Cache usage
AWeb uses a special caching system, partially in memory and partially
on disk, to reduce the number of network accesses.
Note that the AWeb cache is a cache, not a proxy system.
This means that the cache is cleared when AWeb finishes. Also, the cache
doesn't take the HTTP expiration date into account. This might change in
later versions of AWeb.
Documents
Documents that can be displayed by AWeb are initially loaded in memory.
When the document cache is full, the least recently displayed document is
swapped out to disk, thereby freeing memory. If a swapped-out page must
be displayed again, it is swapped back into memory, thereby probably
swapping out other pages.
The swapped documents are stored in AWeb's
temporary directory. It should be
clear that this would be only meaningful if the temporary directory isn't
in RAM. So, if you are using a temporary directory in RAM, be sure to set
the document cache memory size large enough.
When the total size of swapped out documents is larger than the
document cache disk size, the least recently displayed documents
are deleted.
Images
Inlined images are treated completely differently. Images are stored in
the temporary directory when they are loaded. If the image is received
completely, the datatype will process the file, resulting in a
displayable image in chip memory (the image cache). When the
image cache is full, undisplayed images in memory are removed, but the disk
file remains. If the image must be displayed later, the disk file is
processed again, but no network access is needed.
Because the datatype locks the file, the disk file must remain while the
image is in memory.
When the total size of image files is larger than the image cache
disk size, the least recently displayed images are deleted.
Low memory
To avoid crashes when running out of memory (caused by the datatypes or
other external programs), AWeb tries to leave at least 100 kB of chip
memory free. Whenever there is less than 100 kB total memory free,
AWeb will swap out documents, even if the document cache isn't full yet.
Displayed documents will never be swapped out.
When there is more than 100 kB total
free memory, but less than 100 kB free chip memory, AWeb will flush
images from memory, even if they are being displayed. As long as the
image disk cache isn't full, they remain on disk.
Setting the cache sizes
You can set the cache sizes from the
Program 1: General page in the
settings requester.
If you are using a 2MB Amiga, have a look at the
2MB tips.
Otherwise, you will probably want to use a
- temporary directory in RAM;
- a document memory cache large enough,
- a document disk cache of size 0;
- a reasonably sized image memory cache (this will take
up chip memory),
- a large image disk cache.
Of course, you can use other settings if you like. You can fine-tune the
memory and disk usage by changing these settings.