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/*
* Async Postgres connection.
*
* Copyright (c) 2009 Marko Kreen
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <usual/pgsocket.h>
#include <stdarg.h>
#include <usual/event.h>
#include <usual/logging.h>
#include <usual/time.h>
#include <usual/string.h>
#define MAX_QRY_ARGS 32
/* PgSocket.wait_type */
enum WType {
W_NONE = 0,
W_SOCK,
W_TIME
};
typedef void (*libev_cb)(int sock, short flags, void *arg);
struct PgSocket {
/* libevent state */
struct event ev;
/* track wait state */
enum WType wait_type;
/* EV_READ / EV_WRITE */
uint8_t wait_event;
/* should connect after sleep */
bool reconnect;
/* current connection */
PGconn *con;
/* user handler */
pgs_handler_f handler_func;
void *handler_arg;
/* saved connect string */
const char *connstr;
/* custom base or NULL */
struct event_base *base;
/* temp place for resultset */
PGresult *last_result;
usec_t connect_time;
usec_t lifetime;
};
/* report event to user callback */
static void send_event(struct PgSocket *db, enum PgEvent ev)
{
db->handler_func(db, db->handler_arg, ev, NULL);
}
/* wait socket event from libevent */
static void wait_event(struct PgSocket *db, short ev, libev_cb fn)
{
Assert(!db->wait_type);
event_set(&db->ev, PQsocket(db->con), ev, fn, db);
if (db->base)
event_base_set(db->base, &db->ev);
if (event_add(&db->ev, NULL) < 0)
fatal_perror("event_add");
db->wait_type = W_SOCK;
db->wait_event = ev;
}
/* wait timeout from libevent */
static void timeout_cb(int sock, short flags, void *arg)
{
struct PgSocket *db = arg;
db->wait_type = W_NONE;
if (db->reconnect) {
db->reconnect = false;
pgs_connect(db);
} else {
send_event(db, PGS_TIMEOUT);
}
}
/* some error happened */
static void conn_error(struct PgSocket *db, enum PgEvent ev, const char *desc)
{
log_error("connection error: %s", desc);
log_error("libpq: %s", PQerrorMessage(db->con));
send_event(db, ev);
}
/* report previously stored result */
static void report_last_result(struct PgSocket *db)
{
PGresult *res = db->last_result;
if (!res)
return;
db->last_result = NULL;
switch (PQresultStatus(res)) {
default:
log_error("%s: %s", PQdb(db->con), PQresultErrorMessage(res));
case PGRES_COMMAND_OK:
case PGRES_TUPLES_OK:
case PGRES_COPY_OUT:
case PGRES_COPY_IN:
db->handler_func(db, db->handler_arg, PGS_RESULT_OK, res);
}
PQclear(res);
}
/*
* Called when select() told that conn is avail for reading.
*
* It should call postgres handlers and then change state if needed.
*
* Because the callback may want to close the connection when processing
* last resultset, the PGresult handover is delayed one step.
*/
static void result_cb(int sock, short flags, void *arg)
{
struct PgSocket *db = arg;
PGresult *res;
db->wait_type = W_NONE;
if (!PQconsumeInput(db->con)) {
conn_error(db, PGS_RESULT_BAD, "PQconsumeInput");
return;
}
/* loop until PQgetResult returns NULL */
while (db->con) {
/* incomplete result? */
if (PQisBusy(db->con)) {
wait_event(db, EV_READ, result_cb);
return;
}
/* next result */
res = PQgetResult(db->con);
if (!res)
break;
report_last_result(db);
db->last_result = res;
}
report_last_result(db);
}
static void flush(struct PgSocket *db);
static void send_cb(int sock, short flags, void *arg)
{
struct PgSocket *db = arg;
db->wait_type = W_NONE;
flush(db);
}
/* handle connect states */
static void connect_cb(int sock, short flags, void *arg)
{
struct PgSocket *db = arg;
PostgresPollingStatusType poll_res;
db->wait_type = W_NONE;
poll_res = PQconnectPoll(db->con);
switch (poll_res) {
case PGRES_POLLING_WRITING:
wait_event(db, EV_WRITE, connect_cb);
break;
case PGRES_POLLING_READING:
wait_event(db, EV_READ, connect_cb);
break;
case PGRES_POLLING_OK:
