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/* 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.
*/
#ifndef APR_RESLIST_H
#define APR_RESLIST_H
/**
* @file apr_reslist.h
* @brief APR-UTIL Resource List Routines
*/
#include "apr.h"
#include "apu.h"
#include "apr_pools.h"
#include "apr_errno.h"
#include "apr_time.h"
#if APR_HAS_THREADS
/**
* @defgroup APR_Util_RL Resource List Routines
* @ingroup APR_Util
* @{
* @warning
* <strong><em>Resource list data types and routines are only available when
* threads are enabled (i.e. APR_HAS_THREADS is not zero).</em></strong>
*/
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/** Opaque resource list object */
typedef struct apr_reslist_t apr_reslist_t;
/* Generic constructor called by resource list when it needs to create a
* resource.
* @param resource opaque resource
* @param param flags
* @param pool Pool
*/
typedef apr_status_t (*apr_reslist_constructor)(void **resource, void *params,
apr_pool_t *pool);
/* Generic destructor called by resource list when it needs to destroy a
* resource.
* @param resource opaque resource
* @param param flags
* @param pool Pool
*/
typedef apr_status_t (*apr_reslist_destructor)(void *resource, void *params,
apr_pool_t *pool);
/**
* Create a new resource list with the following parameters:
* @param reslist An address where the pointer to the new resource
* list will be stored.
* @param min Allowed minimum number of available resources. Zero
* creates new resources only when needed.
* @param smax Resources will be destroyed to meet this maximum
* restriction as they expire.
* @param hmax Absolute maximum limit on the number of total resources.
* @param ttl If non-zero, sets the maximum amount of time in microseconds a
* resource may be available while exceeding the soft limit.
* @param con Constructor routine that is called to create a new resource.
* @param de Destructor routine that is called to destroy an expired resource.
* @param params Passed to constructor and deconstructor
* @param pool The pool from which to create this resource list. Also the
* same pool that is passed to the constructor and destructor
* routines.
* @warning If you're creating a sub-pool of the pool passed into this
* function in your constructor, you will need to follow some rules
* when it comes to destruction of that sub-pool, as calling
* apr_pool_destroy() outright on it in your destructor may create
* double free situations. That is because by the time destructor is
* called, the sub-pool may have already been destroyed. This also
* means that in the destructor, memory from the sub-pool should be
* treated as invalid. For examples of how to do this correctly, see
* mod_dbd of Apache 2.2 and memcache support in APR Util 1.3.
*/
APU_DECLARE(apr_status_t) apr_reslist_create(apr_reslist_t **reslist,
int min, int smax, int hmax,
apr_interval_time_t ttl,
apr_reslist_constructor con,
apr_reslist_destructor de,
void *params,
apr_pool_t *pool);
/**
* Destroy the given resource list and all resources controlled by
* this list.
* FIXME: Should this block until all resources become available,
* or maybe just destroy all the free ones, or maybe destroy
* them even though they might be in use by something else?
* Currently it will abort if there are resources that haven't
* been released, so there is an assumption that all resources
* have been released to the list before calling this function.
* @param reslist The reslist to destroy
*/
APU_DECLARE(apr_status_t) apr_reslist_destroy(apr_reslist_t *reslist);
/**
* Retrieve a resource from the list, creating a new one if necessary.
* If we have met our maximum number of resources, we will block
* until one becomes available.
*/
APU_DECLARE(apr_status_t) apr_reslist_acquire(apr_reslist_t *reslist,
void **resource);
/**
* Return a resource back to the list of available resources.
*/
APU_DECLARE(apr_status_t) apr_reslist_release(apr_reslist_t *reslist,
void *resource);
/**
* Set the timeout the acquire will wait for a free resource
* when the maximum number of resources is exceeded.
* @param reslist The resource list.
* @param timeout Timeout to wait. The zero waits forever.
*/
APU_DECLARE(void) apr_reslist_timeout_set(apr_reslist_t *reslist,
apr_interval_time_t timeout);
/**
* Return the number of outstanding resources.
* @param reslist The resource list.
*/
APU_DECLARE(apr_uint32_t) apr_reslist_acquired_count(apr_reslist_t *reslist);
/**
* Invalidate a resource in the pool - e.g. a database connection
* that returns a "lost connection" error and can't be restored.
* Use this instead of apr_reslist_release if the resource is bad.
*/
APU_DECLARE(apr_status_t) apr_reslist_invalidate(apr_reslist_t *reslist,
void *resource);
#ifdef __cplusplus
}
#endif
/** @} */
#endif /* APR_HAS_THREADS */
#endif /* ! APR_RESLIST_H */
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