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rocksdb/db/db_impl/db_impl_debug.cc
Xingbo Wang af4e32945b Blob direct write v1: write-path blob separation with partitioned files (reduced scope) (#14535)
Summary:
This PR introduces **blob direct write v1**, a reduced-scope write-path optimization where large values (>= `min_blob_size`) are written directly to blob files during `Put()` and replaced in the memtable with compact `BlobIndex` references. This avoids holding full values in memory until flush time.

### Motivation

In the existing BlobDB architecture, values are written to the WAL and memtable in their full form and separated into blob files only at flush time. This means:
- Large values are held in memory twice (raw in memtable + blob file at flush)
- Blob I/O is serialized through a single flush thread per column family

Blob direct write addresses both: values leave the write path as small `BlobIndex` references, and multiple **partitions** (configurable via `blob_direct_write_partitions`) allow concurrent blob writes with independent locks.

### Design (v1 — single-writer, WAL-disabled, reduced scope)

The v1 design intentionally keeps scope narrow for correctness and reviewability:

- **Single writer thread assumption**: no concurrent writes to the same partition file. One logical writer serializes the batch.
- **WAL-disabled**: direct-write blob files are only registered in MANIFEST at flush time. WAL replay cannot recover unregistered blob references, so WAL is disabled for this v1.
- **Flush-on-write**: each `AddRecord` call flushes to the OS immediately.
- **FIFO generation batching**: each memtable switch creates one generation batch. Direct-write files for that memtable are sealed and registered atomically when the batch is flushed to MANIFEST.
- **Round-robin partitions**: blob writes are distributed across `blob_direct_write_partitions` files using an atomic counter.

### New components

| Component | Description |
|---|---|
| `BlobFilePartitionManager` | Owns N partition files per CF. Manages open/seal/register lifecycle tied to memtable generations. |
| `BlobWriteBatchTransformer` | A `WriteBatch::Handler` that rewrites qualifying `Put` values as `BlobIndex` entries before the batch enters the write group. |

### Write path integration

1. `DBImpl::WriteImpl` calls `BlobWriteBatchTransformer::TransformBatch` before entering the writer group (for default write path), or before joining the batch group (for pipelined/unordered write).
2. Values >= `min_blob_size` are written to a partition file; the key is stored with a `BlobIndex` in the transformed batch. A rollback guard marks blob bytes as initial garbage if the write fails.
3. On `SwitchMemtable`, `RotateCurrentGeneration` moves active partitions into the next immutable batch.
4. `FlushMemTableToOutputFile` / `AtomicFlushMemTablesToOutputFiles` call `PrepareFlushAdditions` to seal partition files and collect `BlobFileAddition` + `BlobFileGarbage` entries registered to MANIFEST alongside the flush.
5. Shutdown paths (`CancelAllBackgroundWork`, `WaitForCompact` with `close_db=true`) force-flush all CFs with active direct-write managers to ensure blob files are registered before close.

### Read path

- **Get/MultiGet**: `MaybeResolveBlobForWritePath` resolves `BlobIndex` references found in memtable or immutable memtable via `BlobFilePartitionManager::ResolveBlobDirectWriteIndex`, which first checks manifest-visible state and falls back to direct blob-file reads via `BlobFileCache`.
- **Iterator**: `DBIter::BlobReader` is extended with a `BlobFilePartitionManager*` to resolve direct-write blob indexes during iteration. The unified `ResolveBlobDirectWriteIndex` path handles both manifest-visible and not-yet-flushed files.

### New options

| Option | Default | Description |
|---|---|---|
| `enable_blob_direct_write` | `false` | Enable write-path blob separation for this CF. Requires `enable_blob_files = true`. Not dynamically changeable. |
| `blob_direct_write_partitions` | `1` | Number of parallel partition files per CF. Not dynamically changeable. |

### Feature incompatibilities (reduced v1 scope)

The following features are *not supported* when `enable_blob_direct_write = true`, and are enforced both in `db_stress_tool` validation and `db_crashtest.py` sanitization:

**Write model constraints:**
- `threads` must be 1 (single writer assumption)
- `allow_concurrent_memtable_write` = 0
- `enable_pipelined_write` = 0 (transformation done before batch group, but pipelined path supported with pre-transform)
- `two_write_queues` = 0
- `unordered_write` = 0 (transformation done before batch group, but unordered path supported with pre-transform)

