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693c24ef9d
Libevent's current timeout code is relatively optimized for the randomly scattered timeout case, where events are added with their timeouts in no particular order. We add and remove timeouts with O(lg n) behavior. Frequently, however, an application will want to have many timeouts of the same value. For example, we might have 1000 bufferevents, each with a 2 second timeout on reading or writing. If we knew this were always the case, we could just put timeouts in a queue and get O(1) add and remove behavior. Of course, a queue would give O(n) performance for a scattered timeout pattern, so we don't want to just switch the implementation. This patch gives the user the ability to explicitly tag certain timeout values as being "very common". These timeout values have a cookie encoded in the high bits of their tv_usec field to indicate which queue they belong on. The queues themselves are each triggered by an entry in the minheap. See the regress_main.c code for an example use. svn:r1517
99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
/*
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* Copyright (c) 2009 Niels Provos and Nick Mathewson
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdlib.h>
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#include <event2/event_struct.h>
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#include "tinytest.h"
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#include "tinytest_macros.h"
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#include "../minheap-internal.h"
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static void
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set_random_timeout(struct event *ev)
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{
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ev->ev_timeout.tv_sec = rand();
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ev->ev_timeout.tv_usec = rand() & 0xfffff;
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ev->ev_timeout_pos.min_heap_idx = -1;
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}
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static void
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check_heap(struct min_heap *heap)
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{
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unsigned i;
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for (i = 1; i < heap->n; ++i) {
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unsigned parent_idx = (i-1)/2;
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tt_want(evutil_timercmp(&heap->p[i]->ev_timeout,
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&heap->p[parent_idx]->ev_timeout, >=));
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}
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}
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static void
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test_heap_randomized(void *ptr)
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{
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struct min_heap heap;
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struct event *inserted[1024];
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struct event *e, *last_e;
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int i;
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min_heap_ctor(&heap);
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for (i = 0; i < 1024; ++i) {
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inserted[i] = malloc(sizeof(struct event));
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set_random_timeout(inserted[i]);
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min_heap_push(&heap, inserted[i]);
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}
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check_heap(&heap);
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tt_assert(min_heap_size(&heap) == 1024);
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for (i = 0; i < 512; ++i) {
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min_heap_erase(&heap, inserted[i]);
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if (0 == (i % 32))
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check_heap(&heap);
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}
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tt_assert(min_heap_size(&heap) == 512);
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last_e = min_heap_pop(&heap);
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while (1) {
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e = min_heap_pop(&heap);
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if (!e)
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break;
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tt_want(evutil_timercmp(&last_e->ev_timeout,
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&e->ev_timeout, <=));
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}
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tt_assert(min_heap_size(&heap) == 0);
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end:
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for (i = 0; i < 1024; ++i)
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free(inserted[i]);
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min_heap_dtor(&heap);
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}
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struct testcase_t minheap_testcases[] = {
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{ "randomized", test_heap_randomized, 0, NULL, NULL },
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END_OF_TESTCASES
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};
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