ladybird/Userland/Libraries/LibSQL/Heap.cpp
Timothy Flynn 7a912ca891 LibSQL: Reset the highest written block during the zeroth block init
Otherwise, when changing the SQL heap version, the value from the now-
stale heap file will continue to be used.
2024-01-10 23:26:40 +01:00

368 lines
13 KiB
C++

/*
* Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
* Copyright (c) 2023, Jelle Raaijmakers <jelle@gmta.nl>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ByteString.h>
#include <AK/Format.h>
#include <AK/QuickSort.h>
#include <LibCore/System.h>
#include <LibSQL/Heap.h>
#include <sys/stat.h>
namespace SQL {
ErrorOr<NonnullRefPtr<Heap>> Heap::create(ByteString file_name)
{
return adopt_nonnull_ref_or_enomem(new (nothrow) Heap(move(file_name)));
}
Heap::Heap(ByteString file_name)
: m_name(move(file_name))
{
}
Heap::~Heap()
{
if (m_file && !m_write_ahead_log.is_empty()) {
if (auto maybe_error = flush(); maybe_error.is_error())
warnln("~Heap({}): {}", name(), maybe_error.error());
}
}
ErrorOr<void> Heap::open()
{
VERIFY(!m_file);
size_t file_size = 0;
struct stat stat_buffer;
if (stat(name().characters(), &stat_buffer) != 0) {
if (errno != ENOENT) {
warnln("Heap::open({}): could not stat: {}"sv, name(), strerror(errno));
return Error::from_string_literal("Heap::open(): could not stat file");
}
} else if (!S_ISREG(stat_buffer.st_mode)) {
warnln("Heap::open({}): can only use regular files"sv, name());
return Error::from_string_literal("Heap::open(): can only use regular files");
} else {
file_size = stat_buffer.st_size;
}
if (file_size > 0) {
m_next_block = file_size / Block::SIZE;
m_highest_block_written = m_next_block - 1;
}
auto file = TRY(Core::File::open(name(), Core::File::OpenMode::ReadWrite));
m_file = TRY(Core::InputBufferedFile::create(move(file)));
if (file_size > 0) {
if (auto error_maybe = read_zero_block(); error_maybe.is_error()) {
m_file = nullptr;
return error_maybe.release_error();
}
} else {
TRY(initialize_zero_block());
}
// FIXME: We should more gracefully handle version incompatibilities. For now, we drop the database.
if (m_version != VERSION) {
dbgln_if(SQL_DEBUG, "Heap file {} opened has incompatible version {}. Deleting for version {}.", name(), m_version, VERSION);
m_file = nullptr;
TRY(Core::System::unlink(name()));
return open();
}
// Perform a heap scan to find all free blocks
// FIXME: this is very inefficient; store free blocks in a persistent heap structure
for (Block::Index index = 1; index <= m_highest_block_written; ++index) {
auto block_data = TRY(read_raw_block(index));
auto size_in_bytes = *reinterpret_cast<u32*>(block_data.data());
if (size_in_bytes == 0)
TRY(m_free_block_indices.try_append(index));
}
dbgln_if(SQL_DEBUG, "Heap file {} opened; number of blocks = {}; free blocks = {}", name(), m_highest_block_written, m_free_block_indices.size());
return {};
}
ErrorOr<size_t> Heap::file_size_in_bytes() const
{
TRY(m_file->seek(0, SeekMode::FromEndPosition));
return TRY(m_file->tell());
}
bool Heap::has_block(Block::Index index) const
{
return (index <= m_highest_block_written || m_write_ahead_log.contains(index))
&& !m_free_block_indices.contains_slow(index);
}
Block::Index Heap::request_new_block_index()
{
if (!m_free_block_indices.is_empty())
return m_free_block_indices.take_last();
return m_next_block++;
}
ErrorOr<ByteBuffer> Heap::read_storage(Block::Index index)
{
dbgln_if(SQL_DEBUG, "{}({})", __FUNCTION__, index);
// Reconstruct the data storage from a potential chain of blocks
ByteBuffer data;
while (index > 0) {
auto block = TRY(read_block(index));
dbgln_if(SQL_DEBUG, " -> {} bytes", block.size_in_bytes());
TRY(data.try_append(block.data().bytes().slice(0, block.size_in_bytes())));
index = block.next_block();
}
return data;
}
ErrorOr<void> Heap::write_storage(Block::Index index, ReadonlyBytes data)
{
dbgln_if(SQL_DEBUG, "{}({}, {} bytes)", __FUNCTION__, index, data.size());
if (index == 0)
return Error::from_string_view("Writing to zero block is not allowed"sv);
if (data.is_empty())
return Error::from_string_view("Writing empty data is not allowed"sv);
if (m_free_block_indices.contains_slow(index))
return Error::from_string_view("Invalid write to a free block index"sv);
// Split up the storage across multiple blocks if necessary, creating a chain
u32 remaining_size = static_cast<u32>(data.size());
u32 offset_in_data = 0;
Block::Index existing_next_block_index = 0;
while (remaining_size > 0) {
auto block_data_size = AK::min(remaining_size, Block::DATA_SIZE);
remaining_size -= block_data_size;
ByteBuffer block_data;
if (has_block(index)) {
auto existing_block = TRY(read_block(index));
block_data = existing_block.data();
TRY(block_data.try_resize(block_data_size));
existing_next_block_index = existing_block.next_block();
} else {
block_data = TRY(ByteBuffer::create_uninitialized(block_data_size));
existing_next_block_index = 0;
}
Block::Index next_block_index = existing_next_block_index;
if (next_block_index == 0 && remaining_size > 0)
next_block_index = request_new_block_index();
else if (remaining_size == 0)
next_block_index = 0;
block_data.bytes().overwrite(0, data.offset(offset_in_data), block_data_size);
TRY(write_block({ index, block_data_size, next_block_index, move(block_data) }));
index = next_block_index;
offset_in_data += block_data_size;
}
// Free remaining blocks in existing chain, if any
if (existing_next_block_index > 0)
TRY(free_storage(existing_next_block_index));
return {};
}
ErrorOr<ByteBuffer> Heap::read_raw_block(Block::Index index)
{
VERIFY(m_file);
VERIFY(index < m_next_block);
if (auto wal_entry = m_write_ahead_log.get(index); wal_entry.has_value())
return wal_entry.value();
TRY(m_file->seek(index * Block::SIZE, SeekMode::SetPosition));
auto buffer = TRY(ByteBuffer::create_uninitialized(Block::SIZE));
TRY(m_file->read_until_filled(buffer));
return buffer;
}
ErrorOr<Block> Heap::read_block(Block::Index index)
{
dbgln_if(SQL_DEBUG, "{}({})", __FUNCTION__, index);
auto buffer = TRY(read_raw_block(index));
auto size_in_bytes = *reinterpret_cast<u32*>(buffer.offset_pointer(0));
auto next_block = *reinterpret_cast<Block::Index*>(buffer.offset_pointer(sizeof(u32)));
auto data = TRY(buffer.slice(Block::HEADER_SIZE, Block::DATA_SIZE));
return Block { index, size_in_bytes, next_block, move(data) };
}
ErrorOr<void> Heap::write_raw_block(Block::Index index, ReadonlyBytes data)
{
dbgln_if(SQL_DEBUG, "Write raw block {}", index);
VERIFY(m_file);
VERIFY(data.size() == Block::SIZE);
TRY(m_file->seek(index * Block::SIZE, SeekMode::SetPosition));
TRY(m_file->write_until_depleted(data));
if (index > m_highest_block_written)
m_highest_block_written = index;
return {};
}
ErrorOr<void> Heap::write_raw_block_to_wal(Block::Index index, ByteBuffer&& data)
{
dbgln_if(SQL_DEBUG, "{}({})", __FUNCTION__, index);
VERIFY(index < m_next_block);
VERIFY(data.size() == Block::SIZE);
TRY(m_write_ahead_log.try_set(index, move(data)));
return {};
}
ErrorOr<void> Heap::write_block(Block const& block)
{
dbgln_if(SQL_DEBUG, "{}({})", __FUNCTION__, block.index());
VERIFY(block.index() < m_next_block);
VERIFY(block.next_block() < m_next_block);
VERIFY(block.size_in_bytes() > 0);
VERIFY(block.data().size() <= Block::DATA_SIZE);
auto size_in_bytes = block.size_in_bytes();
auto next_block = block.next_block();
auto heap_data = TRY(ByteBuffer::create_zeroed(Block::SIZE));
heap_data.overwrite(0, &size_in_bytes, sizeof(size_in_bytes));
heap_data.overwrite(sizeof(size_in_bytes), &next_block, sizeof(next_block));
block.data().bytes().copy_to(heap_data.bytes().slice(Block::HEADER_SIZE));
return write_raw_block_to_wal(block.index(), move(heap_data));
}
ErrorOr<void> Heap::free_storage(Block::Index index)
{
dbgln_if(SQL_DEBUG, "{}({})", __FUNCTION__, index);
VERIFY(index > 0);
while (index > 0) {
auto block = TRY(read_block(index));
TRY(free_block(block));
index = block.next_block();
}
return {};
}
ErrorOr<void> Heap::free_block(Block const& block)
{
auto index = block.index();
