[TYPO3-dev] better cache management in extensions (tt_news example)

[Krystian Szymukowicz]

hi

Today typical use of tt_news extension and cache settings:

root
   |-- sys folder - tt_news records (id = 2) TCEMAIN.clearCacheCmd = 3,4
   |-- standard page - tt_news LIST_VIEW (id = 3)
   |-- standard page - tt_news SINGLE VIEW (id = 4)


With every change on sys_folder (id = 2) all cache of id 3,4 are cleared.

It is not optimal.

In systems with few thousand tt_news records and average 1000ms tt_news 
item rendering we have thousand seconds of server usage (3600s = 1h).


Is seems like there is a way to clear only cache of pages that have changed.


FIRST STEP
--------------------------
Mark every occurrence of tt_news record at page (let's call it "tt_news 
record marker"). This is simple. We can use id of the news with proper 
word.

It is up to webdesigner how he will integrate it into his tt_news 
template. Few possibilities:

1) additional class in <a>
<a href=”...” class=”designclass ttnews_cache_232”>tt news reecord 232 
title</a>
<a href=”...” class=”designclass ttnews_cache_212”>tt news reecord 212 
title</a>

2) id in <a>
<a href=”...” class=”designclass” id=”ttnews_cache_232”>tt news reecord 
232 title</a>
<a href=”...” class=”designclass” id=”ttnews_cache_212”>tt news reecord 
212 title</a>

3) additional div
<div id=”ttnews_cache_232”><a href=”...” class=”designclass” >tt news 
reecord 232 title</a></div>
<div id=”ttnews_cache_232”><a href=”...” class=”designclass” 
id=”ttnews_cache_212”>tt news reecord 212 title</a></div>

4) simple html comments after record link
<a href=”...” class=”designclass” id=”ttnews_cache_212”>tt news reecord 
212 title</a><!-- ttnews_cache_232 -->


SECOND STEP
--------------------------------------
Define what "cache_pages" to search in for "tt_news record markers".
This id for performance issue in order not to search in all cache_pages 
records.
This setting is similar "TCEMAIN.clearCacheCmd = 3,4" but because 
TCEMAIN.clearCacheCmd is not optimal in this scenario we have to define 
that another way: For example something like:

plugin.tt_news.clearCache = 3,4



THIRD STEP
--------------------------------
A hook "after record save" will get pids from plugin.tt_news.clearCache 
and id of tt_news that was modified and will delete from "cache_pages" 
table all records with ttnews_cache_[id] in "HTML" field of "cache_pages".



Above clear cache system is good for the case the tt_news record was 
only edited.
If we add or delete tt_news record we have to clear LIST_VIEWS anyway 
but do not have to clear cache of SINGLE_VIEW page (which we have to do 
with standard TCEMAIN.clearCacheCMD).


To get add/delete into account the TS settings needs to be little expanded.

Example:

    plugin.tt_news.clearCache.list_view_pids = 3
    plugin.tt_news.clearCache.single_view_pids = 4


Lets see what have to be done in different tt_news record operation.
a) RECORD EDIT

    For "RECORD EDIT" use "tt_news record markers" search and delete in
    	plugin.tt_news.clearCache.list_view_pids
	plugin.tt_news.clearCache.single_view_pids


b) RECORD ADD/DELETE

    For "add,delete" clear all page_cache for:
	plugin.tt_news.clearCache.list_view_pids

    AND use "tt_news record markers" for
	plugin.tt_news.clearCache.single_view_pids

    to search for bi-directional relation of new/deleted record.




Take into account that in both cases we didn't have to clear all 
SINGLE_VIEW cache and in case of simple tt_news edit we delete really 
only those pages that are needed.


Although it seems to be possible I would like to have your opinion, 
because I am not very good in TYPO3 internals and maybe there is a 
simple misunderstanding in my idea.


--
grtz
Krystian