perf: Use a buffered writer to reduce IO overhead

[Taknok]

As ToSteam (used by XMLTransformer) writes char by char, using a buffered writer improves significantly the performance of the writing.

See #339 for the tests and the discussion

[kitadai31]

The JavaDoc of StreamResult says that you should use OutputStream usually.
https://docs.oracle.com/en/java/javase/17/docs/api/java.xml/javax/xml/transform/stream/StreamResult.html#%3Cinit%3E(java.io.OutputStream)

Normally, a stream should be used rather than a reader

So it should be it.outputStream().buffered().use {.

Moreover, you can use StreamResult(File f)
Neither the Writer nor the OutputStream is necessary.

[Taknok]

StreamResult(File f) will force a buffered writer ?

[Taknok]

it.outputStream().buffered().use { output ->
    TransformerFactory.newInstance()
        .newTransformer()
        .transform(DOMSource(this), StreamResult(output))
}

Will force a buffered path, but it does not differ from the approach

it.bufferedWriter().use { writer ->
    TransformerFactory.newInstance()
        .newTransformer()
        .transform(DOMSource(this), StreamResult(writer))
}

FileOutputStream is not buffered by default, so when you write to a FileOutputStream, every write() call can result in a system-level I/O operation, which is what it was asked to fix/avoid in this PR no ?

[kitadai31]

StreamResult(File f) will force a buffered writer ?

Apparently, it does not
https://github.com/openjdk/jdk/blob/33970629ac63eea6009fca7a34c8f333f1a60a37/src/java.xml/share/classes/com/sun/org/apache/xalan/internal/xsltc/trax/TransformerImpl.java#L533
When I set a File to SrteamResult, it creates a FileOutputStream without BufferedOutputStream
Yes, you are right, thx

FileOutputStream is not buffered by default, so when you write to a FileOutputStream, every write() call can result in a system-level I/O operation, which is what it was asked to fix/avoid in this PR no ?

File.outputStream().buffered() is a kotlin extension function equivalent to BufferedOutputStream(FileOutputStream(file))

[Taknok]

Which method would you prefer ReVanced to use — File.outputStream().buffered() or File.bufferedWriter()? From a system-level performance perspective, they are effectively equivalent.

[kitadai31]

I think ReVanced should use OutputStream according to the JavaDoc.

[Taknok]

Done