Curl is very powerful and takes a lot of arguments. Not only is it used on the command line, but there are extensions of curl in PHP, and the libcurl library is well supported.
Curl projects: github.com/curl/curl
Curl specifies parameters for time control and retries
curl --help
--connect-timeout SECONDS Maximum time allowed for connection
-m, --max-time SECONDS Maximum time allowed for the transfer
...
--retry NUM Retry request NUM times if transient problems occur
--retry-delay SECONDS Wait SECONDS between retries
--retry-max-time SECONDS Retry only within this period
Copy the codeThe above is a part of the parameters related to time that I sorted out, so let’s experiment in turn.
Connection timeout parameter connect-timeout
instructions
--connect-timeout SECONDS Maximum time allowed for connection
Copy the codeThe sample
# Here we set the timeout to 2s and request an address that cannot be resolved
curl --connect-timeout 2 --url http://xxx.com
curl: (28) Connection timed out after 2002 milliseconds
Copy the codeDisplay connection timeout, timeout time 2002 ms. Note that the duration of this warning may vary from count to count and is usually a little longer than our preset value.
# For a high return time requirement, you can set floating-point accuracy to millisecondsCurl --connect-timeout 0.3 -- URL http://xxx.com curl: (28) Connection timed out after 300 millisecondsCopy the codeRequest timeout –max-time
instructions
-m, --max-time SECONDS Maximum time allowed for the transfer
Copy the codeThe sample
# Here we set the timeout to 2s, sleep 2 in the application
curl --max-time 2 --url http://www.shuai.com
curl: (28) Operation timed out after 2002 milliseconds with 0 bytes received
Copy the codeConnect-time and max-time are used together:
# Here we used an unresolvable address
curl --connect-time 3 --max-time 2 --url http://xxx.com
> curl: (28) Connection timed out after 2001 milliseconds
curl --connect-time 3 --max-time 4 --url http://xxx.com
> curl: (28) Operation timed out after 4002 milliseconds with 0 bytes received
Copy the codeHere we find that the return result is a connection timeout of 2001 milliseconds. When used together, the connection is the minimum time, and the return time is the max-time limit.
Request retry retry
instructions
--retry NUM Retry request NUM times if transient problems occur
Copy the codeThe sample
Again, let's ask for an address for Sleep 2Curl --max-time 0.1 --retry 3 -- URL http://www.shuai.com > Warning: Transient problem: timeout Will retryin 1 seconds. 3 retries left.
> Warning: Transient problem: timeout Will retry in 2 seconds. 2 retries left.
> Warning: Transient problem: timeout Will retry in 4 seconds. 1 retries left.
> curl: (28) Operation timed out after 100 milliseconds with 0 bytes received
Copy the codeWe found that three retries were made, but not immediately after failure, but 1 s after the first retry, 2 s after the second retry, 4 s after the third retry, and so on (each retry is limited by max-time).
Retry timeout retry-max-time
We find that our max-time only restricts the time of a single request, thereby affecting the total retry time, but what if we want to complete the retry in unit time? Curl also provides a retry-max-time timeout for retries
Curl --retry 3 --retry-max-time 2 --max-time 0.1 -- URL http://www.shuai.com > Warning: Transient problem: timeout Will retryin 1 seconds. 3 retries left.
> Warning: Transient problem: timeout Will retry in 2 seconds. 2 retries left.
> curl: (28) Operation timed out after 101 milliseconds with 0 bytes received
Copy the codeWe configured three retries with a total timeout of 2 seconds, but the timeout ended after only two retries.
Retry delay Retry-delay
As we discussed in request retries, instead of retries immediately after failure, the default retry time is incremental, and we can use retry-delay to control the retry interval.
# Here we set the retry time to 5s and retry 3 timesCurl --retry 3 --retry-delay 5 --max-time 0.1 -- URL http://xxx.com > Warning: Transient problem: timeout Will retryin 5 seconds. 3 retries left.
> Warning: Transient problem: timeout Will retry in 5 seconds. 2 retries left.
> Warning: Transient problem: timeout Will retry in 5 seconds. 1 retries left.
> curl: (28) Connection timed out after 101 milliseconds
Copy the codeWe find that Will retry in becomes 5 s per time
PHP uses the Guzzle package
The Guzzle is a PHP HTTP client for sending requests easily and integrating them into our WEB service.
Fast installation
{
"require": {
"guzzlehttp/guzzle": "6.0 ~ 5.3 | ~"
},
"repositories": {
"packagist": {
"type": "composer"."url": "https://mirrors.aliyun.com/composer/"}}}Copy the codePerform composer
composer install
Copy the codeSample code (timeout mechanism)
require "./vendor/autoload.php";
$client = new GuzzleHttp\Client();
$res = $client->request('GET'.'http://xxx.com'['connect_timeout'= > 3,'timeout'= > 2,]);echo $res->getBody() . PHP_EOL;
Copy the codeThe output:
PHP Fatal error: Uncaught GuzzleHttp\Exception\ConnectException:
cURL error 28: Connection timed out after 2002 milliseconds
(see https://curl.haxx.se/libcurl/c/libcurl-errors.html)
....
Copy the codeWe have configured a connect_TIMEOUT timeout period of 3 s and a timeout period of 2 s
Guzzle retry mechanism
The retry mechanism is a bit cumbersome and needs to be implemented using Middleware, but it’s easy to understand
require "./vendor/autoload.php";
$handlerStack= GuzzleHttp\HandlerStack::create(); // Bind middleware and retry three times$restryCount = 3;
$handlerStack->push(\GuzzleHttp\Middleware::retry(function () use (&$restryCount) {
if (--$restryCount< = 0) {return false;
}
return true;
}, function () use ($restryCount) {
return1000; / / ms}));$client = new GuzzleHttp\Client(['handler'= >$handlerStack]);
$res = $client->request('GET'.'http://xxx.xxx.com'['connect_timeout'= > 3,'timeout'= > 2,]);echo $res->getBody() . PHP_EOL;
Copy the codeWhen defining the retry time, you need to implement policies such as whether to continue retry and when to retry, providing great retry flexibility.
Note that curl retries in seconds, whereas this is set to milliseconds.