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Buffer pair offsets as a list to prepare for page splits
+48
-33
+2
-2
lib/btree/btree.ex
+2
-2
lib/btree/btree.ex
···
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[root_index, leaf_index] = FreeList.reserve_pages(free_list, 2)
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-
leaf_data = Page.encode_page_from_pairs(:leaf, opt_page_size, [])
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[leaf_data] = Page.encode_page_from_pairs(:leaf, opt_page_size, [])
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leaf_checksum = checksum(leaf_data)
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:ok = write_page(page_store, leaf_index, leaf_data)
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···
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leaf_address = <<leaf_index::integer-64, leaf_checksum::binary-16>>
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root_pairs = [{leaf_end_key, leaf_address}]
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root_data = Page.encode_page_from_pairs(:inner, opt_page_size, root_pairs)
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[root_data] = Page.encode_page_from_pairs(:inner, opt_page_size, root_pairs)
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root_checksum = checksum(root_data)
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:ok = write_page(page_store, root_index, root_data)
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+45
-30
lib/btree/page.ex
+45
-30
lib/btree/page.ex
···
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def encode_page_from_pairs(page_type, opt_page_size, pairs) do
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type_byte = encode_type(page_type)
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{body, slots, pair_count} = do_encode_page(pairs, "", "", 0)
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{body, offsets, pair_count} = do_encode_page(pairs, "", [], 0)
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maybe_split(opt_page_size, type_byte, body, offsets, pair_count)
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end
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-
# TODO: probably large enough?
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assert pair_count < (2 ** 16)
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# See constant: c_page_trailer_bytes()
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trailer = <<
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pair_count::integer-16,
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type_byte::integer-8,
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>>
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defp maybe_split(opt_page_size, type_byte, body, offsets, pair_count) do
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data_size = byte_size(body) + (pair_count * c_page_slot_entry_bytes()) + c_page_trailer_bytes()
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case data_size > opt_page_size do
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true ->
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assert false
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pad_bytes = opt_page_size - byte_size(body) - byte_size(slots) - byte_size(trailer)
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assert pad_bytes >= 0
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false ->
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pad_bytes = opt_page_size - data_size
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assert pad_bytes >= 0
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page_data = <<
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body::binary,
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0::integer-unit(8)-size(pad_bytes),
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>>
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page_data = encode_slots(offsets, page_data)
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assert pair_count < (2 ** 16)
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# See constant: c_page_trailer_bytes()
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page_data = <<
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page_data::binary,
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pair_count::integer-16,
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type_byte::integer-8,
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>>
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[page_data]
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end
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end
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page_data = <<
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body::binary,
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0::integer-unit(8)-size(pad_bytes),
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slots::binary,
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trailer::binary,
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defp encode_slots([], acc), do: acc
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defp encode_slots([offset | offsets_rest], acc) do
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assert offset < (2 ** 16)
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# See constant: c_page_slot_entry_bytes()
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acc = <<
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acc::binary,
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offset::integer-16,
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>>
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assert byte_size(page_data) == opt_page_size
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page_data
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encode_slots(offsets_rest, acc)
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end
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defp do_encode_page([], body_acc, slots_acc, count_acc) do
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{body_acc, slots_acc, count_acc}
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defp do_encode_page([], body_acc, offsets_acc, count_acc) do
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{body_acc, Enum.reverse(offsets_acc), count_acc}
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end
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defp do_encode_page([{key, value} | pairs_rest], body_acc, slots_acc, count_acc) do
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defp do_encode_page([{key, value} | pairs_rest], body_acc, offsets_acc, count_acc) do
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pair_offset = byte_size(body_acc)
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key_size = byte_size(key)
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value_size = byte_size(value)
···
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value::binary,
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>>
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# TODO: support >64KiB pages?
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assert pair_offset < (2 ** 16)
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# See constant: c_page_slot_entry_bytes()
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slots_acc = <<
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slots_acc::binary,
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pair_offset::integer-16,
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>>
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offsets_acc = [pair_offset | offsets_acc]
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count_acc = count_acc + 1
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do_encode_page(pairs_rest, body_acc, slots_acc, count_acc)
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do_encode_page(pairs_rest, body_acc, offsets_acc, count_acc)
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end
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def decode_page(page_data) do
+1
-1
lib/btree/writer.ex
+1
-1
lib/btree/writer.ex
···
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:leaf -> fill_leaf(btree.write_buffer, page_ek, pairs)
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end
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new_page_data = Page.encode_page_from_pairs(page_type, btree.opts.page_size, pairs)
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[new_page_data] = Page.encode_page_from_pairs(page_type, btree.opts.page_size, pairs)
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[new_page_index] = FreeList.reserve_pages(btree.free_list, 1)
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new_page_checksum = BTree.checksum(new_page_data)
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:ok = BTree.write_page(btree.page_store, new_page_index, new_page_data)