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Diffstat (limited to 'misc/apr_reslist.c')
| -rw-r--r-- | misc/apr_reslist.c | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/misc/apr_reslist.c b/misc/apr_reslist.c new file mode 100644 index 0000000..12ae96a --- /dev/null +++ b/misc/apr_reslist.c @@ -0,0 +1,479 @@ +/* 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); + if (reslist->ttl) { + 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, + * nor need we check for expiry if no ttl is configure. + */ + if (created_one || !reslist->ttl) { +#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 = 0; + +#if APR_HAS_THREADS + apr_thread_mutex_lock(reslist->listlock); +#endif + /* If there are idle resources on the available list, use + * them right away. */ + if (reslist->ttl) { + 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); +} |