**WAL and recovery:**
- `disable_wal` = 1 (required — WAL replay of unregistered blob files is out of v1 scope)
- `best_efforts_recovery` = 0
- `reopen` = 0 (no crash-restart with WAL replay)
- All WAL-related stress features disabled: `manual_wal_flush_one_in`, `sync_wal_one_in`, `lock_wal_one_in`, `get_sorted_wal_files_one_in`, `get_current_wal_file_one_in`, `track_and_verify_wals`, `rate_limit_auto_wal_flush`, `recycle_log_file_num`

**Blob GC and dynamic options:**
- `use_blob_db` = 0 (stacked BlobDB not supported)
- `allow_setting_blob_options_dynamically` = 0
- `enable_blob_garbage_collection` = 0
- `blob_compaction_readahead_size` = 0
- `blob_file_starting_level` = 0

**Unsupported value types and APIs:**
- Merge (`use_merge`, `use_full_merge_v1`) — merge values pass through untransformed
- Entity APIs (`use_put_entity_one_in`, `use_get_entity`, `use_multi_get_entity`, `use_attribute_group`)
- `use_timed_put_one_in`
- User-defined timestamps (`user_timestamp_size`, `persist_user_defined_timestamps`, `create_timestamped_snapshot_one_in`)
- Transactions (`use_txn`, `use_optimistic_txn`, `test_multi_ops_txns`, `commit_bypass_memtable_one_in`) — though `WriteCommittedTxn::CommitInternal` falls back from bypass-memtable to normal path when BDW is active
- `IngestWriteBatchWithIndex` returns `NotSupported`
- `inplace_update_support` = 0

**Fault injection:**
- All write/read/metadata fault injection disabled (`sync_fault_injection`, `write_fault_one_in`, `metadata_write_fault_one_in`, `read_fault_one_in`, `metadata_read_fault_one_in`, `open_*_fault_one_in`)

**Infrastructure/snapshot APIs:**
- `remote_compaction_worker_threads` = 0
- `test_secondary` = 0
- `backup_one_in` = 0
- `checkpoint_one_in` = 0
- `get_live_files_apis_one_in` = 0
- `ingest_external_file_one_in` = 0
- `ingest_wbwi_one_in` = 0

### Tests

- `db/blob/db_blob_basic_test.cc`: ~660 lines of new direct-write unit tests covering basic put/get, multi-partition, flush/compaction, recovery, and error injection.
- `db/blob/blob_file_cache_test.cc`: ~96 lines of new tests for direct-write blob file cache behavior.
- `db/write_batch_test.cc`: ~96 lines of tests for WriteBatch with blob index entries.
- `utilities/transactions/transaction_test.cc`: verifies transaction commit path falls back correctly with direct write enabled.
- `db_stress_tool/`: full stress test support with `--enable_blob_direct_write` and `--blob_direct_write_partitions` flags, integrated into `db_crashtest.py` with 10% random selection alongside regular blob params.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/14535

Test Plan:
```
make -j128 db_blob_basic_test && ./db_blob_basic_test
make -j128 blob_file_cache_test && ./blob_file_cache_test
make -j128 write_batch_test && ./write_batch_test
make -j128 transaction_test && ./transaction_test
make -j128 check
```

Stress test:
```
python3 tools/db_crashtest.py blackbox --enable_blob_direct_write=1 \
  --enable_blob_files=1 --blob_direct_write_partitions=4 \
  --disable_wal=1 --threads=1
```

Reviewed By: pdillinger

Differential Revision: D98766843

Pulled By: xingbowang

fbshipit-source-id: 1577653826913a59d05680a87bce5534ac5a5e69
2026-04-02 07:31:56 -07:00

