Select in PHP

PHP doesn’t have built-in support for concurrent programming like goroutines and channels. However, we can simulate similar behavior using multi-threading with the pthreads extension or using asynchronous programming with libraries like ReactPHP. For this example, we’ll use a simplified approach with sleep() to simulate concurrent operations.

<?php

// For our example we'll use two functions to simulate channels.
function channel1() {
    sleep(1);
    return "one";
}

function channel2() {
    sleep(2);
    return "two";
}

// We'll use an array to store our "channels"
$channels = [
    'c1' => 'channel1',
    'c2' => 'channel2'
];

// We'll use select to await both of these values
// simultaneously, printing each one as it arrives.
for ($i = 0; $i < 2; $i++) {
    $start = microtime(true);
    $result = [];
    
    // Simulate select behavior
    while (empty($result)) {
        foreach ($channels as $key => $channel) {
            if ($channel() !== null) {
                $result[$key] = $channel();
                break;
            }
        }
    }
    
    $end = microtime(true);
    $executionTime = $end - $start;
    
    echo "received " . reset($result) . "\n";
    echo "Execution time: " . number_format($executionTime, 3) . " seconds\n";
    
    // Remove the completed "channel" from the array
    unset($channels[key($result)]);
}

To run the program, save it as select.php and use the PHP CLI:

$ php select.php
received one
Execution time: 1.001 seconds
received two
Execution time: 2.001 seconds

Note that the total execution time is approximately 3 seconds because PHP executes sequentially by default. To achieve true concurrency in PHP, you would need to use multi-threading or asynchronous programming libraries.

This example demonstrates how we can simulate the behavior of selecting from multiple channels in PHP. However, it’s important to note that this is not an exact equivalent to Go’s select statement, as PHP doesn’t have built-in support for concurrent operations in the same way Go does.

For more advanced concurrent programming in PHP, you might want to explore libraries like ReactPHP or Amp, which provide event-driven, non-blocking I/O paradigms.