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/******************************************************************************
*
* Project: MapServer
* Purpose: MapCache connection pooling
* Author: Thomas Bonfort and the MapServer team.
*
******************************************************************************
* Copyright (c) 1996-2011 Regents of the University of Minnesota.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies of this Software or works derived from this Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*****************************************************************************/
#include <apr_reslist.h>
#include "mapcache.h"
struct mapcache_connection_pool {
apr_pool_t *server_pool;
apr_reslist_t *connexions;
};
struct mapcache_pooled_connection_container {
mapcache_pooled_connection *head;
apr_pool_t *pool;
unsigned int max_list_size;
};
struct mapcache_pooled_connection_private_data {
char *key;
mapcache_connection_destructor destructor;
mapcache_pooled_connection *next;
mapcache_pooled_connection_container *pcc;
};
static apr_status_t mapcache_connection_container_creator(void **conn_, void *params, apr_pool_t *pool) {
mapcache_pooled_connection_container *pcc;
pcc = calloc(1, sizeof(mapcache_pooled_connection_container));
pcc->max_list_size = 10;
pcc->pool = pool;
*conn_ = pcc;
return APR_SUCCESS;
}
static apr_status_t mapcache_connection_container_destructor(void *conn_, void *params, apr_pool_t *pool) {
mapcache_pooled_connection_container *pcc = (mapcache_pooled_connection_container*)conn_;
mapcache_pooled_connection *pc = pcc->head;
while(pc) {
mapcache_pooled_connection *this = pc;
this->private->destructor(this->connection);
free(this->private->key);
pc = this->private->next;
free(this);
}
free(pcc);
return MAPCACHE_SUCCESS;
}
apr_status_t mapcache_connection_pool_create(mapcache_connection_pool **cp, apr_pool_t *server_pool) {
apr_status_t rv;
*cp = apr_pcalloc(server_pool, sizeof(mapcache_connection_pool));
(*cp)->server_pool = server_pool;
rv = apr_reslist_create(&((*cp)->connexions), 1, 5, 200, 60*1000000,
mapcache_connection_container_creator,
mapcache_connection_container_destructor,
NULL,
server_pool);
return rv;
}
mapcache_pooled_connection* mapcache_connection_pool_get_connection(mapcache_context *ctx, char *key,
mapcache_connection_constructor constructor, mapcache_connection_destructor destructor,
void *params) {
apr_status_t rv;
int count = 0;
mapcache_pooled_connection_container *pcc;
mapcache_pooled_connection *pc,*pred=NULL;
rv = apr_reslist_acquire(ctx->connection_pool->connexions, (void**)&pcc);
if(rv != APR_SUCCESS || !pcc) {
char errmsg[120];
ctx->set_error(ctx,500, "failed to acquire connection from mapcache connection pool: (%s)", apr_strerror(rv, errmsg,120));
return NULL;
}
/* loop through existing connections to see if we find one matching the given key */
pc = pcc->head;
while(pc) {
count++;
if(!strcmp(key,pc->private->key)) {
/* move current connection to head of list, and return it. We only move the connection
to the front of the list if it wasn't in the first 2 connections, as in the seeding
case we are always alternating between read and write operations (i.e. potentially
2 different connections and in that cas we end up switching connections each time
there's an access */
if(pc != pcc->head && count>2) {
assert(pred);
pred->private->next = pc->private->next;
pc->private->next = pcc->head;
pcc->head = pc;
}
return pc;
}
pred = pc;
pc = pc->private->next;
}
/* connection not found in pool */
pc = calloc(1,sizeof(mapcache_pooled_connection));
/*
ctx->log(ctx, MAPCACHE_DEBUG, "calling constructor for pooled connection (%s)", key);
*/
constructor(ctx, &pc->connection, params);
if(GC_HAS_ERROR(ctx)) {
free(pc);
apr_reslist_release(ctx->connection_pool->connexions, pcc);
return NULL;
}
pc->private = calloc(1,sizeof(mapcache_pooled_connection_private_data));
pc->private->key = strdup(key);
pc->private->destructor = destructor;
pc->private->next = pcc->head;
pc->private->pcc = pcc;
if(count == pcc->max_list_size) {
/* max number of connections atained, we must destroy the last one that was used */
mapcache_pooled_connection *opc;
opc = pcc->head;
count = 1;
while(count < pcc->max_list_size) {
pred = opc;
opc = opc->private->next;
count++;
}
ctx->log(ctx, MAPCACHE_DEBUG, "tearing down pooled connection (%s) to make room", opc->private->key);
opc->private->destructor(opc->connection);
free(opc->private->key);
free(opc->private);
free(opc);
if(pred) {
pred->private->next = NULL;
}
}
pcc->head = pc;
return pc;
}
void mapcache_connection_pool_invalidate_connection(mapcache_context *ctx, mapcache_pooled_connection *connection) {
mapcache_pooled_connection_container *pcc = connection->private->pcc;
mapcache_pooled_connection *pc = pcc->head, *pred=NULL;
while(pc) {
if(pc == connection) {
if(pred) {
pred->private->next = pc->private->next;
} else {
pcc->head = pc->private->next;
}
pc->private->destructor(pc->connection);
free(pc->private->key);
free(pc);
}
pred = pc;
pc = pc->private->next;
}
}
void mapcache_connection_pool_release_connection(mapcache_context *ctx, mapcache_pooled_connection *connection) {
if(connection) {
mapcache_pooled_connection_container *pcc = connection->private->pcc;
apr_reslist_release(ctx->connection_pool->connexions,(void*)pcc);
}
}
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