vss: add state variable for fec client
authorGerrit Renker <grenker@cscs.ch>
Sun, 23 May 2010 05:43:04 +0000 (07:43 +0200)
committerAndre Noll <maan@systemlinux.org>
Mon, 7 Jun 2010 21:24:52 +0000 (23:24 +0200)
This merges the two boolean/integer members 'error' and 'ready' into a
single state variable with the same effect:
 * the specific value of 'error' was not evaluated within vss.c,
   where error < 0 used to disable the fec_client;
 * the ready/and error states are mutually exclusive;
 * the assertion that compute_next_fec_slice() is not called when
   the fec_client is disabled has been removed, since this function is only
   called from vss_send(), which ensures that this condition holds;
 * likewise, vss_playing() holds in compute_slice_timeout() since
   this condition is tested earlier in the caller vss_compute_timeout().

vss.c

diff --git a/vss.c b/vss.c
index 4be6e18..14cff69 100644 (file)
--- a/vss.c
+++ b/vss.c
@@ -131,14 +131,18 @@ struct fec_group {
        uint8_t num_header_slices;
 };
 
+enum fec_client_state {
+       FEC_STATE_NONE = 0,     /**< not initialized and not enabled */
+       FEC_STATE_DISABLED,     /**< temporarily disabled */
+       FEC_STATE_READY_TO_RUN  /**< initialized and enabled */
+};
+
 /**
  * Describes one connected FEC client.
  */
 struct fec_client {
-       /** If negative, this client is temporarily disabled. */
-       int error;
-       /** Whether the sender client is ready to push out data. */
-       bool ready;
+       /** Current state of the client */
+       enum fec_client_state state;
        /** The connected sender client (transport layer). */
        struct sender_client *sc;
        /** Parameters requested by the client. */
@@ -375,7 +379,6 @@ static int setup_next_fec_group(struct fec_client *fc, struct vss_task *vsst)
 
 static int compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
 {
-       assert(fc->error >= 0);
        if (fc->first_stream_chunk < 0 || fc->current_slice_num
                        == fc->fcp->slices_per_group + fc->num_extra_slices) {
                int ret = setup_next_fec_group(fc, vsst);
@@ -384,8 +387,8 @@ static int compute_next_fec_slice(struct fec_client *fc, struct vss_task *vsst)
                if (ret < 0) {
                        PARA_ERROR_LOG("%s\n", para_strerror(-ret));
                        PARA_ERROR_LOG("FEC client temporarily disabled\n");
-                       fc->error = ret;
-                       return fc->error;
+                       fc->state = FEC_STATE_DISABLED;
+                       return ret;
                }
        }
        write_fec_header(fc, vsst);
@@ -469,11 +472,10 @@ static void compute_slice_timeout(struct timeval *timeout)
 {
        struct fec_client *fc;
 
-       assert(vss_playing());
        list_for_each_entry(fc, &fec_client_list, node) {
                struct timeval diff;
 
-               if (fc->error < 0)
+               if (fc->state != FEC_STATE_READY_TO_RUN)
                        continue;
                if (next_slice_is_due(fc, &diff)) {
                        timeout->tv_sec = 0;
@@ -496,7 +498,7 @@ static void set_eof_barrier(struct vss_task *vsst)
        list_for_each_entry(fc, &fec_client_list, node) {
                struct timeval group_duration;
 
-               if (fc->error < 0)
+               if (fc->state != FEC_STATE_READY_TO_RUN)
                        continue;
                tv_scale(fc->group.num_chunks, chunk_tv, &group_duration);
                if (tv_diff(&timeout, &group_duration, NULL) < 0)
@@ -700,7 +702,7 @@ static void vss_pre_select(struct sched *s, struct task *t)
                                senders[i].shutdown_clients();
                list_for_each_entry_safe(fc, tmp, &fec_client_list, node) {
                        fc->first_stream_chunk = -1;
-                       fc->error = 0;
+                       fc->state = FEC_STATE_NONE;
                }
                mmd->stream_start.tv_sec = 0;
                mmd->stream_start.tv_usec = 0;
@@ -854,7 +856,7 @@ static int initialize_fec_client(struct fec_client *fc)
        fc->num_extra_slices = 0;
        fc->extra_src_buf = para_calloc(fc->fcp->max_slice_bytes);
        fc->next_header_time.tv_sec = 0;
-       fc->ready = true;
+       fc->state = FEC_STATE_READY_TO_RUN;
        return 1;
 err:
        fec_free(fc->parms);
@@ -884,14 +886,18 @@ static void vss_send(struct vss_task *vsst)
                        &due, 1) < 0)
                return;
        list_for_each_entry_safe(fc, tmp_fc, &fec_client_list, node) {
-               if (fc->error < 0)
+               switch (fc->state) {
+               case FEC_STATE_DISABLED:
                        continue;
-               if (!fc->ready) {
+               case FEC_STATE_NONE:
                        ret = initialize_fec_client(fc);
                        if (ret < 0) {
                                PARA_ERROR_LOG("%s\n", para_strerror(-ret));
                                continue;
                        }
+                       /* fall through */
+               case FEC_STATE_READY_TO_RUN:
+                       break;
                }
                if (!next_slice_is_due(fc, NULL)) {
                        fec_active = 1;