RFR: 8343791: Socket.connect API should document whether the socket will be closed when hostname resolution fails or another error occurs [v12]

[Daniel Fuchs]

On Thu, 21 Nov 2024 10:47:54 GMT, Volkan Yazıcı <duke at openjdk.org> wrote:

>> This PR, addressing 8343791, enhances `Socket#connect()` and effectively makes it close the `Socket` if `SocketImpl#connect()` fails with a
>> 
>> 1. `SocketTimeoutException`
>> 2. `InterruptedIOException` in an interrupted vthread
>> 3. `IOException` that is *not* an `UnknownHostException`
>> 
>> On the other hand, socket will *not* be closed if `SocketImpl#connect()` fails with a
>> 
>> * `InterruptedIOException` that is neither a `SocketTimeoutException`, nor from an interrupted vthread
>> * `UnknownHostException`
>> 
>> Note that in case of an `UHE`, `Socket` and `SocketImpl` states will match, i.e., `SOCKET_CREATED`.
>> 
>> One peculiar detail retained from the old code is that `InterruptedIOException` is causing a socket close *iff* we are in an interrupted vhtread. (Guess: To ensure resources within a vthread task scope is released in tandem with the completion of the scope?) I don't know why other `InterruptedIOException` cases are left out.
>> 
>> Before "8284161: Implementation of Virtual Threads (Preview)" (9583e365), `connect()` failures were getting propagated untouched. 8284161 added the logic to throw `SocketException("Closed by interrupt")` *and* close the socket if `InterruptedIOException` is caught in an interrupted vthread.
>> 
>> Judging from the last state of the `Socket#connect()` javadoc, I find it very difficult to wrap ones mind around in which cases the socket will be closed. As a user, I'd be in favor of a simpler approach – e.g., `try { socketImpl.connect(); } catch (Exception e) { closeQuietly(e); throw e }` – at the cost of incorporating a backward incompatible behavioral change. I would appreciate your advice on how shall we proceed further.
>
> Volkan Yazıcı has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Handle `SocketTimeoutException` in `NioSocketImpl::connect()`

OK, this looks good. I believe we are in a good place too.
We throw SocketException and leave the socket opened if the socket is already connected, but the API documentation no longer implies that the socket would also get closed in that case, so we're good.

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Marked as reviewed by dfuchs (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22160#pullrequestreview-2451171659