modify cache expiration of existing full page cache hole punch

Question

I'd like to punch a hole in the full page cache for the top menu of a site. While digging through some Enterprise code, I see that the top menu has an existing hole punched:

// app/code/coe/Enterprise/PageCache/etc/cache.xml
<catalog_navigation>
 <block>page/html_topmenu</block>
 <name>catalog.topnav</name>
 <placeholder>TOPMENU</placeholder>
 <container>Enterprise_PageCache_Model_Container_Catalognavigation</container>
 <cache_lifetime>86400</cache_lifetime>
</catalog_navigation>

However, I'd like to change the cache_lifetime to be much shorter (1 second). What is the best way to modify the cache_lifetime without modifying core code?

• benmarks: Why on earth do you want a 1s cache expiry??
• Ryre: To effectively disable caching the top menu. It's very... dynamic.
• benmarks: This is the wrong way to go about it, I believe. I think if you pass <cache_lifetime /> you will get what you want. FWIW I can't imagine such dynamism to be good for the user or for search engines, but obviously I don't know your use case.
• Ryre: B2B site that's closed to the world. SEO isn't a concern. They dynamic aspects weren't my idea. =/

Answer 1

I believe that if you declare a custom module as <depends> on <Enterprise_PageCache/> and create a cache.xml file which contains the following, you will effectively override the core cache_lifetime value:

<?xml version="1.0"?>
<cache>
 <catalog_navigation>
 <cache_lifetime>1</cache_lifetime>
 </catalog_navigation>
</cache>

• MagePsycho: Shouldn't catalog_navigation be wrapped in :<config><placeholders>?