lib: Add basic FRCT mechanisms

This adds the basic FRCT mechanisms to the library. Upon flow alloc or
accept an FRCT instance is now created and used when reading or
writing to the flow. The timerwheel has been refactored to allow
recharging timers and removing them and is now part of the
library. The first SDU sent over the connection has the DRF set and
this initializes the connection. Sender and receiver inactivity timers
are added.

1 files changed, 371 insertions, 0 deletions

diff --git a/src/lib/timerwheel.c b/src/lib/timerwheel.c
new file mode 100644
index 00000000..7e2779d0
--- /dev/null
+++ b/src/lib/timerwheel.c
@@ -0,0 +1,371 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2017
+ *
+ * Timerwheel
+ *
+ *    Dimitri Staessens <[email protected]>
+ *    Sander Vrijders   <[email protected]>
+ *
+ * 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/config.h>
+#include <ouroboros/time_utils.h>
+#include <ouroboros/errno.h>
+#include <ouroboros/list.h>
+
+#include <pthread.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+
+#define FRAC 10 /* accuracy of the timer */
+
+#define tw_used(tw) ((tw->head + tw->elements - tw->tail) & (tw->elements - 1));
+#define tw_free(tw) (tw_used(tw) + 1 < tw->elements)
+#define tw_empty(tw) (tw->head == tw->tail)
+
+enum tw_state {
+        TW_NULL = 0,
+        TW_RUNNING,
+        TW_DESTROY
+};
+
+struct tw_f {
+        struct list_head next;
+        void (* func)(void *);
+        void * arg;
+};
+
+struct tw_el {
+        struct list_head funcs;
+        struct timespec  expiry;
+};
+
+struct timerwheel {
+        struct tw_el *   wheel;
+
+        struct timespec  intv;
+
+        size_t           pos;
+
+        struct list_head wq;
+
+        pthread_cond_t   work;
+        pthread_mutex_t  lock;
+
+        int              resolution;
+        unsigned int     elements;
+
+        enum tw_state    state;
+        pthread_mutex_t  s_lock;
+
+        pthread_t        ticker;
+        pthread_t        worker;
+};
+
+static void tw_el_fini(struct tw_el * e)
+{
+        struct list_head * p;
+        struct list_head * h;
+
+        list_for_each_safe(p, h, &e->funcs) {
+                struct tw_f * f = list_entry(p, struct tw_f, next);
+                list_del(&f->next);
+        }
+}
+
+static enum tw_state tw_get_state(struct timerwheel * tw)
+{
+        enum tw_state state;
+
+        assert(tw);
+
+        pthread_mutex_lock(&tw->s_lock);
+
+        state = tw->state;
+
+        pthread_mutex_unlock(&tw->s_lock);
+
+        return state;
+}
+
+static void tw_set_state(struct timerwheel * tw, enum tw_state state)
+{
+        assert(tw);
+        assert(state != TW_NULL);
+
+        pthread_mutex_lock(&tw->s_lock);
+
+        tw->state = state;
+
+        pthread_mutex_unlock(&tw->s_lock);
+}
+
+static void * worker(void * o)
+{
+        struct list_head * p;
+        struct list_head * h;
+
+        struct timerwheel * tw = (struct timerwheel *) o;
+        struct timespec dl;
+        struct timespec now;
+
+        clock_gettime(PTHREAD_COND_CLOCK, &now);
+
+        ts_add(&now, &tw->intv, &dl);
+
+        pthread_mutex_lock(&tw->lock);
+
+        while (tw_get_state(tw) == TW_RUNNING) {
+                if (pthread_cond_timedwait(&tw->work, &tw->lock, &dl)
+                    == ETIMEDOUT)
+                        ts_add(&dl, &tw->intv, &dl);
+
+                list_for_each_safe(p, h, &tw->wq) {
+                        struct tw_f * f = list_entry(p, struct tw_f, next);
+                        list_del(&f->next);
+                        pthread_mutex_unlock(&tw->lock);
+                        f->func(f->arg);
+                        free(f);
+
+                        pthread_mutex_lock(&tw->lock);
+                }
+        }
+
+        pthread_mutex_unlock(&tw->lock);
+
+        return (void *) o;
+}
+
+static void * movement(void * o)
+{
+        struct timerwheel * tw = (struct timerwheel *) o;
+        struct timespec now = {0, 0};
+        long ms = tw->resolution * tw->elements;
+        struct timespec total = {ms / 1000,
+                                 (ms % 1000) * MILLION};
+        struct list_head * p;
+        struct list_head * h;
+
+        while (tw_get_state(tw) == TW_RUNNING) {
+                clock_gettime(CLOCK_MONOTONIC, &now);
+
+                pthread_mutex_lock(&tw->lock);
+
+                if (ts_diff_us(&tw->wheel[tw->pos].expiry, &now) < 0) {
+                        pthread_mutex_unlock(&tw->lock);
+                        nanosleep(&tw->intv, NULL);
+                        continue;
+                }
+
+                list_for_each_safe(p, h, &tw->wheel[tw->pos].funcs) {
+                        struct tw_f * f = list_entry(p, struct tw_f, next);
+                        list_del(&f->next);
+                        list_add(&f->next, &tw->wq);
+                }
+
+                ts_add(&tw->wheel[tw->pos].expiry,
+                       &total,
+                       &tw->wheel[tw->pos].expiry);
+
