From 26d4a6072cbf59708071dac8393c88ddacd69a37 Mon Sep 17 00:00:00 2001
From: Sander Vrijders <sander.vrijders@ugent.be>
Date: Thu, 14 Sep 2017 13:43:09 +0200
Subject: lib: Add reordering queue to FRCT

This adds a reordering queue to FRCT so that SDUs can be delivered
in-order when requested.
---
 src/lib/dev.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 57 insertions(+), 13 deletions(-)

(limited to 'src/lib/dev.c')

diff --git a/src/lib/dev.c b/src/lib/dev.c
index 47fec48d..14ee31f4 100644
--- a/src/lib/dev.c
+++ b/src/lib/dev.c
@@ -39,6 +39,7 @@
 #include <ouroboros/qoscube.h>
 #include <ouroboros/timerwheel.h>
 #include <ouroboros/frct_pci.h>
+#include <ouroboros/rq.h>
 
 #include <stdlib.h>
 #include <string.h>
@@ -50,7 +51,8 @@
 #define TW_ELEMENTS   6000
 #define TW_RESOLUTION 1   /* ms */
 
-#define MPL 2000 /* ms */
+#define MPL            2000 /* ms */
+#define RQ_SIZE        20
 
 #ifndef CLOCK_REALTIME_COARSE
 #define CLOCK_REALTIME_COARSE CLOCK_REALTIME
@@ -89,6 +91,8 @@ struct frcti {
 
         uint16_t         conf_flags;
 
+        struct rq *      rq;
+
         pthread_rwlock_t lock;
 };
 
@@ -269,6 +273,12 @@ static int frcti_init(int fd)
         frcti->rcv_lwe = 0;
         frcti->rcv_rwe = 0;
 
+        frcti->conf_flags = 0;
+
+        frcti->rq = rq_create(RQ_SIZE);
+        if (frcti->rq == NULL)
+                return -1;
+
         return 0;
 }
 
@@ -285,6 +295,8 @@ static void frcti_fini(int fd)
          */
 
         frcti_clear(fd);
+
+        rq_destroy(ai.frcti[fd].rq);
 }
 
 static int frcti_send(int                  fd,
@@ -382,6 +394,25 @@ static ssize_t frcti_read(int fd)
         struct frcti *       frcti;
         struct frct_pci      pci;
         struct shm_du_buff * sdb;
+        uint64_t             seqno;
+        bool                 nxt_pdu = true;
+
+        frcti = &(ai.frcti[fd]);
+
+        /* See if we already have the next PDU */
+        pthread_rwlock_wrlock(&frcti->lock);
+
+        if (!rq_is_empty(frcti->rq)) {
+                seqno = rq_peek(frcti->rq);
+                if (seqno == frcti->rcv_lwe) {
+                        frcti->rcv_lwe++;
+                        idx = rq_pop(frcti->rq);
+                        pthread_rwlock_unlock(&frcti->lock);
+                        return idx;
+                }
+        }
+
+        pthread_rwlock_unlock(&frcti->lock);
 
         do {
                 struct timespec    now;
@@ -390,7 +421,7 @@ static ssize_t frcti_read(int fd)
                 struct shm_rbuff * rb;
                 bool               noblock;
 
-                clock_gettime(PTHREAD_COND_CLOCK, &now);
+                clock_gettime(CLOCK_REALTIME_COARSE, &now);
 
                 pthread_rwlock_rdlock(&ai.lock);
 
@@ -404,18 +435,16 @@ static ssize_t frcti_read(int fd)
 
                 pthread_rwlock_unlock(&ai.lock);
 
-                if (noblock)
+                if (noblock) {
                         idx = shm_rbuff_read(rb);
-                else
+                } else {
                         idx = shm_rbuff_read_b(rb, abstime);
+                        clock_gettime(CLOCK_REALTIME_COARSE, &now);
+                }
 
                 if (idx < 0)
                         return idx;
 
-                clock_gettime(CLOCK_REALTIME_COARSE, &now);
-
-                frcti = &(ai.frcti[fd]);
-
                 sdb = shm_rdrbuff_get(ai.rdrb, idx);
 
                 pthread_rwlock_wrlock(&frcti->lock);
@@ -432,10 +461,11 @@ static ssize_t frcti_read(int fd)
                     ts_diff_ms(&now, &frcti->last_rcv) > 3 * MPL)
                         frcti->rcv_drf = true;
 
-                /* We don't accept packets when there is receiver inactivity. */
+                /* When there is receiver inactivity queue the packet. */
                 if (frcti->rcv_drf && !(pci.flags & FLAG_DATA_RUN)) {
+                        if (rq_push(frcti->rq, pci.seqno, idx))
+                                shm_rdrbuff_remove(ai.rdrb, idx);
                         pthread_rwlock_unlock(&frcti->lock);
-                        shm_rdrbuff_remove(ai.rdrb, idx);
                         return -EAGAIN;
                 }
 
@@ -451,12 +481,26 @@ static ssize_t frcti_read(int fd)
 
                 frcti->last_rcv = now;
 
-                pthread_rwlock_unlock(&frcti->lock);
+                nxt_pdu = true;
 
-                if (!(pci.type & PDU_TYPE_DATA))
+                if (!(pci.type & PDU_TYPE_DATA)) {
                         shm_rdrbuff_remove(ai.rdrb, idx);
+                        nxt_pdu = false;
+                }
+
+                if (frcti->conf_flags & FRCTFORDERING) {
+                        if (pci.seqno != frcti->rcv_lwe) {
+                                if (rq_push(frcti->rq, pci.seqno, idx))
+                                        shm_rdrbuff_remove(ai.rdrb, idx);
+                                nxt_pdu = false;
+                        } else {
+                                frcti->rcv_lwe++;
+                        }
+                }
+
+                pthread_rwlock_unlock(&frcti->lock);
 
-        } while (!(pci.type & PDU_TYPE_DATA));
+        } while (!nxt_pdu);
 
         return idx;
 }
-- 
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