Disk cache
The disk cache subsystem of Challenger handles caching for proxy
modules. Currently only the HTTP-Proxy module caches
requests. The disk cache is enabled by the global variable Global Variables/Proxy
disk cache.../Enabled.
It is the disk cache system that handles which requests are to be
cached. Files in the disk cache are removed by a garbage collector
process, that is run at specified intervals.
- Base Cache Dir
-
The directory where the disk cache should
be kept.
- Bytes per second
-
How the garbage collector should
treat file size. Each byte of file size will be equal to a certain
number of seconds of age. This way, really large files will be treated
as older files and removed before smaller files of the same age.
- Clean size
-
Minimum number of megabytes to remove per
garbage collect.
- Garbage collector logfile
-
If set, a log file will be
kept with information about removed and refreshed files, as well as
cache and disk status.
- Keep without Content-Length
-
Keep files that have no
Content-Length header. This will make the cache store more files, but
it will also be possible that partially downloaded files, as well as
dynamic pages, are cached.
- Last resort
-
How many days to keep files with no
Expire or Last-Modified headers.
- Maximum number of files
-
Maximum number of files to be
cached.
- Minimum available free space and inodes
-
What
percentage of disk space and disk inodes must be available on the file
system with the cache. By setting this variable, it is possible to
make sure that the disk cache will never fill the entire file system.
- Number of hash directories
-
The number of directories
the cache should consist of.
- If this variable is changed, it will no longer be possible to
access the old cache.
- Refresh on Last-Modified
-
If set, the disk cache will
use the Last-Modified header to determine how long a file should be
cached, if the file doesn't contain any Expire header. The file will
be kept until it has doubled it's age.
- Size
-
The maximum size of the cache, in megabytes.
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