# HG changeset patch
# User Matthew Wild <mwild1@gmail.com>
# Date 1433343067 -3600
# Node ID d4a6c9ee4bc5f5a2036be1e95a0173a36be850d3
# Parent  7889515bac86a6853c3034d4777a6b4e4ce9212e
util.queue: Allow optional wrap-around when pushing, overwriting oldest unread item

diff -r 7889515bac86 -r d4a6c9ee4bc5 util/queue.lua
--- a/util/queue.lua	Sat May 30 22:23:19 2015 +0100
+++ b/util/queue.lua	Wed Jun 03 15:51:07 2015 +0100
@@ -11,7 +11,7 @@
 
 local have_utable, utable = pcall(require, "util.table"); -- For pre-allocation of table
 
-local function new(size)
+local function new(size, allow_wrapping)
 	-- Head is next insert, tail is next read
 	local head, tail = 1, 1;
 	local items = 0; -- Number of stored items
@@ -22,7 +22,12 @@
 		count = function (self) return items; end;
 		push = function (self, item)
 			if items >= size then
-				return nil, "queue full";
+				if allow_wrapping then
+					tail = (tail%size)+1; -- Advance to next oldest item
+					items = items - 1;
+				else
+					return nil, "queue full";
+				end
 			end
 			t[head] = item;
 			items = items + 1;