RFR: 8146879: Add option for handling existing log files in UL

[Robbin Ehn]

Hi Marcus,

On 03/18/2016 02:04 PM, Marcus Larsson wrote:
> Updated patch after feedback.
>
> New webrev:
> http://cr.openjdk.java.net/~mlarsson/8146879/webrev.04/
>
> Incremental:
> http://cr.openjdk.java.net/~mlarsson/8146879/webrev.03-04/
>
> Tested with internal VM tests through RBT.
>
> Changes:
> * Rotation filecount is now limited to 1000 files.
> * Removed loop in os::compare_file_modified_times.
> * Added a check before rotating/truncating an existing log file, and
> will only do so if it's a regular file.
> * Added test case to check that logging to a directory gives the
> intended error message.
> * Fixed test help method to handle arbitrary length log lines.

I tested this and it works fine.

Code looks good to me.

Thanks for fixing this!

/Robbin

>
> Thanks,
> Marcus
>
> On 03/11/2016 03:21 PM, Marcus Larsson wrote:
>> Third time's the charm.
>>
>> Webrev:
>> http://cr.openjdk.java.net/~mlarsson/8146879/webrev.03/
>>
>> This patch makes log file rotation the default. Default thresholds are
>> 5 rotated files with a target size of 20MiB. Truncating behavior can
>> be achieved by setting filecount to 0 (-Xlog::myfile.log::filecount=0).
>>
>> If a log file already exists during log file initialization it will be
>> rotated. If any of the target file names (file.0 to file.4 in the
>> default case) are available, that filename will be used for the
>> existing log. If all names are taken the VM will attempt to overwrite
>> the oldest file.
>>
>> This should prevent unlimited log file creations and avoid accidental
>> loss of log files from previous runs. The default thresholds (5 files,
>> 20MiB each) is just a suggestion. If you think it should be
>> higher/lower let me know.
>>
>> Tested with included internal VM tests through RBT.
>>
>> Thanks,
>> Marcus
>>
>> On 2016-03-01 15:05, Marcus Larsson wrote:
>>> Hi,
>>>
>>> After some offline discussions I'm withdrawing this patch. I will
>>> instead investigate if I can achieve similar behavior using log
>>> rotation as the default.
>>>
>>> Thanks,
>>> Marcus
>>>
>>> On 03/01/2016 12:11 PM, Marcus Larsson wrote:
>>>> Hi again,
>>>>
>>>> Taking a different approach to this.
>>>>
>>>> New webrev:
>>>> http://cr.openjdk.java.net/~mlarsson/8146879/webrev.01/
>>>>
>>>> Existing files will now by default be renamed/archived with a .X
>>>> suffix where X is the lowest number such that the resulting file
>>>> name is available (jvm.log becomes jvm.log.0). A mode option for
>>>> controlling this behavior has been added as well. It can be set to
>>>> archive, append, or truncate (i.e. -Xlog::jvm.log::mode=truncate).
>>>>
>>>> Tested with included jtreg test through JPRT.
>>>>
>>>> Thanks,
>>>> Marcus
>>>>
>>>> On 01/14/2016 04:00 PM, Marcus Larsson wrote:
>>>>> Hi,
>>>>>
>>>>> Please review the following patch to make sure UL truncates
>>>>> existing log files before writing to them. Since files are opened
>>>>> in append mode, truncation isn't done automatically, so instead the
>>>>> patch adds an attempt to remove the log file before opening it.
>>>>>
>>>>> Webrev:
>>>>> http://cr.openjdk.java.net/~mlarsson/8146879/webrev.00/
>>>>>
>>>>> Issue:
>>>>> https://bugs.openjdk.java.net/browse/JDK-8146879
>>>>>
>>>>> Testing:
>>>>> Included test through JPRT
>>>>>
>>>>> Thanks,
>>>>> Marcus
>>>>
>>>
>>
>