MEDIUM: stconn: merge the app_ops and the data_cb fields

For historical reasons (stream-interface and connections), we used to
require two independent fields for the application level callbacks and
the transport-level functions. Over time the distinction faded away so
much that the low-level functions became specific to the application
and conversely. For example, applets may only work with streams on top
since they rely on the channels, and the stream-level functions differ
between applets and connections. Right now the application level only
contains a wake() callback and the low-level ones contain the functions
that act at the lower level to perform the shutr/shutw and at the upper
level to notify about readability and writability. Let's just merge them
together into a single set and get rid of this confusing distinction.
Note that the check ops do not define any app-level function since these
are only called by streams.

include/haproxy/conn_stream-t.h

@@ -136,19 +136,6 @@ enum cs_state_bit {
 
 struct stconn;
 
-/* cs_data_cb describes the data layer's recv and send callbacks which are called
- * when I/O activity was detected after the transport layer is ready. These
- * callbacks are supposed to make use of the xprt_ops above to exchange data
- * from/to buffers and pipes. The <wake> callback is used to report activity
- * at the transport layer, which can be a connection opening/close, or any
- * data movement. It may abort a connection by returning < 0.
- */
-struct data_cb {
-	int  (*wake)(struct stconn *sc);        /* data-layer callback to report activity */
-	char name[8];                           /* data layer name, zero-terminated */
-};
-
-
 /* A Stream Endpoint Descriptor (sedesc) is the link between the stream
  * connector (ex. conn_stream) and the Stream Endpoint (mux or appctx).
  * It always exists for either of them, and binds them together. It also
@@ -173,12 +160,17 @@ struct sedesc {
 	unsigned int flags;
 };
 
-/* operations available on a stream connector */
+/* sc_app_ops describes the application layer's operations and notification
+ * callbacks when I/O activity is reported and to use to perform shutr/shutw.
+ * There are very few combinations in practice (strm/chk <-> none/mux/applet).
+ */
 struct sc_app_ops {
 	void (*chk_rcv)(struct stconn *);    /* chk_rcv function, may not be null */
 	void (*chk_snd)(struct stconn *);    /* chk_snd function, may not be null */
 	void (*shutr)(struct stconn *);      /* shut read function, may not be null */
 	void (*shutw)(struct stconn *);      /* shut write function, may not be null */
+	int  (*wake)(struct stconn *);       /* data-layer callback to report activity */
+	char name[8];                        /* data layer name, zero-terminated */
 };
 
 /*
@@ -194,8 +186,7 @@ struct stconn {
 	struct wait_event wait_event;        /* We're in a wait list */
 	struct sedesc *sedesc;               /* points to the stream endpoint descriptor */
 	enum obj_type *app;                  /* points to the applicative point (stream or check) */
-	const struct data_cb *data_cb;       /* data layer callbacks. Must be set before xprt->init() */
+	const struct sc_app_ops *app_ops;    /* general operations used at the app layer */
-	struct sc_app_ops *ops;              /* general operations used at the app layer */
 	struct sockaddr_storage *src;        /* source address (pool), when known, otherwise NULL */
 	struct sockaddr_storage *dst;        /* destination address (pool), when known, otherwise NULL */
 };

include/haproxy/conn_stream.h

@@ -217,9 +217,9 @@ static inline struct check *cs_check(const struct stconn *cs)
 }
 static inline const char *cs_get_data_name(const struct stconn *cs)
 {
-	if (!cs->data_cb)
+	if (!cs->app_ops)
 		return "NONE";
-	return cs->data_cb->name;
+	return cs->app_ops->name;
 }
 
 /* shut read */

include/haproxy/cs_utils.h

@@ -275,15 +275,15 @@ static inline void cs_must_kill_conn(struct stconn *cs)
 /* Sends a shutr to the endpoint using the data layer */
 static inline void cs_shutr(struct stconn *cs)
 {
-	if (likely(cs->ops->shutr))
+	if (likely(cs->app_ops->shutr))
-		cs->ops->shutr(cs);
+		cs->app_ops->shutr(cs);
 }
 
 /* Sends a shutw to the endpoint using the data layer */
 static inline void cs_shutw(struct stconn *cs)
 {
-	if (likely(cs->ops->shutw))
+	if (likely(cs->app_ops->shutw))
-		cs->ops->shutw(cs);
+		cs->app_ops->shutw(cs);
 }
 
