On Jul 1, 2011, at 12:04 PM, stef...@apache.org wrote: > Author: stefan2 > Date: Fri Jul 1 19:04:29 2011 > New Revision: 1142026 > > URL: http://svn.apache.org/viewvc?rev=1142026&view=rev > Log: > Introduce the svn_mutex API and implement it > > * subversion/include/private/svn_mutex.h > new private API header > * subversion/libsvn_subr/svn_mutex.c > implement the new API > > Added: > subversion/branches/svn_mutex/subversion/include/private/svn_mutex.h > subversion/branches/svn_mutex/subversion/libsvn_subr/svn_mutex.c > > Added: subversion/branches/svn_mutex/subversion/include/private/svn_mutex.h > URL: > http://svn.apache.org/viewvc/subversion/branches/svn_mutex/subversion/include/private/svn_mutex.h?rev=1142026&view=auto > ============================================================================== > --- subversion/branches/svn_mutex/subversion/include/private/svn_mutex.h > (added) > +++ subversion/branches/svn_mutex/subversion/include/private/svn_mutex.h Fri > Jul 1 19:04:29 2011 > @@ -0,0 +1,82 @@ > +/** > + * @copyright > + * ==================================================================== > + * Licensed to the Apache Software Foundation (ASF) under one > + * or more contributor license agreements. See the NOTICE file > + * distributed with this work for additional information > + * regarding copyright ownership. The ASF licenses this file > + * to you under the Apache License, Version 2.0 (the > + * "License"); you may not use this file except in compliance > + * with the License. You may obtain a copy of the License at > + * > + * http://www.apache.org/licenses/LICENSE-2.0 > + * > + * Unless required by applicable law or agreed to in writing, > + * software distributed under the License is distributed on an > + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY > + * KIND, either express or implied. See the License for the > + * specific language governing permissions and limitations > + * under the License. > + * ==================================================================== > + * @endcopyright > + * > + * @file svn_mutex.h > + * @brief Strutures and functions for mutual exclusion > + */ > + > +#ifndef SVN_MUTEX_H > +#define SVN_MUTEX_H > + > +#include <apr_thread_mutex.h> > +#include "svn_error.h" > + > +#ifdef __cplusplus > +extern "C" { > +#endif /* __cplusplus */ > + > +/** > + * This is a simple wrapper around @c apr_thread_mutex_t and will be a > + * valid identifier even if APR does not support threading. > + */ > +typedef struct svn_mutex__t > +{ > +#if APR_HAS_THREADS > + > + /** A mutex for synchronization between threads. It may be NULL, in > + * which case no synchronization will take place. The latter is useful, > + * if implement some functionality where synchronization is optional. > + */ > + apr_thread_mutex_t *mutex; > + > +#endif > +} svn_mutex__t; > + > +/** Initialize the @a *mutex with a lifetime defined by @a pool, if > + * @a enable_mutex is TRUE and with @c NULL otherwise. If @a enable_mutex > + * is set but threading is not supported by APR, this function returns an > + * @c APR_ENOTIMPL error.
The NULL part is a little confusing, it took a couple of reads to see the NULL was associated with *mutex. Suggest changing it so something like /** If @a enable_mutex is TRUE, initialize the @a *mutex with a lifetime * defined by @a pool, otherwise initialize it with @c NULL. How would we use enable_mutex? Seems like a compile time constant, not a runtime one. > + */ > +svn_error_t * > +svn_mutex__init(svn_mutex__t *mutex, > + svn_boolean_t enable_mutex, > + apr_pool_t *pool); > + > +/** Acquire the @a mutex, if that has been enabled in @ref svn_mutex__init. > + * Make sure to call @ref svn_mutex__unlock some time later in the same > + * thread to release the mutex again. Recursive locking are not supported. > + */ > +svn_error_t * > +svn_mutex__lock(svn_mutex__t mutex); > + > +/** Release the @a mutex, previously acquired using @ref svn_mutex__lock > + * that has been enabled in @ref svn_mutex__init. > + */ > +svn_error_t * > +svn_mutex__unlock(svn_mutex__t mutex, > + svn_error_t *err); What is the input err for? Blair
