4.x is outdated, please check the latest version 22.x

Latest version: pecl install openswoole-22.1.2


<?php Swoole\Coroutine\Client->peek(int $length = 65535): string



The total length of data to read, in bytes.


Returns false if there is no data to be returned from the buffer, if there is content to be read from the cache, then the data is returned as a string. See description for more details.


The peek method is used to read only part of the data, you can specify how much using the $length parameter.

When calling this method, it is non-blocking, it returns immediately, you can use recv() to still read the same data, However, calling peek allows you to read data directly from the kernel socket cache buffer, when the buffer has data it will return it immediately, if it doesn't false is returned to indicate no data is currently available in the buffer. An empty string is returned when the connection has been closed.

Calling this method does not cause coroutines to be switched/scheduled as this method returns immediately.



use Swoole\Coroutine\Client;

    $client = new Client(SWOOLE_SOCK_TCP);

    if(!$client->connect('', 9501, 0.5))
        echo "Connection failed with error: {$client->errCode}\n";

    // Should not rely on this 100%, see description as to why
    if($client->isConnected() === false)
        echo "Connection failed with error: {$client->errCode}\n";

    $client->send("Hello World! - from Swoole\n");

    if($data = $client->peek())

    echo $client->recv();

Last updated on August 31, 2022