Michael Cook
6dd80ffd2f
Synchronized with emane.git's implementation of this code which includes a unit test. This commit also fixes two bugs in unqueue_matching and one inb unqueue: - unqueue_matching was returning the wrong pointer when there was no match - both unqueue_matching and unqueue were not clearing the vacated queue entry after removing the item
62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
/*
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queue_t is a basic thread-safe non-blocking fixed-size queue.
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put_queue returns false if the queue is full.
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get_queue returns NULL if the queue is empty.
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Example usage:
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// Initialization:
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queue_t fooq;
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init_queue(&fooq);
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// Producer:
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foo_t *item = new_foo();
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if (!put_queue(&fooq, item))
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delete_foo(item);
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// Consumer:
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foo_t *item = get_queue(&fooq);
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if (item)
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{
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do_something_with_foo(item);
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delete_foo(item);
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}
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*/
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#pragma once
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#include <stdbool.h>
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#include <stdint.h>
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#include <pthread.h>
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#define MAX_QUEUE_SIZE 512
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typedef struct queue_t
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{
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void *items[MAX_QUEUE_SIZE];
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size_t read_index, write_index;
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size_t num_items;
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pthread_mutex_t mutex;
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} queue_t;
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void init_queue(queue_t *q);
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bool put_queue(queue_t *q, void *item);
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void *get_queue(queue_t *q);
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/* Put the given item back onto this queue at the head.
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(The next call to put_queue would return this item.)
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Return true if successful, false if the queue was full */
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bool requeue(queue_t *q, void *item);
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/* Remove the last item queued.
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Return the item or NULL if the queue was empty */
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void *unqueue(queue_t *q);
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typedef bool queue_matcher_t(void *wanted, void *candidate);
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/* Unqueue the most recently queued item for watch `matcher(wanted, candidate)`
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returns true where `candidate` is an item currently on the queue.
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Returns the candidate item, or NULL if none matches */
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void *unqueue_matching(queue_t *q, queue_matcher_t *matcher, void *wanted);
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