dbgln_if(SQL_DEBUG, "{}({})", __FUNCTION__, index);
VERIFY(index > 0);
VERIFY(has_block(index));
// Zero out freed blocks to facilitate a free block scan upon opening the database later
auto zeroed_data = TRY(ByteBuffer::create_zeroed(Block::SIZE));
TRY(write_raw_block_to_wal(index, move(zeroed_data)));
return m_free_block_indices.try_append(index);
}
ErrorOr<void> Heap::flush()
{
VERIFY(m_file);
auto indices = m_write_ahead_log.keys();
quick_sort(indices);
for (auto index : indices) {
dbgln_if(SQL_DEBUG, "Flushing block {}", index);
auto& data = m_write_ahead_log.get(index).value();
TRY(write_raw_block(index, data));
}
m_write_ahead_log.clear();
dbgln_if(SQL_DEBUG, "WAL flushed; new number of blocks = {}", m_highest_block_written);
return {};
}
constexpr static auto FILE_ID = "SerenitySQL "sv;
constexpr static auto VERSION_OFFSET = FILE_ID.length();
constexpr static auto SCHEMAS_ROOT_OFFSET = VERSION_OFFSET + sizeof(u32);
constexpr static auto TABLES_ROOT_OFFSET = SCHEMAS_ROOT_OFFSET + sizeof(u32);
constexpr static auto TABLE_COLUMNS_ROOT_OFFSET = TABLES_ROOT_OFFSET + sizeof(u32);
constexpr static auto USER_VALUES_OFFSET = TABLE_COLUMNS_ROOT_OFFSET + sizeof(u32);
ErrorOr<void> Heap::read_zero_block()
{
dbgln_if(SQL_DEBUG, "Read zero block from {}", name());
auto block = TRY(read_raw_block(0));
auto file_id_buffer = TRY(block.slice(0, FILE_ID.length()));
auto file_id = StringView(file_id_buffer);
if (file_id != FILE_ID) {
warnln("{}: Zero page corrupt. This is probably not a {} heap file"sv, name(), FILE_ID);
return Error::from_string_literal("Heap()::read_zero_block(): Zero page corrupt. This is probably not a SerenitySQL heap file");
}
memcpy(&m_version, block.offset_pointer(VERSION_OFFSET), sizeof(u32));
dbgln_if(SQL_DEBUG, "Version: {}.{}", (m_version & 0xFFFF0000) >> 16, (m_version & 0x0000FFFF));
memcpy(&m_schemas_root, block.offset_pointer(SCHEMAS_ROOT_OFFSET), sizeof(u32));
dbgln_if(SQL_DEBUG, "Schemas root node: {}", m_schemas_root);
memcpy(&m_tables_root, block.offset_pointer(TABLES_ROOT_OFFSET), sizeof(u32));
dbgln_if(SQL_DEBUG, "Tables root node: {}", m_tables_root);
memcpy(&m_table_columns_root, block.offset_pointer(TABLE_COLUMNS_ROOT_OFFSET), sizeof(u32));
dbgln_if(SQL_DEBUG, "Table columns root node: {}", m_table_columns_root);
memcpy(m_user_values.data(), block.offset_pointer(USER_VALUES_OFFSET), m_user_values.size() * sizeof(u32));
for (auto ix = 0u; ix < m_user_values.size(); ix++) {
if (m_user_values[ix])
dbgln_if(SQL_DEBUG, "User value {}: {}", ix, m_user_values[ix]);
}
return {};
}
ErrorOr<void> Heap::update_zero_block()
{
dbgln_if(SQL_DEBUG, "Write zero block to {}", name());
dbgln_if(SQL_DEBUG, "Version: {}.{}", (m_version & 0xFFFF0000) >> 16, (m_version & 0x0000FFFF));
dbgln_if(SQL_DEBUG, "Schemas root node: {}", m_schemas_root);
dbgln_if(SQL_DEBUG, "Tables root node: {}", m_tables_root);
dbgln_if(SQL_DEBUG, "Table Columns root node: {}", m_table_columns_root);
for (auto ix = 0u; ix < m_user_values.size(); ix++) {
if (m_user_values[ix] > 0)
dbgln_if(SQL_DEBUG, "User value {}: {}", ix, m_user_values[ix]);
}
auto buffer = TRY(ByteBuffer::create_zeroed(Block::SIZE));
auto buffer_bytes = buffer.bytes();
buffer_bytes.overwrite(0, FILE_ID.characters_without_null_termination(), FILE_ID.length());
buffer_bytes.overwrite(VERSION_OFFSET, &m_version, sizeof(u32));
buffer_bytes.overwrite(SCHEMAS_ROOT_OFFSET, &m_schemas_root, sizeof(u32));
buffer_bytes.overwrite(TABLES_ROOT_OFFSET, &m_tables_root, sizeof(u32));
buffer_bytes.overwrite(TABLE_COLUMNS_ROOT_OFFSET, &m_table_columns_root, sizeof(u32));
buffer_bytes.overwrite(USER_VALUES_OFFSET, m_user_values.data(), m_user_values.size() * sizeof(u32));
return write_raw_block_to_wal(0, move(buffer));
}
ErrorOr<void> Heap::initialize_zero_block()
{
m_version = VERSION;
m_schemas_root = 0;
m_tables_root = 0;
m_table_columns_root = 0;
m_next_block = 1;
m_highest_block_written = 0;
for (auto& user : m_user_values)
user = 0u;
return update_zero_block();
}
}