rocksdb/db/version_util.h

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Add manifest fix-up utility for file temperatures (#9683) Summary: The goal of this change is to allow changes to the "current" (in FileSystem) file temperatures to feed back into DB metadata, so that they can inform decisions and stats reporting. In part because of modular code factoring, it doesn't seem easy to do this automagically, where opening an SST file and observing current Temperature different from expected would trigger a change in metadata and DB manifest write (essentially giving the deep read path access to the write path). It is also difficult to do this while the DB is open because of the limitations of LogAndApply. This change allows updating file temperature metadata on a closed DB using an experimental utility function UpdateManifestForFilesState() or `ldb update_manifest --update_temperatures`. This should suffice for "migration" scenarios where outside tooling has placed or re-arranged DB files into a (different) tiered configuration without going through RocksDB itself (currently, only compaction can change temperature metadata). Some details: * Refactored and added unit test for `ldb unsafe_remove_sst_file` because of shared functionality * Pulled in autovector.h changes from https://github.com/facebook/rocksdb/issues/9546 to fix SuperVersionContext move constructor (related to an older draft of this change) Possible follow-up work: * Support updating manifest with file checksums, such as when a new checksum function is used and want existing DB metadata updated for it. * It's possible that for some repair scenarios, lighter weight than full repair, we might want to support UpdateManifestForFilesState() to modify critical file details like size or checksum using same algorithm. But let's make sure these are differentiated from modifying file details in ways that don't suspect corruption (or require extreme trust). Pull Request resolved: https://github.com/facebook/rocksdb/pull/9683 Test Plan: unit tests added Reviewed By: jay-zhuang Differential Revision: D34798828 Pulled By: pdillinger fbshipit-source-id: cfd83e8fb10761d8c9e7f9c020d68c9106a95554
2022-03-19 00:35:51 +01:00
// Copyright (c) Facebook, Inc. and its affiliates. 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 "db/version_set.h"
namespace ROCKSDB_NAMESPACE {
// Instead of opening a `DB` to perform certain manifest updates, this
// uses the underlying `VersionSet` API to read and modify the MANIFEST. This
// allows us to use the user's real options, while not having to worry about
// the DB persisting new SST files via flush/compaction or attempting to read/
// compact files which may fail, particularly for the file we intend to remove
// (the user may want to remove an already deleted file from MANIFEST).
class OfflineManifestWriter {
public:
OfflineManifestWriter(const DBOptions& options, const std::string& db_path)
: wc_(options.delayed_write_rate),
wb_(options.db_write_buffer_size),
immutable_db_options_(WithDbPath(options, db_path)),
tc_(NewLRUCache(1 << 20 /* capacity */,
options.table_cache_numshardbits)),
versions_(db_path, &immutable_db_options_, sopt_, tc_.get(), &wb_, &wc_,
/*block_cache_tracer=*/nullptr, /*io_tracer=*/nullptr,
/*db_session_id*/ "") {}
Status Recover(const std::vector<ColumnFamilyDescriptor>& column_families) {
return versions_.Recover(column_families);
}
Status LogAndApply(ColumnFamilyData* cfd, VersionEdit* edit) {
// Use `mutex` to imitate a locked DB mutex when calling `LogAndApply()`.
InstrumentedMutex mutex;
mutex.Lock();
Status s = versions_.LogAndApply(cfd, *cfd->GetLatestMutableCFOptions(),
edit, &mutex, nullptr /* db_directory */,
false /* new_descriptor_log */);
mutex.Unlock();
return s;
}
VersionSet& Versions() { return versions_; }
const ImmutableDBOptions& IOptions() { return immutable_db_options_; }
private:
WriteController wc_;
WriteBufferManager wb_;
ImmutableDBOptions immutable_db_options_;
std::shared_ptr<Cache> tc_;
EnvOptions sopt_;
VersionSet versions_;
static ImmutableDBOptions WithDbPath(const DBOptions& options,
const std::string& db_path) {
ImmutableDBOptions rv(options);
if (rv.db_paths.empty()) {
// `VersionSet` expects options that have been through
// `SanitizeOptions()`, which would sanitize an empty `db_paths`.
rv.db_paths.emplace_back(db_path, 0 /* target_size */);
}
return rv;
}
};
} // namespace ROCKSDB_NAMESPACE