util.datamanager: Pad list writes to avoid crossing block boundaries By padding items so that they do not cross block boundaries, it becomes eaiser to delete whole blocks with fallocate() without cutting items in half, improving efficiency of such operations. Since list stores are used for message archives, where the most common deletion operation would be of the oldest entires, at the top of the file. With this, all blocks that contain items to be removed could be deleted without needing to read, delete and write out the whole file.

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local s_char = string.char;

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local s_format = string.format;

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local s_gsub = string.gsub;

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local s_lower = string.lower;

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local char_to_hex = {};

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local hex_to_char = {};

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do

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	local char, hex;

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	for i = 0,255 do

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		char, hex = s_char(i), s_format("%02x", i);

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		char_to_hex[char] = hex;

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		hex_to_char[hex] = char;

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	end

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end

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local function to(s)

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	return (s_gsub(s, ".", char_to_hex));

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end

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local function from(s)

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	return (s_gsub(s_lower(s), "%X*(%x%x)%X*", hex_to_char));

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end

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return {

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	encode = to, decode = from;

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	-- COMPAT w/pre-0.12:

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	to = to, from = from;

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};