db->connect_time = get_time_usec();
send_event(db, PGS_CONNECT_OK);
break;
default:
conn_error(db, PGS_CONNECT_FAILED, "PQconnectPoll");
}
}
/* send query to server */
static void flush(struct PgSocket *db)
{
int res = PQflush(db->con);
if (res > 0) {
wait_event(db, EV_WRITE, send_cb);
} else if (res == 0) {
wait_event(db, EV_READ, result_cb);
} else
conn_error(db, PGS_RESULT_BAD, "PQflush");
}
/* override default notice receiver */
static void custom_notice_receiver(void *arg, const PGresult *res)
{
/* do nothing */
}
/*
* Public API
*/
struct PgSocket *pgs_create(const char *connstr, pgs_handler_f fn, void *handler_arg)
{
struct PgSocket *db;
db = calloc(1, sizeof(*db));
if (!db)
return NULL;
db->handler_func = fn;
db->handler_arg = handler_arg;
db->connstr = strdup(connstr);
if (!db->connstr) {
pgs_free(db);
return NULL;
}
return db;
}
void pgs_set_event_base(struct PgSocket *pgs, struct event_base *base)
{
pgs->base = base;
}
void pgs_set_lifetime(struct PgSocket *pgs, double lifetime)
{
pgs->lifetime = USEC * lifetime;
}
void pgs_connect(struct PgSocket *db)
{
if (db->con)
pgs_disconnect(db);
db->con = PQconnectStart(db->connstr);
if (db->con == NULL) {
conn_error(db, PGS_CONNECT_FAILED, "PQconnectStart");
return;
}
if (PQstatus(db->con) == CONNECTION_BAD) {
conn_error(db, PGS_CONNECT_FAILED, "PQconnectStart");
return;
}
PQsetNoticeReceiver(db->con, custom_notice_receiver, db);
wait_event(db, EV_WRITE, connect_cb);
}
void pgs_disconnect(struct PgSocket *db)
{
if (db->wait_type) {
event_del(&db->ev);
db->wait_type = W_NONE;
db->reconnect = false;
}
if (db->con) {
PQfinish(db->con);
db->con = NULL;
}
if (db->last_result) {
PQclear(db->last_result);
db->last_result = NULL;
}
}
void pgs_free(struct PgSocket *db)
{
if (db) {
pgs_disconnect(db);
free(db->connstr);
free(db);
}
}
void pgs_sleep(struct PgSocket *db, double timeout)
{
struct timeval tv;
Assert(!db->wait_type);
if (db->con && db->lifetime) {
usec_t now = get_time_usec();
if (db->connect_time + db->lifetime < now) {
pgs_disconnect(db);
db->reconnect = true;
}
}
tv.tv_sec = timeout;
tv.tv_usec = (timeout - tv.tv_sec) * USEC;
evtimer_set(&db->ev, timeout_cb, db);
if (db->base)
event_base_set(db->base, &db->ev);
if (evtimer_add(&db->ev, &tv) < 0)
fatal_perror("event_add");
db->wait_type = W_TIME;
}
void pgs_reconnect(struct PgSocket *db, double timeout)
{
pgs_disconnect(db);
pgs_sleep(db, timeout);
db->reconnect = true;
}
void pgs_send_query_simple(struct PgSocket *db, const char *q)
{
int res;
log_noise("%s", q);
res = PQsendQuery(db->con, q);
if (!res) {
conn_error(db, PGS_RESULT_BAD, "PQsendQuery");
return;
}
flush(db);
}
void pgs_send_query_params(struct PgSocket *db, const char *q, int cnt, ...)
{
int i;
va_list ap;
const char * args[MAX_QRY_ARGS];
if (cnt < 0 || cnt > MAX_QRY_ARGS) {
log_warning("bad query arg cnt");
send_event(db, PGS_RESULT_BAD);
return;
}
va_start(ap, cnt);
for (i = 0; i < cnt; i++)
args[i] = va_arg(ap, char *);
va_end(ap);
pgs_send_query_params_list(db, q, cnt, args);
}
void pgs_send_query_params_list(struct PgSocket *db, const char *q, int cnt, const char *args[])
{
int res;
log_noise("%s", q);
res = PQsendQueryParams(db->con, q, cnt, NULL, args, NULL, NULL, 0);
if (!res) {
conn_error(db, PGS_RESULT_BAD, "PQsendQueryParams");
return;
}
flush(db);
}
int pgs_connection_valid(struct PgSocket *db)
{
return (db->con != NULL);
}
PGconn *pgs_get_connection(struct PgSocket *db)
{
return db->con;
}
bool pgs_waiting_for_reply(struct PgSocket *db)
{
if (!db->con)
return false;
if (PQstatus(db->con) != CONNECTION_OK)
return false;
return (db->wait_type == W_SOCK) && (db->wait_event == EV_READ);
}
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