RFR: 8346383: Cannot use DllMain in libdt_socket for static builds [v2]

[David Holmes]

On Mon, 13 Jan 2025 13:31:44 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> To be able to properly support static builds on Windows in [JDK-8346377](https://bugs.openjdk.org/browse/JDK-8346377), we cannot use `DllMain`, for two reasons:
>> 
>> 1) This is not called for statically linked libraries, and
>> 2) There are multiple `DllMain` definitions throughout the JDK native libraries, causing name collisions.
>> 
>> While it could have been possible to keep the `DllMain` function for non-static builds and just use an alternative solution for static builds, I think it is preferable to have a single solution that works as well for both static and dynamic builds.
>> 
>> On top of this, the existing solution was contrary to [Microsoft recommendations](https://learn.microsoft.com/en-us/windows/win32/api/winsock/nf-winsock-wsacleanup), which state: "The WSACleanup function typically leads to protocol-specific helper DLLs being unloaded. As a result, the WSACleanup function should not be called from the DllMain function in a application DLL. This can potentially cause deadlocks. "
>
> Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update copyright years to 2025

I will click approve but I think we need to keep a careful eye out for odd network related failures during shutdown.

Thanks

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Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22789#pullrequestreview-2547910996