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MINOR: backend: extract conn reuse from connect_server()

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Following the previous patch, the part directly related to connection
reuse is extracted from connect_server(). It is now define in a new
function be_reuse_connection().
This commit is contained in:
Amaury Denoyelle 2025-03-27 10:37:48 +01:00
parent c7cc6b6401
commit ee94a6cfc1
2 changed files with 129 additions and 104 deletions
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2
include/haproxy/backend.h
View File

@ -50,6 +50,8 @@ int64_t be_calculate_conn_hash(struct server *srv, struct stream *strm,
struct session *sess, struct session *sess,
struct sockaddr_storage *src, struct sockaddr_storage *src,
struct sockaddr_storage *dst); struct sockaddr_storage *dst);
int be_reuse_connection(int64_t hash, struct session *sess, struct server *srv,
struct stconn *sc, struct stream *strm);
int srv_redispatch_connect(struct stream *t); int srv_redispatch_connect(struct stream *t);
void back_try_conn_req(struct stream *s); void back_try_conn_req(struct stream *s);

235
src/backend.c
View File

@ -1531,6 +1531,19 @@ kill_random_idle_conn(struct server *srv)
return 0; return 0;
} }
/* Returns backend reuse policy depending on <be>. It can be forced to always
* mode if <srv> is not NULL and uses reverse HTTP.
*/
static int be_reuse_mode(struct proxy *be, struct server *srv)
{
if (srv && srv->flags & SRV_F_RHTTP) {
/* Override reuse-mode if reverse-connect is used. */
return PR_O_REUSE_ALWS;
}
return be->options & PR_O_REUSE_MASK;
}
/* Calculate hash to select a matching connection for reuse. Here is the list /* Calculate hash to select a matching connection for reuse. Here is the list
* of input parameters : * of input parameters :
* - <srv> is the server instance. Can be NULL on dispatch/transparent proxy. * - <srv> is the server instance. Can be NULL on dispatch/transparent proxy.
@ -1621,68 +1634,27 @@ int64_t be_calculate_conn_hash(struct server *srv, struct stream *strm,
return conn_calculate_hash(&hash_params); return conn_calculate_hash(&hash_params);
} }
/*
* This function initiates a connection to the server assigned to this stream /* Try to reuse a connection for <strm> stream, first from <sess> session, then
* (s->target, (s->scb)->addr.to). It will assign a server if none * to <srv> server lists if not NULL, matching <hash> value. If reuse is
* is assigned yet. * successful, connection is attached to <sc> stconn instance.
* It can return one of : *
* - SF_ERR_NONE if everything's OK * Returns SF_ERR_NONE if a connection has been reused. The connection instance
* - SF_ERR_SRVTO if there are no more servers * can be retrieve via <sc> stconn. SF_ERR_RESOURCE is returned if no matching
* - SF_ERR_SRVCL if the connection was refused by the server * connection found. SF_ERR_INTERNAL is used on internal error.
* - SF_ERR_PRXCOND if the connection has been limited by the proxy (maxconn)
* - SF_ERR_RESOURCE if a system resource is lacking (eg: fd limits, ports, ...)
* - SF_ERR_INTERNAL for any other purely internal errors
* Additionally, in the case of SF_ERR_RESOURCE, an emergency log will be emitted.
* The server-facing stream connector is expected to hold a pre-allocated connection.
*/ */
int connect_server(struct stream *s) int be_reuse_connection(int64_t hash, struct session *sess, struct server *srv,
struct stconn *sc, struct stream *strm)
{ {
struct connection *cli_conn = objt_conn(strm_orig(s)); struct connection *srv_conn;
struct connection *srv_conn = NULL; const int reuse_mode = be_reuse_mode(strm->be, srv);
struct server *srv;
int reuse_mode = s->be->options & PR_O_REUSE_MASK;
int reuse = 0;
int init_mux = 0;
int err;
struct sockaddr_storage *bind_addr = NULL;
int64_t hash = 0;
/* in standard configuration, srv will be valid
* it can be NULL for dispatch mode or transparent backend */
srv = objt_server(s->target);
/* Override reuse-mode if reverse-connect is used. */
if (srv && srv->flags & SRV_F_RHTTP)
reuse_mode = PR_O_REUSE_ALWS;
err = alloc_dst_address(&s->scb->dst, srv, s);
if (err != SRV_STATUS_OK)
return SF_ERR_INTERNAL;
err = alloc_bind_address(&bind_addr, srv, s->be, s);
if (err != SRV_STATUS_OK)
return SF_ERR_INTERNAL;
/* disable reuse if websocket stream and the protocol to use is not the
* same as the main protocol of the server.
