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rocksdb/include/rocksdb/perf_context.h

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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 <stdint.h>
#include <map>
#include <string>
#include "rocksdb/perf_level.h"
namespace rocksdb {
// A thread local context for gathering performance counter efficiently
// and transparently.
// Use SetPerfLevel(PerfLevel::kEnableTime) to enable time stats.
// Break down performance counters by level and store per-level perf context in
// PerfContextByLevel
struct PerfContextByLevel {
// # of times bloom filter has avoided file reads, i.e., negatives.
uint64_t bloom_filter_useful = 0;
// # of times bloom FullFilter has not avoided the reads.
uint64_t bloom_filter_full_positive = 0;
// # of times bloom FullFilter has not avoided the reads and data actually
// exist.
uint64_t bloom_filter_full_true_positive = 0;
// total number of user key returned (only include keys that are found, does
// not include keys that are deleted or merged without a final put
uint64_t user_key_return_count;
// total nanos spent on reading data from SST files
uint64_t get_from_table_nanos;
uint64_t block_cache_hit_count = 0; // total number of block cache hits
uint64_t block_cache_miss_count = 0; // total number of block cache misses
void Reset(); // reset all performance counters to zero
};
struct PerfContext {
~PerfContext();
PerfContext() {}
PerfContext(const PerfContext&);
PerfContext& operator=(const PerfContext&);
PerfContext(PerfContext&&) noexcept;
void Reset(); // reset all performance counters to zero
std::string ToString(bool exclude_zero_counters = false) const;
// enable per level perf context and allocate storage for PerfContextByLevel
void EnablePerLevelPerfContext();
// temporarily disable per level perf contxt by setting the flag to false
void DisablePerLevelPerfContext();
// free the space for PerfContextByLevel, also disable per level perf context
void ClearPerLevelPerfContext();
uint64_t user_key_comparison_count; // total number of user key comparisons
uint64_t block_cache_hit_count; // total number of block cache hits
uint64_t block_read_count; // total number of block reads (with IO)
uint64_t block_read_byte; // total number of bytes from block reads
uint64_t block_read_time; // total nanos spent on block reads
uint64_t block_cache_index_hit_count; // total number of index block hits
uint64_t index_block_read_count; // total number of index block reads
uint64_t block_cache_filter_hit_count; // total number of filter block hits
uint64_t filter_block_read_count; // total number of filter block reads
uint64_t compression_dict_block_read_count; // total number of compression
// dictionary block reads
uint64_t block_checksum_time; // total nanos spent on block checksum
uint64_t block_decompress_time; // total nanos spent on block decompression
uint64_t get_read_bytes; // bytes for vals returned by Get
uint64_t multiget_read_bytes; // bytes for vals returned by MultiGet
uint64_t iter_read_bytes; // bytes for keys/vals decoded by iterator
// total number of internal keys skipped over during iteration.
// There are several reasons for it:
// 1. when calling Next(), the iterator is in the position of the previous
// key, so that we'll need to skip it. It means this counter will always
// be incremented in Next().
// 2. when calling Next(), we need to skip internal entries for the previous
// keys that are overwritten.
// 3. when calling Next(), Seek() or SeekToFirst(), after previous key
// before calling Next(), the seek key in Seek() or the beginning for
// SeekToFirst(), there may be one or more deleted keys before the next
// valid key that the operation should place the iterator to. We need
// to skip both of the tombstone and updates hidden by the tombstones. The
// tombstones are not included in this counter, while previous updates
// hidden by the tombstones will be included here.
// 4. symmetric cases for Prev() and SeekToLast()
// internal_recent_skipped_count is not included in this counter.
//
uint64_t internal_key_skipped_count;
// Total number of deletes and single deletes skipped over during iteration
// When calling Next(), Seek() or SeekToFirst(), after previous position
// before calling Next(), the seek key in Seek() or the beginning for
// SeekToFirst(), there may be one or more deleted keys before the next valid
// key. Every deleted key is counted once. We don't recount here if there are
// still older updates invalidated by the tombstones.
//
uint64_t internal_delete_skipped_count;
// How many times iterators skipped over internal keys that are more recent
// than the snapshot that iterator is using.
//
uint64_t internal_recent_skipped_count;
// How many values were fed into merge operator by iterators.
