RFR: 8262910: Cleanup THREAD/TRAPS/naming and typing issues in ObjectMonitor and related code [v3]

[Ioi Lam]

On Wed, 3 Mar 2021 16:24:52 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> David Holmes has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   More pointer declaration style fixups
>
> src/hotspot/share/runtime/synchronizer.hpp line 92:
> 
>> 90:   // This is the "slow path" version of monitor enter and exit.
>> 91:   static void enter(Handle obj, BasicLock* lock, JavaThread* current);
>> 92:   static void exit(oop obj, BasicLock* lock, TRAPS);
> 
> So are you suggesting that we should have the convention that if a function takes a Thread/JavaThread argument as the last argument, to use "current" rather than "THREAD", since the latter implies it is supposed to be used to pass an argument for the parameter to TRAPS?  I think this is good.  It manages some confusion about trailing THREAD arguments in some callers.  Specializing further to JavaThread from Thread is also a good change.

A suggestion (perhaps as a future RFE), if a function never throws:

void foo(Class* c, Method*m, Thread* current);

maybe we should move the last `thread` argument to first:

void foo(Thread* current, Class* c, Method*m);

This will make it absolutely sure that `foo` will never throw an exception -- when you are reading a caller of `foo`, you don't need to refer to the declaration of `foo` to know that.

Also, this will be consistent with our usual convention of passing "bigger" arguments first (Process > Thread -> Class -> method -> bci, etc).

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PR: https://git.openjdk.java.net/jdk/pull/2802