*/
if (unlikely(s->flags & SF_WEBSOCKET) && srv) {
if (!srv_check_reuse_ws(srv)) {
DBG_TRACE_STATE("skip idle connections reuse: websocket stream", STRM_EV_STRM_PROC|STRM_EV_CS_ST, s);
goto skip_reuse;
}
}
hash = be_calculate_conn_hash(srv, s, s->sess, bind_addr, s->scb->dst);
/* first, search for a matching connection in the session's idle conns */ /* first, search for a matching connection in the session's idle conns */
srv_conn = session_get_conn(s->sess, s->target, hash); srv_conn = session_get_conn(sess, strm->target, hash);
if (srv_conn) { if (srv_conn) {
DBG_TRACE_STATE("reuse connection from session", STRM_EV_STRM_PROC|STRM_EV_CS_ST, s); DBG_TRACE_STATE("reuse connection from session", STRM_EV_STRM_PROC|STRM_EV_CS_ST, strm);
reuse = 1;
} }
else if (srv && reuse_mode != PR_O_REUSE_NEVR) {
if (srv && !reuse && reuse_mode != PR_O_REUSE_NEVR) {
/* Below we pick connections from the safe, idle or /* Below we pick connections from the safe, idle or
* available (which are safe too) lists based * available (which are safe too) lists based
* on the strategy, the fact that this is a first or second * on the strategy, the fact that this is a first or second
@ -1706,53 +1678,133 @@ int connect_server(struct stream *s)
if (srv_conn) { if (srv_conn) {
/* connection cannot be in idle list if used as an avail idle conn. */ /* connection cannot be in idle list if used as an avail idle conn. */
BUG_ON(LIST_INLIST(&srv_conn->idle_list)); BUG_ON(LIST_INLIST(&srv_conn->idle_list));
DBG_TRACE_STATE("reuse connection from avail", STRM_EV_STRM_PROC|STRM_EV_CS_ST, strm);
DBG_TRACE_STATE("reuse connection from avail", STRM_EV_STRM_PROC|STRM_EV_CS_ST, s);
reuse = 1;
} }
} }
/* if no available connections found, search for an idle/safe */ /* if no available connections found, search for an idle/safe */
if (!srv_conn && srv->max_idle_conns && srv->curr_idle_conns > 0) { if (!srv_conn && srv->max_idle_conns && srv->curr_idle_conns > 0) {
const int not_first_req = s->txn && s->txn->flags & TX_NOT_FIRST; const int not_first_req = strm->txn && strm->txn->flags & TX_NOT_FIRST;
const int idle = srv->curr_idle_nb > 0; const int idle = srv->curr_idle_nb > 0;
const int safe = srv->curr_safe_nb > 0; const int safe = srv->curr_safe_nb > 0;
const int retry_safe = (s->be->retry_type & (PR_RE_CONN_FAILED | PR_RE_DISCONNECTED | PR_RE_TIMEOUT)) == const int retry_safe = (strm->be->retry_type & (PR_RE_CONN_FAILED | PR_RE_DISCONNECTED | PR_RE_TIMEOUT)) ==
(PR_RE_CONN_FAILED | PR_RE_DISCONNECTED | PR_RE_TIMEOUT); (PR_RE_CONN_FAILED | PR_RE_DISCONNECTED | PR_RE_TIMEOUT);
/* second column of the tables above, /* second column of the tables above, search for an idle then safe conn */
* search for an idle then safe conn */
if (not_first_req || retry_safe) { if (not_first_req || retry_safe) {
if (idle || safe) if (idle || safe)
srv_conn = conn_backend_get(reuse_mode, srv, s->sess, 0, hash); srv_conn = conn_backend_get(reuse_mode, srv, sess, 0, hash);
} }
/* first column of the tables above */ /* first column of the tables above */
else if (reuse_mode >= PR_O_REUSE_AGGR) { else if (reuse_mode >= PR_O_REUSE_AGGR) {
/* search for a safe conn */ /* search for a safe conn */
if (safe) if (safe)
srv_conn = conn_backend_get(reuse_mode, srv, s->sess, 1, hash); srv_conn = conn_backend_get(reuse_mode, srv, sess, 1, hash);
/* search for an idle conn if no safe conn found /* search for an idle conn if no safe conn found on always reuse mode */
* on always reuse mode */
if (!srv_conn && if (!srv_conn &&
reuse_mode == PR_O_REUSE_ALWS && idle) { reuse_mode == PR_O_REUSE_ALWS && idle) {
/* TODO conn_backend_get should not check the /* TODO conn_backend_get should not check the safe list is this case */
* safe list is this case */ srv_conn = conn_backend_get(reuse_mode, srv, sess, 0, hash);
srv_conn = conn_backend_get(reuse_mode, srv, s->sess, 0, hash);
} }
} }
if (srv_conn) { if (srv_conn) {
DBG_TRACE_STATE("reuse connection from idle/safe", STRM_EV_STRM_PROC|STRM_EV_CS_ST, s); DBG_TRACE_STATE("reuse connection from idle/safe", STRM_EV_STRM_PROC|STRM_EV_CS_ST, strm);
}
}
}
if (srv_conn) {
if (srv_conn->mux) {
int avail = srv_conn->mux->avail_streams(srv_conn);
if (avail <= 1) {
/* no more streams available, remove it from the list */
HA_SPIN_LOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
conn_delete_from_tree(srv_conn);
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}
if (avail >= 1) {
if (srv_conn->mux->attach(srv_conn, sc->sedesc, sess) == -1) {
if (sc_reset_endp(sc) < 0)
goto err;
sc_ep_clr(sc, ~SE_FL_DETACHED);
}
}
else {
/* TODO cannot reuse conn finally due to no more avail
* streams. May be possible to lookup for a new conn
* to improve reuse rate, with a max retry limit.
