MEDIUM: mux-fcgi: do not try to stop sending streams on blocked mux

This is essentially the same change as applied to mux-h2 in previous commit
"MEDIUM: mux-h2: do not try to stop sending streams on blocked mux". The
goal is to make sure we don't need to keep the item in the send_wait list
until it's executed so that we can later merge it with the recv_wait list.
No performance changes were observed.

diff --git a/src/mux_fcgi.c b/src/mux_fcgi.c
index 2290a48d5cceba0e2597dcabcf35116ff4fd1e5a..1b0495d9072a42e88756ec482d640faa21c99da9 100644 (file)
--- a/src/mux_fcgi.c
+++ b/src/mux_fcgi.c
@@ -107,7 +107,6 @@ struct fcgi_conn {
        struct eb_root streams_by_id;        /* all active streams by their ID */
 
        struct list send_list;               /* list of blocked streams requesting to send */
-       struct list sending_list;            /* list of fcgi_strm scheduled to send data */
 
        struct buffer_wait buf_wait;         /* Wait list for buffer allocation */
        struct wait_event wait_event;        /* To be used if we're waiting for I/Os */
@@ -139,6 +138,7 @@ enum fcgi_strm_st {
 
 #define FCGI_SF_BEGIN_SENT     0x00000100  /* a BEGIN_REQUEST record was sent for this stream */
 #define FCGI_SF_OUTGOING_DATA  0x00000200  /* set whenever we've seen outgoing data */
+#define FCGI_SF_NOTIFIED       0x00000400  /* a paused stream was notified to try to send again */
 
 #define FCGI_SF_WANT_SHUTR     0x00001000  /* a stream couldn't shutr() (mux full/busy) */
 #define FCGI_SF_WANT_SHUTW     0x00002000  /* a stream couldn't shutw() (mux full/busy) */
@@ -168,7 +168,6 @@ struct fcgi_strm {
        struct wait_event *recv_wait; /* Address of the wait_event the conn_stream associated is waiting on */
        struct wait_event *send_wait; /* Address of the wait_event the conn_stream associated is waiting on */
        struct list send_list;        /* To be used when adding in fcgi_conn->send_list */
-       struct list sending_list;     /* To be used when adding in fcgi_conn->sending_list */
 };
 
 /* Flags representing all default FCGI parameters */
@@ -762,7 +761,6 @@ static int fcgi_init(struct connection *conn, struct proxy *px, struct session *
        br_init(fconn->mbuf, sizeof(fconn->mbuf) / sizeof(fconn->mbuf[0]));
        fconn->streams_by_id = EB_ROOT;
        LIST_INIT(&fconn->send_list);
-       LIST_INIT(&fconn->sending_list);
        LIST_INIT(&fconn->buf_wait.list);
 
        conn->ctx = fconn;
@@ -929,12 +927,13 @@ static void fcgi_strm_notify_send(struct fcgi_strm *fstrm)
 {
        struct wait_event *sw;
 
-       if (fstrm->send_wait && !LIST_ADDED(&fstrm->sending_list)) {
+       if (fstrm->send_wait) {
                TRACE_POINT(FCGI_EV_STRM_WAKE, fstrm->fconn->conn, fstrm);
                sw = fstrm->send_wait;
                sw->events &= ~SUB_RETRY_SEND;
-               LIST_ADDQ(&fstrm->fconn->sending_list, &fstrm->sending_list);
+               fstrm->flags |= FCGI_SF_NOTIFIED;
                tasklet_wakeup(sw->tasklet);
+               fstrm->send_wait = NULL;
        }
 }
 
@@ -1023,10 +1022,6 @@ static void fcgi_strm_destroy(struct fcgi_strm *fstrm)
         * we're in it, we're getting out anyway
         */
        LIST_DEL_INIT(&fstrm->send_list);
-       if (LIST_ADDED(&fstrm->sending_list)) {
-               tasklet_remove_from_tasklet_list(fstrm->send_wait->tasklet);
-               LIST_DEL_INIT(&fstrm->sending_list);
-       }
        tasklet_free(fstrm->wait_event.tasklet);
        pool_free(pool_head_fcgi_strm, fstrm);
 
