cURL：空闲超时间隔超过指定值
我正在使用 libcurl 创建到服务器的 http 连接。在初始化期间，我指定了 5 秒的空闲超时值，并指定为进度回调函数。我原本期望 cURL 在 5 秒不活动后中止连接并停止调用进度回调，但我发现 cURL 在大约 15 秒后超时。为什么curl 超时的时间比我指定的要长？将超时设置为较大的值并没有帮助。如果我指定 100 秒，则在 105 秒不活动后超时。
code = s_curl_easy_setopt(m_curl_handle, CURLOPT_NOPROGRESS, 0);
assert(code == CURLE_OK);
code = s_curl_easy_setopt(m_curl_handle, CURLOPT_PROGRESSFUNCTION, progress_callback);
assert(code == CURLE_OK);
编辑：超时代码
//this will set the timeout for quitting in case the network goes down
code = s_curl_easy_setopt(m_curl_handle, CURLOPT_LOW_SPEED_LIMIT, 1);
code = s_curl_easy_setopt(m_curl_handle, CURLOPT_LOW_SPEED_TIME, m_idle_timeout);
I am using libcurl to create an http connection to a server. During initialization I have specified an idle timeout value of 5 seconds and also specified as progress callback function. I was expecting cURL to abort the connection after 5 seconds of inactivity and to stop calling the progress callback but I found that curl times out after around 15 seconds. Why is curl taking more time to timeout than I what I have specified? Setting timeout to a larger value does not help. If I specify 100 secs, it timesout after 105 secs of inactivity.
code = s_curl_easy_setopt(m_curl_handle, CURLOPT_NOPROGRESS, 0);
assert(code == CURLE_OK);
code = s_curl_easy_setopt(m_curl_handle, CURLOPT_PROGRESSFUNCTION, progress_callback);
assert(code == CURLE_OK);
EDIT: The timeout code
//this will set the timeout for quitting in case the network goes down
code = s_curl_easy_setopt(m_curl_handle, CURLOPT_LOW_SPEED_LIMIT, 1);
code = s_curl_easy_setopt(m_curl_handle, CURLOPT_LOW_SPEED_TIME, m_idle_timeout);
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我已经弄清楚了这一点。 cURL 大约每秒更新一次其进度。为了计算空闲超时，cURL 计算 6 次更新的平均字节/秒，并将其与
CURLOPT_LOW_SPEED_LIMIT进行比较。如果此值小于CURLOPT_LOW_SPEED_LIMIT的时间超过CURLOPT_LOW_SPEED_TIME秒，则会超时。因此，如果CURLOPT_LOW_SPEED_TIME为 5 秒，cURL 将计算最近 6 次进度更新（大约 5 秒）的平均字节/秒，然后检查它是否小于CURLOPT_LOW_SPEED_LIMIT至少 5 秒，因此总共需要约 20 分钟。 10秒。I have figured this one out. cURL updates its progress approximately one per second. To calculate idle timeout cURL calculates the average bytes/sec over 6 updates and compares it with the
CURLOPT_LOW_SPEED_LIMIT. If this value is less thanCURLOPT_LOW_SPEED_LIMITfor more thanCURLOPT_LOW_SPEED_TIMEseconds at a stretch, it times out. So if theCURLOPT_LOW_SPEED_TIMEis 5 seconds, cURL will calculate the average bytes/sec over the last 6 progress updates (approx 5 secs) and then check if it is less thanCURLOPT_LOW_SPEED_LIMITfor at least 5 seconds, thus taking total time of approx. 10 seconds.(1) 关于 PROGRESSFUNCTION 的 Libcurl 文档说：
(2) 您指的是哪个“超时”？我能找到的唯一一个与连接超时有关，这与建立连接后终止连接无关，并且没有发送数据 - 正如您似乎暗示的那样。
(1) Libcurl docs on the PROGRESSFUNCTION say:
(2) Which "timeout" are you referring to? The only one I could find related to a connection timeout, which would not pertain to terminating the connection after it was established, and no data was sent - as you seem to be implying.