The output in the example says:
$f__bar == 1 ? 2 : 1 = fail
but in reality it should be:
$f__bar == 1 ? 2 : 1 = ok
the first time the code is ran as the cache is empty and apcu_cas allows the key to be inserted.
(PECL apcu >= 4.0.0)
apcu_cas — Updates an old value with a new value
$key, int $old, int $new): bool
apcu_cas() updates an already existing integer value if the
old parameter matches the currently stored value
with the value of the new parameter.
keyThe key of the value being updated.
oldThe old value (the value currently stored).
newThe new value to update to.
成功时返回 true， 或者在失败时返回 false。
示例 #1 apcu_cas() example
<?php
apcu_store('foobar', 2);
echo '$foobar = 2', PHP_EOL;
echo '$foobar == 1 ? 2 : 1 = ', (apcu_cas('foobar', 1, 2) ? 'ok' : 'fail'), PHP_EOL;
echo '$foobar == 2 ? 1 : 2 = ', (apcu_cas('foobar', 2, 1) ? 'ok' : 'fail'), PHP_EOL;
echo '$foobar = ', apcu_fetch('foobar'), PHP_EOL;
echo '$f__bar == 1 ? 2 : 1 = ', (apcu_cas('f__bar', 1, 2) ? 'ok' : 'fail'), PHP_EOL;
apcu_store('perfection', 'xyz');
echo '$perfection == 2 ? 1 : 2 = ', (apcu_cas('perfection', 2, 1) ? 'ok' : 'epic fail'), PHP_EOL;
echo '$foobar = ', apcu_fetch('foobar'), PHP_EOL;
?>以上示例的输出类似于：
$foobar = 2 $foobar == 1 ? 2 : 1 = fail $foobar == 2 ? 1 : 2 = ok $foobar = 1 $f__bar == 1 ? 2 : 1 = fail $perfection == 2 ? 1 : 2 = epic fail $foobar = 1