From 96e11423b32302287a90123b8ead227b80c4bb68 Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jow@openwrt.org>
Date: Thu, 26 Jun 2008 20:25:02 +0000
Subject: [PATCH] * libs/http:	implement caching in http.protocol.date

---
 libs/http/luasrc/http/protocol/date.lua | 62 ++++++++++++++-----------
 1 file changed, 36 insertions(+), 26 deletions(-)

diff --git a/libs/http/luasrc/http/protocol/date.lua b/libs/http/luasrc/http/protocol/date.lua
index d40360494..a7edcfd02 100644
--- a/libs/http/luasrc/http/protocol/date.lua
+++ b/libs/http/luasrc/http/protocol/date.lua
@@ -15,6 +15,10 @@ $Id$
 
 module("luci.http.protocol.date", package.seeall)
 
+local ucache = { }
+local hcache = { }
+
+
 MONTHS = {
 	"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
 	"Sep", "Oct", "Nov", "Dec"
@@ -151,40 +155,46 @@ end
 -- Convert a HTTP date to unixtime
 function to_unix(date)
 
-	local wd, day, mon, yr, hr, min, sec, tz = date:match(
-		"([A-Z][a-z][a-z]), ([0-9]+) " ..
-		"([A-Z][a-z][a-z]) ([0-9]+) " ..
-		"([0-9]+):([0-9]+):([0-9]+) " ..
-		"([A-Z0-9%+%-]+)"
-	)
-
-	if day and mon and yr and hr and min and sec then
-		-- find month
-		local month = 1
-		for i = 1, 12 do
-			if MONTHS[i] == mon then
-				month = i
-				break
+	if not ucache[date] then
+		local wd, day, mon, yr, hr, min, sec, tz = date:match(
+			"([A-Z][a-z][a-z]), ([0-9]+) " ..
+			"([A-Z][a-z][a-z]) ([0-9]+) " ..
+			"([0-9]+):([0-9]+):([0-9]+) " ..
+			"([A-Z0-9%+%-]+)"
+		)
+
+		if day and mon and yr and hr and min and sec then
+			-- find month
+			local month = 1
+			for i = 1, 12 do
+				if MONTHS[i] == mon then
+					month = i
+					break
+				end
 			end
-		end
 
-		-- convert to epoch time
-		return tz_offset(tz) + os.time( {
-			year  = yr,
-			month = month,
-			day   = day,
-			hour  = hr,
-			min   = min,
-			sec   = sec
-		} )
+			-- convert to epoch time
+			ucache[date] = tz_offset(tz) + os.time( {
+				year  = yr,
+				month = month,
+				day   = day,
+				hour  = hr,
+				min   = min,
+				sec   = sec
+			} )
+		end
 	end
 
-	return 0
+	return ucache[date] or 0
 end
 
 -- Convert a unixtime to HTTP date
 function to_http(time)
-	return os.date( "%a, %d %b %Y %H:%M:%S GMT", time )
+	if not hcache[time] then
+		hcache[time] = os.date( "%a, %d %b %Y %H:%M:%S GMT", time )
+	end
+
+	return hcache[time]
 end
 
 -- Compare two dates
-- 
2.25.1