408 lines
12 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).
//
// Copyright (c) 2011 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.
#ifndef NDEBUG
#include <iostream>
#include <unordered_set>
#include "db/blob/blob_file_cache.h"
#include "db/blob/blob_file_partition_manager.h"
#include "db/column_family.h"
#include "db/db_impl/db_impl.h"
#include "db/error_handler.h"
#include "db/periodic_task_scheduler.h"
#include "monitoring/thread_status_updater.h"
#include "util/cast_util.h"
#include "util/hash_containers.h"
namespace ROCKSDB_NAMESPACE {
uint64_t DBImpl::TEST_GetLevel0TotalSize() {
InstrumentedMutexLock l(&mutex_);
return default_cf_handle_->cfd()->current()->storage_info()->NumLevelBytes(0);
}
Status DBImpl::TEST_SwitchWAL() {
WriteContext write_context;
InstrumentedMutexLock l(&mutex_);
void* writer = TEST_BeginWrite();
auto s = SwitchWAL(&write_context);
TEST_EndWrite(writer);
return s;
}
uint64_t DBImpl::TEST_MaxNextLevelOverlappingBytes(
ColumnFamilyHandle* column_family) {
ColumnFamilyData* cfd;
if (column_family == nullptr) {
cfd = default_cf_handle_->cfd();
} else {
auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(column_family);
cfd = cfh->cfd();
}
InstrumentedMutexLock l(&mutex_);
return cfd->current()->storage_info()->MaxNextLevelOverlappingBytes();
}
void DBImpl::TEST_GetFilesMetaData(
ColumnFamilyHandle* column_family,
std::vector<std::vector<FileMetaData>>* metadata,
std::vector<std::shared_ptr<BlobFileMetaData>>* blob_metadata) {
assert(metadata);
auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(column_family);
assert(cfh);
auto cfd = cfh->cfd();
assert(cfd);
InstrumentedMutexLock l(&mutex_);
const auto* current = cfd->current();
assert(current);
const auto* vstorage = current->storage_info();
assert(vstorage);
metadata->resize(NumberLevels());
for (int level = 0; level < NumberLevels(); ++level) {
const std::vector<FileMetaData*>& files = vstorage->LevelFiles(level);
(*metadata)[level].clear();
(*metadata)[level].reserve(files.size());
for (const auto& f : files) {
(*metadata)[level].push_back(*f);
}
}
if (blob_metadata) {
*blob_metadata = vstorage->GetBlobFiles();
}
}
uint64_t DBImpl::TEST_Current_Manifest_FileNo() {
InstrumentedMutexLock l(&mutex_);
return versions_->manifest_file_number();
}
uint64_t DBImpl::TEST_Current_Next_FileNo() {
return versions_->current_next_file_number();
}
Status DBImpl::TEST_CompactRange(int level, const Slice* begin,
const Slice* end,
ColumnFamilyHandle* column_family,
bool disallow_trivial_move) {
ColumnFamilyData* cfd;
if (column_family == nullptr) {
cfd = default_cf_handle_->cfd();
} else {
auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(column_family);
cfd = cfh->cfd();
}
int output_level =
(cfd->ioptions().compaction_style == kCompactionStyleUniversal ||
cfd->ioptions().compaction_style == kCompactionStyleFIFO)
? level
: level + 1;
return RunManualCompaction(
cfd, level, output_level, CompactRangeOptions(), begin, end, true,
disallow_trivial_move,
std::numeric_limits<uint64_t>::max() /*max_file_num_to_ignore*/,
"" /*trim_ts*/);
}
Status DBImpl::TEST_SwitchMemtable(ColumnFamilyData* cfd) {
WriteContext write_context;
InstrumentedMutexLock l(&mutex_);
if (cfd == nullptr) {
cfd = default_cf_handle_->cfd();
}
Status s;
void* writer = TEST_BeginWrite();
if (two_write_queues_) {
WriteThread::Writer nonmem_w;
nonmem_write_thread_.EnterUnbatched(&nonmem_w, &mutex_);
s = SwitchMemtable(cfd, &write_context);
nonmem_write_thread_.ExitUnbatched(&nonmem_w);
} else {
s = SwitchMemtable(cfd, &write_context);
}
TEST_EndWrite(writer);
return s;
}
Status DBImpl::TEST_FlushMemTable(bool wait, bool allow_write_stall,
ColumnFamilyHandle* cfh) {
FlushOptions fo;
fo.wait = wait;
fo.allow_write_stall = allow_write_stall;
