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224804b424
Unfortunately this patch is quite large. The main functionality included are a BTree index implementation and the Heap class which manages persistent storage. Also included are a Key subclass of the Tuple class, which is a specialization for index key tuples. This "dragged in" the Meta layer, which has classes defining SQL objects like tables and indexes.
220 lines
7.2 KiB
C++
220 lines
7.2 KiB
C++
/*
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* Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Format.h>
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#include <AK/QuickSort.h>
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#include <AK/String.h>
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#include <LibCore/IODevice.h>
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#include <LibSQL/Heap.h>
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#include <LibSQL/Serialize.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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namespace SQL {
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Heap::Heap(String file_name)
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{
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set_name(move(file_name));
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size_t file_size = 0;
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struct stat stat_buffer;
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if (stat(name().characters(), &stat_buffer) != 0) {
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if (errno != ENOENT) {
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perror("stat");
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VERIFY_NOT_REACHED();
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}
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} else {
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file_size = stat_buffer.st_size;
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}
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if (file_size > 0)
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m_next_block = m_end_of_file = file_size / BLOCKSIZE;
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auto file_or_error = Core::File::open(name(), Core::OpenMode::ReadWrite);
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if (file_or_error.is_error()) {
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warnln("Couldn't open '{}': {}", name(), file_or_error.error());
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VERIFY_NOT_REACHED();
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}
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m_file = file_or_error.value();
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if (file_size > 0)
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read_zero_block();
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else
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initialize_zero_block();
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}
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Result<ByteBuffer, String> Heap::read_block(u32 block)
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{
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auto buffer_or_empty = m_write_ahead_log.get(block);
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if (buffer_or_empty.has_value())
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return buffer_or_empty.value();
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VERIFY(block < m_next_block);
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dbgln_if(SQL_DEBUG, "Read heap block {}", block);
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if (!seek_block(block))
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VERIFY_NOT_REACHED();
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auto ret = m_file->read(BLOCKSIZE);
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if (ret.is_empty())
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return String("Could not read block");
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return ret;
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}
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bool Heap::write_block(u32 block, ByteBuffer& buffer)
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{
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VERIFY(block < m_next_block);
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if (!seek_block(block))
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VERIFY_NOT_REACHED();
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dbgln_if(SQL_DEBUG, "Write heap block {} size {}", block, buffer.size());
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VERIFY(buffer.size() <= BLOCKSIZE);
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auto sz = buffer.size();
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if (sz < BLOCKSIZE) {
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buffer.resize(BLOCKSIZE);
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memset(buffer.offset_pointer((int)sz), 0, BLOCKSIZE - sz);
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}
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if (m_file->write(buffer.data(), (int)buffer.size())) {
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if (block == m_end_of_file)
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m_end_of_file++;
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return true;
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}
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return false;
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}
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bool Heap::seek_block(u32 block)
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{
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if (block == m_end_of_file) {
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off_t pos;
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if (!m_file->seek(0, Core::SeekMode::FromEndPosition, &pos)) {
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warnln("Could not seek block {} from file {}, which is at the end of the file", block, name());
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warnln("FD: {} Position: {} error: {}", m_file->fd(), pos, m_file->error_string());
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return false;
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}
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} else if (block > m_end_of_file) {
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warnln("Seeking block {} of file {} which is beyond the end of the file", block, name());
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return false;
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} else {
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if (!m_file->seek(block * BLOCKSIZE)) {
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warnln("Could not seek block {} of file {}. The current size is {} blocks",
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block, name(), m_end_of_file);
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return false;
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}
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}
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return true;
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}
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u32 Heap::new_record_pointer()
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{
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if (m_free_list) {
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auto block_or_error = read_block(m_free_list);
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if (block_or_error.is_error()) {
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warnln("FREE LIST CORRUPTION");
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VERIFY_NOT_REACHED();
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}
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auto new_pointer = m_free_list;
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size_t offset = 0;
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deserialize_from<u32>(block_or_error.value(), offset, m_free_list);
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update_zero_block();
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return new_pointer;
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}
