From 251ebf5dc70129ad3c38193fe6c99a5b0ec6b9fa Mon Sep 17 00:00:00 2001 From: Sanjay Ghemawat Date: Thu, 11 Dec 2014 08:13:18 -0800 Subject: [PATCH] LevelDB now attempts to reuse the preceding MANIFEST and log file when re-opened. (Based on a suggestion by cmumford.) "open" benchmark on my workstation speeds up significantly since we can now avoid three fdatasync calls and a compaction per open: Before: ~80000 microseconds After: ~130 microseconds Details: (1) Added Options::reuse_logs (currently defaults to false) to control new behavior. The intention is to change the default to true after some baking. (2) Added Env::NewAppendableFile() whose default implementation returns a not-supported error. (3) VersionSet::Recovery attempts to reuse the MANIFEST from which it is recovering. (4) DBImpl recovery attempts to reuse the last log file and memtable. (5) db_test.cc now tests a new configuration that sets reuse_logs to true. (6) fault_injection_test also tests a reuse_logs==true config. (7) Added a new recovery_test. --- Makefile | 4 + db/corruption_test.cc | 2 +- db/db_bench.cc | 7 + db/db_impl.cc | 178 +++++++++++-------- db/db_impl.h | 8 +- db/db_test.cc | 21 ++- db/fault_injection_test.cc | 148 +++++++++------- db/log_test.cc | 24 ++- db/log_writer.cc | 17 +- db/log_writer.h | 6 + db/recovery_test.cc | 324 ++++++++++++++++++++++++++++++++++ db/version_set.cc | 37 +++- db/version_set.h | 4 +- helpers/memenv/memenv.cc | 13 ++ helpers/memenv/memenv_test.cc | 13 +- include/leveldb/env.h | 18 ++ include/leveldb/options.h | 6 + include/leveldb/status.h | 3 + util/env.cc | 4 + util/env_posix.cc | 13 ++ util/options.cc | 2 +- util/testutil.h | 10 ++ 22 files changed, 707 insertions(+), 155 deletions(-) create mode 100644 db/recovery_test.cc diff --git a/Makefile b/Makefile index 24f214a..b1a1702 100644 --- a/Makefile +++ b/Makefile @@ -57,6 +57,7 @@ TESTS = \ issue200_test \ log_test \ memenv_test \ + recovery_test \ skiplist_test \ table_test \ version_edit_test \ @@ -177,6 +178,9 @@ issue200_test: issues/issue200_test.o $(LIBOBJECTS) $(TESTHARNESS) log_test: db/log_test.o $(LIBOBJECTS) $(TESTHARNESS) $(CXX) $(LDFLAGS) db/log_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS) +recovery_test: db/recovery_test.o $(LIBOBJECTS) $(TESTHARNESS) + $(CXX) $(LDFLAGS) db/recovery_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS) + table_test: table/table_test.o $(LIBOBJECTS) $(TESTHARNESS) $(CXX) $(LDFLAGS) table/table_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LIBS) diff --git a/db/corruption_test.cc b/db/corruption_test.cc index 96afc68..37a484d 100644 --- a/db/corruption_test.cc +++ b/db/corruption_test.cc @@ -36,7 +36,7 @@ class CorruptionTest { tiny_cache_ = NewLRUCache(100); options_.env = &env_; options_.block_cache = tiny_cache_; - dbname_ = test::TmpDir() + "/db_test"; + dbname_ = test::TmpDir() + "/corruption_test"; DestroyDB(dbname_, options_); db_ = NULL; diff --git a/db/db_bench.cc b/db/db_bench.cc index e5975bd..691fd28 100644 --- a/db/db_bench.cc +++ b/db/db_bench.cc @@ -100,6 +100,9 @@ static int FLAGS_bloom_bits = -1; // benchmark will fail. static bool FLAGS_use_existing_db = false; +// If true, reuse existing log/MANIFEST files when re-opening a database. +static bool FLAGS_reuse_logs = false; + // Use the db with the following name. static const char* FLAGS_db = NULL; @@ -700,6 +703,7 @@ class Benchmark { options.write_buffer_size = FLAGS_write_buffer_size; options.max_open_files = FLAGS_open_files; options.filter_policy = filter_policy_; + options.reuse_logs = FLAGS_reuse_logs; Status s = DB::Open(options, FLAGS_db, &db_); if (!s.ok()) { fprintf(stderr, "open error: %s\n", s.ToString().c_str()); @@ -954,6 +958,9 @@ int main(int argc, char** argv) { } else if (sscanf(argv[i], "--use_existing_db=%d%c", &n, &junk) == 1 && (n == 0 || n == 1)) { FLAGS_use_existing_db = n; + } else if (sscanf(argv[i], "--reuse_logs=%d%c", &n, &junk) == 1 && + (n == 0 || n == 1)) { + FLAGS_reuse_logs = n; } else if (sscanf(argv[i], "--num=%d%c", &n, &junk) == 1) { FLAGS_num = n; } else if (sscanf(argv[i], "--reads=%d%c", &n, &junk) == 1) { diff --git a/db/db_impl.cc b/db/db_impl.cc index 49b9595..3fd21b0 100644 --- a/db/db_impl.cc +++ b/db/db_impl.cc @@ -125,7 +125,7 @@ DBImpl::DBImpl(const Options& raw_options, const std::string& dbname) db_lock_(NULL), shutting_down_(NULL), bg_cv_(&mutex_), - mem_(new MemTable(internal_comparator_)), + mem_(NULL), imm_(NULL), logfile_(NULL), logfile_number_(0), @@ -134,7 +134,6 @@ DBImpl::DBImpl(const Options& raw_options, const std::string& dbname) tmp_batch_(new WriteBatch), bg_compaction_scheduled_(false), manual_compaction_(NULL) { - mem_->Ref(); has_imm_.Release_Store(NULL); // Reserve ten files or so for other uses and give the rest to TableCache. @@ -271,7 +270,7 @@ void DBImpl::DeleteObsoleteFiles() { } } -Status DBImpl::Recover(VersionEdit* edit) { +Status DBImpl::Recover(VersionEdit* edit, bool *save_manifest) { mutex_.AssertHeld(); // Ignore error from CreateDir since the creation of the DB is @@ -301,66 +300,69 @@ Status DBImpl::Recover(VersionEdit* edit) { } } - s = versions_->Recover(); - if (s.ok()) { - SequenceNumber