RFR: 8341566: Adding factory for non-synchronized CharSequence Reader [v2]

[Markus KARG]

On Mon, 7 Oct 2024 19:44:12 GMT, Chen Liang <liach at openjdk.org> wrote:

>> I really do see you point, nevertheless I think we should be kind to "bad" users, too. In the end, there is *no* specification which explicitly tells "bad" users that readers are support to be short-living (despite it being rather obvious), while `close` explicitly mentions freeing *all* resources, so it is rather unexpected to keep something past `close`, even for short term. NB: `StringReader` applies the very same behavior, too (using `s` and `str` variables), that's where I copied the code from originally. It is not a big problem for us to have two variables, neither that the name of the variable is `source` (in fact, I do like `source` even more than `cs`, but this is just my personal preference). To sum up, I really dislike the idea to keep the reference for any longer than essentially needed. If it's just about the name of the variable, I could simply switch them if you prefer that.
>
> On a linux x64 build:
> 
> ./javap -p java.io.Reader$2
> Compiled from "Reader.java"
> class java.io.Reader$2 extends java.io.Reader {
>   private final int length;
>   private java.lang.CharSequence cs;
>   private int next;
>   private int mark;
>   final java.lang.CharSequence val$source;
>   java.io.Reader$2(java.lang.CharSequence);
>   private void ensureOpen() throws java.io.IOException;
>   public int read() throws java.io.IOException;
>   public int read(char[], int, int) throws java.io.IOException;
>   public long skip(long) throws java.io.IOException;
>   public boolean ready() throws java.io.IOException;
>   public boolean markSupported();
>   public void mark(int) throws java.io.IOException;
>   public void reset() throws java.io.IOException;
>   public void close();
> }
> 
> 
> The javap in the built binaries of this patch shows that this anonymous class already keeps the `CharSequence val$source` in a final field; therefore, your setting the `cs` field to `null` will not help GC or anything of that sort.

Sigh, too bad, as keeping `val$source` is actually useless in our case, but I understand that this happens due to our class being an anonymous inner class, not a standalone class (as it was the case with `StringReader`, where this source code originates from).

Anyways, adopted your proposal now to proceed with this PR.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/21371#discussion_r1791494712