Run a task in the background

# GearmanClient::doBackground

(PECL gearman >= 0.5.0)

GearmanClient::doBackground — Run a task in the background

### 说明

public function GearmanClient::doBackground(string `$function`, string `$workload`, ?string `$unique` = `null`): string

Runs a task in the background, returning a job handle which can be used to get the status of the running task.

### 参数

`function`
  由程序自动执行的已注册函数。
`workload`
  被处理的序列化数据。
`unique`
  用于标识特定任务的唯一性 ID。

### 返回值

The job handle for the submitted task.

### 示例

示例 #1 Submit and monitor a background job

The worker in this example has an artificial delay introduced to mimic a long running job. The client script periodically checks the status of the running job.

    <?php

    /* create our object */
    $gmclient= new GearmanClient();

    /* add the default server */
    $gmclient->addServer();

    /* run reverse client */
    $job_handle = $gmclient->doBackground("reverse", "this is a test");

    if ($gmclient->returnCode() != GEARMAN_SUCCESS)
    {
      echo "bad return code\n";
      exit;
    }

    $done = false;
    do
    {
       sleep(3);
       $stat = $gmclient->jobStatus($job_handle);
       if (!$stat[0]) // the job is known so it is not done
          $done = true;
       echo "Running: " . ($stat[1] ? "true" : "false") . ", numerator: " . $stat[2] . ", denominator: " . $stat[3] . "\n";
    }
    while(!$done);

    echo "done!\n";

    ?>

以上示例的输出类似于：

    Running: true, numerator: 3, denominator: 14
    Running: true, numerator: 6, denominator: 14
    Running: true, numerator: 9, denominator: 14
    Running: true, numerator: 12, denominator: 14
    Running: false, numerator: 0, denominator: 0
    done!

### 参见

- GearmanClient::doNormal() - Run a single task and return a result
- GearmanClient::doHigh() - Run a single high priority task
- GearmanClient::doLow() - Run a single low priority task
- GearmanClient::doHighBackground() - Run a high priority task in the background
- GearmanClient::doLowBackground() - Run a low priority task in the background

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