mirror of
https://github.com/cesanta/mongoose.git
synced 2024-12-28 07:28:13 +08:00
41 lines
1.5 KiB
C
41 lines
1.5 KiB
C
|
#include "queue.h"
|
||
|
|
|
||
|
|
// Every message in the queue is prepended by the message length (ML)
|
||
|
|
// ML is sizeof(size_t) in size
|
||
|
|
// Tail points to the message data
|
||
|
|
//
|
||
|
|
// |------| ML | message1 | ML | message2 |--- free space ---|
|
||
|
|
// ^ ^ ^ ^
|
||
|
|
// buf tail head len
|
||
|
|
|
||
|
|
size_t mg_queue_space(struct mg_queue *q, char **buf) {
|
||
|
|
size_t ofs;
|
||
|
|
if (q->head > 0 && q->tail >= q->head) { // All messages read?
|
||
|
|
q->head = 0; // Yes. Reset head first
|
||
|
|
q->tail = 0; // Now reset the tail
|
||
|
|
}
|
||
|
|
ofs = q->head + sizeof(size_t);
|
||
|
|
if (buf != NULL) *buf = q->buf + ofs;
|
||
|
|
return ofs > q->len ? 0 : q->len - ofs;
|
||
|
|
}
|
||
|
|
|
||
|
|
size_t mg_queue_next(struct mg_queue *q, char **buf) {
|
||
|
|
size_t len = MG_QUEUE_EMPTY;
|
||
|
|
if (q->tail < q->head) memcpy(&len, &q->buf[q->tail], sizeof(len));
|
||
|
|
if (buf != NULL) *buf = &q->buf[q->tail + sizeof(len)];
|
||
|
|
return len;
|
||
|
|
}
|
||
|
|
|
||
|
|
void mg_queue_add(struct mg_queue *q, size_t len) {
|
||
|
|
size_t head = q->head + len + (size_t) sizeof(head); // New head
|
||
|
|
if (head <= q->len) { // Have space ?
|
||
|
|
memcpy(q->buf + q->head, &len, sizeof(len)); // Yes. Store ML
|
||
|
|
q->head = head; // Advance head
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void mg_queue_del(struct mg_queue *q) {
|
||
|
|
size_t len = mg_queue_next(q, NULL), tail = q->tail + len + sizeof(size_t);
|
||
|
|
if (len != MG_QUEUE_EMPTY) q->tail = tail;
|
||
|
|
}
|