max_sequence(0); + s = versions_->Recover(save_manifest); + if (!s.ok()) { + return s; + } + SequenceNumber max_sequence(0); - // Recover from all newer log files than the ones named in the - // descriptor (new log files may have been added by the previous - // incarnation without registering them in the descriptor). - // - // Note that PrevLogNumber() is no longer used, but we pay - // attention to it in case we are recovering a database - // produced by an older version of leveldb. - const uint64_t min_log = versions_->LogNumber(); - const uint64_t prev_log = versions_->PrevLogNumber(); - std::vector filenames; - s = env_->GetChildren(dbname_, &filenames); + // Recover from all newer log files than the ones named in the + // descriptor (new log files may have been added by the previous + // incarnation without registering them in the descriptor). + // + // Note that PrevLogNumber() is no longer used, but we pay + // attention to it in case we are recovering a database + // produced by an older version of leveldb. + const uint64_t min_log = versions_->LogNumber(); + const uint64_t prev_log = versions_->PrevLogNumber(); + std::vector filenames; + s = env_->GetChildren(dbname_, &filenames); + if (!s.ok()) { + return s; + } + std::set expected; + versions_->AddLiveFiles(&expected); + uint64_t number; + FileType type; + std::vector logs; + for (size_t i = 0; i < filenames.size(); i++) { + if (ParseFileName(filenames[i], &number, &type)) { + expected.erase(number); + if (type == kLogFile && ((number >= min_log) || (number == prev_log))) + logs.push_back(number); + } + } + if (!expected.empty()) { + char buf[50]; + snprintf(buf, sizeof(buf), "%d missing files; e.g.", + static_cast(expected.size())); + return Status::Corruption(buf, TableFileName(dbname_, *(expected.begin()))); + } + + // Recover in the order in which the logs were generated + std::sort(logs.begin(), logs.end()); + for (size_t i = 0; i < logs.size(); i++) { + s = RecoverLogFile(logs[i], (i == logs.size() - 1), save_manifest, edit, + &max_sequence); if (!s.ok()) { return s; } - std::set expected; - versions_->AddLiveFiles(&expected); - uint64_t number; - FileType type; - std::vector logs; - for (size_t i = 0; i < filenames.size(); i++) { - if (ParseFileName(filenames[i], &number, &type)) { - expected.erase(number); - if (type == kLogFile && ((number >= min_log) || (number == prev_log))) - logs.push_back(number); - } - } - if (!expected.empty()) { - char buf[50]; - snprintf(buf, sizeof(buf), "%d missing files; e.g.", - static_cast(expected.size())); - return Status::Corruption(buf, TableFileName(dbname_, *(expected.begin()))); - } - // Recover in the order in which the logs were generated - std::sort(logs.begin(), logs.end()); - for (size_t i = 0; i < logs.size(); i++) { - s = RecoverLogFile(logs[i], edit, &max_sequence); - - // The previous incarnation may not have written any MANIFEST - // records after allocating this log number. So we manually - // update the file number allocation counter in VersionSet. - versions_->MarkFileNumberUsed(logs[i]); - } - - if (s.ok()) { - if (versions_->LastSequence() < max_sequence) { - versions_->SetLastSequence(max_sequence); - } - } + // The previous incarnation may not have written any MANIFEST + // records after allocating this log number. So we manually + // update the file number allocation counter in VersionSet. + versions_->MarkFileNumberUsed(logs[i]); } - return s; + if (versions_->LastSequence() < max_sequence) { + versions_->SetLastSequence(max_sequence); + } + + return Status::OK(); } -Status DBImpl::RecoverLogFile(uint64_t log_number, - VersionEdit* edit, +Status DBImpl::RecoverLogFile(uint64_t log_number, bool last_log, + bool* save_manifest, VersionEdit* edit, SequenceNumber* max_sequence) { struct LogReporter : public log::Reader::Reporter { Env* env; @@ -405,6 +407,7 @@ Status DBImpl::RecoverLogFile(uint64_t log_number, std::string scratch; Slice record; WriteBatch batch; + int compactions = 0; MemTable* mem = NULL; while (reader.ReadRecord(&record, &scratch) && status.ok()) { @@ -432,25 +435,52 @@ Status DBImpl::RecoverLogFile(uint64_t log_number, } if (mem->ApproximateMemoryUsage() > options_.write_buffer_size) { + compactions++; + *save_manifest = true; status = WriteLevel0Table(mem, edit, NULL); + mem->Unref(); + mem = NULL; if (!status.ok()) { // Reflect errors immediately so that conditions like full // file-systems cause the DB::Open() to fail. break; } - mem->Unref(); - mem = NULL; } } - if (status.ok() && mem != NULL) { - status = WriteLevel0Table(mem, edit, NULL); - // Reflect errors immediately so that conditions like full - // file-systems cause the DB::Open() to fail. + delete file; + + // See if we should keep reusing the last log file. + if (status.ok() && options_.reuse_logs && last_log && compactions == 0) { + assert(logfile_ == NULL); + assert(log_ == NULL); + assert(mem_ == NULL); + uint64_t lfile_size; + if (env_->GetFileSize(fname, &lfile_size).ok() && + env_->NewAppendableFile(fname, &logfile_).ok()) { + Log(options_.info_log, "Reusing old log %s \n", fname.c_str()); + log_ = new log::Writer(logfile_, lfile_size); + logfile_number_ = log_number; + if (mem != NULL) { + mem_ = mem; + mem = NULL; + } else { + // mem can be NULL if lognum exists but was empty. + mem_ = new MemTable(internal_comparator_); + mem_->Ref(); + } + } + } + + if (mem != NULL) { + // mem did not get reused; compact it. + if (status.ok()) { + *save_manifest = true; + status = WriteLevel0Table(mem, edit, NULL); + } + mem->Unref(); } - if (mem != NULL) mem->Unref(); - delete file; return status; } @@ -1449,8 +1479,11 @@ Status DB::Open(const Options& options, const std::string& dbname, DBImpl* impl = new DBImpl(options, dbname); impl->mutex_.Lock(); VersionEdit edit; - Status s = impl->Recover(&edit); // Handles create_if_missing, error_if_exists - if (s.ok()) { + // Recover handles create_if_missing, error_if_exists + bool save_manifest = false; + Status s = impl->Recover(&edit, &save_manifest); + if (s.ok() && impl->mem_ == NULL) { + // Create new log and a corresponding memtable. uint64_t new_log_number = impl->versions_->NewFileNumber(); WritableFile* lfile; s = options.env->NewWritableFile(LogFileName(dbname, new_log_number), @@ -1460,15 +1493,22 @@ Status DB::Open(const Options& options, const std::string& dbname, impl->logfile_ = lfile; impl->logfile_number_ = new_log_number; impl->log_ = new log::Writer(lfile); - s = impl->versions_->LogAndApply(&edit, &impl->mutex_); - } - if (s.ok()) { - impl->DeleteObsoleteFiles(); - impl->MaybeScheduleCompaction(); + impl->mem_ = new MemTable(impl->internal_comparator_); + impl->mem_->Ref(); } } + if (s.ok() && save_manifest) { + edit.SetPrevLogNumber(0); // No older logs needed after recovery. + edit.SetLogNumber(impl->logfile_number_); + s = impl->versions_->LogAndApply(&edit, &impl->mutex_); + } + if (s.ok()) { + impl->DeleteObsoleteFiles(); + impl->MaybeScheduleCompaction(); + } impl->mutex_.Unlock(); if (s.ok()) { + assert(impl->mem_ != NULL); *dbptr = impl; } else { delete impl; diff --git a/db/db_impl.h b/db/db_impl.h index cfc9981..8ff323e 100644 --- a/db/db_impl.h +++ b/db/db_impl.h @@ -78,7 +78,8 @@ class DBImpl : public DB { // Recover the descriptor from persistent storage. May do a significant // amount of work to recover recently logged updates. Any changes to // be made to the descriptor are added to *edit. - Status Recover(VersionEdit* edit) EXCLUSIVE_LOCKS_REQUIRED(mutex_); + Status Recover(VersionEdit* edit, bool* save_manifest) + EXCLUSIVE_LOCKS_REQUIRED(mutex_); void MaybeIgnoreError(Status* s) const; @@ -90,9 +91,8 @@ class DBImpl : public DB { // Errors are recorded in bg_error_. void CompactMemTable() EXCLUSIVE_LOCKS_REQUIRED(mutex_); - Status RecoverLogFile(uint64_t log_number, - VersionEdit* edit, - SequenceNumber* max_sequence) + Status RecoverLogFile(uint64_t log_number, bool last_log, bool* save_manifest, + VersionEdit* edit, SequenceNumber* max_sequence) EXCLUSIVE_LOCKS_REQUIRED(mutex_); Status WriteLevel0Table(MemTable* mem, VersionEdit* edit, Version* base) diff --git a/db/db_test.cc b/db/db_test.cc index 0fed913..74ba8b0 100644 --- a/db/db_test.cc +++ b/db/db_test.cc @@ -193,6 +193,7 @@ class DBTest { // Sequence of option configurations to try enum OptionConfig { kDefault, + kReuse, kFilter, kUncompressed, kEnd @@ -237,7 +238,11 @@ class DBTest { // Return the current option configuration. Options CurrentOptions() { Options options; + options.reuse_logs = false; switch (option_config_) { + case kReuse: + options.reuse_logs = true; + break; case kFilter: options.filter_policy = filter_policy_; break; @@ -1080,6 +1085,14 @@ TEST(DBTest, ApproximateSizes) { // 0 because GetApproximateSizes() does not account for memtable space ASSERT_TRUE(Between(Size("", Key(50)), 0, 0)); + if (options.reuse_logs) { + // Recovery will reuse memtable, and GetApproximateSizes() does not + // account for memtable usage; + Reopen(&options); + ASSERT_TRUE(Between(Size("", Key(50)), 0, 0)); + continue; + } + // Check sizes across recovery by reopening a few times for (int run = 0; run < 3; run++) { Reopen(&options); @@ -1123,6 +1136,11 @@ TEST(DBTest, ApproximateSizes_MixOfSmallAndLarge) { ASSERT_OK(Put(Key(6), RandomString(&rnd, 300000))); ASSERT_OK(Put(Key(7), RandomString(&rnd, 10000))); + if (options.reuse_logs) { + // Need to force a memtable compaction since recovery does not do so. + ASSERT_OK(dbfull()->TEST_CompactMemTable()); + } + // Check sizes across recovery by reopening a few times for (int run = 0; run < 3; run++) { Reopen(&options); @@ -2084,7 +2102,8 @@ void BM_LogAndApply(int iters, int num_base_files) { InternalKeyComparator cmp(BytewiseComparator()); Options options; VersionSet vset(dbname, &options, NULL, &cmp); - ASSERT_OK(vset.Recover()); + bool save_manifest; + ASSERT_OK(vset.Recover(&save_manifest)); VersionEdit vbase; uint64_t fnum = 1; for (int i = 0; i < num_base_files; i++) { diff --git a/db/fault_injection_test.cc b/db/fault_injection_test.cc index 8e3e603..875dfe8 100644 --- a/db/fault_injection_test.cc +++ b/db/fault_injection_test.cc @@ -106,7 +106,7 @@ struct FileState { // is written to or sync'ed. class TestWritableFile : public WritableFile { public: - TestWritableFile(const std::string& fname, + TestWritableFile(const