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/*
* Copyright (c) 2021, Jan de Visser <jan@de-visser.net>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Array.h>
#include <AK/Debug.h>
#include <AK/DeprecatedString.h>
#include <AK/HashMap.h>
#include <AK/Vector.h>
#include <LibCore/Object.h>
#include <LibCore/Stream.h>
namespace SQL {
constexpr static u32 BLOCKSIZE = 1024;
/**
* A Heap is a logical container for database (SQL) data. Conceptually a
* Heap can be a database file, or a memory block, or another storage medium.
* It contains datastructures, like B-Trees, hash_index tables, or tuple stores
* (basically a list of data tuples).
*
* A Heap can be thought of the backing storage of a single database. It's
* assumed that a single SQL database is backed by a single Heap.
*
* Currently only B-Trees and tuple stores are implemented.
*/
class Heap : public Core::Object {
C_OBJECT(Heap);
public:
static constexpr inline u32 current_version = 3;
virtual ~Heap() override;
ErrorOr<void> open();
u32 size() const { return m_end_of_file; }
ErrorOr<ByteBuffer> read_block(u32);
[[nodiscard]] u32 new_record_pointer();
[[nodiscard]] bool valid() const { return static_cast<bool>(m_file); }
u32 schemas_root() const { return m_schemas_root; }
void set_schemas_root(u32 root)
{
m_schemas_root = root;
update_zero_block();
}
u32 tables_root() const { return m_tables_root; }
void set_tables_root(u32 root)
{
m_tables_root = root;
update_zero_block();
}
u32 table_columns_root() const { return m_table_columns_root; }
void set_table_columns_root(u32 root)
{
m_table_columns_root = root;
update_zero_block();
}
u32 version() const { return m_version; }
u32 user_value(size_t index) const
{
VERIFY(index < m_user_values.size());
return m_user_values[index];
}
void set_user_value(size_t index, u32 value)
{
VERIFY(index < m_user_values.size());
m_user_values[index] = value;
update_zero_block();
}
void add_to_wal(u32 block, ByteBuffer& buffer)
{
dbgln_if(SQL_DEBUG, "Adding to WAL: block #{}, size {}", block, buffer.size());
dbgln_if(SQL_DEBUG, "{:hex-dump}", buffer.bytes().trim(8));
m_write_ahead_log.set(block, buffer);
}
ErrorOr<void> flush();
private:
explicit Heap(DeprecatedString);
ErrorOr<void> write_block(u32, ByteBuffer&);
ErrorOr<void> seek_block(u32);
ErrorOr<void> read_zero_block();
void initialize_zero_block();
void update_zero_block();
OwnPtr<Core::Stream::BufferedFile> m_file;
u32 m_free_list { 0 };
u32 m_next_block { 1 };
u32 m_end_of_file { 1 };
u32 m_schemas_root { 0 };
u32 m_tables_root { 0 };
u32 m_table_columns_root { 0 };
u32 m_version { current_version };
Array<u32, 16> m_user_values { 0 };
HashMap<u32, ByteBuffer> m_write_ahead_log;
};
}
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