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-rw-r--r--src/lib/timerwheel.c409
1 files changed, 409 insertions, 0 deletions
diff --git a/src/lib/timerwheel.c b/src/lib/timerwheel.c
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+++ b/src/lib/timerwheel.c
@@ -0,0 +1,409 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2020
+ *
+ * Timerwheel
+ *
+ * Dimitri Staessens <dimitri.staessens@ugent.be>
+ * Sander Vrijders <sander.vrijders@ugent.be>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2.1 as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+#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)
+#define ts_to_ack_slot(ts) (ts_to_ns(ts) >> ACKQ_RES)
+
+struct rxm {
+ struct list_head next;
+ uint32_t seqno;
+ struct shm_du_buff * sdb;
+ uint8_t * head;
+ uint8_t * tail;
+ time_t t0; /* Time when original was sent (us). */
+ size_t mul; /* RTO multiplier. */
+ struct frcti * frcti;
+ int fd;
+ int flow_id; /* Prevent rtx when fd reused. */
+};
+
+struct ack {
+ struct list_head next;
+ struct frcti * frcti;
+ int fd;
+ int flow_id;
+};
+
+struct {
+ /*
+ * At a 1 ms min resolution, every level bumps the
+ * resolution by a factor of 16.
+ */
+ struct list_head rxms[RXMQ_LVLS][RXMQ_SLOTS];
+
+ struct list_head acks[ACKQ_SLOTS];
+ bool map[ACKQ_SLOTS][PROG_MAX_FLOWS];
+
+ size_t prv_rxm; /* Last processed rxm slot at lvl 0. */
+ size_t prv_ack; /* Last processed ack slot. */
+ pthread_mutex_t lock;
+} rw;
+
+static void timerwheel_fini(void)
+{
+ size_t i;
+ size_t j;
+ struct list_head * p;
+ struct list_head * h;
+
+ pthread_mutex_lock(&rw.lock);
+
+ for (i = 0; i < RXMQ_LVLS; ++i) {
+ for (j = 0; j < RXMQ_SLOTS; j++) {
+ list_for_each_safe(p, h, &rw.rxms[i][j]) {
+ struct rxm * rxm;
+ rxm = list_entry(p, struct rxm, next);
+ list_del(&rxm->next);
+ shm_du_buff_ack(rxm->sdb);
+ ipcp_sdb_release(rxm->sdb);
+ free(rxm);
+ }
+ }
+ }
+
+ for (i = 0; i < ACKQ_SLOTS; ++i) {
+ list_for_each_safe(p, h, &rw.acks[i]) {
+ struct ack * a = list_entry(p, struct ack, next);
+ list_del(&a->next);
+ free(a);
+ }
+ }
+
+ pthread_mutex_unlock(&rw.lock);
+
+ pthread_mutex_destroy(&rw.lock);
+}
+
+static int timerwheel_init(void)
+{
+ struct timespec now;
+ size_t i;
+ size_t j;
+
+ if (pthread_mutex_init(&rw.lock, NULL))
+ return -1;
+
+ clock_gettime(PTHREAD_COND_CLOCK, &now);
+
+ rw.prv_rxm = (ts_to_rxm_slot(now) - 1) & (RXMQ_SLOTS - 1);
+ for (i = 0; i < RXMQ_LVLS; ++i) {
+ for (j = 0; j < RXMQ_SLOTS; ++j)
+ list_head_init(&rw.rxms[i][j]);
+ }
+
+ rw.prv_ack = (ts_to_ack_slot(now) - 1) & (ACKQ_SLOTS - 1);
+ for (i = 0; i < ACKQ_SLOTS; ++i)
+ list_head_init(&rw.acks[i]);
+
+ return 0;
+}
+
+static void timerwheel_move(void)
+{
+ struct timespec now;
+ struct list_head * p;
+ struct list_head * h;
+ size_t rxm_slot;
+ size_t ack_slot;
+ size_t i;
+ size_t j;
+
+ pthread_mutex_lock(&rw.lock);
+
+ pthread_cleanup_push((void (*) (void *)) pthread_mutex_unlock,
+ (void *) &rw.lock);
+
+ clock_gettime(PTHREAD_COND_CLOCK, &now);
+
+ rxm_slot = ts_to_ns(now) >> RXMQ_RES;
+ j = rw.prv_rxm;
+ rw.prv_rxm = rxm_slot & (RXMQ_SLOTS - 1);
+
+ for (i = 0; i < RXMQ_LVLS; ++i) {
+ size_t j_max_slot = rxm_slot & (RXMQ_SLOTS - 1);
+ if (j_max_slot < j)
+ j_max_slot += RXMQ_SLOTS;
+
+ while (j++ < j_max_slot) {
+ list_for_each_safe(p,
+ h,
+ &rw.rxms[i][j & (RXMQ_SLOTS - 1)]) {
+ struct rxm * r;
+ struct frct_cr * snd_cr;
+ struct frct_cr * rcv_cr;
+ size_t rslot;
+ ssize_t idx;
+ struct shm_du_buff * sdb;
+ uint8_t * head;
+ struct flow * f;
+ uint32_t snd_lwe;
+ uint32_t rcv_lwe;
