On Tue, May 19, 2009 at 11:46 PM, Nick Mathewson wrote:
On Tue, May 19, 2009 at 10:20:08PM +1000, Peter Ross wrote:
Hi,
I've been tracking down a bug with boehm gc prematurely collecting the
bufferevent callback arg value. This occurs when one is the middle of
processing another bufferevent in the read callback.
I've tried to grok the code to understand how one would get from the
eventbase to the other bufferevent, so I can check where the boehm gc
is losing the pointer, but having difficulty understanding the code.
Could someone explain how I get from an event base to all the
bufferevents associated with that base?
You don't. Only when a bufferevent is actively listening for read or
write events does it have any references from the event base.
The bufferevent is listening for more read data
Assuming that the event_base is at address 0x4803d38 and fd is the
file descriptor of the bufferevent that we are interested in. Then I
think this is how you get from the base to the event associated with
this base.
*(((struct evmap_io *) ((struct event_base *)
0x4803d38)-io-entries[fd])-events-tqh_first)
Anyway there is no tricky bit twiddling going on to confuse the gc, so
as far as I can see the gc should be able to trace all this memory.
Pete
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