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Changed from using raw byte access methods to PageContent read/write methods

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krishvishal
2025-03-11 22:49:18 +05:30
parent 91fa6a5fa3
commit 6093994bd2
1 changed files with 10 additions and 5 deletions
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15
core/storage/btree.rs
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@@ -2316,7 +2316,6 @@ fn find_free_cell(page_ref: &PageContent, usable_space: u16, amount: usize) -> R
// unuse_space is reserved bytes at the end of page, therefore we must substract from maxpc
let mut prev_pc = page_ref.offset + PAGE_HEADER_OFFSET_FIRST_FREEBLOCK;
let mut pc = page_ref.first_freeblock() as usize;
let buf = page_ref.as_ptr();
let maxpc = usable_space as usize - amount;
while pc <= maxpc {
@@ -2324,23 +2323,29 @@ fn find_free_cell(page_ref: &PageContent, usable_space: u16, amount: usize) -> R
return_corrupt!("Free block header extends beyond page");
}
let next = u16::from_be_bytes(buf[pc..pc + 2].try_into().unwrap());
let size = u16::from_be_bytes(buf[pc + 2..pc + 4].try_into().unwrap());
let next = page_ref.read_u16_no_offset(pc);
let size = page_ref.read_u16_no_offset(pc + 2);
if amount <= size as usize {
let new_size = size as usize - amount;
if new_size < 4 {
// The code is checking if using a free slot that would leave behind a very small fragment (x < 4 bytes)
// would cause the total fragmentation to exceed the limit of 60 bytes
// check sqlite docs https://www.sqlite.org/fileformat.html#:~:text=A%20freeblock%20requires,not%20exceed%2060
if page_ref.num_frag_free_bytes() > 57 {
return Ok(0);
}
buf[prev_pc..prev_pc + 2].copy_from_slice(&next.to_be_bytes());
// Delete the slot from freelist and update the page's fragment count.
page_ref.write_u16(prev_pc, next);
let frag = page_ref.num_frag_free_bytes() + new_size as u8;
page_ref.write_u8(PAGE_HEADER_OFFSET_FRAGMENTED_BYTES_COUNT, frag);
return Ok(pc);
} else if new_size + pc > maxpc {
return_corrupt!("Free block extends beyond page end");
} else {
buf[pc + 2..pc + 4].copy_from_slice(&(new_size as u16).to_be_bytes());
// Requested amount fits inside the current free slot so we reduce its size
// to account for newly allocated space.
page_ref.write_u16(pc + 2, new_size as u16);
return Ok(pc + new_size);
}
}