From 80368f8ba7a8bab13440463a254888311efe3986 Mon Sep 17 00:00:00 2001 From: Stephan Hartmann Date: Tue, 04 May 2021 15:00:19 +0000 Subject: [PATCH] sql: make VirtualCursor standard layout type sql::recover::VirtualCursor needs to be a standard layout type, but has members of type std::unique_ptr. However, std::unique_ptr is not guaranteed to be standard layout. Compiling with clang combined with gcc-11 libstdc++ fails because of this. Replace std::unique_ptr with raw pointers. Bug: 1189788 Change-Id: Ia6dc388cc5ef1c0f2afc75f8ca45b9f12687ca9c --- diff --git a/sql/recover_module/btree.cc b/sql/recover_module/btree.cc index 9ecaafe..839318a 100644 --- a/sql/recover_module/btree.cc +++ b/sql/recover_module/btree.cc @@ -135,16 +135,25 @@ "Move the destructor to the .cc file if it's non-trival"); #endif // !DCHECK_IS_ON() -LeafPageDecoder::LeafPageDecoder(DatabasePageReader* db_reader) noexcept - : page_id_(db_reader->page_id()), - db_reader_(db_reader), - cell_count_(ComputeCellCount(db_reader)), - next_read_index_(0), - last_record_size_(0) { +void LeafPageDecoder::Initialize(DatabasePageReader* db_reader) { + DCHECK(db_reader); DCHECK(IsOnValidPage(db_reader)); + page_id_ = db_reader->page_id(); + db_reader_ = db_reader; + cell_count_ = ComputeCellCount(db_reader); + next_read_index_ = 0; + last_record_size_ = 0; DCHECK(DatabasePageReader::IsValidPageId(page_id_)); } +void LeafPageDecoder::Reset() { + db_reader_ = nullptr; + page_id_ = 0; + cell_count_ = 0; + next_read_index_ = 0; + last_record_size_ = 0; +} + bool LeafPageDecoder::TryAdvance() { DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); DCHECK(CanAdvance()); diff --git a/sql/recover_module/btree.h b/sql/recover_module/btree.h index d76d076..33114b0 100644 --- a/sql/recover_module/btree.h +++ b/sql/recover_module/btree.h @@ -102,7 +102,7 @@ // // |db_reader| must have been used to read an inner page of a table B-tree. // |db_reader| must outlive this instance. - explicit LeafPageDecoder(DatabasePageReader* db_reader) noexcept; + explicit LeafPageDecoder() noexcept = default; ~LeafPageDecoder() noexcept = default; LeafPageDecoder(const LeafPageDecoder&) = delete; @@ -150,6 +150,15 @@ // read as long as CanAdvance() returns true. bool TryAdvance(); + // Initialize with DatabasePageReader + void Initialize(DatabasePageReader* db_reader); + + // Reset internal DatabasePageReader + void Reset(); + + // True if DatabasePageReader is valid + bool IsValid() { return (db_reader_ != nullptr); } + // True if the given reader may point to an inner page in a table B-tree. // // The last ReadPage() call on |db_reader| must have succeeded. @@ -163,14 +172,14 @@ static int ComputeCellCount(DatabasePageReader* db_reader); // The number of the B-tree page this reader is reading. - const int64_t page_id_; + int64_t page_id_; // Used to read the tree page. // // Raw pointer usage is acceptable because this instance's owner is expected // to ensure that the DatabasePageReader outlives this. - DatabasePageReader* const db_reader_; + DatabasePageReader* db_reader_; // Caches the ComputeCellCount() value for this reader's page. - const int cell_count_ = ComputeCellCount(db_reader_); + int cell_count_; // The reader's cursor state. // diff --git a/sql/recover_module/cursor.cc b/sql/recover_module/cursor.cc index 0029ff9..42548bc 100644 --- a/sql/recover_module/cursor.cc +++ b/sql/recover_module/cursor.cc @@ -26,7 +26,7 @@ int VirtualCursor::First() { DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); inner_decoders_.clear(); - leaf_decoder_ = nullptr; + leaf_decoder_.Reset(); AppendPageDecoder(table_->root_page_id()); return Next(); @@ -36,18 +36,18 @@ DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); record_reader_.Reset(); - while (!inner_decoders_.empty() || leaf_decoder_.get()) { - if (leaf_decoder_.get()) { - if (!leaf_decoder_->CanAdvance()) { + while (!inner_decoders_.empty() || leaf_decoder_.IsValid()) { + if (leaf_decoder_.IsValid()) { + if (!leaf_decoder_.CanAdvance()) { // The leaf has been exhausted. Remove it from the DFS stack. - leaf_decoder_ = nullptr; + leaf_decoder_.Reset(); continue; } - if (!leaf_decoder_->TryAdvance()) + if (!leaf_decoder_.TryAdvance()) continue; - if (!payload_reader_.Initialize(leaf_decoder_->last_record_size(), - leaf_decoder_->last_record_offset())) { + if (!payload_reader_.Initialize(leaf_decoder_.last_record_size(), + leaf_decoder_.last_record_offset())) { continue; } if (!record_reader_.Initialize()) @@ -99,13 +99,13 @@ int64_t VirtualCursor::RowId() { DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); DCHECK(record_reader_.IsInitialized()); - DCHECK(leaf_decoder_.get()); - return leaf_decoder_->last_record_rowid(); + DCHECK(leaf_decoder_.IsValid()); + return leaf_decoder_.last_record_rowid(); } void VirtualCursor::AppendPageDecoder(int page_id) { DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); - DCHECK(leaf_decoder_.get() == nullptr) + DCHECK(!leaf_decoder_.IsValid()) << __func__ << " must only be called when the current path has no leaf decoder"; @@ -113,7 +113,7 @@ return; if (LeafPageDecoder::IsOnValidPage(&db_reader_)) { - leaf_decoder_ = std::make_unique(&db_reader_); + leaf_decoder_.Initialize(&db_reader_); return; } diff --git a/sql/recover_module/cursor.h b/sql/recover_module/cursor.h index afcd690..b15c31d 100644 --- a/sql/recover_module/cursor.h +++ b/sql/recover_module/cursor.h @@ -129,7 +129,7 @@ std::vector> inner_decoders_; // Decodes the leaf page containing records. - std::unique_ptr leaf_decoder_; + LeafPageDecoder leaf_decoder_; SEQUENCE_CHECKER(sequence_checker_); }; diff --git a/sql/recover_module/pager.cc b/sql/recover_module/pager.cc index 58e75de..5fe9620 100644 --- a/sql/recover_module/pager.cc +++ b/sql/recover_module/pager.cc @@ -23,8 +23,7 @@ "ints are not appropriate for representing page IDs"); DatabasePageReader::DatabasePageReader(VirtualTable* table) - : page_data_(std::make_unique(table->page_size())), - table_(table) { + : page_data_(), table_(table) { DCHECK(table != nullptr); DCHECK(IsValidPageSize(table->page_size())); } @@ -57,8 +56,8 @@ std::numeric_limits::max(), "The |read_offset| computation above may overflow"); - int sqlite_status = - RawRead(sqlite_file, read_size, read_offset, page_data_.get()); + int sqlite_status = RawRead(sqlite_file, read_size, read_offset, + const_cast(page_data_.data())); // |page_id_| needs to be set to kInvalidPageId if the read failed. // Otherwise, future ReadPage() calls with the previous |page_id_| value diff --git a/sql/recover_module/pager.h b/sql/recover_module/pager.h index 0e388ddc..99314e3 100644 --- a/sql/recover_module/pager.h +++ b/sql/recover_module/pager.h @@ -5,6 +5,7 @@ #ifndef SQL_RECOVER_MODULE_PAGER_H_ #define SQL_RECOVER_MODULE_PAGER_H_ +#include #include #include @@ -70,7 +71,7 @@ DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); DCHECK_NE(page_id_, kInvalidPageId) << "Successful ReadPage() required before accessing pager state"; - return page_data_.get(); + return page_data_.data(); } // The number of bytes in the page read by the last ReadPage() call. @@ -137,7 +138,7 @@ int page_id_ = kInvalidPageId; // Stores the bytes of the last page successfully read by ReadPage(). // The content is undefined if the last call to ReadPage() did not succeed. - const std::unique_ptr page_data_; + const std::array page_data_; // Raw pointer usage is acceptable because this instance's owner is expected // to ensure that the VirtualTable outlives this. VirtualTable* const table_;