如何等待curl（php）执行3秒..？

Question

$testingURL = "https://www.testing.com?......";
do {
    $lastData = "";
    curl_setopt($ch, CURLOPT_URL,$testingURL);
    curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (AppleWebKit/537.3e/37.0.2062.124 Safari/537.36.....");
    curl_setopt($ch, CURLOPT_POST, 1); 
    curl_setopt($ch, CURLOPT_POSTFIELDS, 'username=testuser&password=testpwd'); 
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
    curl_setopt($ch, CURLOPT_COOKIEFILE, $cookie_file);
    curl_setopt($ch, CURLOPT_COOKIEJAR, $cookie_file);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers_curl);
    curl_setopt($ch, CURLOPT_REFERER, "www.test...com");
    $result = curl_exec($ch);
    // sleep(3);
    preg_match_all('/name="_checkkey".*?<\/td>/s',$result,$lastData);
    $lastData[1] = preg_replace('/[^a-zA-Z0-9_ %\[\]\.\(\)%&-]/s', '', $lastData[1]);
    $testingURL = "https://www.testing.com?_chkKey=".$lastData[1][0]."&chiId=".$lastData[1][1];

} while (isset($lastData[1][1]) && $lastData[1][1] == "checkOneMoreTime");

(Note : in my code i want to stop my execution upto 3 seconds

if i give sleep(3) (will it work), in $testingURL will test 2 to 3 seconds and then form will submit, at the same time me too want execute loop again,

Answer 1

do {
$lastData = "";
$result = "";
curl_setopt($ch, CURLOPT_URL,$testingURL);
curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (AppleWebKit/537.3e/37.0.2062.124 Safari/537.36.....");
curl_setopt($ch, CURLOPT_POST, 1); 
curl_setopt($ch, CURLOPT_POSTFIELDS, 'username=testuser&password=testpwd'); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_COOKIEFILE, $cookie_file);
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookie_file);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers_curl);
curl_setopt($ch, CURLOPT_REFERER, "www.test...com");
$result = curl_exec($ch);
sleep(3);
$testingURL = "";
preg_match_all('/name="_checkkey".*?<\/td>/s',$result,$lastData);
$lastData[1] = preg_replace('/[^a-zA-Z0-9_ %\[\]\.\(\)%&-]/s', '', $lastData[1]);
$testingURL = "https://www.testing.com?_chkKey=".$lastData[1][0]."&chiId=".$lastData[1][1];    }    while (isset($lastData[1][1]) && $lastData[1][1] == "checkOneMoreTime");