RFR: 8343791: Socket.connect API should document whether the socket will be closed when hostname resolution fails or another error occurs [v16]

[Daniel Fuchs]

On Tue, 26 Nov 2024 09:07:33 GMT, Volkan Yazıcı <duke at openjdk.org> wrote:

>> Volkan Yazıcı has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 23 commits:
>> 
>>  - Merge remote-tracking branch 'upstream/master' into Socket-CloseOnFailure-8343791
>>  - Add tests using real sockets
>>  - Add tests with real sockets
>>  - Relax assertion to fix failing `IDNTest`
>>  - Merge remote-tracking branch 'upstream/master' into Socket-CloseOnFailure-8343791
>>  - Reflect behavioral changes to `SocketAdaptor`
>>  - Improve variable names
>>  - Improve naming in tests
>>  - Handle `SocketTimeoutException` in `NioSocketImpl::connect()`
>>  - Revert `UHE` message change in `NioSocketImpl`
>>  - ... and 13 more: https://git.openjdk.org/jdk/compare/9793e73b...e0fb7061
>
> test/jdk/java/net/Socket/CloseOnFailureTest.java line 345:
> 
>> 343:             SocketAddress serverSocketAddress = serverSocket().getLocalSocketAddress();
>> 344:             try (Socket socket = createConnectedSocket(serverSocketAddress)) {
>> 345:                 assertReconnectFailure(() -> socket.connect(REFUSING_SOCKET_ADDRESS));
> 
> I needed to delegate the assertion to the implementation because when I call `connect()` on a `Socket` created using `SocketChannel.open(address).socket()` and `new Socket(address, port)`, the former throws an `AlreadyConnectedException`, whereas the latter throws a `SocketException`. Is this discrepancy expected?

There are some subtle behaviour discrepancies between plain Socket (created with new Socket()) and the SocketAdaptor (created from SocketChannel.socket()). SocketChannel::connect will throw AlreadyConnectedException, and so that's what the socket adaptor also does. Ideally we'd want to reduce the distance between plain Socket and the Socket adaptor - but changing behaviours in these APIs is always tricky and a bit risky (and can require a lot of efforts). FWIW - SocketChannel does the right thing - but we're stuck with SocketException in the Socket API due to compatibility reason.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22160#discussion_r1858226183