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

[Markus KARG]

On Mon, 7 Oct 2024 16:06:08 GMT, Chen Liang <liach at openjdk.org> wrote:

>> This is correct, but then we would keep the reference to the char sequence "forever", without any good reason. This content could be *huge* (and often it is, as `CharSequence` most often is a `StringBuilder` just because the application *wants* to create huge content, and `String`-concatenation would be too costly with *huge* content). In fact, I see this scenario as the top use case for this new API.
>> 
>> Having said that, I would really like to have this field non-final to unlink the reference to the source as soon as possible, implicitly allowing GC to free this unused memory.
>
>> keep the reference to the char sequence "forever"
> 
> Note that this only happens if the `Reader` instance is kept forever; but a `Reader` is supposed to be used and closed and discarded instead of being held indefinitely after closing. If users are bad enough, they can never call `close` and the non-final `cs` is still leaked.
> 
> The right way of GC freeing is to let the GC free the reader and the char sequence together, instead of allowing to free when a client keeps this reader instance erroneously after closing.

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.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21371#discussion_r1790631189