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rocksdb/file/random_access_file_reader_test.cc
Andrew Kryczka babe56ddba Add rate limiter priority to ReadOptions (#9424) 
Summary:
Users can set the priority for file reads associated with their operation by setting `ReadOptions::rate_limiter_priority` to something other than `Env::IO_TOTAL`. Rate limiting `VerifyChecksum()` and `VerifyFileChecksums()` is the motivation for this PR, so it also includes benchmarks and minor bug fixes to get that working.

`RandomAccessFileReader::Read()` already had support for rate limiting compaction reads. I changed that rate limiting to be non-specific to compaction, but rather performed according to the passed in `Env::IOPriority`. Now the compaction read rate limiting is supported by setting `rate_limiter_priority = Env::IO_LOW` on its `ReadOptions`.

There is no default value for the new `Env::IOPriority` parameter to `RandomAccessFileReader::Read()`. That means this PR goes through all callers (in some cases multiple layers up the call stack) to find a `ReadOptions` to provide the priority. There are TODOs for cases I believe it would be good to let user control the priority some day (e.g., file footer reads), and no TODO in cases I believe it doesn't matter (e.g., trace file reads).

The API doc only lists the missing cases where a file read associated with a provided `ReadOptions` cannot be rate limited. For cases like file ingestion checksum calculation, there is no API to provide `ReadOptions` or `Env::IOPriority`, so I didn't count that as missing.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9424

Test Plan:
- new unit tests
- new benchmarks on ~50MB database with 1MB/s read rate limit and 100ms refill interval; verified with strace reads are chunked (at 0.1MB per chunk) and spaced roughly 100ms apart.
  - setup command: `./db_bench -benchmarks=fillrandom,compact -db=/tmp/testdb -target_file_size_base=1048576 -disable_auto_compactions=true -file_checksum=true`
  - benchmarks command: `strace -ttfe pread64 ./db_bench -benchmarks=verifychecksum,verifyfilechecksums -use_existing_db=true -db=/tmp/testdb -rate_limiter_bytes_per_sec=1048576 -rate_limit_bg_reads=1 -rate_limit_user_ops=true -file_checksum=true`
- crash test using IO_USER priority on non-validation reads with https://github.com/facebook/rocksdb/issues/9567 reverted: `python3 tools/db_crashtest.py blackbox --max_key=1000000 --write_buffer_size=524288 --target_file_size_base=524288 --level_compaction_dynamic_level_bytes=true --duration=3600 --rate_limit_bg_reads=true --rate_limit_user_ops=true --rate_limiter_bytes_per_sec=10485760 --interval=10`

Reviewed By: hx235

Differential Revision: D33747386

Pulled By: ajkr

fbshipit-source-id: a2d985e97912fba8c54763798e04f006ccc56e0c
2022-02-16 23:18:14 -08:00

