RFR: 8253742: POSIX signal code cleanup [v3]

[Thomas Stuefe]

On Fri, 6 Nov 2020 16:35:14 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> src/hotspot/os/posix/signals_posix.hpp line 33:
>> 
>>> 31: 
>>> 32: typedef siginfo_t siginfo_t;
>>> 33: typedef sigset_t sigset_t;
>> 
>> I don't see why this is needed/wanted. We can include signal.h without a problem.
>> 
>> I'm not even sure what these typedefs means ??
>
> Coleen asked me to remove <signal.h> from the signals_posix.hpp, so those are forward declarations for the signal types we use.
> 
> I thought it was a reasonable request to minimize the number of headers. I saw some efforts in the past to cleanup header files, which is supposed to help with build times, so every little bit helps.

Hi Gerard,

the proper way to do this would be to remove the header and forward declare the structures like this:

struct sigset_t;
struct siginfo_t;
struct ucontext_t;
That means we can use pointers to those things without including their definition.

But in this case I believe you could just remove signal.h without forward declaring anything. System headers are usually included via globalDefinitions.hpp, which we do include here. See globalDefinitions_gcc.hpp in this case.

Cheers, Thomas

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PR: https://git.openjdk.java.net/jdk/pull/636