Initial version.

src/nxt_event_timer.c

@@ -0,0 +1,320 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) NGINX, Inc.
+ */
+
+#include <nxt_main.h>
+
+
+/*
+ * Timer operations are batched to improve instruction and data
+ * cache locality of rbtree operations.
+ *
+ * nxt_event_timer_add() adds a timer to the changes array to add or to
+ * modify the timer.  The changes are processed by nxt_event_timer_find().
+ *
+ * nxt_event_timer_disable() disables a timer.  The disabled timer may
+ * however present in rbtree for a long time and may be eventually removed
+ * by nxt_event_timer_find() or nxt_event_timer_expire().
+ *
+ * nxt_event_timer_delete() removes a timer at once from both the rbtree and
+ * the changes array and should be used only if the timer memory must be freed.
+ */
+
+static nxt_int_t nxt_event_timer_rbtree_compare(nxt_rbtree_node_t *node1,
+    nxt_rbtree_node_t *node2);
+static void nxt_event_timer_change(nxt_event_timers_t *timers,
+    nxt_event_timer_t *ev, nxt_msec_t time);
+static void nxt_event_commit_timer_changes(nxt_event_timers_t *timers);
+static void nxt_event_timer_drop_changes(nxt_event_timers_t *timers,
+    nxt_event_timer_t *ev);
+
+
+nxt_int_t
+nxt_event_timers_init(nxt_event_timers_t *timers, nxt_uint_t mchanges)
+{
+    nxt_rbtree_init(&timers->tree, nxt_event_timer_rbtree_compare, NULL);
+
+    timers->mchanges = mchanges;
+
+    timers->changes = nxt_malloc(sizeof(nxt_event_timer_change_t) * mchanges);
+
+    if (nxt_fast_path(timers->changes != NULL)) {
+        return NXT_OK;
+    }
+
+    return NXT_ERROR;
+}
+
+
+static nxt_int_t
+nxt_event_timer_rbtree_compare(nxt_rbtree_node_t *node1,
+    nxt_rbtree_node_t *node2)
+{
+    nxt_event_timer_t  *ev1, *ev2;
+
+    ev1 = (nxt_event_timer_t *) node1;
+    ev2 = (nxt_event_timer_t *) node2;
+
+    /*
+     * Timer values are distributed in small range, usually several minutes
+     * and overflow every 49 days if nxt_msec_t is stored in 32 bits.
+     * This signed comparison takes into account that overflow.
+     */
+                      /* ev1->time < ev2->time */
+    return nxt_msec_diff(ev1->time, ev2->time);
+}
+
+
+void
+nxt_event_timer_add(nxt_event_engine_t *engine, nxt_event_timer_t *ev,
+    nxt_msec_t timer)
+{
+    int32_t   diff;
+    uint32_t  time;
+
+    time = engine->timers.now + timer;
+
+    if (nxt_event_timer_is_in_tree(ev)) {
+
+        diff = nxt_msec_diff(time, ev->time);
+
+        /*
+         * Use the previous timer if difference between it and the
+         * new timer is less than required precision milliseconds:
+         * this decreases rbtree operations for fast connections.
+         */
+
+        if (nxt_abs(diff) < ev->precision) {
+            nxt_log_debug(ev->log, "event timer previous: %D: %d:%M",
+                          ev->ident, ev->state, time);
+
+            if (ev->state == NXT_EVENT_TIMER_DISABLED) {
+                ev->state = NXT_EVENT_TIMER_ACTIVE;
+            }
+
+            return;
+        }
+
+        nxt_log_debug(ev->log, "event timer change: %D: %d:%M",
+                      ev->ident, ev->state, ev->time);
+
+    } else {
+        /*
+         * The timer's time is updated here just to log a correct
+         * value by debug logging in nxt_event_timer_disable().
+         * It could be updated only in nxt_event_commit_timer_changes()
+         * just before nxt_rbtree_insert().