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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).
#include "file/random_access_file_reader.h"
#include <algorithm>
#include "file/file_util.h"
#include "port/port.h"
#include "port/stack_trace.h"
#include "rocksdb/file_system.h"
#include "test_util/sync_point.h"
#include "test_util/testharness.h"
#include "test_util/testutil.h"
#include "util/random.h"
namespace ROCKSDB_NAMESPACE {
class RandomAccessFileReaderTest : public testing::Test {
public:
void SetUp() override {
SetupSyncPointsToMockDirectIO();
env_ = Env::Default();
fs_ = FileSystem::Default();
test_dir_ = test::PerThreadDBPath("random_access_file_reader_test");
ASSERT_OK(fs_->CreateDir(test_dir_, IOOptions(), nullptr));
}
void TearDown() override { EXPECT_OK(DestroyDir(env_, test_dir_)); }
void Write(const std::string& fname, const std::string& content) {
std::unique_ptr<FSWritableFile> f;
ASSERT_OK(fs_->NewWritableFile(Path(fname), FileOptions(), &f, nullptr));
ASSERT_OK(f->Append(content, IOOptions(), nullptr));
ASSERT_OK(f->Close(IOOptions(), nullptr));
}
void Read(const std::string& fname, const FileOptions& opts,
std::unique_ptr<RandomAccessFileReader>* reader) {
std::string fpath = Path(fname);
std::unique_ptr<FSRandomAccessFile> f;
ASSERT_OK(fs_->NewRandomAccessFile(fpath, opts, &f, nullptr));
reader->reset(new RandomAccessFileReader(std::move(f), fpath,
env_->GetSystemClock().get()));
}
void AssertResult(const std::string& content,
const std::vector<FSReadRequest>& reqs) {
for (const auto& r : reqs) {
ASSERT_OK(r.status);
ASSERT_EQ(r.len, r.result.size());
ASSERT_EQ(content.substr(r.offset, r.len), r.result.ToString());
}
}
private:
Env* env_;
std::shared_ptr<FileSystem> fs_;
std::string test_dir_;
std::string Path(const std::string& fname) {
return test_dir_ + "/" + fname;
}
};
// Skip the following tests in lite mode since direct I/O is unsupported.
#ifndef ROCKSDB_LITE
TEST_F(RandomAccessFileReaderTest, ReadDirectIO) {
std::string fname = "read-direct-io";
Random rand(0);
std::string content = rand.RandomString(kDefaultPageSize);
Write(fname, content);
FileOptions opts;
opts.use_direct_reads = true;
std::unique_ptr<RandomAccessFileReader> r;
Read(fname, opts, &r);
ASSERT_TRUE(r->use_direct_io());
const size_t page_size = r->file()->GetRequiredBufferAlignment();
size_t offset = page_size / 2;
size_t len = page_size / 3;
Slice result;
AlignedBuf buf;
for (Env::IOPriority rate_limiter_priority : {Env::IO_LOW, Env::IO_TOTAL}) {
ASSERT_OK(r->Read(IOOptions(), offset, len, &result, nullptr, &buf,
rate_limiter_priority));
ASSERT_EQ(result.ToString(), content.substr(offset, len));
}
}
TEST_F(RandomAccessFileReaderTest, MultiReadDirectIO) {
std::vector<FSReadRequest> aligned_reqs;
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
"RandomAccessFileReader::MultiRead:AlignedReqs", [&](void* reqs) {
// Copy reqs, since it's allocated on stack inside MultiRead, which will
// be deallocated after MultiRead returns.
aligned_reqs = *reinterpret_cast<std::vector<FSReadRequest>*>(reqs);
});
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
// Creates a file with 3 pages.
std::string fname = "multi-read-direct-io";
Random rand(0);
std::string content = rand.RandomString(3 * kDefaultPageSize);
Write(fname, content);
FileOptions opts;
opts.use_direct_reads = true;
std::unique_ptr<RandomAccessFileReader> r;
Read(fname, opts, &r);
ASSERT_TRUE(r->use_direct_io());
const size_t page_size = r->file()->GetRequiredBufferAlignment();
{
// Reads 2 blocks in the 1st page.
// The results should be SharedSlices of the same underlying buffer.
//
// Illustration (each x is a 1/4 page)
// First page: xxxx
// 1st block: x
// 2nd block: xx
FSReadRequest r0;
r0.offset = 0;
r0.len = page_size / 4;