@@ -1060,7 +1055,6 @@ static struct fcgi_strm *fcgi_strm_new(struct fcgi_conn *fconn, int id)
        fstrm->wait_event.tasklet->context = fstrm;
        fstrm->wait_event.events = 0;
        LIST_INIT(&fstrm->send_list);
-       LIST_INIT(&fstrm->sending_list);
        fstrm->fconn = fconn;
        fstrm->cs = NULL;
        fstrm->flags = FCGI_SF_NONE;
@@ -2649,7 +2643,7 @@ static int fcgi_process_mux(struct fcgi_conn *fconn)
                if (fconn->state == FCGI_CS_CLOSED || fconn->flags & FCGI_CF_MUX_BLOCK_ANY)
                        break;
 
-               if (LIST_ADDED(&fstrm->sending_list))
+               if (fstrm->flags & FCGI_SF_NOTIFIED)
                        continue;
 
                /* For some reason, the upper layer failed to subsribe again,
@@ -2662,7 +2656,7 @@ static int fcgi_process_mux(struct fcgi_conn *fconn)
                TRACE_POINT(FCGI_EV_STRM_WAKE, fconn->conn, fstrm);
                fstrm->flags &= ~FCGI_SF_BLK_ANY;
                fstrm->send_wait->events &= ~SUB_RETRY_SEND;
-               LIST_ADDQ(&fconn->sending_list, &fstrm->sending_list);
+               fstrm->flags |= FCGI_SF_NOTIFIED;
                tasklet_wakeup(fstrm->send_wait->tasklet);
        }
 
@@ -2857,7 +2851,7 @@ static int fcgi_send(struct fcgi_conn *fconn)
                        if (fconn->state == FCGI_CS_CLOSED || fconn->flags & FCGI_CF_MUX_BLOCK_ANY)
                                break;
 
-                       if (LIST_ADDED(&fstrm->sending_list))
+                       if (fstrm->flags & FCGI_SF_NOTIFIED)
                                continue;
 
                        /* For some reason, the upper layer failed to subsribe again,
@@ -2871,7 +2865,7 @@ static int fcgi_send(struct fcgi_conn *fconn)
                        fstrm->send_wait->events &= ~SUB_RETRY_SEND;
                        TRACE_DEVEL("waking up pending stream", FCGI_EV_FCONN_SEND|FCGI_EV_STRM_WAKE, conn, fstrm);
                        tasklet_wakeup(fstrm->send_wait->tasklet);
-                       LIST_ADDQ(&fconn->sending_list, &fstrm->sending_list);
+                       fstrm->flags |= FCGI_SF_NOTIFIED;
                }
        }
        /* We're done, no more to send */
@@ -3412,25 +3406,8 @@ static void fcgi_detach(struct conn_stream *cs)
                return;
        }
 
-       /* The stream is about to die, so no need to attempt to run its task */
-       if (LIST_ADDED(&fstrm->sending_list)  &&
-           fstrm->send_wait != &fstrm->wait_event) {
-               tasklet_remove_from_tasklet_list(fstrm->send_wait->tasklet);
-               LIST_DEL_INIT(&fstrm->sending_list);
-               /*
-                * At this point, the stream_interface is supposed to have called
-                * fcgi_unsubscribe(), so the only way there's still a
-                * subscription that came from the stream_interface (as we
-                * can subscribe ourself, in fcgi_do_shutw() and fcgi_do_shutr(),
-                * without the stream_interface involved) is that we subscribed
-                * for sending, we woke the tasklet up and removed the
-                * SUB_RETRY_SEND flag, so the stream_interface would not
-                * know it has to unsubscribe for send, but the tasklet hasn't
-                * run yet. Make sure to handle that by explicitely setting
-                * send_wait to NULL, as nothing else will do it for us.
-                */
-               fstrm->send_wait = NULL;
-       }
+       /* there's no txbuf so we're certain no to be able to send anything */
+       fstrm->flags &= ~FCGI_SF_NOTIFIED;
 
        sess = fstrm->sess;
        fconn = fstrm->fconn;
@@ -3646,7 +3623,7 @@ static struct task *fcgi_deferred_shut(struct task *t, void *ctx, unsigned short
 
        TRACE_ENTER(FCGI_EV_STRM_SHUT, fconn->conn, fstrm);
 
