mod_dbd.c revision 842ae4bd224140319ae7feec1872b93dfd491143
/* 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.
*/
/* Overview of what this is and does:
* http://www.apache.org/~niq/dbd.html
* or
* http://apache.webthing.com/database/
*/
#include <ctype.h>
#include "http_protocol.h"
#include "http_config.h"
#include "http_log.h"
#include "apr_reslist.h"
#include "apr_strings.h"
#include "apr_dbd.h"
#include "mod_dbd.h"
extern module AP_MODULE_DECLARE_DATA dbd_module;
/************ svr cfg: manage db connection pool ****************/
#define NMIN_SET 0x1
#define NKEEP_SET 0x2
#define NMAX_SET 0x4
#define EXPTIME_SET 0x8
typedef struct dbd_prepared {
const char *label;
const char *query;
struct dbd_prepared *next;
} dbd_prepared;
typedef struct svr_cfg {
const char *name;
const char *params;
int persist;
dbd_prepared *prepared;
#if APR_HAS_THREADS
apr_thread_mutex_t *mutex;
apr_pool_t *pool;
apr_reslist_t *dbpool;
int nmin;
int nkeep;
int nmax;
int exptime;
#else
ap_dbd_t *conn;
#endif
unsigned int set;
} svr_cfg;
typedef enum { cmd_name, cmd_params, cmd_persist,
cmd_min, cmd_keep, cmd_max, cmd_exp
} cmd_parts;
/* a default DBDriver value that'll generate meaningful error messages */
static const char *const no_dbdriver = "[DBDriver unset]";
#define ISINT(val) \
for (p = val; *p; ++p) \
if (!isdigit(*p)) \
return "Argument must be numeric!"
static const char *dbd_param(cmd_parms *cmd, void *cfg, const char *val)
{
const char *p;
const apr_dbd_driver_t *driver = NULL;
svr_cfg *svr = (svr_cfg*) ap_get_module_config
(cmd->server->module_config, &dbd_module);
switch ((long) cmd->info) {
case cmd_name:
svr->name = val;
/* loading the driver involves once-only dlloading that is
* best done at server startup. This also guarantees that
* we won't return an error later.
*/
switch (apr_dbd_get_driver(cmd->pool, svr->name, &driver)) {
case APR_ENOTIMPL:
return apr_psprintf(cmd->pool, "DBD: No driver for %s", svr->name);
case APR_EDSOOPEN:
return apr_psprintf(cmd->pool,
"DBD: Can't load driver file apr_dbd_%s.so",
svr->name);
case APR_ESYMNOTFOUND:
return apr_psprintf(cmd->pool,
"DBD: Failed to load driver apr_dbd_%s_driver",
svr->name);
}
break;
case cmd_params:
svr->params = val;
break;
#if APR_HAS_THREADS
case cmd_min:
ISINT(val);
svr->nmin = atoi(val);
svr->set |= NMIN_SET;
break;
case cmd_keep:
ISINT(val);
svr->nkeep = atoi(val);
svr->set |= NKEEP_SET;
break;
case cmd_max:
ISINT(val);
svr->nmax = atoi(val);
svr->set |= NMAX_SET;
break;
case cmd_exp:
ISINT(val);
svr->exptime = atoi(val);
svr->set |= EXPTIME_SET;
break;
#endif
}
return NULL;
}
static const char *dbd_param_flag(cmd_parms *cmd, void *cfg, int flag)
{
svr_cfg *svr = (svr_cfg*) ap_get_module_config
(cmd->server->module_config, &dbd_module);
switch ((long) cmd->info) {
case cmd_persist:
svr->persist = flag;
break;
}
return NULL;
}
DBD_DECLARE_NONSTD(void) ap_dbd_prepare(server_rec *s, const char *query,
const char *label)
{
svr_cfg *svr = ap_get_module_config(s->module_config, &dbd_module);
dbd_prepared *prepared = apr_pcalloc(s->process->pool, sizeof(dbd_prepared));
prepared->label = label;
prepared->query = query;
prepared->next = svr->prepared;
svr->prepared = prepared;
}
