[libvirt] [PATCH 1/5] Add a read/write lock implementation

[Laine Stump]

On 01/23/2014 02:37 PM, Daniel P. Berrange wrote:
> Add virRWLock backed up by a POSIX rwlock primitive
>
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
>  src/libvirt_private.syms    |  5 +++++
>  src/util/virthread.h        | 10 ++++++++++
>  src/util/virthreadpthread.c | 31 +++++++++++++++++++++++++++++++
>  src/util/virthreadpthread.h |  4 ++++
>  4 files changed, 50 insertions(+)
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index d1a58f9..eb91693 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -1816,6 +1816,11 @@ virMutexInitRecursive;
>  virMutexLock;
>  virMutexUnlock;
>  virOnce;
> +virRWLockInit;
> +virRWLockDestroy;
> +virRWLockRead;
> +virRWLockWrite;
> +virRWLockUnlock;

These are out of order.

>  virThreadCancel;
>  virThreadCreate;
>  virThreadID;
> diff --git a/src/util/virthread.h b/src/util/virthread.h
> index 84d3bdc..7015d60 100644
> --- a/src/util/virthread.h
> +++ b/src/util/virthread.h
> @@ -28,6 +28,9 @@
>  typedef struct virMutex virMutex;
>  typedef virMutex *virMutexPtr;
>  
> +typedef struct virRWLock virRWLock;
> +typedef virRWLock *virRWLockPtr;
> +
>  typedef struct virCond virCond;
>  typedef virCond *virCondPtr;
>  
> @@ -89,6 +92,13 @@ void virMutexLock(virMutexPtr m);
>  void virMutexUnlock(virMutexPtr m);
>  
>  
> +int virRWLockInit(virRWLockPtr m) ATTRIBUTE_RETURN_CHECK;
> +void virRWLockDestroy(virRWLockPtr m);
> +
> +void virRWLockRead(virRWLockPtr m);
> +void virRWLockWrite(virRWLockPtr m);
> +void virRWLockUnlock(virRWLockPtr m);
> +

I was about to predict a build failure on Windows since you haven't
defined these functions in virthreadwin32.c, but then realized you
aren't yet calling them from anywhere, so the build will complete just fine.

It would reduce code motion a bit to swap this patch with patch 2, but
functionally there's no difference.

As far as the implementation of the functions - it can't get any more
striaghtforward that this!

ACK.

>  
>  int virCondInit(virCondPtr c) ATTRIBUTE_RETURN_CHECK;
>  int virCondDestroy(virCondPtr c);
> diff --git a/src/util/virthreadpthread.c b/src/util/virthreadpthread.c
> index ca841e4..2efb4c1 100644
> --- a/src/util/virthreadpthread.c
> +++ b/src/util/virthreadpthread.c
> @@ -91,6 +91,37 @@ void virMutexUnlock(virMutexPtr m)
>  }
>  
>  
> +int virRWLockInit(virRWLockPtr m)
> +{
> +    if (pthread_rwlock_init(&m->lock, NULL) != 0) {
> +        errno = EINVAL;
> +        return -1;
> +    }
> +    return 0;
> +}
> +
> +void virRWLockDestroy(virRWLockPtr m)
> +{
> +    pthread_rwlock_destroy(&m->lock);
> +}
> +
> +
> +void virRWLockRead(virRWLockPtr m)
> +{
> +    pthread_rwlock_rdlock(&m->lock);
> +}
> +
> +void virRWLockWrite(virRWLockPtr m)
> +{
> +    pthread_rwlock_wrlock(&m->lock);
> +}
> +
> +
> +void virRWLockUnlock(virRWLockPtr m)
> +{
> +    pthread_rwlock_unlock(&m->lock);
> +}
> +
>  int virCondInit(virCondPtr c)
>  {
>      int ret;
> diff --git a/src/util/virthreadpthread.h b/src/util/virthreadpthread.h
> index b9f1319..cb607d0 100644
> --- a/src/util/virthreadpthread.h
> +++ b/src/util/virthreadpthread.h
> @@ -27,6 +27,10 @@ struct virMutex {
>      pthread_mutex_t lock;
>  };
>  
> +struct virRWLock {
> +    pthread_rwlock_t lock;
> +};
> +
>  struct virCond {
>      pthread_cond_t cond;
>  };