1 local queue = require("util.queue");

     2 

     3 local lib = { smqueue = {} }

     4 

     5 local smqueue = lib.smqueue;

     6 

     7 function smqueue:push(v)

     8 	self._head = self._head + 1;

     9 

    10 	assert(self._queue:push(v));

    11 end

    12 

    13 function smqueue:ack(h)

    14 	if h < self._tail then

    15 		return nil, "tail"

    16 	elseif h > self._head then

    17 		return nil, "head"

    18 	end

    19 

    20 	local acked = {};

    21 	self._tail = h;

    22 	local expect = self._head - self._tail;

    23 	while expect < self._queue:count() do

    24 		local v = self._queue:pop();

    25 		if not v then return nil, "pop" end

    26 		table.insert(acked, v);

    27 	end

    28 	return acked

    29 end

    30 

    31 function smqueue:count_unacked() return self._head - self._tail end

    32 

    33 function smqueue:count_acked() return self._tail end

    34 

    35 function smqueue:resumable() return self._queue:count() >= (self._head - self._tail) end

    36 

    37 function smqueue:resume() return self._queue:items() end

    38 

    39 function smqueue:consume() return self._queue:consume() end

    40 

    41 local compat_mt = {}

    42 

    43 function compat_mt:__index(i)

    44 	if i < self._queue._tail then return nil end

    45 	return self._queue._queue._items[(i + self._queue._tail) % self._queue._queue.size]

    46 end

    47 

    48 function compat_mt:__len() return self._queue:count_unacked() end

    49 

    50 function smqueue:table() return setmetatable({ _queue = self }, compat_mt) end

    51 

    52 local function freeze(q) return { head = q._head; tail = q._tail } end

    53 

    54 local queue_mt = { __name = "smqueue"; __index = smqueue; __len = smqueue.count_unacked; __freeze = freeze }

    55 

    56 function lib.new(size)

    57 	assert(size > 0);

    58 	return setmetatable({ _head = 0; _tail = 0; _queue = queue.new(size, true) }, queue_mt)

    59 end

    60 

    61 return lib