StringBuilder version of java.util.regex.Matcher.append*
Xueming Shen
xueming.shen at oracle.com
Mon Apr 7 17:00:51 UTC 2014
On 04/04/2014 10:08 AM, Xueming Shen wrote:
> On 4/3/14 4:43 PM, Jeremy Manson wrote:
>> Good catch, thanks.
>>
>> I think we should probably just go with the (equivalent to the) StringBuffer variant. I'm pretty loathe to modify the StringBuilder directly if we are going to back that change out.
>>
>> Do you want me to generate a new patch?
>
> I can/will send out an updated webrev before push.
the latest webrev.
http://cr.openjdk.java.net/~sherman/8039124/webrev
-Sherman
>
> -Sherman
>
>>
>> Jeremy
>>
>>
>> On Thu, Apr 3, 2014 at 2:27 PM, Xueming Shen <xueming.shen at oracle.com <mailto:xueming.shen at oracle.com>> wrote:
>>
>> On 03/25/2014 02:07 PM, Jeremy Manson wrote:
>>> Okay. Thanks, Sherman. Here's an updated version.
>>>
>>> I've diverged a bit from Peter's version. In this version, appendExpandedReplacement takes a StringBuilder. The implications is that In the StringBuilder case, it saves creating a new StringBuilder object. In the StringBuffer case, it creates a new StringBuilder, but it doesn't have to acquire and release all of those locks.
>>
>> Hi Jeremy,
>>
>> It appears the "optimized" StringBuilder version will cause following test case failure,
>> in which the "xyz" will be copied into the result buffer, even when the replacement
>> string triggers a IAE.
>>
>> // Check nothing has been appended into the output buffer if
>> // the replacement string triggers IllegalArgumentException.
>> Pattern p = Pattern.compile("(abc)");
>> Matcher m = p.matcher("abcd");
>> StringBuilder result = new StringBuilder();
>> try {
>> m.appendReplacement(result, ("xyz$g"));
>> } catch (IllegalArgumentException iae) {
>> if (result.length() != 0)
>> System.err.println(" FAILED");
>>
>> }
>>
>> We may have to either catch the IAE and reset the sb, or create
>> a new sb, as the StringBuffer does.
>>
>> -Sherman
>>
>>
>>
>>>
>>> I also noticed a redundant cast to (int), which I removed.
>>>
>>> Jeremy
>>>
>>>
>>> On Fri, Mar 21, 2014 at 7:34 PM, Xueming Shen <xueming.shen at oracle.com <mailto:xueming.shen at oracle.com>> wrote:
>>>
>>> let's add the StringBuilder method(s), if you can provide an updated version, I can run the rest (since it's
>>> to add new api, there is an internal CCC process need to go through).
>>>
>>> -Sherman
>>>
>>>
>>> On 3/21/14 5:18 PM, Jeremy Manson wrote:
>>>> So, this is all a little opaque to me. How do we make the go/no-go decision on something like this? Everyone who has chimed in seems to think it is a good idea.
>>>>
>>>> Jeremy
>>>>
>>>>
>>>> On Thu, Mar 20, 2014 at 10:38 AM, Jeremy Manson <jeremymanson at google.com <mailto:jeremymanson at google.com>> wrote:
>>>>
>>>> Sherman,
>>>>
>>>> If you had released it then (which you wouldn't have been able to do, because you would have to wait another two years for Java 7), you would have found that it improved performance even with C2. It is only post-escape-analysis that the performance in C2 equalized.
>>>>
>>>> Anyway, I think adding the StringBuilder variant and deferring / dealing with the Appendable differently is the right approach, FWIW.
>>>>
>>>> Jeremy
>>>>
>>>>
>>>> On Thu, Mar 20, 2014 at 10:25 AM, Xueming Shen <xueming.shen at oracle.com <mailto:xueming.shen at oracle.com>> wrote:
>>>>
>>>> 2009? I do have something similar back to 2009 :-)
>>>>
>>>> http://cr.openjdk.java.net/~sherman/regex_replace/webrev/ <http://cr.openjdk.java.net/%7Esherman/regex_replace/webrev/>
>>>>
>>>> Then the ball was dropped around the discussion of whether or not
>>>> the IOE should be thrown.
>>>>
>>>> But if we are going to/have to have explicit StringBuilder/Buffer pair
>>>> anyway, then we can keep the Appendable version as private for now
>>>> and deal with the StringBuilder and Appendable as two separate
>>>> issues.
>>>>
>>>> -Sherman
>>>>
>>>>
>>>> On 03/20/2014 09:52 AM, Jeremy Manson wrote:
>>>>
>>>> That's definitely an improvement - I think that when I wrote this (circa
>>>> 2009), I didn't think about Appendable.
>>>>
>>>> I take it my argument convinced someone? :)
>>>>
>>>> Jeremy
>>>>
>>>>
>>>> On Thu, Mar 20, 2014 at 1:32 AM, Peter Levart<peter.levart at gmail.com <mailto:peter.levart at gmail.com>>wrote:
>>>>
>>>> On 03/19/2014 06:51 PM, Jeremy Manson wrote:
>>>>
>>>> I'm told that the diff didn't make it. I've put it in a Google drive
>>>> folder...
>>>>
>>>> https://drive.google.com/file/d/0B_GaXa6O4K5LY3Y0aHpranM3aEU/
>>>> edit?usp=sharing
>>>>
>>>> Jeremy
>>>>
>>>> Hi Jeremy,
>>>>
>>>> Your factoring-out of expandReplacement() method exposed an opportunity to
>>>> further optimize the code. Instead of creating intermediate StringBuilder
>>>> instance for each expandReplacement() call, this method could append
>>>> directly to resulting StringBuffer/StringBuilder, like in the following:
>>>>
>>>> http://cr.openjdk.java.net/~plevart/jdk9-dev/MatcherWithStringBuilder/ <http://cr.openjdk.java.net/%7Eplevart/jdk9-dev/MatcherWithStringBuilder/>
>>>> webrev.01/
>>>>
>>>>
>>>> Regards, Peter
>>>>
>>>>
>>>>
>>>> On Wed, Mar 19, 2014 at 10:41 AM, Jeremy Manson<jeremymanson at google.com <mailto:jeremymanson at google.com>>
>>>> wrote:
>>>>
>>>> Hi folks,
>>>>
>>>> We've had this internally for a while, and I keep meaning to bring it up
>>>> here. The Matcher class has a few public methods that take
>>>> StringBuffers,
>>>> and we've found it useful to add similar versions that take
>>>> StringBuilders.
>>>>
>>>> It has two benefits:
>>>>
>>>> - Users don't have to convert from one to the other when they want to use
>>>> the method in question. The symmetry is nice.
>>>>
>>>> - The StringBuilder variants are faster (if lock optimizations don't kick
>>>> in, which happens in the interpreter and the client compiler). For
>>>> interpreted / client-compiled code, we saw something like a 25% speedup
>>>> on
>>>> String.replaceAll(), which calls into this code.
>>>>
>>>> Any interest? Diff attached.
>>>>
>>>> Jeremy
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
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