r0.scratch = nullptr;
FSReadRequest r1;
r1.offset = page_size / 2;
r1.len = page_size / 2;
r1.scratch = nullptr;
std::vector<FSReadRequest> reqs;
reqs.push_back(std::move(r0));
reqs.push_back(std::move(r1));
AlignedBuf aligned_buf;
ASSERT_OK(r->MultiRead(IOOptions(), reqs.data(), reqs.size(), &aligned_buf,
Env::IO_TOTAL /* rate_limiter_priority */));
AssertResult(content, reqs);
// Reads the first page internally.
ASSERT_EQ(aligned_reqs.size(), 1);
const FSReadRequest& aligned_r = aligned_reqs[0];
ASSERT_OK(aligned_r.status);
ASSERT_EQ(aligned_r.offset, 0);
ASSERT_EQ(aligned_r.len, page_size);
}
{
// Reads 3 blocks:
// 1st block in the 1st page;
// 2nd block from the middle of the 1st page to the middle of the 2nd page;
// 3rd block in the 2nd page.
// The results should be SharedSlices of the same underlying buffer.
//
// Illustration (each x is a 1/4 page)
// 2 pages: xxxxxxxx
// 1st block: x
// 2nd block: xxxx
// 3rd block: x
FSReadRequest r0;
r0.offset = 0;
r0.len = page_size / 4;
r0.scratch = nullptr;
FSReadRequest r1;
r1.offset = page_size / 2;
r1.len = page_size;
r1.scratch = nullptr;
FSReadRequest r2;
r2.offset = 2 * page_size - page_size / 4;
r2.len = page_size / 4;
r2.scratch = nullptr;
std::vector<FSReadRequest> reqs;
reqs.push_back(std::move(r0));
reqs.push_back(std::move(r1));
reqs.push_back(std::move(r2));
AlignedBuf aligned_buf;
ASSERT_OK(r->MultiRead(IOOptions(), reqs.data(), reqs.size(), &aligned_buf,
Env::IO_TOTAL /* rate_limiter_priority */));
AssertResult(content, reqs);
// Reads the first two pages in one request internally.
ASSERT_EQ(aligned_reqs.size(), 1);
const FSReadRequest& aligned_r = aligned_reqs[0];
ASSERT_OK(aligned_r.status);
ASSERT_EQ(aligned_r.offset, 0);
ASSERT_EQ(aligned_r.len, 2 * page_size);
}
{
// Reads 3 blocks:
// 1st block in the middle of the 1st page;
// 2nd block in the middle of the 2nd page;
// 3rd block in the middle of the 3rd page.
// The results should be SharedSlices of the same underlying buffer.
//
// Illustration (each x is a 1/4 page)
// 3 pages: xxxxxxxxxxxx
// 1st block: xx
// 2nd block: xx
// 3rd block: xx
FSReadRequest r0;
r0.offset = page_size / 4;
r0.len = page_size / 2;
r0.scratch = nullptr;
FSReadRequest r1;
r1.offset = page_size + page_size / 4;
r1.len = page_size / 2;
r1.scratch = nullptr;
FSReadRequest r2;
r2.offset = 2 * page_size + page_size / 4;
r2.len = page_size / 2;
r2.scratch = nullptr;
std::vector<FSReadRequest> reqs;
reqs.push_back(std::move(r0));
reqs.push_back(std::move(r1));
reqs.push_back(std::move(r2));
AlignedBuf aligned_buf;
ASSERT_OK(r->MultiRead(IOOptions(), reqs.data(), reqs.size(), &aligned_buf,
Env::IO_TOTAL /* rate_limiter_priority */));
AssertResult(content, reqs);
// Reads the first 3 pages in one request internally.
ASSERT_EQ(aligned_reqs.size(), 1);
const FSReadRequest& aligned_r = aligned_reqs[0];
ASSERT_OK(aligned_r.status);
ASSERT_EQ(aligned_r.offset, 0);
ASSERT_EQ(aligned_r.len, 3 * page_size);
}
{
// Reads 2 blocks:
// 1st block in the middle of the 1st page;
// 2nd block in the middle of the 3rd page.
// The results are two different buffers.
//
// Illustration (each x is a 1/4 page)
// 3 pages: xxxxxxxxxxxx
// 1st block: xx
// 2nd block: xx
FSReadRequest r0;
r0.offset = page_size / 4;
r0.len = page_size / 2;
r0.scratch = nullptr;
FSReadRequest r1;
r1.offset = 2 * page_size + page_size / 4;
r1.len = page_size / 2;
r1.scratch = nullptr;
std::vector<FSReadRequest> reqs;
reqs.push_back(std::move(r0));
reqs.push_back(std::move(r1));
AlignedBuf aligned_buf;
ASSERT_OK(r->MultiRead(IOOptions(), reqs.data(), reqs.size(), &aligned_buf,
Env::IO_TOTAL /* rate_limiter_priority */));
AssertResult(content, reqs);
// Reads the 1st and 3rd pages in two requests internally.
ASSERT_EQ(aligned_reqs.size(), 2);
