On Sat, 5 Oct 2024 16:32:39 GMT, Markus KARG <d...@openjdk.org> wrote:
> This Pull Requests proposes an implementation for > [JDK-8341566](https://bugs.openjdk.org/browse/JDK-8341566): Adding the new > method `public static Reader Reader.of(CharSequence)` will return an > anonymous, non-synchronized implementation of a `Reader` for each kind of > `CharSequence` implementation. It is optimized for `String`, `StringBuilder`, > `StringBuffer` and `CharBuffer`. > > In addition, this Pull Request proposes to replace the implementation of > `StringReader` to become a simple synchronized wrapper around > `Reader.of(CharSequence)` for the case of `String` sources. To ensure > correctness, this PR... > * ...simply moved the **original code** of `StringBuilder` to become the > de-facto implementation of `Reader.of()`, then stripped synchronized from it > on the left hand, but kept just a synchronized wrapper on the right hand. > Then added a `switch` for optimizations within the original code, at the > exact location where previously just an optimization for `String` lived in. > * ...added tests for all methods (`Of.java`), and applied that test upon the > modified `StringBuilder`. > > Wherever new JavaDocs were added, existing phrases from other code locations > have been copied and adapted, to best match the same wording. src/java.base/share/classes/java/io/Reader.java line 341: > 339: public void close() { > 340: cs = null; > 341: } @AlanBateman I need to confess that I did not understand what you had in mind when you wrote this on the mailing list: > That doesn't excuse you completely from thinking about concurrent use as > Readers have a close method so you'll need to think about how close is > specified for when it is called while another thread is reading chars from a > custom CS. As this new implementation explicitly is for single-threaded use only, there is no such other thread that could call `close` concurrently. Maybe I am missing something here, so I would kindly ask for an outline of a scenario where -despite the explicit single-thread note- a second thread *does* exist? src/java.base/share/classes/java/io/StringReader.java line 183: > 181: r.close(); > 182: } catch (IOException e) { > 183: throw new UncheckedIOException(e); In fact, the implementation of `close` in the original class will never throw `IOException`, but unfortunately `Reader.close()` declares `throws IOException`. test/jdk/java/io/Reader/Of.java line 51: > 49: public static Reader[] readers() { > 50: return new Reader[] { > 51: new StringReader(CONTENT), Explicitly including that original class here (even if it has nothing to do with the `of` method) to be sure that we did not modify it in an incompatible way. Unfortunately there is no full test coverage for `StringReader`, and it does not make much sense to duplicate the tests. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/21371#discussion_r1788644851 PR Review Comment: https://git.openjdk.org/jdk/pull/21371#discussion_r1788644490 PR Review Comment: https://git.openjdk.org/jdk/pull/21371#discussion_r1788644282