+ time_t rto;
+
+ r = list_entry(p, struct rxm, next);
+
+ list_del(&r->next);
+
+ snd_cr = &r->frcti->snd_cr;
+ rcv_cr = &r->frcti->rcv_cr;
+ f = &ai.flows[r->fd];
+
+ shm_du_buff_ack(r->sdb);
+
+ if (f->frcti == NULL
+ || f->flow_id != r->flow_id) {
+ ipcp_sdb_release(r->sdb);
+ free(r);
+ continue;
+ }
+
+ pthread_rwlock_wrlock(&r->frcti->lock);
+
+ snd_lwe = snd_cr->lwe;
+ rcv_lwe = rcv_cr->lwe;
+ rto = r->frcti->rto;
+
+ 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;
+ }
+
+ /* 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 (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;
+ }
+
+ idx = shm_du_buff_get_idx(sdb);
+
+ head = shm_du_buff_head(sdb);
+ 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->head = head;
+ r->tail = shm_du_buff_tail(sdb);
+ r->sdb = sdb;
+ r->mul++;
+
+ /* Schedule at least in the next time slot. */
+ rslot = (rxm_slot
+ + MAX(((rto * r->mul) >> RXMQ_RES), 1))
+ & (RXMQ_SLOTS - 1);
+
+ list_add_tail(&r->next, &rw.rxms[i][rslot]);
+ }
+ }
+ /* Move up a level in the wheel. */
+ rxm_slot >>= RXMQ_BUMP;
+ }
+
+ ack_slot = ts_to_ack_slot(now) & (ACKQ_SLOTS - 1) ;
+
+ j = rw.prv_ack;
+
+ if (ack_slot < j)
+ ack_slot += ACKQ_SLOTS;
+
+ while (j++ < ack_slot) {
+ list_for_each_safe(p, h, &rw.acks[j & (ACKQ_SLOTS - 1)]) {
+ struct ack * a;
+ struct flow * f;
+
+ a = list_entry(p, struct ack, next);
+
+ list_del(&a->next);
+
+ f = &ai.flows[a->fd];
+
+ rw.map[j & (ACKQ_SLOTS - 1)][a->fd] = false;
+
+ if (f->flow_id == a->flow_id && f->frcti != NULL)
+ frct_send_ack(a->frcti);
+
+ free(a);
+
+ }
+ }
+
+ rw.prv_ack = ack_slot & (ACKQ_SLOTS - 1);
+
+ pthread_cleanup_pop(true);
+}
+
+static int timerwheel_rxm(struct frcti * frcti,
+ uint32_t seqno,
+ struct shm_du_buff * sdb)
+{
+ struct timespec now;
+ struct rxm * r;
+ size_t slot;
+ size_t lvl = 0;
+ time_t rto_slot;
+
+ r = malloc(sizeof(*r));
+ if (r == NULL)
+ return -ENOMEM;
+
+ clock_gettime(PTHREAD_COND_CLOCK, &now);
+
+ r->t0 = ts_to_ns(now);
+ r->mul = 0;
+ r->seqno = seqno;
+ r->sdb = sdb;
+ r->head = shm_du_buff_head(sdb);
+ r->tail = shm_du_buff_tail(sdb);
+ r->frcti = frcti;
+
+ pthread_rwlock_rdlock(&r->frcti->lock);
+
+ rto_slot = frcti->rto >> RXMQ_RES;
+ slot = r->t0 >> RXMQ_RES;
+
+ r->fd = frcti->fd;
+ r->flow_id = ai.flows[r->fd].flow_id;
+
+ pthread_rwlock_unlock(&r->frcti->lock);
+
+ while (rto_slot >= RXMQ_SLOTS) {
+ ++lvl;
+ rto_slot >>= RXMQ_BUMP;
+ slot >>= RXMQ_BUMP;
+ }
+
+ if (lvl >= RXMQ_LVLS) { /* Out of timerwheel range. */
+ free(r);
+ return -EPERM;
+ }
+
+ slot = (slot + rto_slot) & (RXMQ_SLOTS - 1);
+
+ pthread_mutex_lock(&rw.lock);
+
+ list_add_tail(&r->next, &rw.rxms[lvl][slot]);
+
+ shm_du_buff_wait_ack(sdb);
+
+ pthread_mutex_unlock(&rw.lock);
+
+ return 0;
+}
+
+static int timerwheel_ack(int fd,
+ struct frcti * frcti)
+{
+ struct timespec now;
+ struct ack * a;
+ size_t slot;
+
+ a = malloc(sizeof(*a));
+ if (a == NULL)
+ return -ENOMEM;
+
+ clock_gettime(PTHREAD_COND_CLOCK, &now);
+
+ slot = DELT_ACK >> ACKQ_RES;
+ if (slot >= ACKQ_SLOTS) { /* Out of timerwheel range. */
+ free(a);
+ return -EPERM;
+ }
+
+ slot = (((ts_to_ns(now) + DELT_ACK) >> ACKQ_RES) + 1)
+ & (ACKQ_SLOTS - 1);
+
+ a->fd = fd;
+ a->frcti = frcti;
+ a->flow_id = ai.flows[fd].flow_id;
+
+ pthread_mutex_lock(&rw.lock);
+
+ if (rw.map[slot][fd]) {
+ pthread_mutex_unlock(&rw.lock);
+ free(a);
+ return 0;
+ }
+
+ rw.map[slot][fd] = true;
+
+ list_add_tail(&a->next, &rw.acks[slot]);
+
+ pthread_mutex_unlock(&rw.lock);
+
+ return 0;
+}
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