Cleanup fallthrough in FilePermission and PropertyPermission was: Request for Review of 7116890 (Warning Cleanup java.io)

Brandon Passanisi brandon.passanisi at oracle.com
Fri Dec 2 15:27:34 UTC 2011 

Hi Sebastian.  I'm not sure if you had seen the e-mail from Stuart Marks 
regarding this, but Stuart was able to find more instances of the 
similar block of "fallthrough" code.  I can volunteer to apply your 
upcoming change to FilePermission to the other files if you wish.  Or, 
you can try applying the change to the other files, but if you don't 
have time I don't mind doing it.  Here's the section of Stuart's e-mail 
on this topic:

    -------------------------------------------------------------------------------------
    (Incidentally, this is the third time I've reviewed code today that
    looks exactly like this. The other cases are in java.io.FilePermission
    and java.util.PropertyPermission. They each have the /*FALLTHROUGH*/
    into a set of cases that do nothing but break; and they have similar
    ("ackbarfaccept") comments. It would be nice if these chunks of code
    could be unified, but they differ in a number of fiddly details.)

    (The string "ackbarfaccept" occurs in the following files:
    1. java/io/FilePermission.java
    2. java/net/SocketPermission.java
    3. java/util/PropertyPermission.java
    4. javax/management/MBeanPermission.java
    5. javax/security/auth/kerberos/ServicePermission.java
    Hmmm.)
    -------------------------------------------------------------------------------------

Thanks.