 /* This is to be used after making some room available in a channel. It will
@@ -304,15 +304,15 @@ static inline void cs_chk_rcv(struct stconn *cs)
 		return;
 
 	sc_ep_set(cs, SE_FL_RX_WAIT_EP);
-	if (likely(cs->ops->chk_rcv))
+	if (likely(cs->app_ops->chk_rcv))
-		cs->ops->chk_rcv(cs);
+		cs->app_ops->chk_rcv(cs);
 }
 
 /* Calls chk_snd on the endpoint using the data layer */
 static inline void cs_chk_snd(struct stconn *cs)
 {
-	if (likely(cs->ops->chk_snd))
+	if (likely(cs->app_ops->chk_snd))
-		cs->ops->chk_snd(cs);
+		cs->app_ops->chk_snd(cs);
 }
 
 /* Combines both cs_update_rx() and cs_update_tx() at once */

src/applet.c

@@ -252,7 +252,7 @@ struct task *task_run_applet(struct task *t, void *context, unsigned int state)
 		stream_dump_and_crash(&app->obj_type, read_freq_ctr(&app->call_rate));
 	}
 
-	cs->data_cb->wake(cs);
+	cs->app_ops->wake(cs);
 	channel_release_buffer(cs_ic(cs), &app->buffer_wait);
 	return t;
 }

src/check.c

@@ -140,12 +140,6 @@ struct trace_source trace_check = {
 INITCALL1(STG_REGISTER, trace_register_source, TRACE_SOURCE);
 
 
-struct data_cb check_conn_cb = {
-	.wake = wake_srv_chk,
-	.name = "CHCK",
-};
-
-
 /* Dummy frontend used to create all checks sessions. */
 struct proxy checks_fe;
 

src/conn_stream.c

@@ -41,12 +41,19 @@ static void sc_app_shutw_applet(struct stconn *cs);
 static void sc_app_chk_rcv_applet(struct stconn *cs);
 static void sc_app_chk_snd_applet(struct stconn *cs);
 
+static int cs_conn_process(struct stconn *cs);
+static int cs_conn_recv(struct stconn *cs);
+static int cs_conn_send(struct stconn *cs);
+static int cs_applet_process(struct stconn *cs);
+
 /* stream connector operations for connections */
 struct sc_app_ops sc_app_conn_ops = {
 	.chk_rcv = sc_app_chk_rcv_conn,
 	.chk_snd = sc_app_chk_snd_conn,
 	.shutr   = sc_app_shutr_conn,
 	.shutw   = sc_app_shutw_conn,
+	.wake    = cs_conn_process,
+	.name    = "STRM",
 };
 
 /* stream connector operations for embedded tasks */
@@ -55,31 +62,29 @@ struct sc_app_ops sc_app_embedded_ops = {
 	.chk_snd = sc_app_chk_snd,
 	.shutr   = sc_app_shutr,
 	.shutw   = sc_app_shutw,
+	.wake    = NULL,   /* may never be used */
+	.name    = "NONE", /* may never be used */
 };
 
-/* stream connector operations for connections */
+/* stream connector operations for applets */
 struct sc_app_ops sc_app_applet_ops = {
 	.chk_rcv = sc_app_chk_rcv_applet,
 	.chk_snd = sc_app_chk_snd_applet,
 	.shutr   = sc_app_shutr_applet,
 	.shutw   = sc_app_shutw_applet,
-};
-
-static int cs_conn_process(struct stconn *cs);
-static int cs_conn_recv(struct stconn *cs);
-static int cs_conn_send(struct stconn *cs);
-static int cs_applet_process(struct stconn *cs);
-
-struct data_cb cs_data_conn_cb = {
-	.wake    = cs_conn_process,
-	.name    = "STRM",
-};
-
-struct data_cb cs_data_applet_cb = {
 	.wake    = cs_applet_process,
 	.name    = "STRM",
 };
 
+/* stream connector for health checks on connections */
+struct sc_app_ops sc_app_check_ops = {
+	.chk_rcv = NULL,
+	.chk_snd = NULL,
+	.shutr   = NULL,
+	.shutw   = NULL,
+	.wake    = wake_srv_chk,
+	.name    = "CHCK",
+};
 
