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>  Knowledge Base
I2070: Working with the Cache
Summary
Product: FreeProxy Internet Suite
Versions: all
Note: 2070
Date reported: 18 April 2008

Issue Detail
The Cache in FreeProxy will reduce the internet usage cost and improve performance for recently accessed web pages and objects.

Solution
This technical note covers two aspects of caching
  • Management
  • Measurement

Management
Cache Management is set up in the Cache screen of the Control Centre. There you can specify the type of management you want to use and most of it is self-explanatory. The help file covers this in detail. There are certain limitations in WIN32 which makes management through the operating system cumbersome. Hence from time to time it may be necessary to delete files manually. If you find that FreeProxy is not doing such a good job at maintaining the file system, delete the cache files from the OS. To do this:[List=1][*]Stop FreeProxy[*]Delete all cache files from the Cache folder including the file FPCacheStats.dat. Cache files can be found with the following search strings: FP*.FCD and FP*.FCC.
Monitoring
It may appear that the cache is not working. The rules for caching HTTP objects are complex and not everthing can be served from the cache. From version 4.00/1607 and 3.92/1642 caching has been improved but even so, you should not expect a 100% hit rate. In fact, most caching is done by the browser. Once an item has been stored in your browser's cache, the browser will ask FreeProxy if the item is still valid. These requests are passed to the remote server to answer. If the client is not asking for a re-validation of an object it already has, then FreeProxy will do one of 3 things:
  1. Get the object from its cache and send it to the client
  2. Get the item from the cache, confirming whether the item is still 'fresh' by checking with the web server, and then sending item to the client,or;
  3. Determining that the item is no longer fresh or it simply does not exist in the cache and then getting the object from the web server.
In these circumstances, the best way to determine cache hit rate is to use the following method.
  • Work with 2 browsers. In both browsers, clear their local browser caches (Tools -> Internet Options -> General in Internet Explorer 7).
  • Use a user defined string for the connection stats including the %CCH counter (press F1 when in the options screen of the Control Centre). This counter will provide the number of bytes served from the FreeProxy Cache.
  • Retrieve a number of busy web sites. Newspaper sites are a useful way of testing this. In the connection log you won't see any cache retrievals.
  • Subsequent retrievals from the SAME browser will also not result in many retrievals from the FP cache as most of the caching would have been done in the browser itself.
  • From the second Browser (on a different system), retrieve the same web sites you retrieved on the first browser. Now you should see a measurable performance increase and also a number of Cache hits in the log file.
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MemHT Portal is a free software released under the GNU/GPL License by Miltenovik Manojlo