evhttp_request_new() evhttp_request返回null

Question

我写了一个libevet程序来从某个web界面获取数据。代码如下:有时候self->done的结构evhttp_request *req是空的。我找不到这是为什么。

response->connecttime = spi_utils_float_time();
self->evreq = evhttp_request_new(self->done, task);
if (self->evreq == NULL) {
    SPI_LOG_ERROR("spider", "cannot create evhttp_request");
    goto download_error;
}

/* bson_print(&task->task); */

/** set header and body */
/* TODO: set timeout */
spi_http_request_split_header(self, self->header->str, self->evreq);
if (self->body != NULL)
    evbuffer_add_printf(self->evreq->output_buffer, (const char*)self->body->str);

    if (self->method == spi_http_post)
            cmd_type = EVHTTP_REQ_POST;

self->evcon = evhttp_connection_new(self->host->str, self->port);
if (self->evcon == NULL) {
    SPI_LOG_ERROR("spider", "evhttp_connection_new Failed!\n");
    goto download_error;
}

SPI_LOG_DEBUG("spider", "set retries: %d.", 5);
evhttp_connection_set_retries(self->evcon, 3);
SPI_LOG_DEBUG("spider", "set timeout: %d.", 60);
evhttp_connection_set_timeout(self->evcon, 20);

response->connectedtime = spi_utils_float_time();

response->crawltime = spi_utils_float_time();

SPI_LOG_DEBUG("spider", "evhttp_make_request");
if (evhttp_make_request(self->evcon, self->evreq, cmd_type, self->path->str) == -1) {
    SPI_LOG_ERROR("spider", "evhttp_make_request Failed.\n");
    goto download_error;
}

Answer 1

(从你的问题看，不完全清楚你是从哪里得到NULL的，但你的意思可能是)

如果超时，传递给evhttp_request_new的回调可能会得到NULL。