rocksdb/db/compaction_job_test.cc
Igor Canadi 47b8743984 Make Compaction class easier to use
Summary:
The goal of this diff is to make Compaction class easier to use. This should also make new compaction algorithms easier to write (like CompactFiles from @yhchiang and dynamic leveled and multi-leveled universal from @sdong).

Here are couple of things demonstrating that Compaction class is hard to use:
1. we have two constructors of Compaction class
2. there's this thing called grandparents_, but it appears to only be setup for leveled compaction and not compactfiles
3. it's easy to introduce a subtle and dangerous bug like this: D36225
4. SetupBottomMostLevel() is hard to understand and it shouldn't be. See this comment: afbafeaeae/db/compaction.cc (L236-L241). It also made it harder for @yhchiang to write CompactFiles, as evidenced by this: afbafeaeae/db/compaction_picker.cc (L204-L210)

The problem is that we create Compaction object, which holds a lot of state, and then pass it around to some functions. After those functions are done mutating, then we call couple of functions on Compaction object, like SetupBottommostLevel() and MarkFilesBeingCompacted(). It is very hard to see what's happening with all that Compaction's state while it's travelling across different functions. If you're writing a new PickCompaction() function you need to try really hard to understand what are all the functions you need to run on Compaction object and what state you need to setup.

My proposed solution is to make important parts of Compaction immutable after construction. PickCompaction() should calculate compaction inputs and then pass them onto Compaction object once they are finalized. That makes it easy to create a new compaction -- just provide all the parameters to the constructor and you're done. No need to call confusing functions after you created your object.

This diff doesn't fully achieve that goal, but it comes pretty close. Here are some of the changes:
* have one Compaction constructor instead of two.
* inputs_ is constant after construction
* MarkFilesBeingCompacted() is now private to Compaction class and automatically called on construction/destruction.
* SetupBottommostLevel() is gone. Compaction figures it out on its own based on the input.
* CompactionPicker's functions are not passing around Compaction object anymore. They are only passing around the state that they need.

Test Plan:
make check
make asan_check
make valgrind_check

Reviewers: rven, anthony, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: sdong, yhchiang, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D36687
2015-04-10 15:01:54 -07:00

