freebsd-dev/contrib/apr-util/misc/apr_reslist.c
Peter Wemm 937a200089 Introduce svnlite so that we can check out our source code again.
This is actually a fully functional build except:
* All internal shared libraries are static linked to make sure there
  is no interference with ports (and to reduce build time).
* It does not have the python/perl/etc plugin or API support.
* By default, it installs as "svnlite" rather than "svn".
* If WITH_SVN added in make.conf, you get "svn".
* If WITHOUT_SVNLITE is in make.conf, this is completely disabled.

To be absolutely clear, this is not intended for any use other than
checking out freebsd source and committing, like we once did with cvs.

It should be usable for small scale local repositories that don't
need the python/perl plugin architecture.
2013-06-18 02:53:45 +00:00

474 lines
14 KiB
C

/* 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 <assert.h>
#include "apu.h"
#include "apr_reslist.h"
#include "apr_errno.h"
#include "apr_strings.h"
#include "apr_thread_mutex.h"
#include "apr_thread_cond.h"
#include "apr_ring.h"
/**
* A single resource element.
*/
struct apr_res_t {
apr_time_t freed;
void *opaque;
APR_RING_ENTRY(apr_res_t) link;
};
typedef struct apr_res_t apr_res_t;
/**
* A ring of resources representing the list of available resources.
*/
APR_RING_HEAD(apr_resring_t, apr_res_t);
typedef struct apr_resring_t apr_resring_t;
struct apr_reslist_t {
apr_pool_t *pool; /* the pool used in constructor and destructor calls */
int ntotal; /* total number of resources managed by this list */
int nidle; /* number of available resources */
int min; /* desired minimum number of available resources */
int smax; /* soft maximum on the total number of resources */
int hmax; /* hard maximum on the total number of resources */
apr_interval_time_t ttl; /* TTL when we have too many resources */
apr_interval_time_t timeout; /* Timeout for waiting on resource */
apr_reslist_constructor constructor;
apr_reslist_destructor destructor;
void *params; /* opaque data passed to constructor and destructor calls */
apr_resring_t avail_list;
apr_resring_t free_list;
#if APR_HAS_THREADS
apr_thread_mutex_t *listlock;
apr_thread_cond_t *avail;
#endif
};
/**
* Grab a resource from the front of the resource list.
* Assumes: that the reslist is locked.
*/
static apr_res_t *pop_resource(apr_reslist_t *reslist)
{
apr_res_t *res;
res = APR_RING_FIRST(&reslist->avail_list);
APR_RING_REMOVE(res, link);
reslist->nidle--;
return res;
}
/**
* Add a resource to the beginning of the list, set the time at which
* it was added to the list.
* Assumes: that the reslist is locked.
*/
static void push_resource(apr_reslist_t *reslist, apr_res_t *resource)
{
APR_RING_INSERT_HEAD(&reslist->avail_list, resource, apr_res_t, link);
resource->freed = apr_time_now();
reslist->nidle++;
}
/**
* Get an resource container from the free list or create a new one.
*/
static apr_res_t *get_container(apr_reslist_t *reslist)
{
apr_res_t *res;
if (!APR_RING_EMPTY(&reslist->free_list, apr_res_t, link)) {
res = APR_RING_FIRST(&reslist->free_list);
APR_RING_REMOVE(res, link);
}
else
res = apr_pcalloc(reslist->pool, sizeof(*res));
return res;
}
/**
* Free up a resource container by placing it on the free list.
*/
static void free_container(apr_reslist_t *reslist, apr_res_t *container)
{
APR_RING_INSERT_TAIL(&reslist->free_list, container, apr_res_t, link);
}
/**
* Create a new resource and return it.
* Assumes: that the reslist is locked.
*/
static apr_status_t create_resource(apr_reslist_t *reslist, apr_res_t **ret_res)
{
apr_status_t rv;
apr_res_t *res;
res = get_container(reslist);
rv = reslist->constructor(&res->opaque, reslist->params, reslist->pool);
*ret_res = res;
return rv;
}
/**
* Destroy a single idle resource.
* Assumes: that the reslist is locked.
