On 04/07/2014 07:00 PM, Xueming Shen wrote:
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
Hi Sherman,
This seems most straight-forward and simple. My proposed variant of
appending directly to StringBuffer/StringBuilder (thus to
AbstractStringBuilder) had also a performance disadvantage, since code
in appendExpandedReplacement() could see at least two different
subclasses of AbstractStringBuilder and therefore could not inline calls
to AbstractStringBuilder's virtual methods and had to use duo or even
megamorphic calls. I measured and it appears that this has more overhead
than an additional StringBuilder copy for common-sized replacements...
One thing to note. Matcher.appendReplacement(StringBuffer, ...) has
never been specified as or implemented to be an atomic operation from
the StringBuffer's perspective. But this could easily be achieved:
795 public Matcher appendReplacement(StringBuffer sb, String replacement) {
796 // If no match, return error
797 if (first < 0)
798 throw new IllegalStateException("No match available");
799 StringBuilder result = new StringBuilder();
800 appendExpandedReplacement(replacement, result);
+ synchronized(sb) {
801 // Append the intervening text
802 sb.append(text, lastAppendPosition, first);
803 // Append the match substitution
804 sb.append(result);
+ }
805 lastAppendPosition = last;
806 return this;
807 }
...I don't know if this makes uncontended locking exhibit any
performance penalties since the "sb" monitor is locked twice (nested). I
haven't measured, sorry.
Peter
-Sherman
Jeremy
On Thu, Apr 3, 2014 at 2:27 PM, Xueming Shen
<xueming.s...@oracle.com <mailto:xueming.s...@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.s...@oracle.com <mailto:xueming.s...@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
<jeremyman...@google.com <mailto:jeremyman...@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.s...@oracle.com <mailto:xueming.s...@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.lev...@gmail.com <mailto:peter.lev...@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<jeremyman...@google.com
<mailto:jeremyman...@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
