From 80368f8ba7a8bab13440463a254888311efe3986 Mon Sep 17 00:00:00 2001
From: Stephan Hartmann <stha09@googlemail.com>
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<LeafPageDecoder>(&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<std::unique_ptr<InnerPageDecoder>> inner_decoders_;
// Decodes the leaf page containing records.
- std::unique_ptr<LeafPageDecoder> 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<uint8_t[]>(table->page_size())),
- table_(table) {
+ : page_data_(), table_(table) {
DCHECK(table != nullptr);
DCHECK(IsValidPageSize(table->page_size()));
}
@@ -57,8 +56,8 @@
std::numeric_limits<int64_t>::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<uint8_t*>(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 <array>
#include <cstdint>
#include <memory>
@@ -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<uint8_t[]> page_data_;
+ const std::array<uint8_t, kMaxPageSize> page_data_;
// Raw pointer usage is acceptable because this instance's owner is expected
// to ensure that the VirtualTable outlives this.
VirtualTable* const table_;
