On 8/25/10 1:12 AM, Ben Lerner wrote:
1) "hibernating" documents are very limited in what one can do with
them (e.g. attempting to mutate the document in any way while
hibernating will throw it away).
I assume such mutation could only come from other, fully-active,
same-origin documents. Why should mutating the document cause it to be
thrown away?
In Gecko's case, because such documents should not trigger network
requests, run any script (including mutation event handlers), etc. The
fact that the cache even exists should be as not-exposed to everyone as
possible.
Suppose, for a hypothetical, that instead of throwing away the
hibernated document, you returned an error on the DOM method in the
caller document if it tried to mutate it.
This would almost certainly break pages, which get no exceptions if they
try to do this right now. Worse, it would break them in a
timing-dependent way.
outright broken? (I'm still trying to get a handle on the rationale
behind either reloading or not pausing documents, beyond just
"historical reasons", so I'm just brainstorming here...)
Don't underestimate "historical reasons". They're also known as
"compatibility with deployed content". ;)
Note that in Gecko documents with active network requests never go
into hibernation right now, precisely because we don't want to have to
buffer potentially-arbitrary amounts of data (see JPEG push) for
arbitrary lengths of time. We still wouldn't want to do so in this
case...
That's a tunable policy issue, right? I.e., buffer X Kb of data, then
terminate active network requests.
The problem with that approach is that when the user then navigates back
to the page it will be broken (e.g. if they left it early in the load
its DOM may not even all be there).
Maybe even be so kind as to fake up a
pair of offline/online events. A web program probably has to be robust
to these sorts of network-partitioning events anyway, right?
They aren't. Welcome to the web. Of course such events are also rare;
if and when they happen users tend to just hit the reload button and
move on.
-Boris