On 12/1/2011 10:18 PM, Sebastian Sickelmann wrote:
> Hi Brandon,
>
> i will try to work out a fix for both and cc the review request to you.
>
> -- Sebastian
>
> Am 01.12.2011 23:54, schrieb Brandon Passanisi:
>> Hi Sebastian.  I was speaking with Stuart Marks earlier today and he 
>> mentioned that the "fallthrough" code in FilePermission.java also 
>> exists in java.util.PropertyPermission.java.  Maybe the code author 
>> had done some copy/paste when working on these files.  Stuart had 
>> said that you might be planning on doing some work on this after the 
>> warnings cleanup work.  If/when you do this work, maybe you can let 
>> me know so that I can sync the same changes you apply to 
>> FilePermission.java to PropertyPermission.java?  Or, maybe you can 
>> apply the same changes yourself to PropertyPermission.java?
>>
>> Thanks.
>>
>> On 12/1/2011 8:27 AM, Sebastian Sickelmann wrote:
>>> Am 01.12.2011 10:16, schrieb Stuart Marks:
>>>> Hi Sebastian,
>>>>
>>>> Thanks for submitting this patch! I've filed bug 7116890 to cover 
>>>> this set of changes.
>>>>
>>>> Regarding webrev, it probably does get confused by merges in the 
>>>> history. By default it tries to show differences between the tip of 
>>>> the target repository and tip + uncommitted changes in your local 
>>>> repository. This isn't always the right thing. One thing you might 
>>>> try is to use the -r option to specify a particular revision in the 
>>>> history against which to generate the diffs. But, having a few 
>>>> extra files isn't a big deal.
>>>>
>>>> On to your changes.
>>>>
>>>> Most of them are really good and are exactly the kind of simple 
>>>> change we're looking for, as I posted a little while ago. [1]
>>>>
>>>> The ExpiringCache.java case is an interesting one. I think it's 
>>>> possible to add a static serialVersionUID field within the 
>>>> anonymous class. It's hard to run serialver over an anonymous class 
>>>> (actually it might be possible to run the checksum algorithm on the 
>>>> loaded class) but if in practice it's never serialized, who cares 
>>>> what the "correct" value is? You could just use a value of 0L.
>>>>
>>>> An alternative would also be to use @SuppressWarnings("serial"). 
>>>> Since the constructor is so short, you could just put it on the 
>>>> constructor.
>>>>
>>>> Actually I prefer @SuppressWarnings, since adding serialVersionUID 
>>>> adds to the system's footprint. If it's never used, we shouldn't 
>>>> bother defining it.
>>>>
>>>> Given these alternatives, it's not necessary to create a static 
>>>> CacheHashMapImpl class.
>>>>
>>>> Regarding the FilePermission.java change, yes, I see that the 
>>>> skipBeforePreviousComma() change is problematic. I puzzled over it 
>>>> for a while too. I wish I had sent out the Coding Guideline [1] 
>>>> earlier; it might have saved you an hour. :-) Sorry about that.
>>>>
>>>> A cleanup/rewrite of this code would indeed be better done separate 
>>>> from Warnings Cleanup Day. But I think there might be a simple way 
>>>> to get rid of the warning without doing a cleanup or refactoring. 
>>>> The warning message in question is at line 535 of the original 
>>>> code, about falling through to the next case. But the next case 
>>>> doesn't actually do anything but break. Could we just change the 
>>>> /*FALLTHROUGH*/ comment to a break statement? I think that would 
>>>> fix the warning without changing the logic at all.
>>>>
>>>> s'marks
>>>>
>>>> [1] 
>>>> http://mail.openjdk.java.net/pipermail/jdk8-dev/2011-December/000380.html
>>>>
>>>>
>>>> On 11/30/11 8:33 PM, Sebastian Sickelmann wrote:
>>>>> Hi,
>>>>>
>>>>> i have a webrev[0] that contains some warning cleanup for java.io
>>>>> It is based on rev 7795c41ed54c 
>>>>> http://hg.openjdk.java.net/jdk8/tl/jdk/
>>>>>
>>>>> Some comments to the changes:
>>>>>
>>>>> ExpiringCache.java: Changed anonymous inner class to inner class 
>>>>> with the
>>>>> intention to put serialversion inside of it. But serialver doesn't 
>>>>> want to give
>>>>> my the serialver. I also think that ExpiringCache is not 
>>>>> serializable but the
>>>>> warning was clear: the anonymous inner class is seriallizable and 
>>>>> has no
>>>>> explicit serialversionuid.
>>>>>
>>>>> FilePermission.java: I have starred at the code between line 453 
>>>>> and 547 for
>>>>> over an hour, because i thought that there is a bug within the 
>>>>> expression "i >=
>>>>> matchlen" in line 530 and the both "i != -1" in lines 457 and 461. 
>>>>> But there is
>>>>> no bug. But i wanted to left this code slightly more readable. I 
>>>>> introduced the
>>>>> method skipBeforePreviousComma to make it possible to work-around the
>>>>> fallthought warning with an return statement. This code-change 
>>>>> need's some more
>>>>> review attention. Maybe we should split this up for another 
>>>>> cleanup. I think
>>>>> the whole method needs some rewrite.
>>>>>
>>>>> Some classes had no change at all. Maybe webrev created them 
>>>>> because there
>>>>> where changes in my history/branches. There were some patches from 
>>>>> alan i saw
>>>>> to late. Maybe webrev is confused of the multiple merges.
>>>>>
>>>>> Can someone please create a CR for this and
>>>>>
>>>>> [0]
>>>>> http://dl.dropbox.com/u/43692695/oss-patches/openjdk8/Warning_Cleanup_Java_io/webrev0_based_on_7795c41ed54c/index.html 
>>>>>
>>>>>
>>>>>
>>> Thanks for the good feedback.
>>>
>>> I splitted my change to the trivial part and will start discussion 
>>> of FilePermission change on core-libs-dev after the cleanup event.
>>> I created a new webrev with the suggested changes here[2]
>>>
>>> [2] 
>>> http://dl.dropbox.com/u/43692695/oss-patches/openjdk8/Warning_Cleanup_Java_io/CR7116890_0/index.html
>>>
>>> -- Sebastian
>>
>> -- 
>> Oracle <http://www.oracle.com>
>> Brandon Passanisi | Principle Member of Technical Staff
>>
>> Oracle Java Standards Conformance
>>
>> Green Oracle <http://www.oracle.com/commitment> Oracle is committed 
>> to developing practices and products that help protect the environment
>

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