RFR: JDK-8288003: log events for os::dll_unload [v4]

[Matthias Baesken]

On Fri, 10 Jun 2022 14:22:26 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

>> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   dll_path on Linux - add NULL check, change special output to not available
>
> src/hotspot/os/linux/os_linux.cpp line 1791:
> 
>> 1789: const char* os::Linux::dll_path(void* lib) {
>> 1790:   struct link_map *lmap;
>> 1791:   const char* l_path = "<not available>";
> 
> To be honest, I prefer to return NULL if `dlinfo` is failed.
> IIUC the caller expects return dll path of `lib` - `<not available>` is not the path.
> 
> I think it is better that alternative string would be set by the caller (`os::dll_unload()`) like a change of os_windows. But I do not stick my opinion. I'm ok if other reviewer approve your change.

Adjusted dll_path, it returns now NULL in case of failure.

> src/hotspot/os/windows/os_windows.cpp line 1241:
> 
>> 1239:   char name[MAX_PATH];
>> 1240:   if (::GetModuleFileName((HMODULE)lib, name, sizeof(name)) == 0) {
>> 1241:     name[0] = '\0';
> 
> Should we set `<not available>` to `name` like a change for linux code?

Yes, it is most likely better to have same output in failure case on Windows and other platforms.

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PR: https://git.openjdk.org/jdk/pull/9101