英文:
PHP Fibers return null values
问题
运行以下代码时，返回空值。我已经使用协程运行了该代码，并且使用的PHP版本是8.2。
期望输出：
Array
(
[0] => "A"
[1] => "B"
[2] => "C"
)
但在运行上述代码时，返回以下输出：
Array
(
[0] =>
[1] =>
[2] =>
)
英文:
While running below code, it return empty values. I have used fibers to run the code and used PHP version is 8.2
<?php
$data=["A","B","C"];
$fibers = [];
foreach ($data as $val) {
$fiber = new Fiber(function () use ($val): void {
Fiber::suspend($val);
});
$fiber->start();
$fibers[] = $fiber;
}
$results = [];
foreach ($fibers as $fiber) {
$results[] = $fiber->resume();
}
print_r($results);
?>
Expected Output
Array
(
[0] =>"A"
[1] =>"B"
[2] =>"C"
)
While running above code return this output
Array
(
[0] =>
[1] =>
[2] =>
)
答案1
得分: 1
$fiber->start();调用会消耗掉你的$val。根据文档，start()的返回值是第一个Fiber::suspend()调用传递的变量，如果函数返回了null，则返回null。resume()也是一样的，所以你对start()的调用已经返回了$val，然后就没有留下东西给resume()了。
你想要的结果可以通过以下代码实现：
<?php
$data=["A","B","C"];
$fibers = [];
foreach ($data as $val) {
$fiber = new Fiber(function () use ($val): void {
Fiber::suspend();
Fiber::suspend($val);
});
$fiber->start();
$fibers[] = $fiber;
}
$results = [];
foreach ($fibers as $fiber) {
$results[] = $fiber->resume();
}
print_r($results);
?>
以下是一种在仍然使用Fiber的情况下进行重写的建议：
<?php
$data=["A","B","C"];
$fibers = [];
$callback = function ($val): string {
Fiber::suspend();
return $val;
};
foreach ($data as $val) {
$fiber = new Fiber($callback);
$fiber->start($val);
$fibers[] = $fiber;
}
$results = [];
foreach ($fibers as $fiber) {
$fiber->resume();
$results[] = $fiber->getReturn();
}
print_r($results);
?>
英文:
The call to $fiber->start(); consumes your $val.
As per documentation the return value of start() is the variable given to the first Fiber::suspend() call or null if the function returned. resume() does the same, so your call to start() already returned $val and then there is nothing left for resume().
The result you want would be achieved with this code:
<?php
$data=["A","B","C"];
$fibers = [];
foreach ($data as $val) {
$fiber = new Fiber(function () use ($val): void {
Fiber::suspend();
Fiber::suspend($val);
});
$fiber->start();
$fibers[] = $fiber;
}
$results = [];
foreach ($fibers as $fiber) {
$results[] = $fiber->resume();
}
print_r($results);
?>
And here a suggestion for a rewrite while still using Fiber:
<?php
$data=["A","B","C"];
$fibers = [];
$callback = function ($val): string {
Fiber::suspend();
return $val;
};
foreach ($data as $val) {
$fiber = new Fiber($callback);
$fiber->start($val);
$fibers[] = $fiber;
}
$results = [];
foreach ($fibers as $fiber) {
$fiber->resume();
$results[] = $fiber->getReturn();
}
print_r($results);
?>
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