rocksdb/db/db_impl/db_impl_debug.cc
Peter Dillinger 54cb9c77d9 Prefer static_cast in place of most reinterpret_cast (#12308)
Summary:
The following are risks associated with pointer-to-pointer reinterpret_cast:
* Can produce the "wrong result" (crash or memory corruption). IIRC, in theory this can happen for any up-cast or down-cast for a non-standard-layout type, though in practice would only happen for multiple inheritance cases (where the base class pointer might be "inside" the derived object). We don't use multiple inheritance a lot, but we do.
* Can mask useful compiler errors upon code change, including converting between unrelated pointer types that you are expecting to be related, and converting between pointer and scalar types unintentionally.

I can only think of some obscure cases where static_cast could be troublesome when it compiles as a replacement:
* Going through `void*` could plausibly cause unnecessary or broken pointer arithmetic. Suppose we have
`struct Derived: public Base1, public Base2`.  If we have `Derived*` -> `void*` -> `Base2*` -> `Derived*` through reinterpret casts, this could plausibly work (though technical UB) assuming the `Base2*` is not dereferenced. Changing to static cast could introduce breaking pointer arithmetic.
* Unnecessary (but safe) pointer arithmetic could arise in a case like `Derived*` -> `Base2*` -> `Derived*` where before the Base2 pointer might not have been dereferenced. This could potentially affect performance.

With some light scripting, I tried replacing pointer-to-pointer reinterpret_casts with static_cast and kept the cases that still compile. Most occurrences of reinterpret_cast have successfully been changed (except for java/ and third-party/). 294 changed, 257 remain.

A couple of related interventions included here:
* Previously Cache::Handle was not actually derived from in the implementations and just used as a `void*` stand-in with reinterpret_cast. Now there is a relationship to allow static_cast. In theory, this could introduce pointer arithmetic (as described above) but is unlikely without multiple inheritance AND non-empty Cache::Handle.
* Remove some unnecessary casts to void* as this is allowed to be implicit (for better or worse).

Most of the remaining reinterpret_casts are for converting to/from raw bytes of objects. We could consider better idioms for these patterns in follow-up work.

I wish there were a way to implement a template variant of static_cast that would only compile if no pointer arithmetic is generated, but best I can tell, this is not possible. AFAIK the best you could do is a dynamic check that the void* conversion after the static cast is unchanged.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/12308

Test Plan: existing tests, CI

Reviewed By: ltamasi

Differential Revision: D53204947

Pulled By: pdillinger

fbshipit-source-id: 9de23e618263b0d5b9820f4e15966876888a16e2
2024-02-07 10:44:11 -08:00

323 lines
9.4 KiB
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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).
//
// 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 "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"
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() {
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();
}
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(&log_write_mutex_);
return logs_to_free_.size();
}
uint64_t DBImpl::TEST_LogfileNumber() {
InstrumentedMutexLock l(&mutex_);
return logfile_number_;
}
Status DBImpl::TEST_GetAllImmutableCFOptions(
std::unordered_map<std::string, const ImmutableCFOptions*>* iopts_map) {
std::vector<std::string> cf_names;
std::vector<const ImmutableCFOptions*> iopts;
{
InstrumentedMutexLock l(&mutex_);
for (auto cfd : *versions_->GetColumnFamilySet()) {
cf_names.push_back(cfd->GetName());
iopts.push_back(cfd->ioptions());
}
}
iopts_map->clear();
for (size_t i = 0; i < cf_names.size(); ++i) {
iopts_map->insert({cf_names[i], iopts[i]});
}
return Status::OK();
}
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<MemTable*> 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;
}
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();
}
size_t DBImpl::TEST_EstimateInMemoryStatsHistorySize() const {
InstrumentedMutexLock l(&const_cast<DBImpl*>(this)->stats_history_mutex_);
return EstimateInMemoryStatsHistorySize();
}
} // namespace ROCKSDB_NAMESPACE
#endif // NDEBUG