190 lines
6.6 KiB
C++

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include <map>
#include <string>
#include "db/compaction_job.h"
#include "db/column_family.h"
#include "db/version_set.h"
#include "db/writebuffer.h"
#include "rocksdb/cache.h"
#include "rocksdb/options.h"
#include "rocksdb/db.h"
#include "util/string_util.h"
#include "util/testharness.h"
#include "util/testutil.h"
#include "table/mock_table.h"
namespace rocksdb {
// TODO(icanadi) Make it simpler once we mock out VersionSet
class CompactionJobTest : public testing::Test {
public:
CompactionJobTest()
: env_(Env::Default()),
dbname_(test::TmpDir() + "/compaction_job_test"),
mutable_cf_options_(Options(), ImmutableCFOptions(Options())),
table_cache_(NewLRUCache(50000, 16)),
write_buffer_(db_options_.db_write_buffer_size),
versions_(new VersionSet(dbname_, &db_options_, env_options_,
table_cache_.get(), &write_buffer_,
&write_controller_)),
shutting_down_(false),
mock_table_factory_(new mock::MockTableFactory()) {
EXPECT_OK(env_->CreateDirIfMissing(dbname_));
db_options_.db_paths.emplace_back(dbname_,
std::numeric_limits<uint64_t>::max());
NewDB();
std::vector<ColumnFamilyDescriptor> column_families;
cf_options_.table_factory = mock_table_factory_;
column_families.emplace_back(kDefaultColumnFamilyName, cf_options_);
EXPECT_OK(versions_->Recover(column_families, false));
}
std::string GenerateFileName(uint64_t file_number) {
FileMetaData meta;
std::vector<DbPath> db_paths;
db_paths.emplace_back(dbname_, std::numeric_limits<uint64_t>::max());
meta.fd = FileDescriptor(file_number, 0, 0);
return TableFileName(db_paths, meta.fd.GetNumber(), meta.fd.GetPathId());
}
// returns expected result after compaction
mock::MockFileContents CreateTwoFiles() {
mock::MockFileContents expected_results;
const int kKeysPerFile = 10000;
SequenceNumber sequence_number = 0;
for (int i = 0; i < 2; ++i) {
mock::MockFileContents contents;
SequenceNumber smallest_seqno = 0, largest_seqno = 0;
InternalKey smallest, largest;
for (int k = 0; k < kKeysPerFile; ++k) {
auto key = ToString(i * (kKeysPerFile / 2) + k);
auto value = ToString(i * kKeysPerFile + k);
InternalKey internal_key(key, ++sequence_number, kTypeValue);
// This is how the key will look like once it's written in bottommost
// file
InternalKey bottommost_internal_key(key, 0, kTypeValue);
if (k == 0) {
smallest = internal_key;
smallest_seqno = sequence_number;
} else if (k == kKeysPerFile - 1) {
largest = internal_key;
largest_seqno = sequence_number;
}
std::pair<std::string, std::string> key_value(
{bottommost_internal_key.Encode().ToString(), value});
contents.insert(key_value);
if (i == 1 || k < kKeysPerFile / 2) {
expected_results.insert(key_value);
}
}
uint64_t file_number = versions_->NewFileNumber();
EXPECT_OK(mock_table_factory_->CreateMockTable(
env_, GenerateFileName(file_number), std::move(contents)));
VersionEdit edit;
edit.AddFile(0, file_number, 0, 10, smallest, largest, smallest_seqno,
largest_seqno);
mutex_.Lock();
versions_->LogAndApply(versions_->GetColumnFamilySet()->GetDefault(),
mutable_cf_options_, &edit, &mutex_);
mutex_.Unlock();
}
versions_->SetLastSequence(sequence_number);
return expected_results;
}
void NewDB() {
VersionEdit new_db;
new_db.SetLogNumber(0);
new_db.SetNextFile(2);
new_db.SetLastSequence(0);
const std::string manifest = DescriptorFileName(dbname_, 1);
unique_ptr<WritableFile> file;
Status s = env_->NewWritableFile(
manifest, &file, env_->OptimizeForManifestWrite(env_options_));
ASSERT_OK(s);
{
log::Writer log(std::move(file));
std::string record;
new_db.EncodeTo(&record);
s = log.AddRecord(record);
}
ASSERT_OK(s);
// Make "CURRENT" file that points to the new manifest file.
s = SetCurrentFile(env_, dbname_, 1, nullptr);
}
Env* env_;
std::string dbname_;
EnvOptions env_options_;
MutableCFOptions mutable_cf_options_;
std::shared_ptr<Cache> table_cache_;
WriteController write_controller_;
DBOptions db_options_;
ColumnFamilyOptions cf_options_;
WriteBuffer write_buffer_;
std::unique_ptr<VersionSet> versions_;
InstrumentedMutex mutex_;
std::atomic<bool> shutting_down_;
std::shared_ptr<mock::MockTableFactory> mock_table_factory_;
};
TEST_F(CompactionJobTest, Simple) {
auto cfd = versions_->GetColumnFamilySet()->GetDefault();
auto expected_results = CreateTwoFiles();
auto files = cfd->current()->storage_info()->LevelFiles(0);
ASSERT_EQ(2U, files.size());
CompactionInputFiles compaction_input_files;
compaction_input_files.level = 0;
compaction_input_files.files.push_back(files[0]);
compaction_input_files.files.push_back(files[1]);
std::unique_ptr<Compaction> compaction(new Compaction(
cfd->current()->storage_info(), *cfd->GetLatestMutableCFOptions(),
{compaction_input_files}, 1, 1024 * 1024, 10, 0, kNoCompression, {}));
compaction->SetInputVersion(cfd->current());
SnapshotList snapshots;
int yield_callback_called = 0;
std::function<uint64_t()> yield_callback = [&]() {
yield_callback_called++;
return 0;
};
LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL, db_options_.info_log.get());
mutex_.Lock();
CompactionJob compaction_job(0, compaction.get(), db_options_,
*cfd->GetLatestMutableCFOptions(), env_options_,
versions_.get(), &shutting_down_, &log_buffer,
nullptr, nullptr, nullptr, &snapshots, true,
table_cache_, std::move(yield_callback));
compaction_job.Prepare();
mutex_.Unlock();
ASSERT_OK(compaction_job.Run());
mutex_.Lock();
Status s;
compaction_job.Install(&s, &mutex_);
ASSERT_OK(s);
mutex_.Unlock();
mock_table_factory_->AssertLatestFile(expected_results);
ASSERT_EQ(yield_callback_called, 20000);
}
} // namespace rocksdb
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}