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return m_next_block++;
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}
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void Heap::flush()
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{
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Vector<u32> blocks;
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for (auto& wal_entry : m_write_ahead_log) {
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blocks.append(wal_entry.key);
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}
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quick_sort(blocks);
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for (auto& block : blocks) {
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auto buffer_or_empty = m_write_ahead_log.get(block);
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if (buffer_or_empty->is_empty()) {
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VERIFY_NOT_REACHED();
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}
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dbgln_if(SQL_DEBUG, "Flushing block {} to {}", block, name());
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write_block(block, buffer_or_empty.value());
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}
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m_write_ahead_log.clear();
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}
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constexpr static const char* FILE_ID = "SerenitySQL ";
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constexpr static int VERSION_OFFSET = 12;
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constexpr static int SCHEMAS_ROOT_OFFSET = 16;
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constexpr static int TABLES_ROOT_OFFSET = 20;
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constexpr static int TABLE_COLUMNS_ROOT_OFFSET = 24;
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constexpr static int FREE_LIST_OFFSET = 28;
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constexpr static int USER_VALUES_OFFSET = 32;
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void Heap::read_zero_block()
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{
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char file_id[256];
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auto bytes_or_error = read_block(0);
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if (bytes_or_error.is_error())
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VERIFY_NOT_REACHED();
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auto buffer = bytes_or_error.value();
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memcpy(file_id, buffer.offset_pointer(0), strlen(FILE_ID));
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file_id[strlen(FILE_ID)] = 0;
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if (strncmp(file_id, FILE_ID, strlen(FILE_ID)) != 0) {
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warnln("Corrupt zero page in {}", name());
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VERIFY_NOT_REACHED();
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}
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dbgln_if(SQL_DEBUG, "Read zero block from {}", name());
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memcpy(&m_version, buffer.offset_pointer(VERSION_OFFSET), sizeof(u32));
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dbgln_if(SQL_DEBUG, "Version: {}.{}", (m_version & 0xFFFF0000) >> 16, (m_version & 0x0000FFFF));
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memcpy(&m_schemas_root, buffer.offset_pointer(SCHEMAS_ROOT_OFFSET), sizeof(u32));
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dbgln_if(SQL_DEBUG, "Schemas root node: {}", m_tables_root);
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memcpy(&m_tables_root, buffer.offset_pointer(TABLES_ROOT_OFFSET), sizeof(u32));
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dbgln_if(SQL_DEBUG, "Tables root node: {}", m_tables_root);
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memcpy(&m_table_columns_root, buffer.offset_pointer(TABLE_COLUMNS_ROOT_OFFSET), sizeof(u32));
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dbgln_if(SQL_DEBUG, "Table columns root node: {}", m_table_columns_root);
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memcpy(&m_free_list, buffer.offset_pointer(FREE_LIST_OFFSET), sizeof(u32));
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dbgln_if(SQL_DEBUG, "Free list: {}", m_free_list);
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memcpy(m_user_values.data(), buffer.offset_pointer(USER_VALUES_OFFSET), m_user_values.size() * sizeof(u32));
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for (auto ix = 0u; ix < m_user_values.size(); ix++) {
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if (m_user_values[ix]) {
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dbgln_if(SQL_DEBUG, "User value {}: {}", ix, m_user_values[ix]);
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}
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}
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}
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void Heap::update_zero_block()
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{
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dbgln_if(SQL_DEBUG, "Write zero block to {}", name());
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dbgln_if(SQL_DEBUG, "Version: {}.{}", (m_version & 0xFFFF0000) >> 16, (m_version & 0x0000FFFF));
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dbgln_if(SQL_DEBUG, "Schemas root node: {}", m_schemas_root);
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dbgln_if(SQL_DEBUG, "Tables root node: {}", m_tables_root);
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dbgln_if(SQL_DEBUG, "Table Columns root node: {}", m_table_columns_root);
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dbgln_if(SQL_DEBUG, "Free list: {}", m_free_list);
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for (auto ix = 0u; ix < m_user_values.size(); ix++) {
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if (m_user_values[ix]) {
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dbgln_if(SQL_DEBUG, "User value {}: {}", ix, m_user_values[ix]);
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}
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}
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auto buffer = ByteBuffer::create_zeroed(BLOCKSIZE);
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buffer.overwrite(0, FILE_ID, strlen(FILE_ID));
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buffer.overwrite(VERSION_OFFSET, &m_version, sizeof(u32));
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buffer.overwrite(SCHEMAS_ROOT_OFFSET, &m_schemas_root, sizeof(u32));
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buffer.overwrite(TABLES_ROOT_OFFSET, &m_tables_root, sizeof(u32));
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buffer.overwrite(TABLE_COLUMNS_ROOT_OFFSET, &m_table_columns_root, sizeof(u32));
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buffer.overwrite(FREE_LIST_OFFSET, &m_free_list, sizeof(u32));
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buffer.overwrite(USER_VALUES_OFFSET, m_user_values.data(), m_user_values.size() * sizeof(u32));
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add_to_wal(0, buffer);
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}
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void Heap::initialize_zero_block()
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{
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m_version = 0x00000001;
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m_schemas_root = 0;
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m_tables_root = 0;
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m_table_columns_root = 0;
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m_next_block = 1;
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m_free_list = 0;
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for (auto& user : m_user_values) {
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user = 0u;
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}
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update_zero_block();
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}
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}
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