static const char *dbd_prepare(cmd_parms *cmd, void *cfg, const char *query,
const char *label)
{
ap_dbd_prepare(cmd->server, query, label);
return NULL;
}
static const command_rec dbd_cmds[] = {
AP_INIT_TAKE1("DBDriver", dbd_param, (void*)cmd_name, RSRC_CONF,
"SQL Driver"),
AP_INIT_TAKE1("DBDParams", dbd_param, (void*)cmd_params, RSRC_CONF,
"SQL Driver Params"),
AP_INIT_FLAG("DBDPersist", dbd_param_flag, (void*)cmd_persist, RSRC_CONF,
"Use persistent connection/pool"),
AP_INIT_TAKE2("DBDPrepareSQL", dbd_prepare, NULL, RSRC_CONF,
"Prepared SQL statement, label"),
#if APR_HAS_THREADS
AP_INIT_TAKE1("DBDMin", dbd_param, (void*)cmd_min, RSRC_CONF,
"Minimum number of connections"),
/* XXX: note that mod_proxy calls this "smax" */
AP_INIT_TAKE1("DBDKeep", dbd_param, (void*)cmd_keep, RSRC_CONF,
"Maximum number of sustained connections"),
AP_INIT_TAKE1("DBDMax", dbd_param, (void*)cmd_max, RSRC_CONF,
"Maximum number of connections"),
/* XXX: note that mod_proxy calls this "ttl" (time to live) */
AP_INIT_TAKE1("DBDExptime", dbd_param, (void*)cmd_exp, RSRC_CONF,
"Keepalive time for idle connections"),
#endif
{NULL}
};
static void *dbd_merge(apr_pool_t *pool, void *BASE, void *ADD) {
svr_cfg *base = (svr_cfg*) BASE;
svr_cfg *add = (svr_cfg*) ADD;
svr_cfg *cfg = apr_pcalloc(pool, sizeof(svr_cfg));
cfg->name = (add->name != no_dbdriver) ? add->name : base->name;
cfg->params = strcmp(add->params, "") ? add->params : base->params;
cfg->persist = (add->persist == -1) ? base->persist : add->persist;
#if APR_HAS_THREADS
cfg->nmin = (add->set&NMIN_SET) ? add->nmin : base->nmin;
cfg->nkeep = (add->set&NKEEP_SET) ? add->nkeep : base->nkeep;
cfg->nmax = (add->set&NMAX_SET) ? add->nmax : base->nmax;
cfg->exptime = (add->set&EXPTIME_SET) ? add->exptime : base->exptime;
#endif
cfg->set = add->set | base->set;
cfg->prepared = (add->prepared != NULL) ? add->prepared : base->prepared;
return (void*) cfg;
}
/* A default nmin of >0 will help with generating meaningful
* startup error messages if the database is down.
*/
#define DEFAULT_NMIN 1
#define DEFAULT_NKEEP 2
#define DEFAULT_NMAX 10
#define DEFAULT_EXPTIME 300
static void *dbd_cfg(apr_pool_t *p, server_rec *x)
{
svr_cfg *svr = (svr_cfg*) apr_pcalloc(p, sizeof(svr_cfg));
svr->params = ""; /* don't risk segfault on misconfiguration */
svr->name = no_dbdriver; /* to generate meaningful error messages */
svr->persist = -1;
#if APR_HAS_THREADS
svr->nmin = DEFAULT_NMIN;
svr->nkeep = DEFAULT_NKEEP;
svr->nmax = DEFAULT_NMAX;
svr->exptime = DEFAULT_EXPTIME;
#endif
return svr;
}
static apr_status_t dbd_prepared_init(apr_pool_t *pool, svr_cfg *svr,
ap_dbd_t *dbd)
{
dbd_prepared *p;
apr_status_t ret = APR_SUCCESS;
apr_dbd_prepared_t *stmt;
dbd->prepared = apr_hash_make(pool);
for (p = svr->prepared; p; p = p->next) {
stmt = NULL;
if (apr_dbd_prepare(dbd->driver, pool, dbd->handle, p->query,
p->label, &stmt) == 0) {
apr_hash_set(dbd->prepared, p->label, APR_HASH_KEY_STRING, stmt);
}
else {
ret = APR_EGENERAL;
}
}
return ret;
}
/************ svr cfg: manage db connection pool ****************/
/* an apr_reslist_constructor for SQL connections
* Also use this for opening in non-reslist modes, since it gives
* us all the error-handling in one place.
