1 files changed, 73 insertions, 0 deletions
diff --git a/src/channel.moon b/src/channel.moon
new file mode 100644
index 0000000..968ae09
--- /dev/null
+++ b/src/channel.moon
@@ -0,0 +1,73 @@
+
+-- Implements a channels, an abstraction for sending data
+
+class Channel
+	new: (settings) =>
+		settings = settings or {}
+		--Every channel has at least a buffer, the messages to be read on recv()
+		@buffer = {}
+		for setting_name, setting_value in pairs settings
+			@[setting_name] = setting_value
+	poll: =>
+		error("Channel must implement poll")
+	send: (message) =>
+		error("Channel must implement message")
+	recv: =>
+		error("Channel must implement recv")
+
+class SimpleChannel extends Channel
+	@time = 0
+	new: (settings) =>
+		super(settings)
+	poll: =>
+		#@buffer > 0
+	send: (message) =>
+		table.insert(@buffer, message)
+	recv: =>
+		table.remove(@buffer, 1)
+
+class FaultyChannel extends Channel
+	-- Mock channel for testing
+	@time = 0
+	new: (settings) =>
+		@to_deliver = {}
+		@avg_latency = 0 -- in ms
+		@latency_std = 0
+		-- Latency can never be below 0, but can go up as much as it likes
+		@avg_loss = 0 -- between 0 (never) and 1 (always)
+		@loss_std = 0.1
+		-- Loss is always a percentage between 0 and 1
+		super(settings)
+	normal: (avg, std, n) =>
+		assert(avg and std and n, string.format("normal(avg, std, n) called with %q %q %q", tostring(avg), tostring(std), tostring(n)))
+		-- Normal curve probability at N
+		(1/ (math.sqrt(2*math.pi) * avg)) * math.exp(-(n - avg)^2 / (2 * (std^2)))
+	poll: =>
+		@pump!
+		#@buffer > 0
+	send: (message) =>
+		-- Do we deliver?
+		if @normal(@avg_loss, @loss_std, math.random()) < 0.5
+			return
+		-- How long does it take?
+		time = @normal(@avg_latency, @latency_std, math.random())
+		if time < 0 then
+			time = 0 -- We can't deliver messages in the past
+		table.insert(@to_deliver, {message,time})
+	recv: =>
+		@pump!
+		table.remove(@buffer, 1)
+	pump: =>
+		defrag = 1
+		deliver_len = #@to_deliver
+		for k,tbl in ipairs(@to_deliver)
+			{m, t} = tbl
+			if @@time > t
+				@to_deliver[k] = nil
+				table.insert(@buffer, m)
+			if @to_deliver[defrag] == nil
+				@to_deliver[defrag] = tbl
+		for i = defrag, deliver_len do
+			@to_deliver[i] = nil
+
+{:Channel, :SimpleChannel, :FaultyChannel}