FileState& state, WritableFile* f, FaultInjectionTestEnv* env); virtual ~TestWritableFile(); @@ -130,6 +130,8 @@ class FaultInjectionTestEnv : public EnvWrapper { virtual ~FaultInjectionTestEnv() { } virtual Status NewWritableFile(const std::string& fname, WritableFile** result); + virtual Status NewAppendableFile(const std::string& fname, + WritableFile** result); virtual Status DeleteFile(const std::string& f); virtual Status RenameFile(const std::string& s, const std::string& t); @@ -154,15 +156,14 @@ class FaultInjectionTestEnv : public EnvWrapper { bool filesystem_active_; // Record flushes, syncs, writes }; -TestWritableFile::TestWritableFile(const std::string& fname, +TestWritableFile::TestWritableFile(const FileState& state, WritableFile* f, FaultInjectionTestEnv* env) - : state_(fname), + : state_(state), target_(f), writable_file_opened_(true), env_(env) { assert(f != NULL); - state_.pos_ = 0; } TestWritableFile::~TestWritableFile() { @@ -228,9 +229,12 @@ Status FaultInjectionTestEnv::NewWritableFile(const std::string& fname, WritableFile* actual_writable_file; Status s = target()->NewWritableFile(fname, &actual_writable_file); if (s.ok()) { - *result = new TestWritableFile(fname, actual_writable_file, this); - // WritableFile doesn't append to files, so if the same file is opened again - // then it will be truncated - so forget our saved state. + FileState state(fname); + state.pos_ = 0; + *result = new TestWritableFile(state, actual_writable_file, this); + // NewWritableFile doesn't append to files, so if the same file is + // opened again then it will be truncated - so forget our saved + // state. UntrackFile(fname); MutexLock l(&mutex_); new_files_since_last_dir_sync_.insert(fname); @@ -238,6 +242,26 @@ Status FaultInjectionTestEnv::NewWritableFile(const std::string& fname, return s; } +Status FaultInjectionTestEnv::NewAppendableFile(const std::string& fname, + WritableFile** result) { + WritableFile* actual_writable_file; + Status s = target()->NewAppendableFile(fname, &actual_writable_file); + if (s.ok()) { + FileState state(fname); + state.pos_ = 0; + { + MutexLock l(&mutex_); + if (db_file_state_.count(fname) == 0) { + new_files_since_last_dir_sync_.insert(fname); + } else { + state = db_file_state_[fname]; + } + } + *result = new TestWritableFile(state, actual_writable_file, this); + } + return s; +} + Status FaultInjectionTestEnv::DropUnsyncedFileData() { Status s; MutexLock l(&mutex_); @@ -301,9 +325,10 @@ Status FaultInjectionTestEnv::RenameFile(const std::string& s, } void FaultInjectionTestEnv::ResetState() { + // Since we are not destroying the database, the existing files + // should keep their recorded synced/flushed state. Therefore + // we do not reset db_file_state_ and new_files_since_last_dir_sync_. MutexLock l(&mutex_); - db_file_state_.clear(); - new_files_since_last_dir_sync_.clear(); SetFilesystemActive(true); } @@ -342,51 +367,28 @@ class FaultInjectionTest { Options options_; DB* db_; - FaultInjectionTest() : env_(NULL), tiny_cache_(NULL), db_(NULL) { NewDB(); } - - ~FaultInjectionTest() { ASSERT_OK(TearDown()); } - - Status NewDB() { - assert(db_ == NULL); - assert(tiny_cache_ == NULL); - assert(env_ == NULL); - - env_ = new FaultInjectionTestEnv(); - - options_ = Options(); + FaultInjectionTest() + : env_(new FaultInjectionTestEnv), + tiny_cache_(NewLRUCache(100)), + db_(NULL) { + dbname_ = test::TmpDir() + "/fault_test"; + DestroyDB(dbname_, Options()); // Destroy any db from earlier run + options_.reuse_logs = true; options_.env = env_; options_.paranoid_checks = true; - - tiny_cache_ = NewLRUCache(100); options_.block_cache = tiny_cache_; - dbname_ = test::TmpDir() + "/fault_test"; - options_.create_if_missing = true; - Status s = OpenDB(); - options_.create_if_missing = false; - return s; } - Status SetUp() { - Status s = TearDown(); - if (s.ok()) { - s = NewDB(); - } - return s; - } - - Status TearDown() { + ~FaultInjectionTest() { CloseDB(); - - Status s = DestroyDB(dbname_, Options()); - + DestroyDB(dbname_, Options()); delete tiny_cache_; - tiny_cache_ = NULL; - delete env_; - env_ = NULL; + } - return s; + void ReuseLogs(bool reuse) { + options_.reuse_logs = reuse; } void Build(int start_idx, int num_vals) { @@ -506,33 +508,43 @@ class FaultInjectionTest { ResetDBState(reset_method); ASSERT_OK(OpenDB()); } + + void DoTest() { + Random rnd(0); + ASSERT_OK(OpenDB()); + for (size_t idx = 0; idx < kNumIterations; idx++) { + int num_pre_sync = rnd.Uniform(kMaxNumValues); + int num_post_sync = rnd.Uniform(kMaxNumValues); + + PartialCompactTestPreFault(num_pre_sync, num_post_sync); + PartialCompactTestReopenWithFault(RESET_DROP_UNSYNCED_DATA, + num_pre_sync, + num_post_sync); + + NoWriteTestPreFault(); + NoWriteTestReopenWithFault(RESET_DROP_UNSYNCED_DATA); + + PartialCompactTestPreFault(num_pre_sync, num_post_sync); + // No new files created so we expect all values since no files will be + // dropped. + PartialCompactTestReopenWithFault(RESET_DELETE_UNSYNCED_FILES, + num_pre_sync + num_post_sync, + 0); + + NoWriteTestPreFault(); + NoWriteTestReopenWithFault(RESET_DELETE_UNSYNCED_FILES); + } + } }; -TEST(FaultInjectionTest, FaultTest) { - Random