-       LIST_DEL_INIT(&fstrm->sending_list);
+       fstrm->flags &= ~FCGI_SF_NOTIFIED;
        if (fstrm->flags & FCGI_SF_WANT_SHUTW)
                fcgi_do_shutw(fstrm);
 
@@ -3756,11 +3733,7 @@ static int fcgi_unsubscribe(struct conn_stream *cs, int event_type, void *param)
                LIST_DEL(&fstrm->send_list);
                LIST_INIT(&fstrm->send_list);
                sw->events &= ~SUB_RETRY_SEND;
-               /* We were about to send, make sure it does not happen */
-               if (LIST_ADDED(&fstrm->sending_list) && fstrm->send_wait != &fstrm->wait_event) {
-                       tasklet_remove_from_tasklet_list(fstrm->send_wait->tasklet);
-                       LIST_DEL_INIT(&fstrm->sending_list);
-               }
+               fstrm->flags &= ~FCGI_SF_NOTIFIED;
                fstrm->send_wait = NULL;
        }
        return 0;
@@ -3807,21 +3780,6 @@ static size_t fcgi_rcv_buf(struct conn_stream *cs, struct buffer *buf, size_t co
 }
 
 
-/* stops all senders of this connection for example when the mux buffer is full.
- * They are moved from the sending_list to send_list.
- */
-static void fcgi_stop_senders(struct fcgi_conn *fconn)
-{
-       struct fcgi_strm *fstrm, *fstrm_back;
-
-       list_for_each_entry_safe(fstrm, fstrm_back, &fconn->sending_list, sending_list) {
-               LIST_DEL_INIT(&fstrm->sending_list);
-               tasklet_remove_from_tasklet_list(fstrm->send_wait->tasklet);
-               fstrm->send_wait->events |= SUB_RETRY_SEND;
-       }
-}
-
-
 /* Called from the upper layer, to send data from buffer <buf> for no more than
  * <count> bytes. Returns the number of bytes effectively sent. Some status
  * flags may be updated on the conn_stream.
@@ -3843,16 +3801,11 @@ static size_t fcgi_snd_buf(struct conn_stream *cs, struct buffer *buf, size_t co
         * and there's somebody else that is waiting to send, do nothing,
         * we will subscribe later and be put at the end of the list
         */
-       if (!LIST_ADDED(&fstrm->sending_list) && !LIST_ISEMPTY(&fconn->send_list)) {
+       if (!(fstrm->flags & FCGI_SF_NOTIFIED) && !LIST_ISEMPTY(&fconn->send_list)) {
                TRACE_STATE("other streams already waiting, going to the queue and leaving", FCGI_EV_STRM_SEND|FCGI_EV_FSTRM_BLK, fconn->conn, fstrm);
                return 0;
        }
-       LIST_DEL_INIT(&fstrm->sending_list);
-
-       /* We couldn't set it to NULL before, because we needed it in case
-        * we had to cancel the tasklet
-        */
-       fstrm->send_wait = NULL;
+       fstrm->flags &= ~FCGI_SF_NOTIFIED;
 
        if (fconn->state < FCGI_CS_RECORD_H) {
                TRACE_STATE("connection not ready, leaving", FCGI_EV_STRM_SEND|FCGI_EV_FSTRM_BLK, fconn->conn, fstrm);
@@ -3969,12 +3922,6 @@ static size_t fcgi_snd_buf(struct conn_stream *cs, struct buffer *buf, size_t co
        if (htx)
                htx_to_buf(htx, buf);
 
-       /* The mux is full, cancel the pending tasks */
-       if ((fconn->flags & FCGI_CF_MUX_BLOCK_ANY) || (fstrm->flags & FCGI_SF_BLK_MBUSY)) {
-               TRACE_DEVEL("mux full, stopping senders", FCGI_EV_STRM_SEND|FCGI_EV_FCONN_BLK|FCGI_EV_FSTRM_BLK, fconn->conn, fstrm);
-               fcgi_stop_senders(fconn);
-       }
-
        if (total > 0) {
                if (!(fconn->wait_event.events & SUB_RETRY_SEND)) {
                        TRACE_DEVEL("data queued, waking up fconn sender", FCGI_EV_STRM_SEND|FCGI_EV_FCONN_SEND|FCGI_EV_FCONN_WAKE, fconn->conn, fstrm);