RFR: 8289230: Move PlatformXXX class declarations out of os_xxx.hpp [v3]

[Calvin Cheung]

On Tue, 28 Jun 2022 20:13:01 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> There are only two implementations of these classes (one for windows, and one for posix):
>> 
>> - PlatformEvent
>> - PlatformParker
>> - PlatformMutex
>> - PlatformMonitor
>> - ThreadCrashProtection
>> 
>> Before this PR, these classes are declared in os_xxx.hpp. This causes excessive inclusion of the large header file os.hpp by popular headers such as mutex.hpp, which needs only the declaration of PlatformMutex but not the other stuff in os.hpp
>> 
>> This PR moves the declarations to park_posix.hpp, mutex_posix.hpp, etc.
>> 
>> Note:  ideally, the definition of PlatformParker/PlatformEvent should be moved to park_posix.cpp, and PlatformMutex/PlatformMonitor should be moved to mutex_posix.cpp. However, the definition of these 4 classes are intertwined, so I'll leave them inside os_posix.cpp for now. (Same for the Windows version).
>
> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
> 
>   @coleenp comments

Looks good. Just one nit.

src/hotspot/share/runtime/mutex.cpp line 334:

> 332: }
> 333: 
> 334: 

Line 334 deleted by accident?

-------------

Marked as reviewed by ccheung (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9303