PHP 计算 'downtime'

Question

我用 PHP 编写了一个程序，它在运行时存储在 MySQL 数据库中。显示程序是否正常工作的表格如下所示:

Table_name: downtime
Working(int)    Time(datetime)
1               2011-05-06 15:18:55
0               2011-05-06 15:20:21
1               2011-05-06 15:20:24
0               2011-05-06 16:05:13
1               2011-05-06 16:05:15
0               2011-05-06 16:27:59
1               2011-05-06 16:28:01
0               2011-05-06 16:37:35
1               2011-05-06 16:37:37

现在我想检索日期之间的“停机时间”。假设日期 1 是 2011-05-06 15:20:24，日期 2 是 2011-05-06 16:28:15，那么我希望脚本返回该期间 1 和 0 之间的差值之和.我该怎么做？

重要的是要知道如果日期 1 例如是 2011-05-06 15:20:22，则停机时间会增加两秒。很难想出(几乎)完美的解决方案。

Answer 1

这段代码应该可以工作，我已经用您的示例数据对其进行了测试:

// Example data
// Note: assumes $data is sorted by date already
$data = array(
    "2011-05-06 15:18:55"=>1,
    "2011-05-06 15:20:21"=>0,
    "2011-05-06 15:20:24"=>0,
    "2011-05-06 16:05:13"=>0,
    "2011-05-06 16:05:15"=>0,
    "2011-05-06 16:27:59"=>1,
    "2011-05-06 16:28:01"=>0,
    "2011-05-06 16:37:35"=>0,
    "2011-05-06 16:37:37"=>1
    );

$startTime = strtotime("2011-05-06 15:18:55");
$endTime = strtotime("2011-05-06 16:28:01");

$totalUptime = 0;    
$lastUptime = 0;

foreach ($data as $dateString => $isWorking)
{
    $timestamp = strtotime($dateString);

    if ($lastWorking && $lastTimestamp)
    {
        $allowedStart = $lastTimestamp;
        if ($allowedStart<$startTime)
            $allowedStart = $startTime;

        $allowedEnd = $timestamp;
        if ($allowedEnd>$endTime)
            $allowedEnd = $endTime;

        $diff = $allowedEnd-$allowedStart;

        if ($diff>0)
        {
            $totalUptime += $diff;
        }
    }

    if ($timestamp>=$endTime)
    {
        break;
    }

    $lastTimestamp = $timestamp;    
    $lastWorking = $isWorking;
}

print "Total uptime: ".$totalUptime." seconds";

您只需要用您自己的数据库记录填充$data。