rocksdb/file/file_util.h
gitbw95 4da34b97ee Set Read rate limiter priority dynamically and pass it to FS (#9996)
Summary:
### Context:
Background compactions and flush generate large reads and writes, and can be long running, especially for universal compaction. In some cases, this can impact foreground reads and writes by users.

### Solution
User, Flush, and Compaction reads share some code path. For this task, we update the rate_limiter_priority in ReadOptions for code paths (e.g. FindTable (mainly in BlockBasedTable::Open()) and various iterators), and eventually update the rate_limiter_priority in IOOptions for FSRandomAccessFile.

**This PR is for the Read path.** The **Read:** dynamic priority for different state are listed as follows:

| State | Normal | Delayed | Stalled |
| ----- | ------ | ------- | ------- |
|  Flush (verification read in BuildTable()) | IO_USER | IO_USER | IO_USER |
|  Compaction | IO_LOW  | IO_USER | IO_USER |
|  User | User provided | User provided | User provided |

We will respect the read_options that the user provided and will not set it.
The only sst read for Flush is the verification read in BuildTable(). It claims to be "regard as user read".

**Details**
1. Set read_options.rate_limiter_priority dynamically:
- User: Do not update the read_options. Use the read_options that the user provided.
- Compaction: Update read_options in CompactionJob::ProcessKeyValueCompaction().
- Flush: Update read_options in BuildTable().

2. Pass the rate limiter priority to FSRandomAccessFile functions:
- After calling the FindTable(), read_options is passed through GetTableReader(table_cache.cc), BlockBasedTableFactory::NewTableReader(block_based_table_factory.cc), and BlockBasedTable::Open(). The Open() needs some updates for the ReadOptions variable and the updates are also needed for the called functions,  including PrefetchTail(), PrepareIOOptions(), ReadFooterFromFile(), ReadMetaIndexblock(), ReadPropertiesBlock(), PrefetchIndexAndFilterBlocks(), and ReadRangeDelBlock().
- In RandomAccessFileReader, the functions to be updated include Read(), MultiRead(), ReadAsync(), and Prefetch().
- Update the downstream functions of NewIndexIterator(), NewDataBlockIterator(), and BlockBasedTableIterator().

### Test Plans
Add unit tests.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9996

Reviewed By: anand1976

Differential Revision: D36452483

Pulled By: gitbw95

fbshipit-source-id: 60978204a4f849bb9261cb78d9bc1cb56d6008cf
2022-05-18 19:41:44 -07:00

90 lines
3.8 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 "file/filename.h"
#include "options/db_options.h"
#include "rocksdb/env.h"
#include "rocksdb/file_system.h"
#include "rocksdb/sst_file_writer.h"
#include "rocksdb/status.h"
#include "rocksdb/system_clock.h"
#include "rocksdb/types.h"
#include "trace_replay/io_tracer.h"
namespace ROCKSDB_NAMESPACE {
// use_fsync maps to options.use_fsync, which determines the way that
// the file is synced after copying.
extern IOStatus CopyFile(FileSystem* fs, const std::string& source,
std::unique_ptr<WritableFileWriter>& dest_writer,
uint64_t size, bool use_fsync,
const std::shared_ptr<IOTracer>& io_tracer,
const Temperature temperature);
extern IOStatus CopyFile(FileSystem* fs, const std::string& source,
const std::string& destination, uint64_t size,
bool use_fsync,
const std::shared_ptr<IOTracer>& io_tracer,
const Temperature temperature);
inline IOStatus CopyFile(const std::shared_ptr<FileSystem>& fs,
const std::string& source,
const std::string& destination, uint64_t size,
bool use_fsync,
const std::shared_ptr<IOTracer>& io_tracer,
const Temperature temperature) {
return CopyFile(fs.get(), source, destination, size, use_fsync, io_tracer,
temperature);
}
extern IOStatus CreateFile(FileSystem* fs, const std::string& destination,
const std::string& contents, bool use_fsync);
inline IOStatus CreateFile(const std::shared_ptr<FileSystem>& fs,
const std::string& destination,
const std::string& contents, bool use_fsync) {
return CreateFile(fs.get(), destination, contents, use_fsync);
}
extern Status DeleteDBFile(const ImmutableDBOptions* db_options,
const std::string& fname,
const std::string& path_to_sync, const bool force_bg,
const bool force_fg);
extern IOStatus GenerateOneFileChecksum(
FileSystem* fs, const std::string& file_path,
FileChecksumGenFactory* checksum_factory,
const std::string& requested_checksum_func_name, std::string* file_checksum,
std::string* file_checksum_func_name,
size_t verify_checksums_readahead_size, bool allow_mmap_reads,
std::shared_ptr<IOTracer>& io_tracer, RateLimiter* rate_limiter,
Env::IOPriority rate_limiter_priority);
inline IOStatus PrepareIOFromReadOptions(const ReadOptions& ro,
SystemClock* clock, IOOptions& opts) {
if (ro.deadline.count()) {
std::chrono::microseconds now =
std::chrono::microseconds(clock->NowMicros());
// Ensure there is atleast 1us available. We don't want to pass a value of
// 0 as that means no timeout
if (now >= ro.deadline) {
return IOStatus::TimedOut("Deadline exceeded");
}
opts.timeout = ro.deadline - now;
}
if (ro.io_timeout.count() &&
(!opts.timeout.count() || ro.io_timeout < opts.timeout)) {
opts.timeout = ro.io_timeout;
}
opts.rate_limiter_priority = ro.rate_limiter_priority;
return IOStatus::OK();
}
// Test method to delete the input directory and all of its contents.
// This method is destructive and is meant for use only in tests!!!
Status DestroyDir(Env* env, const std::string& dir);
} // namespace ROCKSDB_NAMESPACE