MINOR: backend: adjust conn_backend_get() API

The main objective of this patch is to remove the stream instance from
conn_backend_get() parameters. This would allow to perform reuse outside
of stream contexts, for example for checks purpose.

diff --git a/src/backend.c b/src/backend.c
index 71a02199454353f9893fd9e0eda8af5a5ab68bb2..e0ac22b319ca0202c7e6830b5e678cb5efa41bb7 100644 (file)
--- a/src/backend.c
+++ b/src/backend.c
@@ -1263,11 +1263,21 @@ int alloc_bind_address(struct sockaddr_storage **ss,
        return SRV_STATUS_OK;
 }
 
-/* Attempt to get a backend connection from the specified mt_list array
- * (safe or idle connections). The <is_safe> argument means what type of
- * connection the caller wants.
+/* Attempt to retrieve a connection matching <hash> from <srv> server lists for
+ * connection reuse. If <is_safe> is true, only connections considered safe for
+ * reuse are inspected. Thread-local list is inspected first. If no matching
+ * connection is found, takeover may be performed to steal a connection from a
+ * foreign thread.
+ *
+ * If <reuse_mode> backend policy is safe and connection MUX is subject to
+ * head-of-line blocking, connection is attached to <sess> session, which
+ * prevents mixing several frontend client over it.
+ *
+ * Returns the connection instance if found.
  */
-struct connection *conn_backend_get(struct stream *s, struct server *srv, int is_safe, int64_t hash)
+struct connection *conn_backend_get(int reuse_mode,
+                                    struct server *srv, struct session *sess,
+                                    int is_safe, int64_t hash)
 {
        const struct tgroup_info *curtg = tg;
        struct connection *conn = NULL;
@@ -1393,17 +1403,16 @@ check_tgid:
                conn->flags &= ~CO_FL_LIST_MASK;
                __ha_barrier_atomic_store();
 
-               if ((s->be->options & PR_O_REUSE_MASK) == PR_O_REUSE_SAFE &&
-                   conn->mux->flags & MX_FL_HOL_RISK) {
-                       /* attach the connection to the session private list
-                        */
-                       conn->owner = s->sess;
-                       session_add_conn(s->sess, conn, conn->target);
+               if (reuse_mode == PR_O_REUSE_SAFE && conn->mux->flags & MX_FL_HOL_RISK) {
+                       /* attach the connection to the session private list */
+                       conn->owner = sess;
+                       session_add_conn(sess, conn, conn->target);
                }
                else {
                        srv_add_to_avail_list(srv, conn);
                }
        }
+
        return conn;
 }
 
@@ -1692,13 +1701,13 @@ int connect_server(struct stream *s)
                         * search for an idle then safe conn */
                        if (not_first_req || retry_safe) {
                                if (idle || safe)
-                                       srv_conn = conn_backend_get(s, srv, 0, hash);
+                                       srv_conn = conn_backend_get(reuse_mode, srv, s->sess, 0, hash);
                        }
                        /* first column of the tables above */
                        else if (reuse_mode >= PR_O_REUSE_AGGR) {
                                /* search for a safe conn */
                                if (safe)
-                                       srv_conn = conn_backend_get(s, srv, 1, hash);
+                                       srv_conn = conn_backend_get(reuse_mode, srv, s->sess, 1, hash);
 
                                /* search for an idle conn if no safe conn found
                                 * on always reuse mode */
@@ -1706,7 +1715,7 @@ int connect_server(struct stream *s)
                                    reuse_mode == PR_O_REUSE_ALWS && idle) {
                                        /* TODO conn_backend_get should not check the
                                         * safe list is this case */
-                                       srv_conn = conn_backend_get(s, srv, 0, hash);
+                                       srv_conn = conn_backend_get(reuse_mode, srv, s->sess, 0, hash);
                                }
                        }