lib: Add compiler configuration for FRCP

This allows configuring some parameters for FRCP at compile time, such
as default values for Delta-t and configuration of the timerwheel. The
timerwheel will now reschedule when it fails to create a packet,
instead of setting the flow down immediately. Some new things added
are options to store packets for retransmission on the heap, and using
non-blocking calls for retransmission. The defaults do not change the
current behaviour.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 82 insertions, 71 deletions

diff --git a/src/lib/timerwheel.c b/src/lib/timerwheel.c
index 33fcbc1c..4443832d 100644
--- a/src/lib/timerwheel.c
+++ b/src/lib/timerwheel.c
@@ -22,14 +22,6 @@
 
 #include <ouroboros/list.h>
 
-#define RXMQ_SLOTS (1 << 8)           /* #slots / level.           */
-#define RXMQ_LVLS  3                  /* #levels, bump for DTN.    */
-#define RXMQ_BUMP  4                  /* factor to bump lvl.       */
-#define RXMQ_RES   20                 /* res (ns) of lowest lvl.   */
-
-#define ACKQ_SLOTS (1 << 7)           /* #slots for delayed ACK.   */
-#define ACKQ_RES   20                 /* resolution for dACK.      */
-
 /* Overflow limits range to about 6 hours. */
 #define ts_to_ns(ts) (ts.tv_sec * BILLION + ts.tv_nsec)
 #define ts_to_rxm_slot(ts) (ts_to_ns(ts) >> RXMQ_RES)
@@ -38,9 +30,14 @@
 struct rxm {
         struct list_head     next;
         uint32_t             seqno;
+#ifdef RXM_BUFFER_ON_HEAP
+        uint8_t *            pkt;
+        size_t               pkt_len;
+#else
         struct shm_du_buff * sdb;
         uint8_t *            head;
         uint8_t *            tail;
+#endif
         time_t               t0;      /* Time when original was sent (us). */
         size_t               mul;     /* RTO multiplier.                   */
         struct frcti *       frcti;
@@ -85,8 +82,12 @@ static void timerwheel_fini(void)
                                 struct rxm * rxm;
                                 rxm = list_entry(p, struct rxm, next);
                                 list_del(&rxm->next);
+#ifdef RXM_BUFFER_ON_HEAP
+                                free(rxm->pkt);
+#else
                                 shm_du_buff_ack(rxm->sdb);
                                 ipcp_sdb_release(rxm->sdb);
+#endif
                                 free(rxm);
                         }
                 }
@@ -156,8 +157,7 @@ static void timerwheel_move(void)
                         j_max_slot += RXMQ_SLOTS;
 
                 while (j++ < j_max_slot) {
-                        list_for_each_safe(p,
-                                           h,
+                        list_for_each_safe(p, h,
                                            &rw.rxms[i][j & (RXMQ_SLOTS - 1)]) {
                                 struct rxm *         r;
                                 struct frct_cr *     snd_cr;
@@ -178,15 +178,12 @@ static void timerwheel_move(void)
                                 snd_cr = &r->frcti->snd_cr;
                                 rcv_cr = &r->frcti->rcv_cr;
                                 f      = &ai.flows[r->fd];
-
+#ifndef RXM_BUFFER_ON_HEAP
                                 shm_du_buff_ack(r->sdb);
-
+#endif
                                 if (f->frcti == NULL
-                                    || f->flow_id != r->flow_id) {
-                                        ipcp_sdb_release(r->sdb);
-                                        free(r);
-                                        continue;
-                                }
+                                    || f->flow_id != r->flow_id)
+                                        goto cleanup;
 
                                 pthread_rwlock_wrlock(&r->frcti->lock);
 
@@ -197,69 +194,57 @@ static void timerwheel_move(void)
                                 pthread_rwlock_unlock(&r->frcti->lock);
 
                                 /* Has been ack'd, remove. */
-                                if ((int) (r->seqno - snd_lwe) < 0) {
-                                        ipcp_sdb_release(r->sdb);
-                                        free(r);
-                                        continue;
-                                }
+                                if ((int) (r->seqno - snd_lwe) < 0)
+                                        goto cleanup;
 
                                 /* Check for r-timer expiry. */
-                                if (ts_to_ns(now) - r->t0 > r->frcti->r) {
-                                        ipcp_sdb_release(r->sdb);
-                                        free(r);
-                                        shm_rbuff_set_acl(f->rx_rb,
-                                                          ACL_FLOWDOWN);
-                                        shm_rbuff_set_acl(f->tx_rb,
-                                                          ACL_FLOWDOWN);
-                                        continue;
-                                }
+                                if (ts_to_ns(now) - r->t0 > r->frcti->r)
+                                        goto flow_down;
 
