2 * Copyright (C) 2007-2009 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file chunk_queue.c Queuing functions for paraslash senders. */
17 * Senders may use the chunk queue facility to deal with laggy connections. It
18 * allows them to enqueue chunks if they can not be sent out immediately.
20 * Chunk queues are "cheap" in the sense that only reference to the audio file
21 * data is stored, but not the data itself.
24 /** The list of pending chunks for this client. */
26 /** The number of pending bytes for this client. */
27 unsigned long num_pending;
28 /** More than that many bytes in the queue is considered an error. */
29 unsigned long max_pending;
32 /** Describes one queued chunk in a chunk queue. */
34 /** Pointer to the data to be queued. */
36 /** The number of bytes of this chunk. */
38 /** Position of the chunk in the chunk queue. */
39 struct list_head node;
43 * Add a chunk to the given queue.
45 * \param cq the queue to add the chunk to.
46 * \param buf Pointer to the data to be queued.
47 * \param num_bytes The size of \a buf.
51 int cq_enqueue(struct chunk_queue *cq, const char *buf, size_t num_bytes)
53 struct queued_chunk *qc;
55 if (cq->num_pending + num_bytes > cq->max_pending)
57 qc = para_malloc(sizeof(struct queued_chunk));
58 cq->num_pending += num_bytes;
60 qc->num_bytes = num_bytes;
61 list_add_tail(&qc->node, &cq->q);
62 PARA_DEBUG_LOG("%lu bytes queued for %p\n", cq->num_pending, &cq->q);
67 * Lookup the next chunk in the queue.
69 * \param cq The chunk queue.
71 * \return The next queued chunk, or \p NULL if there is no chunk available.
73 struct queued_chunk *cq_peek(struct chunk_queue *cq)
75 if (list_empty(&cq->q))
77 return list_entry(cq->q.next, struct queued_chunk, node);
81 * Remove the current chunk from the queue.
83 * \param cq The queue to remove from.
85 void cq_dequeue(struct chunk_queue *cq)
87 struct queued_chunk *qc = cq_peek(cq);
89 assert(cq->num_pending >= qc->num_bytes);
90 cq->num_pending -= qc->num_bytes;
96 * Change the number of bytes sent for the current queued chunk.
98 * \param cq The chunk queue.
99 * \param sent Number of bytes successfully sent.
101 void cq_update(struct chunk_queue *cq, size_t sent)
103 struct queued_chunk *qc = cq_peek(cq);
105 qc->num_bytes -= sent;
107 cq->num_pending -= sent;
111 * Get a pointer to the given queued chunk.
113 * \param qc The queued chunk.
114 * \param buf Result pointer.
115 * \param num_bytes Number of bytes of \a buf.
117 * \return Positive on success, negative on errors.
119 int cq_get(struct queued_chunk *qc, const char **buf, size_t *num_bytes)
122 *num_bytes = qc->num_bytes;
127 * Allocate and initialize a chunk queue.
129 * \param max_pending Maximal number of bytes that will be queued.
131 * \return A pointer to the new queue.
133 struct chunk_queue *cq_new(size_t max_pending)
135 struct chunk_queue *cq = para_malloc(sizeof(*cq));
136 INIT_LIST_HEAD(&cq->q);
137 cq->max_pending = max_pending;
143 * Deallocate all resources of this queue.
145 * \param cq The chunk queue.
147 void cq_destroy(struct chunk_queue *cq)
149 struct queued_chunk *qc, *tmp;
150 list_for_each_entry_safe(qc, tmp, &cq->q, node) {