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LibSQL: Redesign heap storage to support arbitrary amounts of data

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Previously, `Heap` would store serialized data in blocks of 1024 bytes
regardless of the actual length. Data longer than 1024 bytes was
silently truncated causing database corruption.

This changes the heap storage to prefix every block with two new fields:
the total data size in bytes, and the next block to retrieve if the data
is longer than what can be stored inside a single block. By chaining
blocks together, we can store arbitrary amounts of data without needing
to change anything of the logic in the rest of LibSQL.

As part of these changes, the "free list" is also removed from the heap
awaiting an actual implementation: it was never used.

Note that this bumps the database version from 3 to 4, and as such
invalidates (deletes) any database opened with LibSQL that is not
version 4.
This commit is contained in:
Jelle Raaijmakers
2023-04-23 12:38:57 +02:00
committed by Tim Flynn
parent 194f846f12
commit 6601ff9d65
Notes: sideshowbarker 2024-07-16 22:51:10 +09:00 
Author: https://github.com/gmta
Commit: https://github.com/SerenityOS/serenity/commit/6601ff9d65
Pull-request: https://github.com/SerenityOS/serenity/pull/18476
Reviewed-by: https://github.com/trflynn89 ✅
13 changed files with 246 additions and 180 deletions
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8
Userland/Libraries/LibSQL/TreeNode.cpp
View File

@@ -51,7 +51,7 @@ void DownPointer::deserialize(Serializer& serializer)
{
if (m_node || !m_pointer)
return;
serializer.get_block(m_pointer);
serializer.read_storage(m_pointer);
m_node = serializer.make_and_deserialize<TreeNode>(m_owner->tree(), m_owner, m_pointer);
}
@@ -87,7 +87,7 @@ TreeNode::TreeNode(BTree& tree, TreeNode* up, DownPointer& left, u32 pointer)
m_down.append(DownPointer(this, left));
m_is_leaf = left.pointer() == 0;
if (!pointer)
set_pointer(m_tree.new_record_pointer());
set_pointer(m_tree.request_new_block_index());
}
TreeNode::TreeNode(BTree& tree, TreeNode* up, TreeNode* left, u32 pointer)
@@ -271,7 +271,7 @@ void TreeNode::just_insert(Key const& key, TreeNode* right)
m_entries.insert(ix, key);
VERIFY(is_leaf() == (right == nullptr));
m_down.insert(ix + 1, DownPointer(this, right));
if (length() > Heap::BLOCK_SIZE) {
if (length() > Block::DATA_SIZE) {
split();
} else {
dump_if(SQL_DEBUG, "To WAL");
@@ -283,7 +283,7 @@ void TreeNode::just_insert(Key const& key, TreeNode* right)
m_entries.append(key);
m_down.empend(this, right);
if (length() > Heap::BLOCK_SIZE) {
if (length() > Block::DATA_SIZE) {
split();
} else {
dump_if(SQL_DEBUG, "To WAL");