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From 144479ad7b4287bee4067f95e4218f614798a865 Mon Sep 17 00:00:00 2001
From: Stephan Hartmann <stha09@googlemail.com>
Date: Sun, 16 Jan 2022 19:15:26 +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.
Bug: 1189788
Change-Id: Ia6dc388cc5ef1c0f2afc75f8ca45b9f12687ca9c
---
diff --git a/sql/recover_module/btree.cc b/sql/recover_module/btree.cc
index cc9420e5..f12d8fa 100644
--- a/sql/recover_module/btree.cc
+++ b/sql/recover_module/btree.cc
@@ -136,16 +136,22 @@
"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) {
+LeafPageDecoder::LeafPageDecoder() noexcept = default;
+
+void LeafPageDecoder::Initialize(DatabasePageReader* 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(IsOnValidPage(db_reader));
DCHECK(DatabasePageReader::IsValidPageId(page_id_));
}
+void LeafPageDecoder::Reset() {
+ db_reader_ = nullptr;
+}
+
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 eaa087a5..df0e0c9 100644
--- a/sql/recover_module/btree.h
+++ b/sql/recover_module/btree.h
@@ -101,9 +101,7 @@
public:
// Creates a decoder for a DatabasePageReader's last read page.
//
- // |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;
+ LeafPageDecoder() noexcept;
~LeafPageDecoder() noexcept = default;
LeafPageDecoder(const LeafPageDecoder&) = delete;
@@ -151,6 +149,17 @@
// read as long as CanAdvance() returns true.
bool TryAdvance();
+ // Initialize with DatabasePageReader
+ // |db_reader| must have been used to read an inner page of a table B-tree.
+ // |db_reader| must outlive this instance.
+ 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.
@@ -164,14 +173,14 @@
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 4f827ed..240de499 100644
--- a/sql/recover_module/cursor.cc
+++ b/sql/recover_module/cursor.cc
@@ -28,7 +28,7 @@
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();
@@ -38,18 +38,18 @@
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())
@@ -101,13 +101,13 @@
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";
@@ -115,7 +115,7 @@
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 845b785..cc4e85f8 100644
--- a/sql/recover_module/cursor.h
+++ b/sql/recover_module/cursor.h
@@ -130,7 +130,7 @@
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..69d98cef 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->page_size()), table_(table) {
DCHECK(table != nullptr);
DCHECK(IsValidPageSize(table->page_size()));
}
@@ -58,7 +57,7 @@
"The |read_offset| computation above may overflow");
int sqlite_status =
- RawRead(sqlite_file, read_size, read_offset, page_data_.get());
+ RawRead(sqlite_file, read_size, read_offset, 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 07cac3cb..d08f093 100644
--- a/sql/recover_module/pager.h
+++ b/sql/recover_module/pager.h
@@ -6,8 +6,8 @@
#define SQL_RECOVER_MODULE_PAGER_H_
#include <cstdint>
-#include <memory>
#include <ostream>
+#include <vector>
#include "base/check_op.h"
#include "base/memory/raw_ptr.h"
@@ -72,7 +72,7 @@
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.
@@ -139,7 +139,7 @@
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_;
+ std::vector<uint8_t> page_data_;
// Raw pointer usage is acceptable because this instance's owner is expected
// to ensure that the VirtualTable outlives this.
const raw_ptr<VirtualTable> table_;
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