*/
static apr_status_t dbd_construct(void **db, void *params, apr_pool_t *pool)
{
svr_cfg *svr = (svr_cfg*) params;
ap_dbd_t *rec = apr_pcalloc(pool, sizeof(ap_dbd_t));
apr_status_t rv;
/* this pool is mostly so dbd_close can destroy the prepared stmts */
rv = apr_pool_create(&rec->pool, pool);
if (rv != APR_SUCCESS) {
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, pool,
"DBD: Failed to create memory pool");
}
/* The driver is loaded at config time now, so this just checks a hash.
* If that changes, the driver DSO could be registered to unload against
* our pool, which is probably not what we want. Error checking isn't
* necessary now, but in case that changes in the future ...
*/
rv = apr_dbd_get_driver(rec->pool, svr->name, &rec->driver);
switch (rv) {
case APR_ENOTIMPL:
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, rec->pool,
"DBD: driver for %s not available", svr->name);
return rv;
case APR_EDSOOPEN:
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, rec->pool,
"DBD: can't find driver for %s", svr->name);
return rv;
case APR_ESYMNOTFOUND:
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, rec->pool,
"DBD: driver for %s is invalid or corrupted", svr->name);
return rv;
default:
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, rec->pool,
"DBD: mod_dbd not compatible with apr in get_driver");
return rv;
case APR_SUCCESS:
break;
}
rv = apr_dbd_open(rec->driver, rec->pool, svr->params, &rec->handle);
switch (rv) {
case APR_EGENERAL:
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, rec->pool,
"DBD: Can't connect to %s", svr->name);
return rv;
default:
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, rec->pool,
"DBD: mod_dbd not compatible with apr in open");
return rv;
case APR_SUCCESS:
break;
}
*db = rec;
rv = dbd_prepared_init(rec->pool, svr, rec);
if (rv != APR_SUCCESS) {
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, rec->pool,
"DBD: failed to initialise prepared SQL statements");
}
return rv;
}
static apr_status_t dbd_close(void *CONN)
{
ap_dbd_t *conn = CONN;
apr_status_t rv = apr_dbd_close(conn->driver, conn->handle);
apr_pool_destroy(conn->pool);
return rv;
}
#if APR_HAS_THREADS
static apr_status_t dbd_destruct(void *sql, void *params, apr_pool_t *pool)
{
return dbd_close(sql);
}
static apr_status_t dbd_setup(apr_pool_t *pool, svr_cfg *svr)
{
apr_status_t rv;
/* create a pool just for the reslist from a process-lifetime pool;
* that pool (s->process->pool in the dbd_setup_lock case,
* whatever was passed to ap_run_child_init in the dbd_setup_init case)
* will be shared with other threads doing other non-mod_dbd things
* so we can't use it for the reslist directly
*/
rv = apr_pool_create(&svr->pool, pool);
if (rv != APR_SUCCESS) {
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, pool,
"DBD: Failed to create reslist memory pool");
return rv;
}
rv = apr_reslist_create(&svr->dbpool, svr->nmin, svr->nkeep, svr->nmax,
apr_time_from_sec(svr->exptime),
dbd_construct, dbd_destruct, svr, svr->pool);
if (rv == APR_SUCCESS) {
apr_pool_cleanup_register(svr->pool, svr->dbpool,
(void*)apr_reslist_destroy,
apr_pool_cleanup_null);
}
else {
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, svr->pool,
"DBD: failed to initialise");
apr_pool_destroy(svr->pool);
svr->pool = NULL;
}
return rv;
}
static apr_status_t dbd_setup_init(apr_pool_t *pool, server_rec *s)
{
svr_cfg *svr = ap_get_module_config(s->module_config, &dbd_module);
apr_status_t rv;
if (!svr->persist) {
return APR_SUCCESS;