+                tw->pos = (tw->pos + 1) & (tw->elements - 1);
+
+                pthread_cond_signal(&tw->work);
+
+                pthread_mutex_unlock(&tw->lock);
+        }
+
+        return (void *) 0;
+}
+
+struct timerwheel * timerwheel_create(time_t resolution,
+                                      time_t max_delay)
+{
+        struct timespec now = {0, 0};
+        struct timespec res_ts = {resolution / 1000,
+                                  (resolution % 1000) * MILLION};
+        unsigned long i;
+
+        struct timerwheel * tw;
+
+        pthread_condattr_t cattr;
+
+        assert(resolution != 0);
+
+        tw = malloc(sizeof(*tw));
+        if (tw == NULL)
+                return NULL;
+
+        if (pthread_mutex_init(&tw->lock, NULL))
+                return NULL;
+
+        tw->elements = 1;
+
+        while (tw->elements < max_delay / resolution)
+                tw->elements <<= 1;
+
+        tw->wheel = malloc(sizeof(*tw->wheel) * tw->elements);
+        if (tw->wheel == NULL)
+                goto fail_wheel_malloc;
+
+        tw->resolution = resolution;
+
+        tw->intv.tv_sec = (tw->resolution / FRAC) / 1000;
+        tw->intv.tv_nsec = ((tw->resolution / FRAC) % 1000) * MILLION;
+
+        list_head_init(&tw->wq);
+
+        if (pthread_mutex_init(&tw->lock, NULL))
+                goto fail_lock_init;
+
+        if (pthread_mutex_init(&tw->s_lock, NULL))
+                goto fail_s_lock_init;
+
+        if (pthread_condattr_init(&cattr))
+                goto fail_cond_init;
+
+#ifndef __APPLE__
+        pthread_condattr_setclock(&cattr, PTHREAD_COND_CLOCK);
+#endif
+        if (pthread_cond_init(&tw->work, &cattr))
+                goto fail_cond_init;
+
+        tw->pos = 0;
+        tw->state = TW_RUNNING;
+
+        clock_gettime(CLOCK_MONOTONIC, &now);
+        now.tv_nsec -= (now.tv_nsec % MILLION);
+
+        for (i = 0; i < tw->elements; ++i) {
+                list_head_init(&tw->wheel[i].funcs);
+                tw->wheel[i].expiry = now;
+                ts_add(&now, &res_ts, &now);
+        }
+
+        if (pthread_create(&tw->worker, NULL, worker, (void *) tw))
+                goto fail_worker_create;
+
+        if (pthread_create(&tw->ticker, NULL, movement, (void *) tw)) {
+                tw_set_state(tw, TW_DESTROY);
+                goto fail_ticker_create;
+        }
+
+        return tw;
+
+ fail_ticker_create:
+         pthread_join(tw->worker, NULL);
+ fail_worker_create:
+         pthread_cond_destroy(&tw->work);
+ fail_cond_init:
+         pthread_mutex_destroy(&tw->s_lock);
+ fail_s_lock_init:
+         pthread_mutex_destroy(&tw->lock);
+ fail_lock_init:
+         free(tw->wheel);
+ fail_wheel_malloc:
+         free(tw);
+         return NULL;
+}
+
+void timerwheel_destroy(struct timerwheel * tw)
+{
+        unsigned long i;
+
+        struct list_head * p;
+        struct list_head * h;
+
+        tw_set_state(tw, TW_DESTROY);
+
+        pthread_join(tw->ticker, NULL);
+        pthread_join(tw->worker, NULL);
+
+        for (i = 0; i < tw->elements; ++i)
+                tw_el_fini(&tw->wheel[i]);
+
+        pthread_mutex_lock(&tw->lock);
+
+        list_for_each_safe(p, h, &tw->wq) {
+                struct tw_f * f = list_entry(p, struct tw_f, next);
+                list_del(&f->next);
+                free(f);
+        }
+
+        pthread_mutex_unlock(&tw->lock);
+
+        pthread_cond_destroy(&tw->work);
+        pthread_mutex_destroy(&tw->lock);
+        pthread_mutex_destroy(&tw->s_lock);
+
+        free(tw->wheel);
+        free(tw);
+}
+
+struct tw_f * timerwheel_start(struct timerwheel * tw,
+                               void (* func)(void *),
+                               void *              arg,
+                               time_t              delay)
+{
+        int pos;
+        struct tw_f * f = malloc(sizeof(*f));
+        if (f == NULL)
+                return NULL;
+
+        f->func = func;
+        f->arg = arg;
+
+        assert(delay < tw->elements * tw->resolution);
+
+        pthread_mutex_lock(&tw->lock);
+
+        pos = (tw->pos + delay / tw->resolution) & (tw->elements - 1);
+        list_add(&f->next, &tw->wheel[pos].funcs);
+
+        pthread_mutex_unlock(&tw->lock);
+
+        return f;
+}
+
+int timerwheel_restart(struct timerwheel * tw,
+                       struct tw_f *       f,
+                       time_t              delay)
+{
+        int pos;
+
+        assert(tw);
+        assert(delay < tw->elements * tw->resolution);
+
+        pthread_mutex_lock(&tw->lock);
+
+        list_del(&f->next);
+        pos = (tw->pos + delay / tw->resolution) & (tw->elements - 1);
+        list_add(&f->next, &tw->wheel[pos].funcs);
+
+        pthread_mutex_unlock(&tw->lock);
+
+        return 0;
+}
+
+void timerwheel_stop(struct timerwheel * tw,
+                     struct tw_f *       f)
+{
+        assert(tw);
+
+        pthread_mutex_lock(&tw->lock);
+
+        list_del(&f->next);
+        free(f);
+
+        pthread_mutex_unlock(&tw->lock);
+}