*/
srv_conn = NULL;
}
}
}
return srv_conn ? SF_ERR_NONE : SF_ERR_RESOURCE;
err:
return SF_ERR_INTERNAL;
}
/*
* This function initiates a connection to the server assigned to this stream
* (s->target, (s->scb)->addr.to). It will assign a server if none
* is assigned yet.
* It can return one of :
* - SF_ERR_NONE if everything's OK
* - SF_ERR_SRVTO if there are no more servers
* - SF_ERR_SRVCL if the connection was refused by the server
* - SF_ERR_PRXCOND if the connection has been limited by the proxy (maxconn)
* - SF_ERR_RESOURCE if a system resource is lacking (eg: fd limits, ports, ...)
* - SF_ERR_INTERNAL for any other purely internal errors
* Additionally, in the case of SF_ERR_RESOURCE, an emergency log will be emitted.
* The server-facing stream connector is expected to hold a pre-allocated connection.
*/
int connect_server(struct stream *s)
{
struct connection *cli_conn = objt_conn(strm_orig(s));
struct connection *srv_conn = NULL;
struct server *srv;
int reuse_mode;
int reuse = 0;
int init_mux = 0;
int err;
struct sockaddr_storage *bind_addr = NULL;
int64_t hash = 0;
/* in standard configuration, srv will be valid
* it can be NULL for dispatch mode or transparent backend */
srv = objt_server(s->target);
reuse_mode = be_reuse_mode(s->be, srv);
err = alloc_dst_address(&s->scb->dst, srv, s);
if (err != SRV_STATUS_OK)
return SF_ERR_INTERNAL;
err = alloc_bind_address(&bind_addr, srv, s->be, s);
if (err != SRV_STATUS_OK)
return SF_ERR_INTERNAL;
/* disable reuse if websocket stream and the protocol to use is not the
* same as the main protocol of the server.
*/
if (unlikely(s->flags & SF_WEBSOCKET) && srv && !srv_check_reuse_ws(srv)) {
DBG_TRACE_STATE("skip idle connections reuse: websocket stream", STRM_EV_STRM_PROC|STRM_EV_CS_ST, s);
}
else {
hash = be_calculate_conn_hash(srv, s, s->sess, bind_addr, s->scb->dst);
err = be_reuse_connection(hash, s->sess, srv, s->scb, s);
if (err == SF_ERR_INTERNAL)
return err;
if (err == SF_ERR_NONE) {
srv_conn = sc_conn(s->scb);
reuse = 1; reuse = 1;
} }
} }
}
/* here reuse might have been set above, indicating srv_conn finally
* is OK.
*/
if (ha_used_fds > global.tune.pool_high_count && srv) { if (ha_used_fds > global.tune.pool_high_count && srv) {
/* We have more FDs than deemed acceptable, attempt to kill an idling connection. */ /* We have more FDs than deemed acceptable, attempt to kill an idling connection. */
@ -1807,37 +1859,8 @@ int connect_server(struct stream *s)
break; break;
} }
} }
} }
if (reuse) {
if (srv_conn->mux) {
int avail = srv_conn->mux->avail_streams(srv_conn);
if (avail <= 1) {
/* No more streams available, remove it from the list */
HA_SPIN_LOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
conn_delete_from_tree(srv_conn);
HA_SPIN_UNLOCK(IDLE_CONNS_LOCK, &idle_conns[tid].idle_conns_lock);
}
if (avail >= 1) {
if (srv_conn->mux->attach(srv_conn, s->scb->sedesc, s->sess) == -1) {
srv_conn = NULL;
if (sc_reset_endp(s->scb) < 0)
return SF_ERR_INTERNAL;
sc_ep_clr(s->scb, ~SE_FL_DETACHED);
}
}
else
srv_conn = NULL;
}
/* otherwise srv_conn is left intact */
}
else
srv_conn = NULL;
skip_reuse:
/* no reuse or failed to reuse the connection above, pick a new one */ /* no reuse or failed to reuse the connection above, pick a new one */
if (!srv_conn) { if (!srv_conn) {
unsigned int total_conns; unsigned int total_conns;