//
uint64_t internal_merge_count;
uint64_t get_snapshot_time; // total nanos spent on getting snapshot
uint64_t get_from_memtable_time; // total nanos spent on querying memtables
uint64_t get_from_memtable_count; // number of mem tables queried
// total nanos spent after Get() finds a key
uint64_t get_post_process_time;
uint64_t get_from_output_files_time; // total nanos reading from output files
// total nanos spent on seeking memtable
uint64_t seek_on_memtable_time;
// number of seeks issued on memtable
// (including SeekForPrev but not SeekToFirst and SeekToLast)
uint64_t seek_on_memtable_count;
// number of Next()s issued on memtable
uint64_t next_on_memtable_count;
// number of Prev()s issued on memtable
uint64_t prev_on_memtable_count;
// total nanos spent on seeking child iters
uint64_t seek_child_seek_time;
// number of seek issued in child iterators
uint64_t seek_child_seek_count;
uint64_t seek_min_heap_time; // total nanos spent on the merge min heap
uint64_t seek_max_heap_time; // total nanos spent on the merge max heap
// total nanos spent on seeking the internal entries
uint64_t seek_internal_seek_time;
// total nanos spent on iterating internal entries to find the next user entry
uint64_t find_next_user_entry_time;
// This group of stats provide a breakdown of time spent by Write().
// May be inaccurate when 2PC, two_write_queues or enable_pipelined_write
// are enabled.
//
// total nanos spent on writing to WAL
uint64_t write_wal_time;
// total nanos spent on writing to mem tables
uint64_t write_memtable_time;
// total nanos spent on delaying or throttling write
uint64_t write_delay_time;
// total nanos spent on switching memtable/wal and scheduling
// flushes/compactions.
uint64_t write_scheduling_flushes_compactions_time;
// total nanos spent on writing a record, excluding the above four things
uint64_t write_pre_and_post_process_time;
// time spent waiting for other threads of the batch group
uint64_t write_thread_wait_nanos;
// time spent on acquiring DB mutex.
uint64_t db_mutex_lock_nanos;
// Time spent on waiting with a condition variable created with DB mutex.
uint64_t db_condition_wait_nanos;
// Time spent on merge operator.
uint64_t merge_operator_time_nanos;
// Time spent on reading index block from block cache or SST file
uint64_t read_index_block_nanos;
// Time spent on reading filter block from block cache or SST file
uint64_t read_filter_block_nanos;
// Time spent on creating data block iterator
uint64_t new_table_block_iter_nanos;
// Time spent on creating a iterator of an SST file.
uint64_t new_table_iterator_nanos;
// Time spent on seeking a key in data/index blocks
uint64_t block_seek_nanos;
// Time spent on finding or creating a table reader
uint64_t find_table_nanos;
// total number of mem table bloom hits
uint64_t bloom_memtable_hit_count;
// total number of mem table bloom misses
uint64_t bloom_memtable_miss_count;
// total number of SST table bloom hits
uint64_t bloom_sst_hit_count;
// total number of SST table bloom misses
uint64_t bloom_sst_miss_count;
// Time spent waiting on key locks in transaction lock manager.
uint64_t key_lock_wait_time;
// number of times acquiring a lock was blocked by another transaction.
uint64_t key_lock_wait_count;
// Total time spent in Env filesystem operations. These are only populated
// when TimedEnv is used.
uint64_t env_new_sequential_file_nanos;
uint64_t env_new_random_access_file_nanos;
uint64_t env_new_writable_file_nanos;
uint64_t env_reuse_writable_file_nanos;
uint64_t env_new_random_rw_file_nanos;
uint64_t env_new_directory_nanos;
uint64_t env_file_exists_nanos;
uint64_t env_get_children_nanos;
uint64_t env_get_children_file_attributes_nanos;
uint64_t env_delete_file_nanos;
uint64_t env_create_dir_nanos;
uint64_t env_create_dir_if_missing_nanos;
uint64_t env_delete_dir_nanos;
uint64_t env_get_file_size_nanos;
uint64_t env_get_file_modification_time_nanos;
uint64_t env_rename_file_nanos;
uint64_t env_link_file_nanos;
uint64_t env_lock_file_nanos;
uint64_t env_unlock_file_nanos;
uint64_t env_new_logger_nanos;
uint64_t get_cpu_nanos;
uint64_t iter_next_cpu_nanos;
uint64_t iter_prev_cpu_nanos;
uint64_t iter_seek_cpu_nanos;
std::map<uint32_t, PerfContextByLevel>* level_to_perf_context = nullptr;
bool per_level_perf_context_enabled = false;
};
// Get Thread-local PerfContext object pointer
// if defined(NPERF_CONTEXT), then the pointer is not thread-local
PerfContext* get_perf_context();
} // namespace rocksdb