private function waitUntilRequestQuotaAvailable(){    $sleep_until = (float)($this->currentStartTime + $this->intervalSeconds);    $sleep_seconds = $sleep_until - microtime(true);    // Avoid using time_sleep_until() as it appears to be less precise and not sleep long enough.    usleep((int) $sleep_seconds * 1000000);    // Ensure that enough time has passed as usleep() may not have waited long enough.    $this->currentStartTime = microtime(true);    if ($this->currentStartTime < $sleep_until) {        do {            usleep(1000000 / 4);            $this->currentStartTime = microtime(true);        } while ($this->currentStartTime < $sleep_until);    }    $this->currentRequestCount = 0;}

private function waitUntilRequestQuotaAvailable(){    $sleep_until = (float)($this->currentStartTime + $this->intervalSeconds);    $sleep_seconds = $sleep_until - microtime(true);    // Avoid using time_sleep_until() as it appears to be less precise and not sleep long enough.    // Avoid using usleep(): "Values larger than 1000000 (i.e. sleeping for    //   more than a second) may not be supported by the operating system.    //   Use sleep() instead."    $sleep_seconds_int = (int)$sleep_seconds;    if ($sleep_seconds_int >= 1) {        sleep($sleep_seconds_int);    }    // Ensure that enough time has passed as usleep() may not have waited long enough.    $this->currentStartTime = microtime(true);    if ($this->currentStartTime < $sleep_until) {        do {            usleep(1000000 / 4);            $this->currentStartTime = microtime(true);        } while ($this->currentStartTime < $sleep_until);    }    $this->currentRequestCount = 0;}

private function waitUntilRequestQuotaAvailable(){    $sleep_until = (float) ($this->currentStartTime + $this->intervalSeconds);    $sleep_seconds = $sleep_until - microtime(true);    usleep((int) ($sleep_seconds * 1000000));    $this->currentStartTime = microtime(true);    $this->currentRequestCount = 0;}