rnd(0); - ASSERT_OK(SetUp()); - for (size_t idx = 0; idx < kNumIterations; idx++) { - int num_pre_sync = rnd.Uniform(kMaxNumValues); - int num_post_sync = rnd.Uniform(kMaxNumValues); +TEST(FaultInjectionTest, FaultTestNoLogReuse) { + ReuseLogs(false); + DoTest(); +} - PartialCompactTestPreFault(num_pre_sync, num_post_sync); - PartialCompactTestReopenWithFault(RESET_DROP_UNSYNCED_DATA, - num_pre_sync, - num_post_sync); - - NoWriteTestPreFault(); - NoWriteTestReopenWithFault(RESET_DROP_UNSYNCED_DATA); - - PartialCompactTestPreFault(num_pre_sync, num_post_sync); - // No new files created so we expect all values since no files will be - // dropped. - PartialCompactTestReopenWithFault(RESET_DELETE_UNSYNCED_FILES, - num_pre_sync + num_post_sync, - 0); - - NoWriteTestPreFault(); - NoWriteTestReopenWithFault(RESET_DELETE_UNSYNCED_FILES); - } +TEST(FaultInjectionTest, FaultTestWithLogReuse) { + ReuseLogs(true); + DoTest(); } } // namespace leveldb diff --git a/db/log_test.cc b/db/log_test.cc index dcf0562..11e4a47 100644 --- a/db/log_test.cc +++ b/db/log_test.cc @@ -104,7 +104,7 @@ class LogTest { StringSource source_; ReportCollector report_; bool reading_; - Writer writer_; + Writer* writer_; Reader reader_; // Record metadata for testing initial offset functionality @@ -113,14 +113,23 @@ class LogTest { public: LogTest() : reading_(false), - writer_(&dest_), + writer_(new Writer(&dest_)), reader_(&source_, &report_, true/*checksum*/, 0/*initial_offset*/) { } + ~LogTest() { + delete writer_; + } + + void ReopenForAppend() { + delete writer_; + writer_ = new Writer(&dest_, dest_.contents_.size()); + } + void Write(const std::string& msg) { ASSERT_TRUE(!reading_) << "Write() after starting to read"; - writer_.AddRecord(Slice(msg)); + writer_->AddRecord(Slice(msg)); } size_t WrittenBytes() const { @@ -318,6 +327,15 @@ TEST(LogTest, AlignedEof) { ASSERT_EQ("EOF", Read()); } +TEST(LogTest, OpenForAppend) { + Write("hello"); + ReopenForAppend(); + Write("world"); + ASSERT_EQ("hello", Read()); + ASSERT_EQ("world", Read()); + ASSERT_EQ("EOF", Read()); +} + TEST(LogTest, RandomRead) { const int N = 500; Random write_rnd(301); diff --git a/db/log_writer.cc b/db/log_writer.cc index 2da99ac..74a0327 100644 --- a/db/log_writer.cc +++ b/db/log_writer.cc @@ -12,13 +12,22 @@ namespace leveldb { namespace log { +static void InitTypeCrc(uint32_t* type_crc) { + for (int i = 0; i <= kMaxRecordType; i++) { + char t = static_cast(i); + type_crc[i] = crc32c::Value(&t, 1); + } +} + Writer::Writer(WritableFile* dest) : dest_(dest), block_offset_(0) { - for (int i = 0; i <= kMaxRecordType; i++) { - char t = static_cast(i); - type_crc_[i] = crc32c::Value(&t, 1); - } + InitTypeCrc(type_crc_); +} + +Writer::Writer(WritableFile* dest, uint64_t dest_length) + : dest_(dest), block_offset_(dest_length % kBlockSize) { + InitTypeCrc(type_crc_); } Writer::~Writer() { diff --git a/db/log_writer.h b/db/log_writer.h index a3a954d..9e7cc47 100644 --- a/db/log_writer.h +++ b/db/log_writer.h @@ -22,6 +22,12 @@ class Writer { // "*dest" must be initially empty. // "*dest" must remain live while this Writer is in use. explicit Writer(WritableFile* dest); + + // Create a writer that will append data to "*dest". + // "*dest" must have initial length "dest_length". + // "*dest" must remain live while this Writer is in use. + Writer(WritableFile* dest, uint64_t dest_length); + ~Writer(); Status AddRecord(const Slice& slice); diff --git a/db/recovery_test.cc b/db/recovery_test.cc new file mode 100644 index 0000000..e0d0bf8 --- /dev/null +++ b/db/recovery_test.cc @@ -0,0 +1,324 @@ +// Copyright (c) 2014 The LevelDB Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. See the AUTHORS file for names of contributors. + +#include "db/db_impl.h" +#include "db/filename.h" +#include "db/version_set.h" +#include "db/write_batch_internal.h" +#include "leveldb/db.h" +#include "leveldb/env.h" +#include "leveldb/write_batch.h" +#include "util/logging.h" +#include "util/testharness.h" +#include "util/testutil.h" + +namespace leveldb { + +class RecoveryTest { + public: + RecoveryTest() : env_(Env::Default()), db_(NULL) { + dbname_ = test::TmpDir() + "/recovery_test"; + DestroyDB(dbname_, Options()); + Open(); + } + + ~RecoveryTest() { + Close(); + DestroyDB(dbname_, Options()); + } + + DBImpl* dbfull() const { return reinterpret_cast(db_); } + Env* env() const { return env_; } + + bool CanAppend() { + WritableFile* tmp; + Status s = env_->NewAppendableFile(CurrentFileName(dbname_), &tmp); + delete tmp; + if (s.IsNotSupportedError()) { + return false; + } else { + return true; + } + } + + void Close() { + delete db_; + db_ = NULL; + } + + void Open(Options* options = NULL) { + Close(); + Options opts; + if (options != NULL) { + opts = *options; + } else { + opts.reuse_logs = true; // TODO(sanjay): test both ways + opts.create_if_missing = true; + } + if (opts.env == NULL) { + opts.env = env_; + } + ASSERT_OK(DB::Open(opts, dbname_, &db_)); + ASSERT_EQ(1, NumLogs()); + } + + Status Put(const std::string& k, const std::string& v) { + return db_->Put(WriteOptions(), k, v); + } + + std::string Get(const std::string& k, const Snapshot* snapshot = NULL) { + std::string result; + Status s = db_->Get(ReadOptions(), k, &result); + if (s.IsNotFound()) { + result = "NOT_FOUND"; + } else if (!s.ok()) { + result = s.ToString(); + } + return result; + } + + std::string ManifestFileName() { + std::string current; + ASSERT_OK(ReadFileToString(env_, CurrentFileName(dbname_), ¤t)); + size_t len = current.size(); + if (len > 0 && current[len-1] == '\n') { + current.resize(len - 1); + } + return dbname_ + "/" + current; + } + + std::string LogName(uint64_t number) { + return LogFileName(dbname_, number); + } + + size_t DeleteLogFiles() { + std::vector logs = GetFiles(kLogFile); + for (size_t i = 0; i < logs.size(); i++) { + ASSERT_OK(env_->DeleteFile(LogName(logs[i]))) << LogName(logs[i]); + } + return logs.size(); + } + + uint64_t FirstLogFile() { + return GetFiles(kLogFile)[0]; + } + + std::vector GetFiles(FileType t) { + std::vector filenames; + ASSERT_OK(env_->GetChildren(dbname_, &filenames)); + std::vector result; + for (size_t i = 0; i < filenames.size(); i++) { + uint64_t number; + FileType type; + if (ParseFileName(filenames[i], &number, &type) && type == t) { + result.push_back(number); + } + } + return result; + } + + int NumLogs() { + return GetFiles(kLogFile).size(); + } + + int NumTables() { + return GetFiles(kTableFile).size(); + } + + uint64_t FileSize(const std::string& fname) { + uint64_t result; + ASSERT_OK(env_->GetFileSize(fname, &result)) << fname; + return result; + } + + void CompactMemTable() { + dbfull()->TEST_CompactMemTable(); + } + + // Directly construct a log file that sets key to val. + void MakeLogFile(uint64_t lognum, SequenceNumber seq, Slice key, Slice val) { + std::string fname = LogFileName(dbname_, lognum); + WritableFile* file; + ASSERT_OK(env_->NewWritableFile(fname, &file)); + log::Writer writer(file); + WriteBatch batch; + batch.Put(key, val); + WriteBatchInternal::SetSequence(&batch, seq); + ASSERT_OK(writer.AddRecord(WriteBatchInternal::Contents(&batch))); + ASSERT_OK(file->Flush()); + delete file; + } + + private: + std::string dbname_; + Env* env_; + DB* db_; +}; + +TEST(RecoveryTest, ManifestReused) { + if (!CanAppend()) { + fprintf(stderr, "skipping test because env does not support appending\n"); + return; + } + ASSERT_OK(Put("foo", "bar")); + Close(); + std::string old_manifest = ManifestFileName(); + Open(); + ASSERT_EQ(old_manifest, ManifestFileName()); + ASSERT_EQ("bar", Get("foo")); + Open(); + ASSERT_EQ(old_manifest, ManifestFileName()); + ASSERT_EQ("bar", Get("foo")); +} + +TEST(RecoveryTest, LargeManifestCompacted) { + if (!CanAppend()) { + fprintf(stderr, "skipping test because env does not support appending\n"); + return; + } + ASSERT_OK(Put("foo", "bar")); + Close(); + std::string old_manifest = ManifestFileName(); + + // Pad with zeroes to make manifest file very big. + { + uint64_t len = FileSize(old_manifest); + WritableFile* file; + ASSERT_OK(env()->NewAppendableFile(old_manifest, &file)); + std::string zeroes(3*1048576 - static_cast(len), 0); + ASSERT_OK(file->Append(zeroes)); + ASSERT_OK(file->Flush()); + delete file; + } + + Open(); + std::string new_manifest = ManifestFileName(); + ASSERT_NE(old_manifest, new_manifest); + ASSERT_GT(10000, FileSize(new_manifest)); + ASSERT_EQ("bar", Get("foo")); + + Open(); + ASSERT_EQ(new_manifest, ManifestFileName()); + ASSERT_EQ("bar", Get("foo")); +} + +TEST(RecoveryTest, NoLogFiles) { + ASSERT_OK(Put("foo", "bar")); + ASSERT_EQ(1, DeleteLogFiles()); + Open(); + ASSERT_EQ("NOT_FOUND", Get("foo")); + Open(); + ASSERT_EQ("NOT_FOUND", Get("foo")); +} + +TEST(RecoveryTest, LogFileReuse) { + if (!CanAppend()) { + fprintf(stderr, "skipping test because env does not support appending\n"); + return; + } + for (int i = 0; i < 2; i++) { + ASSERT_OK(Put("foo", "bar")); + if (i == 0) { + // Compact to ensure current log is empty + CompactMemTable(); + } + Close(); + ASSERT_EQ(1, NumLogs()); + uint64_t number = FirstLogFile(); + if (i == 0) { + ASSERT_EQ(0, FileSize(LogName(number))); + } else { + ASSERT_LT(0, FileSize(LogName(number))); + } + Open(); + ASSERT_EQ(1, NumLogs()); + ASSERT_EQ(number, FirstLogFile()) << "did not reuse log file"; + ASSERT_EQ("bar", Get("foo")); + Open(); + ASSERT_EQ(1, NumLogs()); + ASSERT_EQ(number, FirstLogFile()) << "did not reuse log file"; + ASSERT_EQ("bar", Get("foo")); + } +} + +TEST(RecoveryTest, MultipleMemTables) { + // Make a large log. + const int kNum = 1000; + for (int i = 0; i < kNum; i++) { + char buf[100]; + snprintf(buf, sizeof(buf), "%050d", i); + ASSERT_OK(Put(buf, buf)); + } + ASSERT_EQ(0, NumTables()); + Close(); + ASSERT_EQ(0, NumTables()); + ASSERT_EQ(1, NumLogs()); + uint64_t old_log_file = FirstLogFile(); + + // Force creation of multiple memtables by reducing the write buffer size. + Options opt; + opt.reuse_logs = true; + opt.write_buffer_size = (kNum*100) / 2; + Open(&opt); + ASSERT_LE(2, NumTables()); + ASSERT_EQ(1, NumLogs()); + ASSERT_NE(old_log_file, FirstLogFile()) << "must not reuse log"; + for (int i = 0; i < kNum; i++) { + char buf[100]; + snprintf(buf, sizeof(buf), "%050d", i); + ASSERT_EQ(buf, Get(buf)); + } +} + +TEST(RecoveryTest, MultipleLogFiles) { + ASSERT_OK(Put("foo", "bar")); + Close(); + ASSERT_EQ(1, NumLogs()); + + // Make