const FSReadRequest& aligned_r0 = aligned_reqs[0];
const FSReadRequest& aligned_r1 = aligned_reqs[1];
ASSERT_OK(aligned_r0.status);
ASSERT_EQ(aligned_r0.offset, 0);
ASSERT_EQ(aligned_r0.len, page_size);
ASSERT_OK(aligned_r1.status);
ASSERT_EQ(aligned_r1.offset, 2 * page_size);
ASSERT_EQ(aligned_r1.len, page_size);
}
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->DisableProcessing();
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->ClearAllCallBacks();
}
#endif // ROCKSDB_LITE
TEST(FSReadRequest, Align) {
FSReadRequest r;
r.offset = 2000;
r.len = 2000;
r.scratch = nullptr;
ASSERT_OK(r.status);
FSReadRequest aligned_r = Align(r, 1024);
ASSERT_OK(r.status);
ASSERT_OK(aligned_r.status);
ASSERT_EQ(aligned_r.offset, 1024);
ASSERT_EQ(aligned_r.len, 3072);
}
TEST(FSReadRequest, TryMerge) {
// reverse means merging dest into src.
for (bool reverse : {true, false}) {
{
// dest: [ ]
// src: [ ]
FSReadRequest dest;
dest.offset = 0;
dest.len = 10;
dest.scratch = nullptr;
ASSERT_OK(dest.status);
FSReadRequest src;
src.offset = 15;
src.len = 10;
src.scratch = nullptr;
ASSERT_OK(src.status);
if (reverse) {
std::swap(dest, src);
}
ASSERT_FALSE(TryMerge(&dest, src));
ASSERT_OK(dest.status);
ASSERT_OK(src.status);
}
{
// dest: [ ]
// src: [ ]
FSReadRequest dest;
dest.offset = 0;
dest.len = 10;
dest.scratch = nullptr;
ASSERT_OK(dest.status);
FSReadRequest src;
src.offset = 10;
src.len = 10;
src.scratch = nullptr;
ASSERT_OK(src.status);
if (reverse) {
std::swap(dest, src);
}
ASSERT_TRUE(TryMerge(&dest, src));
ASSERT_EQ(dest.offset, 0);
ASSERT_EQ(dest.len, 20);
ASSERT_OK(dest.status);
ASSERT_OK(src.status);
}
{
// dest: [ ]
// src: [ ]
FSReadRequest dest;
dest.offset = 0;
dest.len = 10;
dest.scratch = nullptr;
ASSERT_OK(dest.status);
FSReadRequest src;
src.offset = 5;
src.len = 10;
src.scratch = nullptr;
ASSERT_OK(src.status);
if (reverse) {
std::swap(dest, src);
}
ASSERT_TRUE(TryMerge(&dest, src));
ASSERT_EQ(dest.offset, 0);
ASSERT_EQ(dest.len, 15);
ASSERT_OK(dest.status);
ASSERT_OK(src.status);
}
{
// dest: [ ]
// src: [ ]
FSReadRequest dest;
dest.offset = 0;
dest.len = 10;
dest.scratch = nullptr;
ASSERT_OK(dest.status);
FSReadRequest src;
src.offset = 5;
src.len = 5;
src.scratch = nullptr;
ASSERT_OK(src.status);
if (reverse) {
std::swap(dest, src);
}
ASSERT_TRUE(TryMerge(&dest, src));
ASSERT_EQ(dest.offset, 0);
ASSERT_EQ(dest.len, 10);
ASSERT_OK(dest.status);
ASSERT_OK(src.status);
}
{
// dest: [ ]
// src: [ ]
FSReadRequest dest;
dest.offset = 0;
dest.len = 10;
dest.scratch = nullptr;
ASSERT_OK(dest.status);
FSReadRequest src;
src.offset = 5;
src.len = 1;
src.scratch = nullptr;
ASSERT_OK(src.status);
if (reverse) std::swap(dest, src);
ASSERT_TRUE(TryMerge(&dest, src));
ASSERT_EQ(dest.offset, 0);
ASSERT_EQ(dest.len, 10);
ASSERT_OK(dest.status);
ASSERT_OK(src.status);
}
{
// dest: [ ]
// src: [ ]
FSReadRequest dest;
dest.offset = 0;
dest.len = 10;
dest.scratch = nullptr;
ASSERT_OK(dest.status);
FSReadRequest src;
src.offset = 0;
src.len = 10;
src.scratch = nullptr;
ASSERT_OK(src.status);
if (reverse) std::swap(dest, src);
ASSERT_TRUE(TryMerge(&dest, src));
ASSERT_EQ(dest.offset, 0);
ASSERT_EQ(dest.len, 10);
ASSERT_OK(dest.status);
ASSERT_OK(src.status);
}
{
// dest: [ ]
// src: [ ]
FSReadRequest dest;
dest.offset = 0;
dest.len = 10;
dest.scratch = nullptr;
ASSERT_OK(dest.status);
FSReadRequest src;
src.offset = 0;
src.len = 5;
src.scratch = nullptr;
ASSERT_OK(src.status);
if (reverse) std::swap(dest, src);
ASSERT_TRUE(TryMerge(&dest, src));
ASSERT_EQ(dest.offset, 0);
ASSERT_EQ(dest.len, 10);
ASSERT_OK(dest.status);
ASSERT_OK(src.status);
}
}
}
} // namespace ROCKSDB_NAMESPACE
int main(int argc, char** argv) {
ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
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