}
rv = dbd_setup(pool, svr);
if (rv == APR_SUCCESS) {
return rv;
}
/* we failed, so create a mutex so that subsequent competing callers
* to ap_dbd_open can serialize themselves while they retry
*/
rv = apr_thread_mutex_create(&svr->mutex, APR_THREAD_MUTEX_DEFAULT, pool);
if (rv != APR_SUCCESS) {
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, pool,
"DBD: Failed to create thread mutex");
}
return rv;
}
static apr_status_t dbd_setup_lock(apr_pool_t *pool, server_rec *s)
{
svr_cfg *svr = ap_get_module_config(s->module_config, &dbd_module);
apr_status_t rv, rv2 = APR_SUCCESS;
/* several threads could be here at the same time, all trying to
* initialize the reslist because dbd_setup_init failed to do so
*/
if (!svr->mutex) {
/* we already logged an error when the mutex couldn't be created */
return APR_EGENERAL;
}
rv = apr_thread_mutex_lock(svr->mutex);
if (rv != APR_SUCCESS) {
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, pool,
"DBD: Failed to acquire thread mutex");
return rv;
}
if (!svr->dbpool) {
rv2 = dbd_setup(s->process->pool, svr);
}
rv = apr_thread_mutex_unlock(svr->mutex);
if (rv != APR_SUCCESS) {
ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, pool,
"DBD: Failed to release thread mutex");
if (rv2 == APR_SUCCESS) {
rv2 = rv;
}
}
return rv2;
}
#endif
/* Functions we export for modules to use:
- open acquires a connection from the pool (opens one if necessary)
- close releases it back in to the pool
*/
DBD_DECLARE_NONSTD(void) ap_dbd_close(server_rec *s, ap_dbd_t *sql)
{
svr_cfg *svr = ap_get_module_config(s->module_config, &dbd_module);
if (!svr->persist) {
dbd_close((void*) sql);
}
#if APR_HAS_THREADS
else {
apr_reslist_release(svr->dbpool, sql);
}
#endif
}
#define arec ((ap_dbd_t*)rec)
#if APR_HAS_THREADS
DBD_DECLARE_NONSTD(ap_dbd_t*) ap_dbd_open(apr_pool_t *pool, server_rec *s)
{
void *rec = NULL;
svr_cfg *svr = ap_get_module_config(s->module_config, &dbd_module);
apr_status_t rv = APR_SUCCESS;
const char *errmsg;
if (!svr->persist) {
/* Return a once-only connection */
rv = dbd_construct(&rec, svr, s->process->pool);
return (rv == APR_SUCCESS) ? arec : NULL;
}
if (!svr->dbpool) {
if (dbd_setup_lock(pool, s) != APR_SUCCESS) {
return NULL;
}
}
rv = apr_reslist_acquire(svr->dbpool, &rec);
if (rv != APR_SUCCESS) {
ap_log_perror(APLOG_MARK, APLOG_ERR, rv, pool,
"Failed to acquire DBD connection from pool!");
return NULL;
}
rv = apr_dbd_check_conn(arec->driver, pool, arec->handle);
if ((rv != APR_SUCCESS) && (rv != APR_ENOTIMPL)) {
errmsg = apr_dbd_error(arec->driver, arec->handle, rv);
if (!errmsg) {
errmsg = "(unknown)";
}
ap_log_perror(APLOG_MARK, APLOG_ERR, rv, pool,
"DBD[%s] Error: %s", svr->name, errmsg );
apr_reslist_invalidate(svr->dbpool, rec);
return NULL;
}
return arec;
}
#else
DBD_DECLARE_NONSTD(ap_dbd_t*) ap_dbd_open(apr_pool_t *pool, server_rec *s)
{
apr_status_t rv = APR_SUCCESS;
const char *errmsg;
void *rec = NULL;
svr_cfg *svr = ap_get_module_config(s->module_config, &dbd_module);
if (!svr->persist) {
/* Return a once-only connection */
rv = dbd_construct(&rec, svr, s->process->pool);
return (rv == APR_SUCCESS) ? arec : NULL;
}
/* since we're in nothread-land, we can mess with svr->conn with impunity */
/* If we have a persistent connection and it's good, we'll use it */
if (svr->conn) {
rv = apr_dbd_check_conn(svr->conn->driver, pool, svr->conn->handle);
if ((rv != APR_SUCCESS) && (rv != APR_ENOTIMPL)) {
errmsg = apr_dbd_error(arec->driver, arec->handle, rv);
if (!errmsg) {