 /* Initializes an endpoint */
 void sedesc_init(struct sedesc *sedesc)
@@ -130,7 +135,7 @@ static struct stconn *cs_new(struct sedesc *sedesc)
 	cs->state = SC_ST_INI;
 	cs->hcto = TICK_ETERNITY;
 	cs->app = NULL;
-	cs->data_cb = NULL;
+	cs->app_ops = NULL;
 	cs->src = NULL;
 	cs->dst = NULL;
 	cs->wait_event.tasklet = NULL;
@@ -185,8 +190,7 @@ struct stconn *cs_new_from_strm(struct stream *strm, unsigned int flags)
 	cs->flags |= flags;
 	sc_ep_set(cs, SE_FL_DETACHED);
 	cs->app = &strm->obj_type;
-	cs->ops = &sc_app_embedded_ops;
+	cs->app_ops = &sc_app_embedded_ops;
-	cs->data_cb = NULL;
 	return cs;
 }
 
@@ -204,7 +208,7 @@ struct stconn *cs_new_from_check(struct check *check, unsigned int flags)
 	cs->flags |= flags;
 	sc_ep_set(cs, SE_FL_DETACHED);
 	cs->app = &check->obj_type;
-	cs->data_cb = &check_conn_cb;
+	cs->app_ops = &sc_app_check_ops;
 	return cs;
 }
 
@@ -264,8 +268,7 @@ int cs_attach_mux(struct stconn *cs, void *endp, void *ctx)
 			cs->wait_event.events = 0;
 		}
 
-		cs->ops = &sc_app_conn_ops;
+		cs->app_ops = &sc_app_conn_ops;
-		cs->data_cb = &cs_data_conn_cb;
 	}
 	else if (cs_check(cs)) {
 		if (!cs->wait_event.tasklet) {
@@ -277,7 +280,7 @@ int cs_attach_mux(struct stconn *cs, void *endp, void *ctx)
 			cs->wait_event.events = 0;
 		}
 
-		cs->data_cb = &check_conn_cb;
+		cs->app_ops = &sc_app_check_ops;
 	}
 	return 0;
 }
@@ -292,10 +295,8 @@ static void cs_attach_applet(struct stconn *cs, void *endp)
 	cs->sedesc->se = endp;
 	sc_ep_set(cs, SE_FL_T_APPLET);
 	sc_ep_clr(cs, SE_FL_DETACHED);
-	if (cs_strm(cs)) {
+	if (cs_strm(cs))
-		cs->ops = &sc_app_applet_ops;
+		cs->app_ops = &sc_app_applet_ops;
-		cs->data_cb = &cs_data_applet_cb;
-	}
 }
 
 /* Attaches a stconn to a app layer and sets the relevant
@@ -315,16 +316,13 @@ int cs_attach_strm(struct stconn *cs, struct stream *strm)
 		cs->wait_event.tasklet->context = cs;
 		cs->wait_event.events = 0;
 
-		cs->ops = &sc_app_conn_ops;
+		cs->app_ops = &sc_app_conn_ops;
-		cs->data_cb = &cs_data_conn_cb;
 	}
 	else if (sc_ep_test(cs, SE_FL_T_APPLET)) {
-		cs->ops = &sc_app_applet_ops;
+		cs->app_ops = &sc_app_applet_ops;
-		cs->data_cb = &cs_data_applet_cb;
 	}
 	else {
-		cs->ops = &sc_app_embedded_ops;
+		cs->app_ops = &sc_app_embedded_ops;
-		cs->data_cb = NULL;
 	}
 	return 0;
 }
@@ -393,8 +391,9 @@ static void cs_detach_endp(struct stconn **csp)
 	 */
 	cs->flags &= SC_FL_ISBACK;
 	if (cs_strm(cs))
-		cs->ops = &sc_app_embedded_ops;
+		cs->app_ops = &sc_app_embedded_ops;
-	cs->data_cb = NULL;
+	else
+		cs->app_ops = NULL;
 	cs_free_cond(csp);
 }
 
@@ -409,7 +408,7 @@ static void cs_detach_app(struct stconn **csp)
 		return;
 
 	cs->app = NULL;
-	cs->data_cb = NULL;
+	cs->app_ops = NULL;
 	sockaddr_free(&cs->src);
 	sockaddr_free(&cs->dst);
 

src/connection.c

@@ -91,7 +91,7 @@ int conn_create_mux(struct connection *conn)
 		return 0;
 fail:
 		/* let the upper layer know the connection failed */
-		cs->data_cb->wake(cs);
+		cs->app_ops->wake(cs);
 		return -1;
 	} else
 		return conn_complete_session(conn);