ColumnFamilyData* cfd;
if (cfh == nullptr) {
cfd = default_cf_handle_->cfd();
} else {
auto cfhi = static_cast_with_check<ColumnFamilyHandleImpl>(cfh);
cfd = cfhi->cfd();
}
return FlushMemTable(cfd, fo, FlushReason::kTest);
}
Status DBImpl::TEST_FlushMemTable(ColumnFamilyData* cfd,
const FlushOptions& flush_opts) {
return FlushMemTable(cfd, flush_opts, FlushReason::kTest);
}
Status DBImpl::TEST_AtomicFlushMemTables(
const autovector<ColumnFamilyData*>& provided_candidate_cfds,
const FlushOptions& flush_opts) {
return AtomicFlushMemTables(flush_opts, FlushReason::kTest,
provided_candidate_cfds);
}
Status DBImpl::TEST_WaitForBackgroundWork() {
InstrumentedMutexLock l(&mutex_);
WaitForBackgroundWork();
return error_handler_.GetBGError();
}
Status DBImpl::TEST_WaitForFlushMemTable(ColumnFamilyHandle* column_family) {
ColumnFamilyData* cfd;
if (column_family == nullptr) {
cfd = default_cf_handle_->cfd();
} else {
auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(column_family);
cfd = cfh->cfd();
}
return WaitForFlushMemTable(cfd, nullptr, false);
}
Status DBImpl::TEST_WaitForCompact() {
return WaitForCompact(WaitForCompactOptions());
}
Status DBImpl::TEST_WaitForCompact(
const WaitForCompactOptions& wait_for_compact_options) {
return WaitForCompact(wait_for_compact_options);
}
Status DBImpl::TEST_WaitForPurge() {
InstrumentedMutexLock l(&mutex_);
while (bg_purge_scheduled_ && error_handler_.GetBGError().ok()) {
bg_cv_.Wait();
}
return error_handler_.GetBGError();
}
Status DBImpl::TEST_GetBGError() {
InstrumentedMutexLock l(&mutex_);
return error_handler_.GetBGError();
}
bool DBImpl::TEST_IsRecoveryInProgress() {
InstrumentedMutexLock l(&mutex_);
return error_handler_.IsRecoveryInProgress();
}
void DBImpl::TEST_LockMutex() { mutex_.Lock(); }
void DBImpl::TEST_UnlockMutex() { mutex_.Unlock(); }
void DBImpl::TEST_SignalAllBgCv() { bg_cv_.SignalAll(); }
void* DBImpl::TEST_BeginWrite() {
auto w = new WriteThread::Writer();
write_thread_.EnterUnbatched(w, &mutex_);
return static_cast<void*>(w);
}
void DBImpl::TEST_EndWrite(void* w) {
auto writer = static_cast<WriteThread::Writer*>(w);
write_thread_.ExitUnbatched(writer);
delete writer;
}
size_t DBImpl::TEST_LogsToFreeSize() {
InstrumentedMutexLock l(&wal_write_mutex_);
return wals_to_free_.size();
}
uint64_t DBImpl::TEST_LogfileNumber() {
InstrumentedMutexLock l(&mutex_);
return cur_wal_number_;
}
void DBImpl::TEST_GetAllBlockCaches(
std::unordered_set<const Cache*>* cache_set) {
InstrumentedMutexLock l(&mutex_);
for (auto cfd : *versions_->GetColumnFamilySet()) {
if (const auto bbto =
cfd->GetCurrentMutableCFOptions()
.table_factory->GetOptions<BlockBasedTableOptions>()) {
cache_set->insert(bbto->block_cache.get());
}
}
}
uint64_t DBImpl::TEST_FindMinLogContainingOutstandingPrep() {
return logs_with_prep_tracker_.FindMinLogContainingOutstandingPrep();
}
size_t DBImpl::TEST_PreparedSectionCompletedSize() {
return logs_with_prep_tracker_.TEST_PreparedSectionCompletedSize();
}
size_t DBImpl::TEST_LogsWithPrepSize() {
return logs_with_prep_tracker_.TEST_LogsWithPrepSize();
}
uint64_t DBImpl::TEST_FindMinPrepLogReferencedByMemTable() {
autovector<ReadOnlyMemTable*> empty_list;
return FindMinPrepLogReferencedByMemTable(versions_.get(), empty_list);
}
Status DBImpl::TEST_GetLatestMutableCFOptions(
ColumnFamilyHandle* column_family, MutableCFOptions* mutable_cf_options) {
InstrumentedMutexLock l(&mutex_);
auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(column_family);
*mutable_cf_options = cfh->cfd()->GetLatestMutableCFOptions();
return Status::OK();
}
int DBImpl::TEST_BGCompactionsAllowed() const {
InstrumentedMutexLock l(&mutex_);
return GetBGJobLimits().max_compactions;
}
int DBImpl::TEST_BGFlushesAllowed() const {
InstrumentedMutexLock l(&mutex_);
