8220394: bufferedStream does not honor size limit

[David Holmes]

Hi Thomas,

On 22/05/2019 7:25 pm, Thomas Stüfe wrote:
> Hi all,
> 
> third round: 
> http://cr.openjdk.java.net/~stuefe/webrevs/8220394-bufferedstream-does-not-honor-size-limit/webrev.02/webrev/

That version is a lot harder to get my head around. I think it is okay.

Thanks,
David
-----

> I also added a gtest test case for bufferedStream. It tests the static 
> variant, the dynamic variant without truncation and with truncation. The 
> last test, testing with truncation, is commented out - to run this test, 
> you need to manually enable it first. This is because it uses a lot of 
> memory (100M) in release and in debug it would crash as expected.
> 
> Cheers, Thomas
> 
> 
> 
> 
> On Tue, May 21, 2019 at 4:18 PM Thomas Stüfe <thomas.stuefe at gmail.com 
> <mailto:thomas.stuefe at gmail.com>> wrote:
> 
>     Hi,
> 
>     new webrev with the following changes:
> 
>     - reworked comment to make it more concise and clear
>     - the cap where we assert now is guaranteed to be larger than the
>     buffer maximum.
> 
>     http://cr.openjdk.java.net/~stuefe/webrevs/8220394-bufferedstream-does-not-honor-size-limit/webrev.01/webrev/
> 
>     Thanks, Thomas
> 
> 
> 
>     On Tue, May 14, 2019 at 12:25 PM Thomas Stüfe
>     <thomas.stuefe at gmail.com <mailto:thomas.stuefe at gmail.com>> wrote:
> 
>             Hi all,
> 
> 
>         Bug: https://bugs.openjdk.java.net/browse/JDK-8220394
>         cr:
>         http://cr.openjdk.java.net/~stuefe/webrevs/8220394-bufferedstream-does-not-honor-size-limit/webrev.00/webrev/
> 
>         I redid the patch for this in a minimal form. The first version
>         I posted in March but after consideration I found it too invasive.
> 
>         Short story: bufferedStream is misused as a
>         outputStream-with-dynamic-buffer in a number of places - misused
>         since we have stringStream for that.
> 
>         It has something looking like a maximum buffer size cap but that
>         is actually a flush-trigger for child classes of bufferesStream.
>         bufferedStream::flush itself is a noop.
> 
>         That means that printing to this stream may cause high memory
>         footprint or native OOM since the upper limit is not honored. In
>         runaway printing coding this can tear down the process.
> 
>         This patch is a stopgap - when we reach the buffer limit - but
>         not below 100M - we will assert(debug) or truncate (release).
> 
>         I am careful here since I do not know if there are situations
>         where more than buffer-limit bytes are written today and
>         suddenly enforcing this limit now would cause errors. I think
>         100M is safe to be considered "too much".
> 
>         The real correct solution should be that all callers use
>         stringStream and handle truncation. This patch is small and
>         could be, if necessary, ported down to older releases easily.
> 
>         Thanks, Thomas
> 
>