Re: svn commit: r1404112 - in /subversion/trunk/subversion: include/private/svn_named_atomic.h libsvn_fs_fs/fs_fs.c libsvn_subr/named_atomic.c tests/cmdline/svnadmin_tests.py tests/libsvn_subr/named_atomic-test.c

stefan2_at_apache.org writes:

> Author: stefan2
> Date: Wed Oct 31 12:27:29 2012
> New Revision: 1404112
>
> URL: http://svn.apache.org/viewvc?rev=1404112&view=rev
> Log:
> Change the way we implement shared memory setup for our named atomics.
> Instead of using APR's SHM API, we create a persistent file and simply
> mmap it.

> +/* Make sure the revprop_namespace member in FS is set. */
> +static svn_error_t *
> +cleanup_revprop_namespace(svn_fs_t *fs)
> +{
> + const char* name = svn_dirent_join(fs->path,

     const char *name

> + err = svn_io_check_path(shm_name, &kind, sub_pool);
> + if (!err && kind != svn_node_file)
> {
> - apr_err = apr_shm_attach(&shared_mem, shm_name, result_pool);
> - if (!apr_err)
> - {
> - new_ns->data = apr_shm_baseaddr_get(shared_mem);
> - break;
> - }
> -
> - /* First race: failed to attach but another process could create. */
> -
> - apr_err = apr_shm_create(&shared_mem,
> - sizeof(*new_ns->data),
> - shm_name,
> - result_pool);
> - if (!apr_err)
> + err = svn_io_file_open(&file, shm_name,
> + APR_READ | APR_WRITE | APR_CREATE,
> + APR_OS_DEFAULT,
> + result_pool);
> + if (!err)
> {
> - new_ns->data = apr_shm_baseaddr_get(shared_mem);
> -
> - /* Zero all counters, values and names. */
> - memset(new_ns->data, 0, sizeof(*new_ns->data));
> - break;
> + /* Zero all counters, values and names.
> + */
> + struct shared_data_t initial_data;
> + memset(&initial_data, 0, sizeof(initial_data));
> + err = svn_io_file_write_full(file, &initial_data,
> + sizeof(initial_data), NULL,
> + sub_pool);
> }
> -
> - /* Second race: failed to create but another process could delete. */
> + }
> + else
> + {
> + err = svn_io_file_open(&file, shm_name,
> + APR_READ | APR_WRITE, APR_OS_DEFAULT,
> + result_pool);
> }
>
> - if (apr_err)
> - return unlock(&new_ns->mutex,
> - svn_error_wrap_apr(apr_err,
> - _("Can't get shared memory for named atomics")));
> + /* Now, map it into memory.
> + */

Need to do something with err, at present it leaks. The mmap call
probably doesn't make sense if err is set.

> + apr_err = apr_mmap_create(&mmap, file, 0, sizeof(*new_ns->data),
> + APR_MMAP_READ | APR_MMAP_WRITE , result_pool);
> + if (!apr_err)
> + new_ns->data = mmap->mm;
>
> + svn_pool_destroy(sub_pool);

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