return GetBGJobLimits().max_flushes;
}
int DBImpl::TEST_NumRunningBottomCompactions() const {
mutex_.AssertHeld();
return num_running_bottom_compactions_;
}
SequenceNumber DBImpl::TEST_GetLastVisibleSequence() const {
if (last_seq_same_as_publish_seq_) {
return versions_->LastSequence();
} else {
return versions_->LastAllocatedSequence();
}
}
size_t DBImpl::TEST_GetWalPreallocateBlockSize(
uint64_t write_buffer_size) const {
InstrumentedMutexLock l(&mutex_);
return GetWalPreallocateBlockSize(write_buffer_size);
}
void DBImpl::TEST_WaitForPeriodicTaskRun(std::function<void()> callback) const {
periodic_task_scheduler_.TEST_WaitForRun(callback);
}
const PeriodicTaskScheduler& DBImpl::TEST_GetPeriodicTaskScheduler() const {
return periodic_task_scheduler_;
}
SeqnoToTimeMapping DBImpl::TEST_GetSeqnoToTimeMapping() const {
InstrumentedMutexLock l(&mutex_);
return seqno_to_time_mapping_;
}
const autovector<uint64_t>& DBImpl::TEST_GetFilesToQuarantine() const {
InstrumentedMutexLock l(&mutex_);
return error_handler_.GetFilesToQuarantine();
}
void DBImpl::TEST_DeleteObsoleteFiles() {
InstrumentedMutexLock l(&mutex_);
DeleteObsoleteFiles();
}
size_t DBImpl::TEST_EstimateInMemoryStatsHistorySize() const {
InstrumentedMutexLock l(&const_cast<DBImpl*>(this)->stats_history_mutex_);
return EstimateInMemoryStatsHistorySize();
}
void DBImpl::TEST_VerifyNoObsoleteFilesCached(
bool db_mutex_already_held) const {
// This check is somewhat expensive and obscure to make a part of every
// unit test in every build variety. Thus, we only enable it for ASAN builds.
if (!kMustFreeHeapAllocations) {
return;
}
std::optional<InstrumentedMutexLock> l;
if (db_mutex_already_held) {
mutex_.AssertHeld();
} else {
l.emplace(&mutex_);
}
if (!opened_successfully_) {
// We don't need to pro-actively clean up open files during DB::Open()
// if we know we are about to fail and clean up in Close().
return;
}
if (disable_delete_obsolete_files_ > 0) {
// For better or worse, DB::Close() is allowed with deletions disabled.
// Since we generally associate clean-up of open files with deleting them,
// we allow "obsolete" open files when deletions are disabled.
return;
}
// Live and "quarantined" files are allowed to be open in table cache
UnorderedSet<uint64_t> live_and_quar_files;
for (auto cfd : *versions_->GetColumnFamilySet()) {
if (cfd->IsDropped()) {
continue;
}
if (auto* mgr = cfd->blob_partition_manager(); mgr != nullptr) {
mgr->GetActiveBlobFileNumbers(&live_and_quar_files);
mgr->GetProtectedBlobFileNumbers(&live_and_quar_files);
}
// Iterate over live versions
Version* current = cfd->current();
Version* ver = current;
do {
// Sneakily add both SST and blob files to the same list
std::vector<uint64_t> live_files_vec;
ver->AddLiveFiles(&live_files_vec, &live_files_vec);
live_and_quar_files.insert(live_files_vec.begin(), live_files_vec.end());
ver = ver->Next();
} while (ver != current);
}
{
const auto& quar_files = error_handler_.GetFilesToQuarantine();
live_and_quar_files.insert(quar_files.begin(), quar_files.end());
}
auto fn = [&live_and_quar_files](const Slice& key, Cache::ObjectPtr, size_t,
const Cache::CacheItemHelper*) {
// See TableCache and BlobFileCache
assert(key.size() == sizeof(uint64_t));
uint64_t file_number;
GetUnaligned(reinterpret_cast<const uint64_t*>(key.data()), &file_number);
// Assert file is in live/quarantined set
bool cached_file_is_live_or_quar =
live_and_quar_files.find(file_number) != live_and_quar_files.end();
if (!cached_file_is_live_or_quar) {
// Fail with useful info
std::cerr << "File " << file_number << " is not live nor quarantined"
<< std::endl;
assert(cached_file_is_live_or_quar);
}
};
table_cache_->ApplyToAllEntries(fn, {});
}
} // namespace ROCKSDB_NAMESPACE
#endif // NDEBUG