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/* svn_cache_config.c : configuration of internal caches
*
* ====================================================================
* 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.
* ====================================================================
*/
#include <apr_atomic.h>
#include "svn_cache_config.h"
#include "private/svn_atomic.h"
#include "private/svn_cache.h"
#include "svn_pools.h"
/* The cache settings as a process-wide singleton.
*/
static svn_cache_config_t cache_settings =
{
/* default configuration:
*
* Please note that the resources listed below will be allocated
* PER PROCESS. Thus, the defaults chosen here are kept deliberately
* low to still make a difference yet to ensure that pre-fork servers
* on machines with small amounts of RAM aren't severely impacted.
*/
0x1000000, /* 16 MB for caches.
* If you are running a single server process,
* you may easily increase that to 50+% of your RAM
* using svn_fs_set_cache_config().
*/
16, /* up to 16 files kept open.
* Most OS restrict the number of open file handles to
* about 1000. To minimize I/O and OS overhead, values
* of 500+ can be beneficial (use svn_fs_set_cache_config()
* to change the configuration).
* When running with a huge in-process cache, this number
* has little impact on performance and a more modest
* value (< 100) may be more suitable.
*/
#if APR_HAS_THREADS
FALSE /* assume multi-threaded operation.
* Because this simply activates proper synchronization
* between threads, it is a safe default.
*/
#else
TRUE /* single-threaded is the only supported mode of operation */
#endif
};
/* Get the current FSFS cache configuration. */
const svn_cache_config_t *
svn_cache_config_get(void)
{
return &cache_settings;
}
/* Initializer function as required by svn_atomic__init_once. Allocate
* the process-global (singleton) membuffer cache and return it in the
* svn_membuffer_t * in *BATON. UNUSED_POOL is unused and should be NULL.
*/
static svn_error_t *
initialize_cache(void *baton, apr_pool_t *unused_pool)
{
svn_membuffer_t **cache_p = baton;
svn_membuffer_t *cache = NULL;
apr_uint64_t cache_size = cache_settings.cache_size;
if (cache_size)
{
svn_error_t *err;
/* auto-allocate cache */
apr_allocator_t *allocator = NULL;
apr_pool_t *pool = NULL;
if (apr_allocator_create(&allocator))
return SVN_NO_ERROR;
/* Ensure that we free partially allocated data if we run OOM
* before the cache is complete: If the cache cannot be allocated
* in its full size, the create() function will clear the pool
* explicitly. The allocator will make sure that any memory no
* longer used by the pool will actually be returned to the OS.
*
* Please note that this pool and allocator is used *only* to
* allocate the large membuffer. All later dynamic allocations
* come from other, temporary pools and allocators.
*/
apr_allocator_max_free_set(allocator, 1);
/* don't terminate upon OOM but make pool return a NULL pointer
* instead so we can disable caching gracefully and continue
* operation without membuffer caches.
*/
apr_pool_create_ex(&pool, NULL, NULL, allocator);
if (pool == NULL)
return SVN_NO_ERROR;
apr_allocator_owner_set(allocator, pool);
err = svn_cache__membuffer_cache_create(
&cache,
(apr_size_t)cache_size,
(apr_size_t)(cache_size / 10),
0,
! svn_cache_config_get()->single_threaded,
FALSE,
pool);
/* Some error occurred. Most likely it's an OOM error but we don't
* really care. Simply release all cache memory and disable caching
*/
if (err)
{
/* Memory cleanup */
svn_pool_destroy(pool);
/* Document that we actually don't have a cache. */
cache_settings.cache_size = 0;
return svn_error_trace(err);
}
/* done */
*cache_p = cache;
}
return SVN_NO_ERROR;
}
/* Access the process-global (singleton) membuffer cache. The first call
* will automatically allocate the cache using the current cache config.
* NULL will be returned if the desired cache size is 0 or if the cache
* could not be created for some reason.
*/
svn_membuffer_t *
svn_cache__get_global_membuffer_cache(void)
{
static svn_membuffer_t *cache = NULL;
static svn_atomic_t initialized = 0;
svn_error_t *err
= svn_atomic__init_once(&initialized, initialize_cache, &cache, NULL);
if (err)
{
/* no caches today ... */
svn_error_clear(err);
return NULL;
}
return cache;
}
void
svn_cache_config_set(const svn_cache_config_t *settings)
{
cache_settings = *settings;
}
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