On Sat, 28 Oct 2023 18:07:46 GMT, Michael Strauß <[email protected]> wrote:
>> modules/javafx.graphics/src/main/java/com/sun/javafx/util/DataURI.java line
>> 210:
>>
>>> 208:
>>> 209: private static byte[] decodePercentEncoding(String input) {
>>> 210: try (var output = new ByteArrayOutputStream(input.length())) {
>>
>> If deemed important to optimize this a bit:
>>
>> This could allocate an array that's a factor 3 too large, which depending on
>> how these URI's are used can become quite big (although for large amounts of
>> data, base64 is recommended).
>>
>> I noticed that in the URLDecoder they limit the size of the buffer `new
>> StringBuilder(numChars > 500 ? numChars / 2 : numChars);` -- perhaps you
>> could do something similar (`new ByteArrayOutputStream(input.length() > 500
>> ? input.length() / 2 : input.length())`)
>>
>> Another alternative would be to calculate the exact size first (by counting
>> `%`s) avoiding the need to reallocate the `byte[]` -- performance is (IMHO)
>> likely to be better:
>>
>> - ByteArrayOutputStream method
>> - allocate output array: zeroes n*3 bytes
>> - decode: reads whole string once (n to n*3 reads)
>> - decode: writes n bytes
>> - reallocate: reads whole output once (n)
>> - reallocate: writes n bytes
>> - garbage created: n*3 bytes
>> - max memory use: n*3 + n bytes
>>
>> Total read/writes: 4n + 5n
>>
>> - Count method
>> - count: reads whole string once (n to n*3 reads)
>> - allocate output array: zeroes n bytes
>> - decode: reads whole string again (n to n*3 reads)
>> - decode: writes n bytes
>> - garbage created: none
>> - max memory use: n bytes
>>
>> Total read/writes: 6n + 2n
>
> Solved by calculating the exact size first.
Thanks, I see you went this route, you could eliminate the
`ByteArrayOutputStream` now, perhaps have the signature of
`decodePercentEncodingToStream` changed to:
private static byte[] decodePercentEncodingToStream(String input, int size)
-------------
PR Review Comment: https://git.openjdk.org/jfx/pull/1165#discussion_r1375302003
