From 6f44e6e7759a4bf57b9662754d8ea984d9a02eff Mon Sep 17 00:00:00 2001
From: Morten Sorvig <msorvig@trolltech.com>
Date: Fri, 4 Sep 2009 16:08:45 +0200
Subject: Add suport for never-expires data. Does not work yet

---
 src/eventqueue.cpp      |  1 +
 src/webclientserver.cpp | 23 +++++++++++++++++++++--
 src/webclientserver.h   |  2 ++
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/eventqueue.cpp b/src/eventqueue.cpp
index abffaea..bb4bc41 100644
--- a/src/eventqueue.cpp
+++ b/src/eventqueue.cpp
@@ -148,6 +148,7 @@ void EventQueue::handleStaticImageRequest(json_object* jsonRequest, HttpResponse
     quintptr imageid = staticImageHashToWidgetId.value(imageHash);
     QByteArray pngImage = staticCompressedImages.value(imageid);
     DEBUG << imageid << pngImage.count();
+    response->setNeverExpires();
     response->setBody(pngImage);
     response->setContentType("image/png");
 }
diff --git a/src/webclientserver.cpp b/src/webclientserver.cpp
index 44d120e..0e32717 100644
--- a/src/webclientserver.cpp
+++ b/src/webclientserver.cpp
@@ -72,7 +72,7 @@ void HttpRequest::parseText()
 }
 
 HttpResponse::HttpResponse()
-: contentType("text/html"), response304(false) { }
+: contentType("text/html"), response304(false), neverExpires(false) { }
 
 void HttpResponse::setBody(const QByteArray &body)
 {
@@ -99,6 +99,11 @@ void HttpResponse::set304Response()
     response304 = true;
 }
 
+void HttpResponse::setNeverExpires()
+{
+    neverExpires = true;
+}
+
 bool HttpResponse::isHandled() const
 {
     return response304 || body.isEmpty() == false;
@@ -125,7 +130,21 @@ QByteArray HttpResponse::toText()
         text+= "Set-Cookie: " + cookie + "\r\n";
     }
     
-    if (eTag.isEmpty() == false) {
+    // Support three different caching strategies:
+    // 1. Never-expires. Useful when content has a unique
+    // name based on e.g. a hash of the content. Allows the
+    // user agent to get the content once and then cache it
+    // forever.
+    // 2. Etag. The url for the content stays the same, the
+    // etag changes with content changes. Allows the user agent
+    // to ask if a spesific url as been updated, and then skip
+    // the content download if not.
+    // 3. no-cache. For dynamic content. Not cached by the user-agent
+    // and is re-downloaded on each request.
+    if (neverExpires) {
+        text += QByteArray("Cache-control: max-age: 99999 \r\n"); // or -1?
+        text += "eTag: 24 \r\n";
+    } else if (eTag.isEmpty() == false) {
         text += "eTag: " + eTag + "\r\n";
     } else {
         text += QByteArray("Cace-control: no-cache \r\n");
diff --git a/src/webclientserver.h b/src/webclientserver.h
index 2a08b7b..fa4818b 100644
--- a/src/webclientserver.h
+++ b/src/webclientserver.h
@@ -38,6 +38,7 @@ public:
     void setContentType(const QByteArray &contentType);
     void seteTag(const QByteArray &eTag);
     void set304Response();
+    void setNeverExpires();
 
     bool isHandled() const;
     QByteArray toText();
@@ -47,6 +48,7 @@ public:
     QByteArray contentType;
     QByteArray eTag;
     bool response304;
+    bool neverExpires;
 };
 
 class Server;
-- 
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