http2session.ping([payload, ]callback)

• payload <Buffer> | <TypedArray> | <DataView> 可选的 ping 负载。
• callback <Function>
• 返回: <boolean>

向连接的 HTTP/2 对等方发送 PING 帧。 必须提供 callback 函数。 如果发送了 PING，则该方法将返回 true，否则返回 false。

未完成的（未确认的）ping 的最大数量由 maxOutstandingPings 配置选项决定。 默认最大值为 10。

如果提供，则 payload 必须是 Buffer、TypedArray 或 DataView，其中包含 8 个字节的数据，这些数据将与 PING 一起传输并与 ping 确认一起返回。

回调将使用三个参数调用：一个错误参数（如果 PING 被成功确认，则它将是 null），一个 duration 参数（报告自发送 ping 和收到确认以来经过的毫秒数），以及一个 Buffer（包含 8 字节 PING 有效载荷）。

session.ping(Buffer.from('abcdefgh'), (err, duration, payload) => {
  if (!err) {
    console.log(`Ping acknowledged in ${duration} milliseconds`);
    console.log(`With payload '${payload.toString()}'`);
  }
});

如果未指定 payload 参数，则默认负载将是标记 PING 持续时间开始的 64 位时间戳（小端）。

• payload <Buffer> | <TypedArray> | <DataView> Optional ping payload.
• callback <Function>
• Returns: <boolean>

Sends a PING frame to the connected HTTP/2 peer. A callback function must be provided. The method will return true if the PING was sent, false otherwise.

The maximum number of outstanding (unacknowledged) pings is determined by the maxOutstandingPings configuration option. The default maximum is 10.

If provided, the payload must be a Buffer, TypedArray, or DataView containing 8 bytes of data that will be transmitted with the PING and returned with the ping acknowledgment.

The callback will be invoked with three arguments: an error argument that will be null if the PING was successfully acknowledged, a duration argument that reports the number of milliseconds elapsed since the ping was sent and the acknowledgment was received, and a Buffer containing the 8-byte PING payload.

session.ping(Buffer.from('abcdefgh'), (err, duration, payload) => {
  if (!err) {
    console.log(`Ping acknowledged in ${duration} milliseconds`);
    console.log(`With payload '${payload.toString()}'`);
  }
});

If the payload argument is not specified, the default payload will be the 64-bit timestamp (little endian) marking the start of the PING duration.