src/mux_fcgi.c

@@ -977,9 +977,9 @@ static void fcgi_strm_alert(struct fcgi_strm *fstrm)
 		fcgi_strm_notify_recv(fstrm);
 		fcgi_strm_notify_send(fstrm);
 	}
-	else if (fcgi_strm_sc(fstrm) && fcgi_strm_sc(fstrm)->data_cb->wake != NULL) {
+	else if (fcgi_strm_sc(fstrm) && fcgi_strm_sc(fstrm)->app_ops->wake != NULL) {
 		TRACE_POINT(FCGI_EV_STRM_WAKE, fstrm->fconn->conn, fstrm);
-		fcgi_strm_sc(fstrm)->data_cb->wake(fcgi_strm_sc(fstrm));
+		fcgi_strm_sc(fstrm)->app_ops->wake(fcgi_strm_sc(fstrm));
 	}
 }
 

src/mux_h1.c

@@ -2625,9 +2625,9 @@ static void h1_alert(struct h1s *h1s)
 		h1_wake_stream_for_recv(h1s);
 		h1_wake_stream_for_send(h1s);
 	}
-	else if (h1s_sc(h1s) && h1s_sc(h1s)->data_cb->wake != NULL) {
+	else if (h1s_sc(h1s) && h1s_sc(h1s)->app_ops->wake != NULL) {
 		TRACE_POINT(H1_EV_STRM_WAKE, h1s->h1c->conn, h1s);
-		h1s_sc(h1s)->data_cb->wake(h1s_sc(h1s));
+		h1s_sc(h1s)->app_ops->wake(h1s_sc(h1s));
 	}
 }
 

src/mux_h2.c

@@ -1334,9 +1334,9 @@ static void __maybe_unused h2s_alert(struct h2s *h2s)
 		h2s_notify_recv(h2s);
 		h2s_notify_send(h2s);
 	}
-	else if (h2s_sc(h2s) && h2s_sc(h2s)->data_cb->wake != NULL) {
+	else if (h2s_sc(h2s) && h2s_sc(h2s)->app_ops->wake != NULL) {
 		TRACE_POINT(H2_EV_STRM_WAKE, h2s->h2c->conn, h2s);
-		h2s_sc(h2s)->data_cb->wake(h2s_sc(h2s));
+		h2s_sc(h2s)->app_ops->wake(h2s_sc(h2s));
 	}
 
 	TRACE_LEAVE(H2_EV_H2S_WAKE, h2s->h2c->conn, h2s);

src/mux_pt.c

@@ -252,8 +252,8 @@ struct task *mux_pt_io_cb(struct task *t, void *tctx, unsigned int status)
 			ctx->conn->subs->events = 0;
 			tasklet_wakeup(ctx->conn->subs->tasklet);
 			ctx->conn->subs = NULL;
-		} else if (pt_sc(ctx)->data_cb->wake)
+		} else if (pt_sc(ctx)->app_ops->wake)
-			pt_sc(ctx)->data_cb->wake(pt_sc(ctx));
+			pt_sc(ctx)->app_ops->wake(pt_sc(ctx));
 		TRACE_DEVEL("leaving waking up CS", PT_EV_CONN_WAKE, ctx->conn);
 		return t;
 	}
@@ -349,7 +349,7 @@ static int mux_pt_wake(struct connection *conn)
 
 	TRACE_ENTER(PT_EV_CONN_WAKE, ctx->conn);
 	if (!se_fl_test(ctx->endp, SE_FL_ORPHAN)) {
-		ret = pt_sc(ctx)->data_cb->wake ? pt_sc(ctx)->data_cb->wake(pt_sc(ctx)) : 0;
+		ret = pt_sc(ctx)->app_ops->wake ? pt_sc(ctx)->app_ops->wake(pt_sc(ctx)) : 0;
 
 		if (ret < 0) {
 			TRACE_DEVEL("leaving waking up CS", PT_EV_CONN_WAKE, ctx->conn);

src/mux_quic.c

@@ -1594,8 +1594,8 @@ static int qc_wake_some_streams(struct qcc *qcc)
 				qcs_notify_recv(qcs);
 				qcs_notify_send(qcs);
 			}
-			else if (qcs->endp->sc->data_cb->wake) {
+			else if (qcs->endp->sc->app_ops->wake) {
-				qcs->endp->sc->data_cb->wake(qcs->endp->sc);
+				qcs->endp->sc->app_ops->wake(qcs->endp->sc);
 			}
 		}
 	}