a bunch of uncompacted log files. + uint64_t old_log = FirstLogFile(); + MakeLogFile(old_log+1, 1000, "hello", "world"); + MakeLogFile(old_log+2, 1001, "hi", "there"); + MakeLogFile(old_log+3, 1002, "foo", "bar2"); + + // Recover and check that all log files were processed. + Open(); + ASSERT_LE(1, NumTables()); + ASSERT_EQ(1, NumLogs()); + uint64_t new_log = FirstLogFile(); + ASSERT_LE(old_log+3, new_log); + ASSERT_EQ("bar2", Get("foo")); + ASSERT_EQ("world", Get("hello")); + ASSERT_EQ("there", Get("hi")); + + // Test that previous recovery produced recoverable state. + Open(); + ASSERT_LE(1, NumTables()); + ASSERT_EQ(1, NumLogs()); + if (CanAppend()) { + ASSERT_EQ(new_log, FirstLogFile()); + } + ASSERT_EQ("bar2", Get("foo")); + ASSERT_EQ("world", Get("hello")); + ASSERT_EQ("there", Get("hi")); + + // Check that introducing an older log file does not cause it to be re-read. + Close(); + MakeLogFile(old_log+1, 2000, "hello", "stale write"); + Open(); + ASSERT_LE(1, NumTables()); + ASSERT_EQ(1, NumLogs()); + if (CanAppend()) { + ASSERT_EQ(new_log, FirstLogFile()); + } + ASSERT_EQ("bar2", Get("foo")); + ASSERT_EQ("world", Get("hello")); + ASSERT_EQ("there", Get("hi")); +} + +} // namespace leveldb + +int main(int argc, char** argv) { + return leveldb::test::RunAllTests(); +} diff --git a/db/version_set.cc b/db/version_set.cc index aa83df5..a07e7ec 100644 --- a/db/version_set.cc +++ b/db/version_set.cc @@ -893,7 +893,7 @@ Status VersionSet::LogAndApply(VersionEdit* edit, port::Mutex* mu) { return s; } -Status VersionSet::Recover() { +Status VersionSet::Recover(bool *save_manifest) { struct LogReporter : public log::Reader::Reporter { Status* status; virtual void Corruption(size_t bytes, const Status& s) { @@ -1003,11 +1003,46 @@ Status VersionSet::Recover() { last_sequence_ = last_sequence; log_number_ = log_number; prev_log_number_ = prev_log_number; + + // See if we can reuse the existing MANIFEST file. + if (ReuseManifest(dscname, current)) { + // No need to save new manifest + } else { + *save_manifest = true; + } } return s; } +bool VersionSet::ReuseManifest(const std::string& dscname, + const std::string& dscbase) { + FileType manifest_type; + uint64_t manifest_number; + uint64_t manifest_size; + if (!ParseFileName(dscbase, &manifest_number, &manifest_type) || + manifest_type != kDescriptorFile || + !env_->GetFileSize(dscname, &manifest_size).ok() || + // Make new compacted MANIFEST if old one is too big + manifest_size >= kTargetFileSize) { + return false; + } + + assert(descriptor_file_ == NULL); + assert(descriptor_log_ == NULL); + Status r = env_->NewAppendableFile(dscname, &descriptor_file_); + if (!r.ok()) { + Log(options_->info_log, "Reuse MANIFEST: %s\n", r.ToString().c_str()); + assert(descriptor_file_ == NULL); + return false; + } + + Log(options_->info_log, "Reusing MANIFEST %s\n", dscname.c_str()); + descriptor_log_ = new log::Writer(descriptor_file_, manifest_size); + manifest_file_number_ = manifest_number; + return true; +} + void VersionSet::MarkFileNumberUsed(uint64_t number) { if (next_file_number_ <= number) { next_file_number_ = number + 1; diff --git a/db/version_set.h b/db/version_set.h index 8dc14b8..1dec745 100644 --- a/db/version_set.h +++ b/db/version_set.h @@ -179,7 +179,7 @@ class VersionSet { EXCLUSIVE_LOCKS_REQUIRED(mu); // Recover the last saved descriptor from persistent storage. - Status Recover(); + Status Recover(bool *save_manifest); // Return the current version. Version* current() const { return current_; } @@ -274,6 +274,8 @@ class VersionSet { friend class Compaction; friend class Version; + bool ReuseManifest(const std::string& dscname, const std::string& dscbase); + void Finalize(Version* v); void GetRange(const std::vector& inputs, diff --git a/helpers/memenv/memenv.cc b/helpers/memenv/memenv.cc index 43ef2e0..9a98884 100644 --- a/helpers/memenv/memenv.cc +++ b/helpers/memenv/memenv.cc @@ -277,6 +277,19 @@ class InMemoryEnv : public EnvWrapper { return Status::OK(); } + virtual Status NewAppendableFile(const std::string& fname, + WritableFile** result) { + MutexLock lock(&mutex_); + FileState** sptr = &file_map_[fname]; + FileState* file = *sptr; + if (file == NULL) { + file = new FileState(); + file->Ref(); + } + *result = new WritableFileImpl(file); + return Status::OK(); + } + virtual bool FileExists(const std::string& fname) { MutexLock lock(&mutex_); return file_map_.find(fname) != file_map_.end(); diff --git a/helpers/memenv/memenv_test.cc b/helpers/memenv/memenv_test.cc index a44310f..5cff776 100644 --- a/helpers/memenv/memenv_test.cc +++ b/helpers/memenv/memenv_test.cc @@ -40,6 +40,8 @@ TEST(MemEnvTest, Basics) { // Create a file. ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file)); + ASSERT_OK(env_->GetFileSize("/dir/f", &file_size)); + ASSERT_EQ(0, file_size); delete writable_file; // Check that the file exists. @@ -55,9 +57,16 @@ TEST(MemEnvTest, Basics) { ASSERT_OK(writable_file->Append("abc")); delete writable_file; - // Check for expected size. + // Check that append works. + ASSERT_OK(env_->NewAppendableFile("/dir/f", &writable_file)); ASSERT_OK(env_->GetFileSize("/dir/f", &file_size)); ASSERT_EQ(3, file_size); + ASSERT_OK(writable_file->Append("hello")); + delete writable_file; + + // Check for expected size. + ASSERT_OK(env_->GetFileSize("/dir/f", &file_size)); + ASSERT_EQ(8, file_size); // Check that renaming works. ASSERT_TRUE(!env_->RenameFile("/dir/non_existent", "/dir/g").ok()); @@ -65,7 +74,7 @@ TEST(MemEnvTest, Basics) { ASSERT_TRUE(!env_->FileExists("/dir/f")); ASSERT_TRUE(env_->FileExists("/dir/g")); ASSERT_OK(env_->GetFileSize("/dir/g", &file_size)); - ASSERT_EQ(3, file_size); + ASSERT_EQ(8, file_size); // Check that opening non-existent file fails. SequentialFile* seq_file; diff --git a/include/leveldb/env.h b/include/leveldb/env.h index f709514..99b6c21 100644 --- a/include/leveldb/env.h +++ b/include/leveldb/env.h @@ -69,6 +69,21 @@ class Env { virtual Status NewWritableFile(const std::string& fname, WritableFile** result) = 0; + // Create an object that either appends to an existing file, or + // writes to a new file (if the file does not exist to begin with). + // On success, stores a pointer to the new file in *result and + // returns OK. On failure stores NULL in *result and returns + // non-OK. + // + // The returned file will only be accessed by one thread at a time. + // + // May return an IsNotSupportedError error if this Env does + // not allow appending to an existing file. Users of Env (including + // the leveldb implementation) must be prepared to deal with + // an Env that does not support appending. + virtual Status NewAppendableFile(const std::string& fname, + WritableFile** result); + // Returns true iff the named file exists. virtual bool FileExists(const std::string& fname) = 0; @@ -289,6 +304,9 @@ class EnvWrapper : public Env { Status NewWritableFile(const std::string& f, WritableFile** r) { return target_->NewWritableFile(f, r); } + Status NewAppendableFile(const std::string& f, WritableFile** r) { + return target_->NewAppendableFile(f, r); + } bool FileExists(const std::string& f) { return target_->FileExists(f); } Status GetChildren(const std::string& dir, std::vector* r) { return target_->GetChildren(dir, r); diff --git a/include/leveldb/options.h b/include/leveldb/options.h index 7c9b973..83a1ef3 100644 --- a/include/leveldb/options.h +++ b/include/leveldb/options.h @@ -128,6 +128,12 @@ struct Options { // efficiently detect that and will switch to uncompressed mode. CompressionType compression; + // EXPERIMENTAL: If true, append to existing MANIFEST and log files + // when a database is opened. This can significantly speed up open. + // + // Default: currently false, but may become true later. + bool reuse_logs; + // If non-NULL, use the specified filter policy to reduce disk reads. // Many applications will benefit from passing the result of // NewBloomFilterPolicy() here. diff --git a/include/leveldb/status.h b/include/leveldb/status.h index 11dbd4b..d2bdc22 100644 --- a/include/leveldb/status.h +++ b/include/leveldb/status.h @@ -60,6 +60,9 @@ class Status { // Returns true iff the status indicates an IOError. bool IsIOError() const { return code() == kIOError; } + // Returns true iff the status indicates a NotSupportedError. + bool IsNotSupportedError() const { return code() == kNotSupported; } + // Return a string representation of this status suitable for printing. // Returns the string "OK" for success. std::string ToString() const; diff --git a/util/env.cc b/util/env.cc index c2600e9..c58a082 100644 --- a/util/env.cc +++ b/util/env.cc @@ -9,6 +9,10 @@ namespace leveldb { Env::~Env() { } +Status Env::NewAppendableFile(const std::string& fname, WritableFile** result) { + return Status::NotSupported("NewAppendableFile", fname); +} + SequentialFile::~SequentialFile() { } diff --git a/util/env_posix.cc b/util/env_posix.cc index ad56131..a17dec2 100644 --- a/util/env_posix.cc +++ b/util/env_posix.cc @@ -350,6 +350,19 @@ class PosixEnv : public Env { return s; } + virtual Status NewAppendableFile(const std::string& fname, + WritableFile** result) { + Status s; + FILE* f = fopen(fname.c_str(), "a"); + if (f == NULL) { + *result = NULL; + s = IOError(fname, errno); + } else { + *result = new PosixWritableFile(fname, f); + } + return s; + } + virtual bool FileExists(const std::string& fname) { return access(fname.c_str(), F_OK) == 0; } diff --git a/util/options.cc b/util/options.cc index 76af5b9..8b618fb 100644 --- a/util/options.cc +++ b/util/options.cc @@ -22,8 +22,8 @@ Options::Options() block_size(4096), block_restart_interval(16), compression(kSnappyCompression), + reuse_logs(false), filter_policy(NULL) { } - } // namespace leveldb diff --git a/util/testutil.h b/util/testutil.h index adad3fc..d7e4583 100644 --- a/util/testutil.h +++ b/util/testutil.h @@ -45,6 +45,16 @@ class ErrorEnv : public EnvWrapper { } return target()->NewWritableFile(fname, result); } + + virtual Status NewAppendableFile(const std::string& fname, + WritableFile** result) { + if (writable_file_error_) { + ++num_writable_file_errors_; + *result = NULL; + return Status::IOError(fname, "fake error"); + } + return target()->NewAppendableFile(fname, result); + } }; } // namespace test