Hi Ivan,
I will let people to comment on your first version but your second
version uses a Stream and some lambdas which is in my opinion not a good
idea in term of dependencies (Stream will be loaded too soon by example)
and it may create some trouble in the future because lambdas depends on
some classes of java.lang.invoke that are initialized late in the boot
process while java.lang.String is initialized early.
cheers,
Rémi
On 05/24/2015 10:17 PM, Ivan Gerasimov wrote:
Hello everybody!
I know many people here like it when the performance is getting better.
It was suggested to make the literal variant of String.replace() faster.
Currently, this method is implemented as a few calls to regexp API, so
that the whole implementation takes only two lines of code.
I've created two versions of the fix.
In the first one, we scan the string and store indices of the found
substrings in an array.
Then, we allocate the precisely sized char array and fill it it.
The case with the empty target has to be handled separately.
BUGURL: https://bugs.openjdk.java.net/browse/JDK-8058779
WEBREV: http://cr.openjdk.java.net/~igerasim/8058779/00/webrev/
The second variant is much less verbose, however it's less efficient too.
Here the StringJoiner is used as an intermediate storage.
WEBREV: http://cr.openjdk.java.net/~igerasim/8058779/01/webrev/
Here are the micro-benchmark results (in a string of ~300 chars do ~15
replacements).
0) Baseline
MyBenchmark.test thrpt 40 257'051.948 ± 4537.484 ops/s
1) Heavy-duty +308%
MyBenchmark.test thrpt 40 1'049'235.602 ± 15501.803 ops/s
2) StringJoiner +190%
MyBenchmark.test thrpt 40 746'000.629 ± 15387.036 ops/s
Personally, I like my first variant better, even though it adds almost
300 lines of code.
But I'd like to hear what people think of it.
Sincerely yours,
Ivan
