Thank you Roger for review!
On 9/25/17 11:47 AM, Roger Riggs wrote:
Hi Ivan,
Looks ok to me.
I don't see a reason to skimp on the additional size since it is
allocated and then freed immediately.
The increment might as well be as big as the initial size.
Right. Let's use the same value of 15K, which reduces the number of
variables to operate with.
I don't see a reason to retry if the buffer gets close to ULONG_MAX;
I'd just break the for loop
and let it fail. (but the new code is just doing what the old code did
and retry even if the buffer did not increase).
If len is close to ULONG_MAX, it is still larger value of len returned
by the previous call to GetAdaptersAddresses (otherwise we wouldn't have
gotten ERROR_BUFFER_OVERFLOW.)
So, if we're in the loop, there's no way the buffer will not increase
(unless there's a failure due to OOM, of course.)
Also, please introduce a constant for the number of retries; it will
make it clearer
and not need to hard code it in two places.
Done!
Would you please take a look at the updated webrev:
http://cr.openjdk.java.net/~igerasim/8187658/01/webrev/
With kind regards,
Ivan
(I would probably have coded the retry count counting down to zero but
its the same effect).
Regards, Roger
On 9/25/2017 1:03 PM, Ivan Gerasimov wrote:
Ping.
Please review the proposed change at your convenience.
The fix will greatly reduce the possibility of a need to reallocate
the buffer to retrieve the results (something that the documentation
strongly suggests to avoid), and, if such reallocation still occurs
to be necessary, will increase number of retries.
With kind regards,
Ivan
On 9/19/17 10:50 AM, Ivan Gerasimov wrote:
Hello!
When retrieving information about network interfaces on Windows we
make up to 2 attempts to call GetAdaptersAddresses().
It was reported that in very rare cases it may not be sufficient,
and even the second attempt can fail with ERROR_BUFFER_OVERFLOW.
I suggest that we follow the recommendation given in MSDN [1]:
increase the initial buffer size to 15K and do up to 3 attempts to
call GetAdaptersAddresses().
BUGURL: https://bugs.openjdk.java.net/browse/JDK-8187658
WEBREV: http://cr.openjdk.java.net/~igerasim/8187658/00/webrev/
Would you please help review the fix?
[1]
https://msdn.microsoft.com/en-us/library/windows/desktop/aa365915(v=vs.85).aspx
--
With kind regards,
Ivan Gerasimov
