I did this
I send a simple GET request. After receiving the response, I print CURLINFO_PRETRANSFER_TIME_T and CURLINFO_POSTTRANSFER_TIME_T, as well as the difference between them. Here is my code:
CURL* curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
CURLcode res = curl_easy_perform(curl);
if (res != CURLE_OK)
{
curl_easy_cleanup(curl);
return 1;
}
curl_off_t pretransfer = 0;
curl_off_t posttransfer = 0;
curl_easy_getinfo(curl, CURLINFO_PRETRANSFER_TIME_T, &pretransfer);
curl_easy_getinfo(curl, CURLINFO_POSTTRANSFER_TIME_T, &posttransfer);
std::cout << "PRETRANSFER_TIME_T: " << pretransfer << " microseconds\n";
std::cout << "POSTTRANSFER_TIME_T: " << posttransfer << " microseconds\n";
std::cout << "DIFF: " << (posttransfer - pretransfer) << " microseconds\n";
curl_easy_cleanup(curl);I expected the following
I expect that CURLINFO_PRETRANSFER_TIME_T should always be less than CURLINFO_POSTTRANSFER_TIME_T, and the difference between them should always be positive.
However, when sending simple GET requests, I get a CURLINFO_POSTTRANSFER_TIME_T value that is less than the CURLINFO_PRETRANSFER_TIME_T value. How is this possible? This shouldn't happen. Please correct me if I wrong.
Note:
I consider CURLINFO_PRETRANSFER_TIME_T to be the time when libcurl is about to send its first byte to the server, and CURLINFO_POSTTRANSFER_TIME_T to be the time when libcurl sent the last byte to the server. Is my understanding correct?
However, if I send a POST request that sends a file to a remote server, I always get the correct result: CURLINFO_PRETRANSFER_TIME_T < CURLINFO_POSTTRANSFER_TIME_T
curl/libcurl version
libcurl 8.20.0,
operating system
OS: Windows 11, x64
Compiler MSVC (Visual Studio 2022, C++ Project)
I did this
I send a simple GET request. After receiving the response, I print CURLINFO_PRETRANSFER_TIME_T and CURLINFO_POSTTRANSFER_TIME_T, as well as the difference between them. Here is my code:
I expected the following
I expect that CURLINFO_PRETRANSFER_TIME_T should always be less than CURLINFO_POSTTRANSFER_TIME_T, and the difference between them should always be positive.
However, when sending simple GET requests, I get a CURLINFO_POSTTRANSFER_TIME_T value that is less than the CURLINFO_PRETRANSFER_TIME_T value. How is this possible? This shouldn't happen. Please correct me if I wrong.
Note:
I consider CURLINFO_PRETRANSFER_TIME_T to be the time when libcurl is about to send its first byte to the server, and CURLINFO_POSTTRANSFER_TIME_T to be the time when libcurl sent the last byte to the server. Is my understanding correct?
However, if I send a POST request that sends a file to a remote server, I always get the correct result: CURLINFO_PRETRANSFER_TIME_T < CURLINFO_POSTTRANSFER_TIME_T
curl/libcurl version
libcurl 8.20.0,
operating system
OS: Windows 11, x64
Compiler MSVC (Visual Studio 2022, C++ Project)