ostream& os,
const SharedBlobFileMetaData& shared_meta);
// BlobFileMetaData contains the part of the metadata for blob files that can
// vary across versions, like the amount of garbage in the blob file. In
// addition, BlobFileMetaData objects point to and share the ownership of the
// SharedBlobFileMetaData object for the corresponding blob file. Similarly to
// SharedBlobFileMetaData, BlobFileMetaData are not copyable or movable. They
// are meant to be jointly owned by the versions in which the blob file has the
// same (immutable *and* mutable) state.
class BlobFileMetaData {
public:
BlobFileMetaData(std::shared_ptr<SharedBlobFileMetaData> shared_meta,
uint64_t garbage_blob_count, uint64_t garbage_blob_bytes)
: shared_meta_(std::move(shared_meta)),
garbage_blob_count_(garbage_blob_count),
garbage_blob_bytes_(garbage_blob_bytes) {
assert(shared_meta_);
assert(garbage_blob_count_ <= shared_meta_->GetTotalBlobCount());
assert(garbage_blob_bytes_ <= shared_meta_->GetTotalBlobBytes());
}
~BlobFileMetaData() = default;
BlobFileMetaData(const BlobFileMetaData&) = delete;
BlobFileMetaData& operator=(const BlobFileMetaData&) = delete;
const std::shared_ptr<SharedBlobFileMetaData>& GetSharedMeta() const {
return shared_meta_;
}
uint64_t GetBlobFileNumber() const {
assert(shared_meta_);
return shared_meta_->GetBlobFileNumber();
}
uint64_t GetTotalBlobCount() const {
assert(shared_meta_);
return shared_meta_->GetTotalBlobCount();
}
uint64_t GetTotalBlobBytes() const {
assert(shared_meta_);
return shared_meta_->GetTotalBlobBytes();
}
const std::string& GetChecksumMethod() const {
assert(shared_meta_);
return shared_meta_->GetChecksumMethod();
}
const std::string& GetChecksumValue() const {
assert(shared_meta_);
return shared_meta_->GetChecksumValue();
}
uint64_t GetGarbageBlobCount() const { return garbage_blob_count_; }
uint64_t GetGarbageBlobBytes() const { return garbage_blob_bytes_; }
std::string DebugString() const;
private:
std::shared_ptr<SharedBlobFileMetaData> shared_meta_;
uint64_t garbage_blob_count_;
uint64_t garbage_blob_bytes_;
};
std::ostream& operator<<(std::ostream& os, const BlobFileMetaData& meta);
} // namespace ROCKSDB_NAMESPACE