commit 04df0167e6986233390dc01e9081a3bac6768af0
author Alan Stange <astange@gmail.com> Wed May 04 22:07:24 2022 -0400
committer Andrea Del Bene <adelbene@apache.org> Wed Jun 29 22:23:16 2022 +0200
tree 27e52df729561009ae3d01a7f381d8c622555c16
parent 3d80ada9a8cf0ddf0bebdcc9fb8970fca27a9565

WICKET-6992 Reduce object creation and wasted memory in Url toString() methods

The Url class generates a lot of StringBuilders and temporary buffers.  It's a bit frustrating form a performance
standpoint as the builders often need to resize, further compounding the performance impact.

- QueryParameter.toString(...) can be updated to not generate any extraneous garbage objects using JEP 280 String
concatenation.   This is faster than the original code and avoids extra garbage object creation.

- enhance Url.getPath() by using getPathInternal() which allows the code to return an optimal result.  "" for no segments;
the String for 1 segment, and the resulting StringBuilder for more than 2 segments.  This avoids copying the internal byte[]/char[]
array yet again and wasting more memory.  The callers of this method can then use the returned object in the way that best
suits them.   NB the case for two segments should probably also be handled by explicit invocation of
   seg1 + / + seg2 as is would be faster and save memory.
Note that we now compute the size of the StringBuilder in advance, avoiding the repeated resizing of the builder that had been
happening in the original code.

- enhance getQueryString() in a similar manner.  Handle the n=0 and n=1 common cases without generating any extra garbage.
Size the StringBuilder a little better in this case as well.  Again, the n=2 case should probably with String concatenation.

The Url.toString(mode, charset) method is a bit more complicated.  It is rarely called (if ever?) with StringMode=FULL and it
appears as if fragment is commonly unset as well, so handle that 99% code path at the top efficiently without any
wasted memory.   If not, then fall through into the original code.    The call to getPathInternal here avoids making a copy of
that array.

Note that it might be much more efficient to allow this code to pass a StringBuilder instance around.  This would avoid some
repeated copying of byte[]/char[] arrays.   These changes here greatly reduce the memory waste, but more can still be done.

I'm a bit surprised about the missing ).  Must have fat fingered it at the last second.

I'm a bit surprised about the missing ).  Must have fat fingered it at the last second.

I'm not a fan of the brace style used in this project... ;-)

Two changes in response to the feedback.
- cache the result of a function call
- use charAt() and avoid a toString() call.

Fix code formatting.