Question

我编写了一个自由程序来从某个Web界面获取数据。像这样的代码：有时结构evhttp_request * req of self-＆gt; done为NULL。我无法找到原因。

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

（从你的问题来看，你得到NULL的地方并不完全清楚，但也许你的意思是这样的）
如果超时，传递给evhttp_request_new的回调可能会NULL。

evhttp_request_new（）evhttp_request返回null

1 个答案: