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//
// Copyright 2021 Staysail Systems, Inc. <info@staysail.tech>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
#include "nng_impl.h"
// Light-weight message queue. These are derived from our heavy-weight
// message queues, but are less "featured", but more useful for
// performance sensitive contexts. Locking must be done by the caller.
// Note that initialization of a queue is guaranteed to succeed.
// However, if the requested capacity is larger than 2, and memory
// cannot be allocated, then the capacity will only be 2.
void
nni_lmq_init(nni_lmq *lmq, size_t cap)
{
lmq->lmq_len = 0;
lmq->lmq_get = 0;
lmq->lmq_put = 0;
lmq->lmq_alloc = 0;
lmq->lmq_mask = 0;
lmq->lmq_msgs = NULL;
lmq->lmq_msgs = lmq->lmq_buf;
lmq->lmq_cap = 2;
lmq->lmq_mask = 0x1; // only index 0 and 1
if (cap > 2) {
(void) nni_lmq_resize(lmq, cap);
} else {
lmq->lmq_cap = cap;
}
}
void
nni_lmq_fini(nni_lmq *lmq)
{
if (lmq == NULL) {
return;
}
/* Free any orphaned messages. */
while (lmq->lmq_len > 0) {
nng_msg *msg = lmq->lmq_msgs[lmq->lmq_get++];
lmq->lmq_get &= lmq->lmq_mask;
lmq->lmq_len--;
nni_msg_free(msg);
}
if (lmq->lmq_alloc > 0) {
nni_free(lmq->lmq_msgs, lmq->lmq_alloc * sizeof(nng_msg *));
}
}
void
nni_lmq_flush(nni_lmq *lmq)
{
while (lmq->lmq_len > 0) {
nng_msg *msg = lmq->lmq_msgs[lmq->lmq_get++];
lmq->lmq_get &= lmq->lmq_mask;
lmq->lmq_len--;
nni_msg_free(msg);
}
}
size_t
nni_lmq_len(nni_lmq *lmq)
{
return (lmq->lmq_len);
}
size_t
nni_lmq_cap(nni_lmq *lmq)
{
return (lmq->lmq_cap);
}
bool
nni_lmq_full(nni_lmq *lmq)
{
return (lmq->lmq_len >= lmq->lmq_cap);
}
bool
nni_lmq_empty(nni_lmq *lmq)
{
return (lmq->lmq_len == 0);
}
int
nni_lmq_put(nni_lmq *lmq, nng_msg *msg)
{
if (lmq->lmq_len >= lmq->lmq_cap) {
return (NNG_EAGAIN);
}
lmq->lmq_msgs[lmq->lmq_put++] = msg;
lmq->lmq_len++;
lmq->lmq_put &= lmq->lmq_mask;
return (0);
}
int
nni_lmq_get(nni_lmq *lmq, nng_msg **mp)
{
nng_msg *msg;
if (lmq->lmq_len == 0) {
return (NNG_EAGAIN);
}
msg = lmq->lmq_msgs[lmq->lmq_get++];
lmq->lmq_get &= lmq->lmq_mask;
lmq->lmq_len--;
*mp = msg;
return (0);
}
int
nni_lmq_resize(nni_lmq *lmq, size_t cap)
{
nng_msg *msg;
nng_msg **new_q;
size_t alloc;
size_t len;
alloc = 2;
while (alloc < cap) {
alloc *= 2;
}
if ((new_q = nni_alloc(sizeof(nng_msg *) * alloc)) == NULL) {
return (NNG_ENOMEM);
}
len = 0;
while ((len < cap) && (nni_lmq_get(lmq, &msg) == 0)) {
new_q[len++] = msg;
}
// Flush anything left over.
nni_lmq_flush(lmq);
if (lmq->lmq_alloc > 0) {
nni_free(lmq->lmq_msgs, lmq->lmq_alloc * sizeof(nng_msg *));
}
lmq->lmq_msgs = new_q;
lmq->lmq_cap = cap;
lmq->lmq_alloc = alloc;
lmq->lmq_mask = alloc - 1;
lmq->lmq_len = len;
lmq->lmq_put = len;
lmq->lmq_get = 0;
return (0);
}
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