errmsg = "(unknown)";
}
ap_log_perror(APLOG_MARK, APLOG_ERR, rv, pool,
"DBD[%s] Error: %s", svr->name, errmsg);
svr->conn = NULL;
}
}
/* We don't have a connection right now, so we'll open one */
if (!svr->conn) {
if (dbd_construct(&rec, svr, s->process->pool) == APR_SUCCESS) {
svr->conn = arec ;
apr_pool_cleanup_register(s->process->pool, svr->conn,
dbd_close, apr_pool_cleanup_null);
}
}
return svr->conn;
}
#endif
#if APR_HAS_THREADS
typedef struct {
ap_dbd_t *conn;
apr_reslist_t *dbpool;
} dbd_pool_rec;
static apr_status_t dbd_release(void *REQ)
{
dbd_pool_rec *req = REQ;
apr_reslist_release(req->dbpool, req->conn);
return APR_SUCCESS;
}
DBD_DECLARE_NONSTD(ap_dbd_t *) ap_dbd_acquire(request_rec *r)
{
svr_cfg *svr;
dbd_pool_rec *req = ap_get_module_config(r->request_config, &dbd_module);
if (!req) {
req = apr_palloc(r->pool, sizeof(dbd_pool_rec));
req->conn = ap_dbd_open(r->pool, r->server);
if (req->conn) {
svr = ap_get_module_config(r->server->module_config, &dbd_module);
ap_set_module_config(r->request_config, &dbd_module, req);
if (svr->persist) {
req->dbpool = svr->dbpool;
apr_pool_cleanup_register(r->pool, req, dbd_release,
apr_pool_cleanup_null);
}
else {
apr_pool_cleanup_register(r->pool, req->conn, dbd_close,
apr_pool_cleanup_null);
}
}
}
return req->conn;
}
DBD_DECLARE_NONSTD(ap_dbd_t *) ap_dbd_cacquire(conn_rec *c)
{
svr_cfg *svr;
dbd_pool_rec *req = ap_get_module_config(c->conn_config, &dbd_module);
if (!req) {
req = apr_palloc(c->pool, sizeof(dbd_pool_rec));
req->conn = ap_dbd_open(c->pool, c->base_server);
if (req->conn) {
svr = ap_get_module_config(c->base_server->module_config, &dbd_module);
ap_set_module_config(c->conn_config, &dbd_module, req);
if (svr->persist) {
req->dbpool = svr->dbpool;
apr_pool_cleanup_register(c->pool, req, dbd_release,
apr_pool_cleanup_null);
}
else {
apr_pool_cleanup_register(c->pool, req->conn, dbd_close,
apr_pool_cleanup_null);
}
}
}
return req->conn;
}
#else
DBD_DECLARE_NONSTD(ap_dbd_t *) ap_dbd_acquire(request_rec *r)
{
svr_cfg *svr;
ap_dbd_t *ret = ap_get_module_config(r->request_config, &dbd_module);
if (!ret) {
svr = ap_get_module_config(r->server->module_config, &dbd_module);
ret = ap_dbd_open(r->pool, r->server);
if (ret) {
ap_set_module_config(r->request_config, &dbd_module, ret);
if (!svr->persist) {
apr_pool_cleanup_register(r->pool, svr->conn, dbd_close,
apr_pool_cleanup_null);
}
/* if persist then dbd_open registered cleanup on proc pool */
}
}
return ret;
}
DBD_DECLARE_NONSTD(ap_dbd_t *) ap_dbd_cacquire(conn_rec *c)
{
svr_cfg *svr;
ap_dbd_t *ret = ap_get_module_config(c->conn_config, &dbd_module);
if (!ret) {
svr = ap_get_module_config(c->base_server->module_config, &dbd_module);
ret = ap_dbd_open(c->pool, c->base_server);
if (ret) {
ap_set_module_config(c->conn_config, &dbd_module, ret);
if (!svr->persist) {
apr_pool_cleanup_register(c->pool, svr->conn, dbd_close,
apr_pool_cleanup_null);
}
/* if persist then dbd_open registered cleanup on proc pool */
}
}
return ret;
}
#endif
static void dbd_hooks(apr_pool_t *pool)
{
#if APR_HAS_THREADS
ap_hook_child_init((void*)dbd_setup_init, NULL, NULL, APR_HOOK_MIDDLE);
#endif
APR_REGISTER_OPTIONAL_FN(ap_dbd_open);
APR_REGISTER_OPTIONAL_FN(ap_dbd_close);
APR_REGISTER_OPTIONAL_FN(ap_dbd_acquire);
APR_REGISTER_OPTIONAL_FN(ap_dbd_cacquire);
APR_REGISTER_OPTIONAL_FN(ap_dbd_prepare);
apr_dbd_init(pool);
}
module AP_MODULE_DECLARE_DATA dbd_module = {
STANDARD20_MODULE_STUFF,
NULL,
NULL,
dbd_cfg,
dbd_merge,
dbd_cmds,
dbd_hooks
};