for String based replaceAll/First() it might be worth doing something like
http://cr.openjdk.java.net/~sherman/regex_removesb/webrev/
On 4/24/18, 10:47 AM, Isaac Levy wrote:
Hi Sherman,
Thanks for clarifying. Looks like exceptions are caused by invalid
format string. I wouldn't expect most programs to be catching this and
preserving their buffer, but dunno.
How much does it affect perf? Well it depends on use case, a jmh of
replaceAll with a length 200 string of digits and regex "(\w)" shows
about 30% speedup.
[info] Benchmark Mode Cnt Score Error Units
[info] origM avgt 10 11.669 ± 0.211 us/op
[info] newM avgt 10 8.926 ± 0.095 us/op
Isaac
On Tue, Apr 24, 2018 at 12:53 PM, Xueming Shen<xueming.s...@oracle.com> wrote:
Hi Isaac,
I actually meant to say "we are not supposed to output the partial text into
the output buffer in case of an exception". It has nothing to do with the
changeset you cited. This has been the behavior since day one/JDK1.4,
though it is not specified explicitly in the API doc. The newly added
StringBuilder variant simply follows this behavior. If it's really desired
it
is kinda doable to save that StringBuilder without the "incompatible"
behavior
change but just wonder if it is really worth the effort.
Thanks,
Sherman
On 4/24/18, 9:11 AM, Isaac Levy wrote:
(moving this to a separate discussion)
--- a/src/java.base/share/classes/java/util/regex/Matcher.java
+++ b/src/java.base/share/classes/java/util/regex/Matcher.java
@@ -993,13 +993,11 @@
public Matcher appendReplacement(StringBuilder sb, String
replacement) {
// If no match, return error
if (first< 0)
throw new IllegalStateException("No match available");
- StringBuilder result = new StringBuilder();
- appendExpandedReplacement(replacement, result);
// Append the intervening text
sb.append(text, lastAppendPosition, first);
// Append the match substitution
+ appendExpandedReplacement(replacement, sb);
- sb.append(result);
On Mon, Apr 23, 2018 at 5:05 PM Xueming Shen<xueming.s...@oracle.com>
wrote:
I would assume in case of an exception thrown from
appendExpandedReplacement() we don't
want "text" to be pushed into the "sb".
-sherman
Perhaps. Though the behavior under exception is undefined and this
function is probably primarily used though the replaceAll API, which
wouldn’t return the intermediate sb under the case of exception.
My reading of the blame was the temp StringBuilder was an artifact of
the api previously using StringBuffer externally. See
http://hg.openjdk.java.net/jdk9/dev/jdk/rev/763c564451b3
