rocksdb/options/db_options.h
anand76 d8fb849b7e Basic RocksDB follower implementation (#12540)
Summary:
A basic implementation of RocksDB follower mode, which opens a remote database (referred to as leader) on a distributed file system by tailing its MANIFEST. It leverages the secondary instance mode, but is different in some key ways -
1. It has its own directory with links to the leader's database
2. Periodically refreshes itself
3. (Future) Snapshot support
4. (Future) Garbage collection of obsolete links
5. (Long term) Memtable replication

There are two main classes implementing this functionality - `DBImplFollower` and `OnDemandFileSystem`. The former is derived from `DBImplSecondary`. Similar to `DBImplSecondary`, it implements recovery and catch up through MANIFEST tailing using the `ReactiveVersionSet`, but does not consider logs. In a future PR, we will implement memtable replication, which will eliminate the need to catch up using logs. In addition, the recovery and catch-up tries to avoid directory listing as repeated metadata operations are expensive.

The second main piece is the `OnDemandFileSystem`, which plugs in as an `Env` for the follower instance and creates the illusion of the follower directory as a clone of the leader directory. It creates links to SSTs on first reference. When the follower tails the MANIFEST and attempts to create a new `Version`, it calls `VerifyFileMetadata` to verify the size of the file, and optionally the unique ID of the file. During this process, links are created which prevent the underlying files from getting deallocated even if the leader deletes the files.

TODOs: Deletion of obsolete links, snapshots, robust checking against misconfigurations, better observability etc.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/12540

Reviewed By: jowlyzhang

Differential Revision: D56315718

Pulled By: anand1976

fbshipit-source-id: d19e1aca43a6af4000cb8622a718031b69ebd97b
2024-04-19 19:13:31 -07:00

157 lines
5.1 KiB
C++

// 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 <string>
#include <vector>
#include "rocksdb/options.h"
namespace ROCKSDB_NAMESPACE {
class SystemClock;
struct ImmutableDBOptions {
static const char* kName() { return "ImmutableDBOptions"; }
ImmutableDBOptions();
explicit ImmutableDBOptions(const DBOptions& options);
void Dump(Logger* log) const;
bool create_if_missing;
bool create_missing_column_families;
bool error_if_exists;
bool paranoid_checks;
bool flush_verify_memtable_count;
bool compaction_verify_record_count;
bool track_and_verify_wals_in_manifest;
bool verify_sst_unique_id_in_manifest;
Env* env;
std::shared_ptr<RateLimiter> rate_limiter;
std::shared_ptr<SstFileManager> sst_file_manager;
std::shared_ptr<Logger> info_log;
InfoLogLevel info_log_level;
int max_file_opening_threads;
std::shared_ptr<Statistics> statistics;
bool use_fsync;
std::vector<DbPath> db_paths;
std::string db_log_dir;
// The wal_dir option from the file. To determine the
// directory in use, the GetWalDir or IsWalDirSameAsDBPath
// methods should be used instead of accessing this variable directly.
std::string wal_dir;
size_t max_log_file_size;
size_t log_file_time_to_roll;
size_t keep_log_file_num;
size_t recycle_log_file_num;
uint64_t max_manifest_file_size;
int table_cache_numshardbits;
uint64_t WAL_ttl_seconds;
uint64_t WAL_size_limit_MB;
uint64_t max_write_batch_group_size_bytes;
size_t manifest_preallocation_size;
bool allow_mmap_reads;
bool allow_mmap_writes;
bool use_direct_reads;
bool use_direct_io_for_flush_and_compaction;
bool allow_fallocate;
bool is_fd_close_on_exec;
bool advise_random_on_open;
size_t db_write_buffer_size;
std::shared_ptr<WriteBufferManager> write_buffer_manager;
size_t random_access_max_buffer_size;
bool use_adaptive_mutex;
std::vector<std::shared_ptr<EventListener>> listeners;
bool enable_thread_tracking;
bool enable_pipelined_write;
bool unordered_write;
bool allow_concurrent_memtable_write;
bool enable_write_thread_adaptive_yield;
uint64_t write_thread_max_yield_usec;
uint64_t write_thread_slow_yield_usec;
bool skip_stats_update_on_db_open;
bool skip_checking_sst_file_sizes_on_db_open;
WALRecoveryMode wal_recovery_mode;
bool allow_2pc;
std::shared_ptr<Cache> row_cache;
WalFilter* wal_filter;
bool fail_if_options_file_error;
bool dump_malloc_stats;
bool avoid_flush_during_recovery;
bool allow_ingest_behind;
bool two_write_queues;
bool manual_wal_flush;
CompressionType wal_compression;
bool atomic_flush;
bool avoid_unnecessary_blocking_io;
bool persist_stats_to_disk;
bool write_dbid_to_manifest;
size_t log_readahead_size;
std::shared_ptr<FileChecksumGenFactory> file_checksum_gen_factory;
bool best_efforts_recovery;
int max_bgerror_resume_count;
uint64_t bgerror_resume_retry_interval;
bool allow_data_in_errors;
std::string db_host_id;
FileTypeSet checksum_handoff_file_types;
CacheTier lowest_used_cache_tier;
// Convenience/Helper objects that are not part of the base DBOptions
std::shared_ptr<FileSystem> fs;
SystemClock* clock;
Statistics* stats;
Logger* logger;
std::shared_ptr<CompactionService> compaction_service;
bool enforce_single_del_contracts;
uint64_t follower_refresh_catchup_period_ms;
uint64_t follower_catchup_retry_count;
uint64_t follower_catchup_retry_wait_ms;
bool IsWalDirSameAsDBPath() const;
bool IsWalDirSameAsDBPath(const std::string& path) const;
const std::string& GetWalDir() const;
const std::string& GetWalDir(const std::string& path) const;
};
struct MutableDBOptions {
static const char* kName() { return "MutableDBOptions"; }
MutableDBOptions();
explicit MutableDBOptions(const DBOptions& options);
void Dump(Logger* log) const;
int max_background_jobs;
int max_background_compactions;
uint32_t max_subcompactions;
bool avoid_flush_during_shutdown;
size_t writable_file_max_buffer_size;
uint64_t delayed_write_rate;
uint64_t max_total_wal_size;
uint64_t delete_obsolete_files_period_micros;
unsigned int stats_dump_period_sec;
unsigned int stats_persist_period_sec;
size_t stats_history_buffer_size;
int max_open_files;
uint64_t bytes_per_sync;
uint64_t wal_bytes_per_sync;
bool strict_bytes_per_sync;
size_t compaction_readahead_size;
int max_background_flushes;
std::string daily_offpeak_time_utc;
};
Status GetStringFromMutableDBOptions(const ConfigOptions& config_options,
const MutableDBOptions& mutable_opts,
std::string* opt_string);
Status GetMutableDBOptionsFromStrings(
const MutableDBOptions& base_options,
const std::unordered_map<std::string, std::string>& options_map,
MutableDBOptions* new_options);
bool MutableDBOptionsAreEqual(const MutableDBOptions& this_options,
const MutableDBOptions& that_options);
} // namespace ROCKSDB_NAMESPACE