Not sure if this is just a doc issue, or a bug.

I just put Boost on a site. I started slow just put it on and see what it did. After a few days and looking at Apache logs, I wanted to it to preemptively cache about 2 dozen pages on the site. So I turn on the crawler and the preemptive setting. I then, on the front page, it to preemptive cache.

What happened is that the footer showed that page had always expired one second before it was cached. Not what I expected. Looking at the boost settings table it uses "-1" to mean "default" in the block, but the code is taking the -1 and using it directly.

The fix was easy wherever I set a page to preemptively cache a page, then also set the cache time to something, even if it is the same as your site default.

After a few days I went back to the site and started tweaking more things. In this case wanted to set the expire time for some node classes. In this case pictures/images, the body/credits rarely change after they have been uploaded to the site so it makes sense to cache them for much longer than the site default. I went to one image node and changed the cache time from default to 2 weeks, and then changed the pulldown from nodeid to node type of image.

Much to my surprise, Boost was now trying to preemptively cache all nodes of type image, and we have a lot. I had to go back change the setting for preemptive to "No" from "Default".

In the first case the I think he code should be handling the "-1" default case correctly. In the second, something in the doc warning about setting a non-default cache time will also turn on preemptive caching.