*/
static apr_status_t destroy_resource(apr_reslist_t *reslist, apr_res_t *res)
{
return reslist->destructor(res->opaque, reslist->params, reslist->pool);
}
static apr_status_t reslist_cleanup(void *data_)
{
apr_status_t rv = APR_SUCCESS;
apr_reslist_t *rl = data_;
apr_res_t *res;
#if APR_HAS_THREADS
apr_thread_mutex_lock(rl->listlock);
#endif
while (rl->nidle > 0) {
apr_status_t rv1;
res = pop_resource(rl);
rl->ntotal--;
rv1 = destroy_resource(rl, res);
if (rv1 != APR_SUCCESS) {
rv = rv1; /* loses info in the unlikely event of
* multiple *different* failures */
}
free_container(rl, res);
}
assert(rl->nidle == 0);
assert(rl->ntotal == 0);
#if APR_HAS_THREADS
apr_thread_mutex_unlock(rl->listlock);
apr_thread_mutex_destroy(rl->listlock);
apr_thread_cond_destroy(rl->avail);
#endif
return rv;
}
/**
* Perform routine maintenance on the resource list. This call
* may instantiate new resources or expire old resources.
*/
APU_DECLARE(apr_status_t) apr_reslist_maintain(apr_reslist_t *reslist)
{
apr_time_t now;
apr_status_t rv;
apr_res_t *res;
int created_one = 0;
#if APR_HAS_THREADS
apr_thread_mutex_lock(reslist->listlock);
#endif
/* Check if we need to create more resources, and if we are allowed to. */
while (reslist->nidle < reslist->min && reslist->ntotal < reslist->hmax) {
/* Create the resource */
rv = create_resource(reslist, &res);
if (rv != APR_SUCCESS) {
free_container(reslist, res);
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return rv;
}
/* Add it to the list */
push_resource(reslist, res);
/* Update our counters */
reslist->ntotal++;
/* If someone is waiting on that guy, wake them up. */
#if APR_HAS_THREADS
rv = apr_thread_cond_signal(reslist->avail);
if (rv != APR_SUCCESS) {
apr_thread_mutex_unlock(reslist->listlock);
return rv;
}
#endif
created_one++;
}
/* We don't need to see if we're over the max if we were under it before */
if (created_one) {
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return APR_SUCCESS;
}
/* Check if we need to expire old resources */
now = apr_time_now();
while (reslist->nidle > reslist->smax && reslist->nidle > 0) {
/* Peak at the last resource in the list */
res = APR_RING_LAST(&reslist->avail_list);
/* See if the oldest entry should be expired */
if (now - res->freed < reslist->ttl) {
/* If this entry is too young, none of the others
* will be ready to be expired either, so we are done. */
break;
}
APR_RING_REMOVE(res, link);
reslist->nidle--;
reslist->ntotal--;
rv = destroy_resource(reslist, res);
free_container(reslist, res);
if (rv != APR_SUCCESS) {
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return rv;
}
}
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return APR_SUCCESS;
}
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)
{
apr_status_t rv;
apr_reslist_t *rl;
/* Do some sanity checks so we don't thrash around in the
* maintenance routine later. */
if (min < 0 || min > smax || min > hmax || smax > hmax || hmax == 0 ||
ttl < 0) {
return APR_EINVAL;
}
#if !APR_HAS_THREADS
/* There can be only one resource when we have no threads. */
if (min > 0) {
min = 1;
}
if (smax > 0) {
smax = 1;
}
hmax = 1;
#endif
rl = apr_pcalloc(pool, sizeof(*rl));
rl->pool = pool;
rl->min = min;
rl->smax = smax;
rl->hmax = hmax;
rl->ttl = ttl;
rl->constructor = con;
rl->destructor = de;
rl->params = params;
APR_RING_INIT(&rl->avail_list, apr_res_t, link);
APR_RING_INIT(&rl->free_list, apr_res_t, link);
#if APR_HAS_THREADS
rv = apr_thread_mutex_create(&rl->listlock, APR_THREAD_MUTEX_DEFAULT,
pool);
if (rv != APR_SUCCESS) {
return rv;
}
rv = apr_thread_cond_create(&rl->avail, pool);
if (rv != APR_SUCCESS) {
return rv;
}
#endif
rv = apr_reslist_maintain(rl);
if (rv != APR_SUCCESS) {
/* Destroy what we've created so far.
