stellar-stellar/src/packet_io/packet_queue.cpp

#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>

#include "packet_io.h"
#include "packet_utils.h"
#include "packet_queue.h"

struct packet_queue
{
    uint64_t *queue;
    uint32_t size;
    uint32_t head;
    uint32_t tail;
};

struct packet_queue *packet_queue_new(uint32_t size)
{
    struct packet_queue *queue = (struct packet_queue *)calloc(1, sizeof(struct packet_queue));
    if (queue == NULL)
    {
        PACKET_IO_LOG_ERROR("unable to alloc packet queue");
        return NULL;
    }

    queue->queue = (uint64_t *)calloc(size, sizeof(uint64_t));
    if (queue->queue == NULL)
    {
        PACKET_IO_LOG_ERROR("unable to alloc packet queue buffer");
        free(queue);
        return NULL;
    }

    queue->size = size;
    queue->head = 0;
    queue->tail = 0;

    return queue;
}

void packet_queue_free(struct packet_queue *queue)
{
    if (queue == NULL)
    {
        return;
    }

    struct packet *pkt = NULL;
    while (1)
    {
        packet_queue_pop(queue, &pkt);
        if (pkt == NULL)
        {
            break;
        }
        packet_free(pkt);
    }

    if (queue->queue)
    {
        free(queue->queue);
        queue->queue = NULL;
    }

    free(queue);
}

void packet_queue_push(struct packet_queue *queue, struct packet *pkt)
{
    uint64_t wait = 1000;
retry:
    if (__sync_val_compare_and_swap(&queue->queue[queue->tail], 0, pkt) != 0)
    {
        PACKET_IO_LOG_ERROR("packet queue is full, retry later");
        usleep(wait);
        wait *= 2;
        goto retry;
    }

    queue->tail = (queue->tail + 1) % queue->size;
}

void packet_queue_pop(struct packet_queue *queue, struct packet **pkt)
{
    uint64_t read = ATOMIC_READ(&queue->queue[queue->head]);
    if (read == 0)
    {
        *pkt = NULL;
        return;
    }
    __sync_val_compare_and_swap(&queue->queue[queue->head], read, 0);
    *pkt = (struct packet *)read;
    queue->head = (queue->head + 1) % queue->size;
}