Caching file_get_contents output inside APC (Performance improvement).

Hi,
   APC creates a mmap which is used for caching compiled php response. Besides
this APC provides API to cache user data into this mmap. There are many php
apps which uses file_get_contents to read the static files. If APC can cache
these files in it's mmap, it will improve file_get_contents performance.

Based on the above idea, I developed a patch which stores the file_get_contents
output in APC's cache. In this patch, APC intercepts the calls of
file_get_contents and replaces it with apc_file_get_contents function. If file
is a full path and entire file is requested then APC caches the content.

To enable the caching use the following in php.ini :
apc.cache_static_contents=1
apc.user_ttl = 30

apc.user_ttl will decide how long the entry will remain inside the cache.  If
apc.user_ttl is set to 0 then the entry will never be removed from cache.

Here is the performance data collected using Studio 12 on Solaris sparc for
ecommerce php benchmark. (3500 simultaneous users)

Excl.     Incl.     Excl.       Incl.       Excl.     Incl.      Name
User CPU  User CPU  Total LWP   Total LWP   Sys. CPU  Sys. CPU
    sec.      sec.        sec.        sec.      sec.      sec.
No Cache :
  0.831    28.660       1.141     540.018     0.030   344.311
zif_file_get_contents
With Cache :
  1.481   181.537       1.821     282.758     0.140    12.449
zif_apc_file_get_contents


User + System time before Caching = 372 seconds
User + System time after Caching = 193 seconds
Total time reduction in file_cache_contents = 48%

Here is my blog :
http://blogs.sun.com/basant/entry/caching_file_get_contents_output
Here is the link to the patch :
http://blogs.sun.com/basant/resource/apc_file_cache_trunk_patch.txt

There are many other enhancements possible in this patch. I would appreciate
any comments.

Regards,
Basant.