rocksdb/options/db_options.h
Baptiste Lemaire e3a96c4823 Memtable sampling for mempurge heuristic. (#8628)
Summary:
Changes the API of the MemPurge process: the `bool experimental_allow_mempurge` and `experimental_mempurge_policy` flags have been replaced by a `double experimental_mempurge_threshold` option.
This change of API reflects another major change introduced in this PR: the MemPurgeDecider() function now works by sampling the memtables being flushed to estimate the overall amount of useful payload (payload minus the garbage), and then compare this useful payload estimate with the `double experimental_mempurge_threshold` value.
Therefore, when the value of this flag is `0.0` (default value), mempurge is simply deactivated. On the other hand, a value of `DBL_MAX` would be equivalent to always going through a mempurge regardless of the garbage ratio estimate.
At the moment, a `double experimental_mempurge_threshold` value else than 0.0 or `DBL_MAX` is opnly supported`with the `SkipList` memtable representation.
Regarding the sampling, this PR includes the introduction of a `MemTable::UniqueRandomSample` function that collects (approximately) random entries from the memtable by using the new `SkipList::Iterator::RandomSeek()` under the hood, or by iterating through each memtable entry, depending on the target sample size and the total number of entries.
The unit tests have been readapted to support this new API.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8628

Reviewed By: pdillinger

Differential Revision: D30149315

Pulled By: bjlemaire

fbshipit-source-id: 1feef5390c95db6f4480ab4434716533d3947f27
2021-08-10 18:09:03 -07:00

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5.1 KiB
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// 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 track_and_verify_wals_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;
double experimental_mempurge_threshold;
size_t db_write_buffer_size;
std::shared_ptr<WriteBufferManager> write_buffer_manager;
DBOptions::AccessHint access_hint_on_compaction_start;
bool new_table_reader_for_compaction_inputs;
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;
#ifndef ROCKSDB_LITE
WalFilter* wal_filter;
#endif // ROCKSDB_LITE
bool fail_if_options_file_error;
bool dump_malloc_stats;
bool avoid_flush_during_recovery;
bool allow_ingest_behind;
bool preserve_deletes;
bool two_write_queues;
bool manual_wal_flush;
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;
// 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 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 MutableDBOptions& options) = default;
explicit MutableDBOptions(const DBOptions& options);
void Dump(Logger* log) const;
int max_background_jobs;
int base_background_compactions;
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;
};
#ifndef ROCKSDB_LITE
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);
#endif // ROCKSDB_LITE
} // namespace ROCKSDB_NAMESPACE