rocksdb/db/manifest_ops.h
Maciej Szeszko be7703b27d Offline file checksum manifest retriever (#13178)
Summary:
This change introduces a new, lightweight _experimental_ API that reconstructs the [file # -> file checksum -> file checksum function] 1-1-1 mapping directly from the `MANIFEST` file considered `CURRENT` in scope of specific DB instance at the time. The goal is to provide a cheap alternative to `DB::GetLiveFilesMetaData` that doesn't require opening the database, reconstructing version sets and/or accessing files that are _potentially_ in disaggregated storage.

### Housekeeping:

1. Moved the `GetCurrentManifestPath` out of `version_set` to a new `manifest_ops` file(s) dedicated to manifest related operations.
2. Introduced new `Env::IOActivity::kReadManifest` to better reflect the IO intent in offline file checksum retrieving function.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/13178

Test Plan:
Added a unit test comparing the outcome of newly introduced API against the established `GetLiveFilesMetaData`:

```hcl
./db_test2 --gtest_filter="*GetFileChecksumsFromCurrentManifest_CRC32*"
```

Reviewed By: pdillinger

Differential Revision: D66711910

Pulled By: mszeszko-meta

fbshipit-source-id: 57091c550a14ac2e832bf7eea136dab5450e71bc
2024-12-06 13:29:52 -08:00

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// Copyright (c) Meta Platforms, Inc. and affiliates.
//
// 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 <cassert>
#include "rocksdb/env.h"
namespace ROCKSDB_NAMESPACE {
// Parameter is_retry=true sets the verify_and_reconstruct_read flag.
// It comes handy when caller intends to re-read the data with much stronger
// data integrity checking - e.g. in case of a perceived file corruption.
Status GetCurrentManifestPath(const std::string& dbname, FileSystem* fs,
bool is_retry, std::string* manifest_path,
uint64_t* manifest_file_number);
} // namespace ROCKSDB_NAMESPACE