On 06/15/2014 02:29 PM, Claes Redestad wrote:
On 2014-06-15 13:48, Remi Forax wrote:
On 06/15/2014 12:36 AM, Claes Redestad wrote:
Hi,
please review this patch to add offset based variants of
Integer.parseInt/parseUnsignedInt, Long.parseLong/parseUnsignedLong
and expose them through JavaLangAccess along with
formatUnsignedInt/-Long. This is proposed to enable a number of
minor optimizations, starting with
https://bugs.openjdk.java.net/browse/JDK-8006627
Webrev: http://cr.openjdk.java.net/~redestad/8041972/webrev.0/
Thanks!
/Claes
In my opinion, and as suggested in the description of 8041972, these
methods should be public.
Ultimately, yes. The ulterior motive here is to be able to backport
these to 8u40 (maybe even 7) for internal JDK use, while updating to
public (and dropping the SharedSecrets) should be done in a later,
9-only update. Adding public methods would require CCC approval, more
detailed javadocs and possibly be part of a JEP, so pushing a
back-portable internal patch as a first step seems reasonable.
Ok,
Having written my share of scanners/parsers in Java, these methods
are really helpful but
given that they only rely on charAt/length of String, I think they
should take a CharSequence and not a String as first parameter,
in order to support other storages of characters like by example a
java.nio.CharBuffer.
So for me, instead of adding a bunch of method in shared secrets,
those method should be public and take a CharSequence.
I wouldn't mind switching over to CharSequence for the newly added
methods. I wasn't around last time[1] this was proposed for the
existing methods, but I know there were arguments that changing to a
(possibly) mutable input type might have problematic side effects that
would form a valid argument against this switch, while I personally
share the opinion that it's up to the caller to enforce immutability
when necessary and that text parsing methods should all use
CharSequence when possible.
Miinor nits, Integer.parseInt(String,int,int) don't need to test if s
is null given it delegated to parseInt(String, int, int, int),
and Integer.parseInt(String) should directly call parseInt(s, 10, 0,
s.length()) instead of calling parseInt(s, 10) that calls
parseInt(s, 10, 0) that calls parseInt(s, 10, 0, s.length()).
cheers,
Rémi
Not checking for null in parseInt(String, int, int) would mean we
would get a NPE calling s.length() in the call to parseInt(String,
int, int, int), so this is needed for compatibility.
I see, parseInt throws a NumberFormatException instead of a NPE,
Microbenchmarks suggests the extra check does not have any performance
impact since the JIT can easily prove that the inner null checks can
be removed when an outer method.
Calling parseInt(s, 10, 0, s.length()) directly in place of
parseInt(s, 10, 0) would likewise require an earlier null check
(slightly more code duplication) while being performance neutral
either way.
It's not performance neutral. parseInt is already used in converter
(objects that does conversions) as a leaf call,
if you add several layers of calls, the JIT will hit the maximum depth
threshold when inlining (10 by default),
so I think it's better to do the check in parseInt(String) (like you do
in parseInt(String, int radix, int start))
to avoid performance regression.
/Claes
[1]
https://www.mail-archive.com/core-libs-dev@openjdk.java.net/msg09694.html
Rémi
