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Thread: LW_SHARED_MASK macro

LW_SHARED_MASK macro

From
Alexander Korotkov
Date:
Hackers,

while exploring lwlock.c I found following macro to be strange.

#define LW_SHARED_MASK ((uint32)(1 << 23))

This is macro is used to extract number of shared locks from state.

ereport(LOG,
(errhidestmt(true),
errhidecontext(true),
errmsg("%d: %s(%s): excl %u shared %u haswaiters %u waiters %u rOK %d",
MyProcPid,
where, MainLWLockNames[id],
!!(state & LW_VAL_EXCLUSIVE),
state & LW_SHARED_MASK,
!!(state & LW_FLAG_HAS_WAITERS),
pg_atomic_read_u32(&lock->nwaiters),
!!(state & LW_FLAG_RELEASE_OK))));


Should it be ((uint32) ((1 << 24)-1)) instead?

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
Attachment

Re: LW_SHARED_MASK macro

From
Andres Freund
Date:
Hi,


On 2015-09-17 14:35:20 +0300, Alexander Korotkov wrote:
> while exploring lwlock.c I found following macro to be strange.
> 
> #define LW_SHARED_MASK ((uint32)(1 << 23))
> 
> This is macro is used to extract number of shared locks from state.
> 
> ereport(LOG,
> (errhidestmt(true),
> errhidecontext(true),
> errmsg("%d: %s(%s): excl %u shared %u haswaiters %u waiters %u rOK %d",
> MyProcPid,
> where, MainLWLockNames[id],
> !!(state & LW_VAL_EXCLUSIVE),
> state & LW_SHARED_MASK,
> !!(state & LW_FLAG_HAS_WAITERS),
> pg_atomic_read_u32(&lock->nwaiters),
> !!(state & LW_FLAG_RELEASE_OK))));
> 
> 
> Should it be ((uint32) ((1 << 24)-1)) instead?

Argh, that's somewhat embarassing. You're absolutely right. Luckily it's
only used for LOCK_DEBUG, but still...

Andres

Re: LW_SHARED_MASK macro

From
Alexander Korotkov
Date:
On Thu, Sep 17, 2015 at 5:38 PM, Andres Freund <andres@anarazel.de> wrote:
On 2015-09-17 14:35:20 +0300, Alexander Korotkov wrote:
> while exploring lwlock.c I found following macro to be strange.
>
> #define LW_SHARED_MASK ((uint32)(1 << 23))
>
> This is macro is used to extract number of shared locks from state.
>
> ereport(LOG,
> (errhidestmt(true),
> errhidecontext(true),
> errmsg("%d: %s(%s): excl %u shared %u haswaiters %u waiters %u rOK %d",
> MyProcPid,
> where, MainLWLockNames[id],
> !!(state & LW_VAL_EXCLUSIVE),
> state & LW_SHARED_MASK,
> !!(state & LW_FLAG_HAS_WAITERS),
> pg_atomic_read_u32(&lock->nwaiters),
> !!(state & LW_FLAG_RELEASE_OK))));
>
>
> Should it be ((uint32) ((1 << 24)-1)) instead?

Argh, that's somewhat embarassing. You're absolutely right. Luckily it's
only used for LOCK_DEBUG, but still...

Great. BTW, are you going to commit this?

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company 

Re: LW_SHARED_MASK macro

From
Andres Freund
Date:
On 2015-09-21 22:34:46 +0300, Alexander Korotkov wrote:
> Great. BTW, are you going to commit this?

Yes, will do so tomorrow.

Thanks,

Andres

Re: LW_SHARED_MASK macro

From
Andres Freund
Date:
On 2015-09-21 21:36:15 +0200, Andres Freund wrote:
> On 2015-09-21 22:34:46 +0300, Alexander Korotkov wrote:
> > Great. BTW, are you going to commit this?
> 
> Yes, will do so tomorrow.

And done. Thanks for noticing.

Andres