                                 if (r->frcti->probe
                                     && (r->frcti->rttseq + 1) == r->seqno)
                                         r->frcti->probe = false;
-
-                                /* Copy the data, safe rtx in other layers. */
-                                if (ipcp_sdb_reserve(&sdb, r->tail - r->head)) {
-                                        ipcp_sdb_release(r->sdb);
-                                        free(r);
-                                        shm_rbuff_set_acl(f->rx_rb,
-                                                          ACL_FLOWDOWN);
-                                        shm_rbuff_set_acl(f->tx_rb,
-                                                          ACL_FLOWDOWN);
-                                        continue;
-                                }
-
+#ifdef RXM_BLOCKING
+  #ifdef RXM_BUFFER_ON_HEAP
+                                if (ipcp_sdb_reserve(&sdb, r->pkt_len))
+  #else
+                                if (ipcp_sdb_reserve(&sdb, r->tail - r->head))
+  #endif
+#else
+  #ifdef RXM_BUFFER_ON_HEAP
+                                if (shm_rdrbuff_alloc(ai.rdrb, r->pkt_len, NULL,
+                                                      &sdb))
+  #else
+                                if (shm_rdrbuff_alloc(ai.rdrb,
+                                                      r->tail - r->head, NULL,
+                                                      &sdb))
+  #endif
+#endif
+                                        goto reschedule; /* rbuff full */
                                 idx = shm_du_buff_get_idx(sdb);
 
                                 head = shm_du_buff_head(sdb);
+#ifdef RXM_BUFFER_ON_HEAP
+                                memcpy(head, r->pkt, r->pkt_len);
+#else
                                 memcpy(head, r->head, r->tail - r->head);
-
                                 ipcp_sdb_release(r->sdb);
-
-                                ((struct frct_pci *) head)->ackno =
-                                        hton32(rcv_lwe);
-
-                                /* Retransmit the copy. */
-                                if (shm_rbuff_write_b(f->tx_rb, idx, NULL)) {
-                                        ipcp_sdb_release(sdb);
-                                        free(r);
-                                        shm_rbuff_set_acl(f->rx_rb,
-                                                          ACL_FLOWDOWN);
-                                        shm_rbuff_set_acl(f->tx_rb,
-                                                          ACL_FLOWDOWN);
-                                        continue;
-                                }
-
-                                /* Reschedule. */
-                                shm_du_buff_wait_ack(sdb);
-
-                                shm_flow_set_notify(f->set,
-                                                    f->flow_id,
-                                                    FLOW_PKT);
-
+                                r->sdb  = sdb;
                                 r->head = head;
                                 r->tail = shm_du_buff_tail(sdb);
-                                r->sdb  = sdb;
+                                shm_du_buff_wait_ack(sdb);
+#endif
+                                /* Retransmit the copy. */
+                                ((struct frct_pci *) head)->ackno =
+                                        hton32(rcv_lwe);
+#ifdef RXM_BLOCKING
+                                if (shm_rbuff_write_b(f->tx_rb, idx, NULL) == 0)
+#else
+                                if (shm_rbuff_write(f->tx_rb, idx) == 0)
+#endif
+                                        shm_flow_set_notify(f->set, f->flow_id,
+                                                            FLOW_PKT);
+                        reschedule:
                                 r->mul++;
 
                                 /* Schedule at least in the next time slot. */
@@ -268,10 +253,24 @@ static void timerwheel_move(void)
                                         & (RXMQ_SLOTS - 1);
 
                                 list_add_tail(&r->next, &rw.rxms[i][rslot]);
+
+                                continue;
+
+                        flow_down:
+                                shm_rbuff_set_acl(f->tx_rb, ACL_FLOWDOWN);
+                                shm_rbuff_set_acl(f->rx_rb, ACL_FLOWDOWN);
+                        cleanup:
+#ifdef RXM_BUFFER_ON_HEAP
+                                free(r->pkt);
+#else
+                                ipcp_sdb_release(r->sdb);
+#endif
+                                free(r);
                         }
                 }
                 /* Move up a level in the wheel. */
                 rxm_slot >>= RXMQ_BUMP;
+                j >>= RXMQ_BUMP;
         }
 
         ack_slot = ts_to_ack_slot(now) & (ACKQ_SLOTS - 1) ;
@@ -326,11 +325,20 @@ static int timerwheel_rxm(struct frcti *       frcti,
         r->t0    = ts_to_ns(now);
         r->mul   = 0;
         r->seqno = seqno;
+        r->frcti = frcti;
+#ifdef RXM_BUFFER_ON_HEAP
+        r->pkt_len = shm_du_buff_tail(sdb) - shm_du_buff_head(sdb);
+        r->pkt = malloc(r->pkt_len);
+        if (r->pkt == NULL) {
+                free(r);
+                return -ENOMEM;
+        }
+        memcpy(r->pkt, shm_du_buff_head(sdb), r->pkt_len);
+#else
         r->sdb   = sdb;
         r->head  = shm_du_buff_head(sdb);
         r->tail  = shm_du_buff_tail(sdb);
-        r->frcti = frcti;
-
+#endif
         pthread_rwlock_rdlock(&r->frcti->lock);
 
         rto_slot = frcti->rto >> RXMQ_RES;
@@ -348,6 +356,9 @@ static int timerwheel_rxm(struct frcti *       frcti,
         }
 
         if (lvl >= RXMQ_LVLS) { /* Out of timerwheel range. */
+#ifdef RXM_BUFFER_ON_HEAP
+                free(r->pkt);
+#endif
                 free(r);
                 return -EPERM;
         }
@@ -357,9 +368,9 @@ static int timerwheel_rxm(struct frcti *       frcti,
         pthread_mutex_lock(&rw.lock);
 
         list_add_tail(&r->next, &rw.rxms[lvl][slot]);
-
+#ifndef RXM_BUFFER_ON_HEAP
         shm_du_buff_wait_ack(sdb);
-
+#endif
         pthread_mutex_unlock(&rw.lock);
 
         return 0;