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LibSQL: Reuse heap blocks when overwriting storage

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Previously, only the first block in a chain of blocks would be
overwritten while all subsequent blocks would be appended to the heap.
Now we make sure to reuse all existing blocks in the chain.
This commit is contained in:
Jelle Raaijmakers 2023-05-24 14:08:31 +02:00 • committed by Tim Flynn
parent 2d2911e1a3
commit c5ebc4bb40
3 changed files with 68 additions and 3 deletions
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26
Userland/Libraries/LibSQL/Heap.cpp
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@ -72,6 +72,12 @@ ErrorOr<void> Heap::open()
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);
@ -95,6 +101,7 @@ ErrorOr<ByteBuffer> Heap::read_storage(Block::Index index)
ErrorOr<void> Heap::write_storage(Block::Index index, ReadonlyBytes data)
{
dbgln_if(SQL_DEBUG, "{}({}, {} bytes)", __FUNCTION__, index, data.size());
VERIFY(index > 0);
VERIFY(data.size() > 0);
// Split up the storage across multiple blocks if necessary, creating a chain
@ -103,11 +110,24 @@ ErrorOr<void> Heap::write_storage(Block::Index index, ReadonlyBytes data)
while (remaining_size > 0) {
auto block_data_size = AK::min(remaining_size, Block::DATA_SIZE);
remaining_size -= block_data_size;
auto next_block_index = (remaining_size > 0) ? request_new_block_index() : 0;
auto block_data = TRY(ByteBuffer::create_uninitialized(block_data_size));
ByteBuffer block_data;
Block::Index next_block_index = 0;
if (has_block(index)) {
auto existing_block = TRY(read_block(index));
block_data = existing_block.data();
TRY(block_data.try_resize(block_data_size));
next_block_index = existing_block.next_block();
} else {
block_data = TRY(ByteBuffer::create_uninitialized(block_data_size));
}
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;