On 09/10/2015 09:17 AM, Richard Eckart de Castilho wrote:
On 10.09.2015, at 08:46, Richard Eckart de Castilho <[email protected]> wrote:
On 10.09.2015, at 04:06, Marshall Schor <[email protected]> wrote:
I don't think there's support for the 2nd, directly.
It's doable. There are various bits of code around that sequentially walk the
heap, which is what this would amount to, I think.
I'm curious about the need for such a capability?
Basically for doing sanity checks on the CAS, e.g. to detect if client code
creates FSes but never adds them to any index.
We've hit a bug in one piece of software where some annotations were indexed an
others not. The latter were still reachable in that case so I could implement
the sanity check without this capability. But while doing so, I was wondering
whether it was also possible to recover non-indexed FSes.
Another case would be detecting FSes that become unreachable unintentionally.
Cheers,
-- Richard
This used to be easy when I still worked on the code, and it probably
still is. The heap starts at position 1 (position 0 is the reserved null
reference). The first positon of a heap entry is the type of the FS.
There is a table that tells you how much space an entry of a certain
type takes. So you know where the next FS starts. And so on. As soon as
you reach a type cell that contains a 0, you know you have reached the
end of the occupied heap cells. That way you can look at all FSs that
were ever written to the heap.
There are low-level APIs that let you instantiate FSs from a given heap
position (but you probably knew that).
--Thilo
