1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
2 //  This source code is licensed under both the GPLv2 (found in the
3 //  COPYING file in the root directory) and Apache 2.0 License
4 //  (found in the LICENSE.Apache file in the root directory).
5 //
6 #pragma once
7 #include "db/version_edit.h"
8 #include "util/random.h"
9 
10 namespace ROCKSDB_NAMESPACE {
11 static const uint32_t kFileReadSampleRate = 1024;
12 extern bool should_sample_file_read();
13 extern void sample_file_read_inc(FileMetaData*);
14 
should_sample_file_read()15 inline bool should_sample_file_read() {
16   return (Random::GetTLSInstance()->Next() % kFileReadSampleRate == 307);
17 }
18 
sample_file_read_inc(FileMetaData * meta)19 inline void sample_file_read_inc(FileMetaData* meta) {
20   meta->stats.num_reads_sampled.fetch_add(kFileReadSampleRate,
21                                           std::memory_order_relaxed);
22 }
23 }  // namespace ROCKSDB_NAMESPACE
24