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Posted to dev@apr.apache.org by Graham Leggett <mi...@sharp.fm> on 2001/07/30 23:39:01 UTC
Handholding: Locking
Hi all,
I need some handholding with the porting of some of the auth_ldap code
from v1.3 to v2.0.
In the v1.3 code, I have locks being created like this:
mtx = ap_create_mutex(NULL);
GET_MUTEX(mtx);
RELMUTEX(mtx);
What would the above look like using apr_lock.h from APR?
Regards,
Graham
--
-----------------------------------------
minfrin@sharp.fm "There's a moon
over Bourbon Street
tonight..."
Re: Handholding: Locking
Posted by Aaron Bannert <aa...@ebuilt.com>.
On Tue, Jul 31, 2001 at 09:33:42AM +0200, Graham Leggett wrote:
> > A read/write lock will allow simultaneous "readers", and will provide
> > exclusive "writers". As an application developer using APR, you'd have to
> > use apr_lock_acquire_rw() instead of the normal apr_lock_acquire() you
> > use with a mutex, so that you can ask for a read or a write lock. What this
> > gives you is finer grain control over how much parallization certain parts
> > of you code may endure.
>
> Ok - In the code I am busy porting, a shared memory cache is
> implemented. When something writes to the cache, nothing else must read
> or write. When something is read from the cache, anyone else may read
> simultaneously without a problem. Is this a job for a read/write lock?
That sounds right to me. Make sure the lock exists in your shared
memory address space (of course) :)
-aaron
Re: Handholding: Locking
Posted by Graham Leggett <mi...@sharp.fm>.
Justin Erenkrantz wrote:
> > Ok - In the code I am busy porting, a shared memory cache is
> > implemented. When something writes to the cache, nothing else must read
> > or write. When something is read from the cache, anyone else may read
> > simultaneously without a problem. Is this a job for a read/write lock?
>
> I think you've answered your own question. (Yes.) -- justin
Cool :) Just making sure I understand this stuff correctly before I go
missioning off to try and make it work. Thanks :)
Regards,
Graham
--
-----------------------------------------
minfrin@sharp.fm "There's a moon
over Bourbon Street
tonight..."
Re: Handholding: Locking
Posted by Justin Erenkrantz <je...@ebuilt.com>.
On Tue, Jul 31, 2001 at 09:33:42AM +0200, Graham Leggett wrote:
> Ok - In the code I am busy porting, a shared memory cache is
> implemented. When something writes to the cache, nothing else must read
> or write. When something is read from the cache, anyone else may read
> simultaneously without a problem. Is this a job for a read/write lock?
I think you've answered your own question. (Yes.) -- justin
Re: Handholding: Locking
Posted by Graham Leggett <mi...@sharp.fm>.
Aaron Bannert wrote:
> A mutex does simple mutual-exclusion. All accesses to the critical section
> are serialized.
Ok.
> A read/write lock will allow simultaneous "readers", and will provide
> exclusive "writers". As an application developer using APR, you'd have to
> use apr_lock_acquire_rw() instead of the normal apr_lock_acquire() you
> use with a mutex, so that you can ask for a read or a write lock. What this
> gives you is finer grain control over how much parallization certain parts
> of you code may endure.
Ok - In the code I am busy porting, a shared memory cache is
implemented. When something writes to the cache, nothing else must read
or write. When something is read from the cache, anyone else may read
simultaneously without a problem. Is this a job for a read/write lock?
Regards,
Graham
--
-----------------------------------------
minfrin@sharp.fm "There's a moon
over Bourbon Street
tonight..."
Re: Handholding: Locking
Posted by Aaron Bannert <aa...@ebuilt.com>.
On Tue, Jul 31, 2001 at 09:06:49AM +0200, Graham Leggett wrote:
> > This is for a intraprocess mutex. The flags in apr_lock.h can tell you
> > how to do other types of locks.
>
> What is the difference between a APR_MUTEX lock and an APR_READWRITE
> lock?
A mutex does simple mutual-exclusion. All accesses to the critical section
are serialized.
A read/write lock will allow simultaneous "readers", and will provide
exclusive "writers". As an application developer using APR, you'd have to
use apr_lock_acquire_rw() instead of the normal apr_lock_acquire() you
use with a mutex, so that you can ask for a read or a write lock. What this
gives you is finer grain control over how much parallization certain parts
of you code may endure.
HTH,
-aaron
Re: Handholding: Locking
Posted by Graham Leggett <mi...@sharp.fm>.
Justin Erenkrantz wrote:
> > I need some handholding with the porting of some of the auth_ldap code
> > from v1.3 to v2.0.
> >
> > In the v1.3 code, I have locks being created like this:
> >
> > mtx = ap_create_mutex(NULL);
> > GET_MUTEX(mtx);
> > RELMUTEX(mtx);
>
> apr_lock_create(&mtx, APR_MUTEX, APR_INTRAPROCESS, NULL, pool);
> apr_lock_acquire(mtx);
> apr_lock_release(mtx);
>
> This is for a intraprocess mutex. The flags in apr_lock.h can tell you
> how to do other types of locks.
What is the difference between a APR_MUTEX lock and an APR_READWRITE
lock?
Regards,
Graham
--
-----------------------------------------
minfrin@sharp.fm "There's a moon
over Bourbon Street
tonight..."
Re: Handholding: Locking
Posted by Justin Erenkrantz <je...@ebuilt.com>.
On Mon, Jul 30, 2001 at 11:39:01PM +0200, Graham Leggett wrote:
> Hi all,
>
> I need some handholding with the porting of some of the auth_ldap code
> from v1.3 to v2.0.
>
> In the v1.3 code, I have locks being created like this:
>
> mtx = ap_create_mutex(NULL);
> GET_MUTEX(mtx);
> RELMUTEX(mtx);
apr_lock_create(&mtx, APR_MUTEX, APR_INTRAPROCESS, NULL, pool);
apr_lock_acquire(mtx);
apr_lock_release(mtx);
This is for a intraprocess mutex. The flags in apr_lock.h can tell you
how to do other types of locks.
HTH. -- justin