*/
reslist_cleanup(rl);
return rv;
}
apr_pool_cleanup_register(rl->pool, rl, reslist_cleanup,
apr_pool_cleanup_null);
*reslist = rl;
return APR_SUCCESS;
}
APU_DECLARE(apr_status_t) apr_reslist_destroy(apr_reslist_t *reslist)
{
return apr_pool_cleanup_run(reslist->pool, reslist, reslist_cleanup);
}
APU_DECLARE(apr_status_t) apr_reslist_acquire(apr_reslist_t *reslist,
void **resource)
{
apr_status_t rv;
apr_res_t *res;
apr_time_t now;
#if APR_HAS_THREADS
apr_thread_mutex_lock(reslist->listlock);
#endif
/* If there are idle resources on the available list, use
* them right away. */
now = apr_time_now();
while (reslist->nidle > 0) {
/* Pop off the first resource */
res = pop_resource(reslist);
if (reslist->ttl && (now - res->freed >= reslist->ttl)) {
/* this res is expired - kill it */
reslist->ntotal--;
rv = destroy_resource(reslist, res);
free_container(reslist, res);
if (rv != APR_SUCCESS) {
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return rv; /* FIXME: this might cause unnecessary fails */
}
continue;
}
*resource = res->opaque;
free_container(reslist, res);
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return APR_SUCCESS;
}
/* If we've hit our max, block until we're allowed to create
* a new one, or something becomes free. */
while (reslist->ntotal >= reslist->hmax && reslist->nidle <= 0) {
#if APR_HAS_THREADS
if (reslist->timeout) {
if ((rv = apr_thread_cond_timedwait(reslist->avail,
reslist->listlock, reslist->timeout)) != APR_SUCCESS) {
apr_thread_mutex_unlock(reslist->listlock);
return rv;
}
}
else {
apr_thread_cond_wait(reslist->avail, reslist->listlock);
}
#else
return APR_EAGAIN;
#endif
}
/* If we popped out of the loop, first try to see if there
* are new resources available for immediate use. */
if (reslist->nidle > 0) {
res = pop_resource(reslist);
*resource = res->opaque;
free_container(reslist, res);
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return APR_SUCCESS;
}
/* Otherwise the reason we dropped out of the loop
* was because there is a new slot available, so create
* a resource to fill the slot and use it. */
else {
rv = create_resource(reslist, &res);
if (rv == APR_SUCCESS) {
reslist->ntotal++;
*resource = res->opaque;
}
free_container(reslist, res);
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return rv;
}
}
APU_DECLARE(apr_status_t) apr_reslist_release(apr_reslist_t *reslist,
void *resource)
{
apr_res_t *res;
#if APR_HAS_THREADS
apr_thread_mutex_lock(reslist->listlock);
#endif
res = get_container(reslist);
res->opaque = resource;
push_resource(reslist, res);
#if APR_HAS_THREADS
apr_thread_cond_signal(reslist->avail);
apr_thread_mutex_unlock(reslist->listlock);
#endif
return apr_reslist_maintain(reslist);
}
APU_DECLARE(void) apr_reslist_timeout_set(apr_reslist_t *reslist,
apr_interval_time_t timeout)
{
reslist->timeout = timeout;
}
APU_DECLARE(apr_uint32_t) apr_reslist_acquired_count(apr_reslist_t *reslist)
{
apr_uint32_t count;
#if APR_HAS_THREADS
apr_thread_mutex_lock(reslist->listlock);
#endif
count = reslist->ntotal - reslist->nidle;
#if APR_HAS_THREADS
apr_thread_mutex_unlock(reslist->listlock);
#endif
return count;
}
APU_DECLARE(apr_status_t) apr_reslist_invalidate(apr_reslist_t *reslist,
void *resource)
{
apr_status_t ret;
#if APR_HAS_THREADS
apr_thread_mutex_lock(reslist->listlock);
#endif
ret = reslist->destructor(resource, reslist->params, reslist->pool);
reslist->ntotal--;
#if APR_HAS_THREADS
apr_thread_cond_signal(reslist->avail);
apr_thread_mutex_unlock(reslist->listlock);
#endif
return ret;
}
APU_DECLARE(void) apr_reslist_cleanup_order_set(apr_reslist_t *rl,
apr_uint32_t mode)
{
apr_pool_cleanup_kill(rl->pool, rl, reslist_cleanup);
if (mode == APR_RESLIST_CLEANUP_FIRST)
apr_pool_pre_cleanup_register(rl->pool, rl, reslist_cleanup);
else
apr_pool_cleanup_register(rl->pool, rl, reslist_cleanup,
apr_pool_cleanup_null);
}