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Lagrang3Lagrang3
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askrene: add a queue for primitive data types
Changelog-None Signed-off-by: Lagrang3 <[email protected]>
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‎plugins/askrene/Makefile

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@@ -22,6 +22,7 @@ PLUGIN_ASKRENE_HEADER := \
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plugins/askrene/explain_failure.h \
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plugins/askrene/graph.h \
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plugins/askrene/priorityqueue.h \
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plugins/askrene/queue.h \
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plugins/askrene/algorithm.h
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PLUGIN_ASKRENE_OBJS := $(PLUGIN_ASKRENE_SRC:.c=.o)

‎plugins/askrene/queue.h

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#ifndef LIGHTNING_PLUGINS_ASKRENE_QUEUE_H
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#define LIGHTNING_PLUGINS_ASKRENE_QUEUE_H
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#include "config.h"
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#include <ccan/compiler/compiler.h>
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#include <ccan/lqueue/lqueue.h>
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#include <ccan/tal/tal.h>
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/* Generic and efficient queue based on ccan/lqueue for primitive data.
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* The size of the cache of 64 is the smallest power of two for which I obtain a
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* significant time improvement over directly using lqueue, ie. one lqueue
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* element for each item in the queue. For a small problem sizes (~10) the
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* speed-up is 3x, for large problem sizes
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* (>1000) the speed-up is 7x.
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* ~0.5 operations/nsec */
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#define QUEUE_CACHE_SIZE 64
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#define QUEUE_DEFINE_TYPE(type, name) \
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struct name##_qcache_ { \
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struct lqueue_link qlink; \
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int begin, end; \
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type data[QUEUE_CACHE_SIZE]; \
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}; \
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static inline UNNEEDED bool name##_qcache_empty_( \
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const struct name##_qcache_ *qc) \
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{ \
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return qc->begin == qc->end; \
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} \
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/* UB if _qcache is empty */ \
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static inline UNNEEDED type name##_qcache_front_( \
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const struct name##_qcache_ *qc) \
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{ \
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return qc->data[qc->begin]; \
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} \
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static inline UNNEEDED type name##_qcache_pop_( \
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struct name##_qcache_ *qc) \
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{ \
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type r = name##_qcache_front_(qc); \
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qc->begin++; \
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if (qc->begin >= qc->end) { \
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qc->begin = qc->end = 0; \
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} \
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return r; \
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} \
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static inline UNNEEDED bool name##_qcache_insert_( \
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struct name##_qcache_ *qc, type element) \
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{ \
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if (qc->end == QUEUE_CACHE_SIZE) { \
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return false; \
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} \
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qc->data[qc->end++] = element; \
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return true; \
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} \
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static inline UNNEEDED void name##_qcache_init_( \
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struct name##_qcache_ *qc) \
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{ \
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qc->begin = qc->end = 0; \
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} \
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struct name { \
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const tal_t *ctx; \
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struct lqueue_ lq; \
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}; \
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static inline UNNEEDED bool name##_empty(const struct name *q) \
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{ \
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return lqueue_empty_(&q->lq); \
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} \
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static inline UNNEEDED type name##_front(const struct name *q) \
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{ \
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type r; \
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const struct name##_qcache_ *qc = \
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(const struct name##_qcache_ *)lqueue_front_(&q->lq); \
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if (qc) \
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r = name##_qcache_front_(qc); \
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return r; \
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} \
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static inline UNNEEDED type name##_pop(struct name *q) \
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{ \
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type r; \
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struct name##_qcache_ *qc = \
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(struct name##_qcache_ *)lqueue_front_(&q->lq); \
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if (qc) \
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r = name##_qcache_pop_(qc); \
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else \
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memset(&r, 0, sizeof(type)); \
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if (qc && name##_qcache_empty_(qc)) { \
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lqueue_dequeue_(&q->lq); \
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tal_free(qc); \
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} \
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return r; \
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} \
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static inline UNNEEDED void name##_init(struct name *q, \
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const tal_t *ctx) \
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{ \
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q->ctx = ctx; \
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lqueue_init_(&q->lq, NULL); \
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} \
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static inline UNNEEDED void name##_insert(struct name *q, \
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type element) \
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{ \
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struct name##_qcache_ *qc = \
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(struct name##_qcache_ *)lqueue_back_(&q->lq); \
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if (qc && name##_qcache_insert_(qc, element)) \
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return; \
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qc = tal(q->ctx, struct name##_qcache_); \
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name##_qcache_init_(qc); \
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name##_qcache_insert_(qc, element); \
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lqueue_enqueue_(&q->lq, (struct lqueue_link *)qc); \
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} \
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/* QUEUE_DEFINE_TYPE */
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#endif /* LIGHTNING_PLUGINS_ASKRENE_QUEUE_H */

‎plugins/askrene/test/run-queue.c

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#include "config.h"
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#include "../queue.h"
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#include <stdlib.h>
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/* a queue for int */
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QUEUE_DEFINE_TYPE(int, iqueue);
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int main(int argc, char *argv[])
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{
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int x;
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struct iqueue q;
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iqueue_init(&q, NULL);
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iqueue_insert(&q, 1);
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x = iqueue_pop(&q);
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assert(x == 1);
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iqueue_insert(&q, 2);
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x = iqueue_pop(&q);
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assert(x == 2);
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iqueue_insert(&q, 3);
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iqueue_insert(&q, 4);
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x = iqueue_pop(&q);
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assert(x == 3);
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x = iqueue_pop(&q);
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assert(x == 4);
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iqueue_insert(&q, 5);
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iqueue_insert(&q, 6);
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x = iqueue_pop(&q);
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assert(x == 5);
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iqueue_insert(&q, 7);
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x = iqueue_pop(&q);
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assert(x == 6);
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x = iqueue_pop(&q);
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assert(x == 7);
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for (int i = 1; i <= 10000; i++)
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iqueue_insert(&q, i);
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for (int i = 1; i <= 10000; i++) {
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x = iqueue_pop(&q);
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assert(x == i);
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}
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const int MAX_ITEM = 1000000;
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int expected_front = 1, next_insert = 1;
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do {
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if (iqueue_empty(&q) && next_insert > MAX_ITEM)
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break;
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if (iqueue_empty(&q)) {
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/* we can only insert */
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iqueue_insert(&q, next_insert++);
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} else if (next_insert > MAX_ITEM) {
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/* we can only pop */
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x = iqueue_pop(&q);
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assert(x == expected_front);
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expected_front++;
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} else {
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/* we can both insert and pop, throw a coin */
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if (rand() % 2) {
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iqueue_insert(&q, next_insert++);
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} else {
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x = iqueue_pop(&q);
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assert(x == expected_front);
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expected_front++;
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}
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}
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} while (1);
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return 0;
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}

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