+         */
+        ev->time = time;
+
+        nxt_log_debug(ev->log, "event timer add: %D: %M:%M",
+                      ev->ident, timer, time);
+    }
+
+    nxt_event_timer_change(&engine->timers, ev, time);
+}
+
+
+static void
+nxt_event_timer_change(nxt_event_timers_t *timers, nxt_event_timer_t *ev,
+    nxt_msec_t time)
+{
+    nxt_event_timer_change_t  *ch;
+
+    if (timers->nchanges >= timers->mchanges) {
+        nxt_event_commit_timer_changes(timers);
+    }
+
+    ev->state = NXT_EVENT_TIMER_ACTIVE;
+
+    ch = &timers->changes[timers->nchanges];
+    ch->time = time;
+    ch->event = ev;
+    timers->nchanges++;
+}
+
+
+#if (NXT_DEBUG)
+
+void
+nxt_event_timer_disable(nxt_event_timer_t *ev)
+{
+    nxt_log_debug(ev->log, "event timer disable: %D: %d:%M",
+                  ev->ident, ev->state, ev->time);
+
+    ev->state = NXT_EVENT_TIMER_DISABLED;
+}
+
+#endif
+
+
+void
+nxt_event_timer_delete(nxt_event_engine_t *engine, nxt_event_timer_t *ev)
+{
+    if (nxt_event_timer_is_in_tree(ev)) {
+        nxt_log_debug(ev->log, "event timer delete: %D: %d:%M",
+                      ev->ident, ev->state, ev->time);
+
+        nxt_rbtree_delete(&engine->timers.tree, &ev->node);
+        nxt_event_timer_in_tree_clear(ev);
+        ev->state = NXT_EVENT_TIMER_DISABLED;
+    }
+
+    nxt_event_timer_drop_changes(&engine->timers, ev);
+}
+
+
+static void
+nxt_event_timer_drop_changes(nxt_event_timers_t *timers, nxt_event_timer_t *ev)
+{
+    nxt_event_timer_change_t  *dst, *src, *end;
+
+    dst = timers->changes;
+    end = dst + timers->nchanges;
+
+    for (src = dst; src < end; src++) {
+
+        if (src->event == ev) {
+            continue;
+        }
+
+        if (dst != src) {
+            *dst = *src;
+        }
+
+        dst++;
+    }
+
+    timers->nchanges -= end - dst;
+}
+
+
+static void
+nxt_event_commit_timer_changes(nxt_event_timers_t *timers)
+{
+    nxt_event_timer_t         *ev;
+    nxt_event_timer_change_t  *ch, *end;
+
+    nxt_thread_log_debug("event timers changes: %ui", timers->nchanges);
+
+    ch = timers->changes;
+    end = ch + timers->nchanges;
+
+    while (ch < end) {
+        ev = ch->event;
+
+        if (ev->state != NXT_EVENT_TIMER_DISABLED) {
+
+            if (nxt_event_timer_is_in_tree(ev)) {
+                nxt_log_debug(ev->log, "event timer delete: %D: %d:%M",
+                              ev->ident, ev->state, ev->time);
+
+                nxt_rbtree_delete(&timers->tree, &ev->node);
+
+                ev->time = ch->time;
+            }
+
+            nxt_log_debug(ev->log, "event timer add: %D: %M",
+                          ev->ident, ev->time);
+
+            nxt_rbtree_insert(&timers->tree, &ev->node);
+            nxt_event_timer_in_tree_set(ev);
+        }
+
+        ch++;
+    }
+
+    timers->nchanges = 0;
+}
+
+
+nxt_msec_t
+nxt_event_timer_find(nxt_event_engine_t *engine)
+{
+    int32_t            time;
+    nxt_rbtree_node_t  *node, *next;
+    nxt_event_timer_t  *ev;
+
+    if (engine->timers.nchanges != 0) {
+        nxt_event_commit_timer_changes(&engine->timers);
+    }
+
+    for (node = nxt_rbtree_min(&engine->timers.tree);
+         nxt_rbtree_is_there_successor(&engine->timers.tree, node);
+         node = next)
+    {
+        next = nxt_rbtree_node_successor(&engine->timers.tree, node);
+
+        ev = (nxt_event_timer_t *) node;
+
+        if (ev->state != NXT_EVENT_TIMER_DISABLED) {
+
+            if (ev->state == NXT_EVENT_TIMER_BLOCKED) {
+                nxt_log_debug(ev->log, "event timer blocked: %D: %M",
+                              ev->ident, ev->time);
+                continue;
+            }
+
+            time = nxt_msec_diff(ev->time, engine->timers.now);
+
+            return (nxt_msec_t) nxt_max(time, 0);
+        }
+
+        /* Delete disabled timer. */
+
+        nxt_log_debug(ev->log, "event timer delete: %D: 0:%M",
+                      ev->ident, ev->time);
+
+        nxt_rbtree_delete(&engine->timers.tree, &ev->node);
+        nxt_event_timer_in_tree_clear(ev);
+    }
+
+    return NXT_INFINITE_MSEC;
+}
+
+
+void
+nxt_event_timer_expire(nxt_thread_t *thr, nxt_msec_t now)
+{
+    nxt_rbtree_t       *tree;
+    nxt_rbtree_node_t  *node, *next;
+    nxt_event_timer_t  *ev;
+
+    thr->engine->timers.now = now;
+    tree = &thr->engine->timers.tree;
+
+    for (node = nxt_rbtree_min(tree);
+         nxt_rbtree_is_there_successor(tree, node);
+         node = next)
+    {
+        ev = (nxt_event_timer_t *) node;
+
+                       /* ev->time > now */
+        if (nxt_msec_diff(ev->time, now) > 0) {
+            return;
+        }
+
+        next = nxt_rbtree_node_successor(tree, node);
+
+        if (ev->state == NXT_EVENT_TIMER_BLOCKED) {
+            nxt_log_debug(ev->log, "event timer blocked: %D: %M",
+                          ev->ident, ev->time);
+            continue;
+        }
+
+        nxt_log_debug(ev->log, "event timer delete: %D: %d:%M",
+                      ev->ident, ev->state, ev->time);
+
+        nxt_rbtree_delete(tree, &ev->node);
+        nxt_event_timer_in_tree_clear(ev);
+
+        if (ev->state != NXT_EVENT_TIMER_DISABLED) {
+            ev->state = NXT_EVENT_TIMER_DISABLED;
+
+            nxt_thread_work_queue_add(thr, ev->work_queue, ev->handler,
+                                      ev, NULL, ev->log);
+        }
+    }
+}