1 files changed, 56 insertions, 0 deletions
diff --git a/util/smqueue.lua b/util/smqueue.lua
new file mode 100644
index 00000000..6d8348d4
--- /dev/null
+++ b/util/smqueue.lua
@@ -0,0 +1,56 @@
+local queue = require("util.queue");
+
+local lib = { smqueue = {} }
+
+local smqueue = lib.smqueue;
+
+function smqueue:push(v)
+	self._head = self._head + 1;
+
+	assert(self._queue:push(v));
+end
+
+function smqueue:ack(h)
+	if h < self._tail then
+		return nil, "tail"
+	elseif h > self._head then
+		return nil, "head"
+	end
+
+	local acked = {};
+	self._tail = h;
+	local expect = self._head - self._tail;
+	while expect < self._queue:count() do
+		local v = self._queue:pop();
+		if not v then return nil, "pop" end
+		table.insert(acked, v);
+	end
+	return acked
+end
+
+function smqueue:count_unacked() return self._head - self._tail end
+
+function smqueue:count_acked() return self._tail end
+
+function smqueue:resumable() return self._queue:count() >= (self._head - self._tail) end
+
+function smqueue:resume() return self._queue:items() end
+
+function smqueue:consume() return self._queue:consume() end
+
+function smqueue:table()
+	local t = {};
+	for i, v in self:resume() do t[i] = v; end
+	return t
+end
+
+local function freeze(q) return { head = q._head; tail = q._tail } end
+
+local queue_mt = { __name = "smqueue"; __index = smqueue; __len = smqueue.count_unacked; __freeze = freeze }
+
+function lib.new(size)
+	assert(size > 0);
+	return setmetatable({ _head = 0; _tail = 0; _queue = queue.new(size, true) }, queue_mt)
+end
+
+return lib