有时候在 php 里类循环引用时,会导致 __destruct() 不触发的问题,先上问题代码:
<?php
class proxy
{
private $object;
public function __construct($object)
{
$this->object = $object;
}
public function __destruct()
{
var_dump('__destruct:proxy');
}
}
class test
{
private $proxy;
public function __construct()
{
$this->proxy = new proxy($this);
}
public function __destruct()
{
var_dump('__destruct:test');
}
}
$test = new test;
unset($test);
echo 'no __destruct, wait 3s', php_eol;
sleep(3);
echo '__destruct now:', php_eol;如上代码,运行unset($test)时,不会触发__destruct(),因为有了循环引用。
再看下面的解决方法1的代码:
<?php
class proxy
{
private $object;
public function __construct($object)
{
$this->object = $object;
}
public function __destruct()
{
var_dump('__destruct:proxy');
}
}
class test
{
private $proxy;
public function __construct()
{
$this->proxy = new proxy($this);
}
public function __destruct()
{
var_dump('__destruct:test');
}
public function close()
{
$this->proxy = null;
}
}
$test = new test;
$test->close();
echo '__destruct now:', php_eol;
unset($test);
sleep(3);
echo 'no operation', php_eol;上面的代码,在unset之前,将test类中的proxy设为null,然后再unset,就可以触发__destruct()了。
当然,你也可以手动gc(解决方法2):
<?php
class proxy
{
private $object;
public function __construct($object)
{
$this->object = $object;
}
public function __destruct()
{
var_dump('__destruct:proxy');
}
}
class test
{
private $proxy;
public function __construct()
{
$this->proxy = new proxy($this);
}
public function __destruct()
{
var_dump('__destruct:test');
}
}
$test = new test;
unset($test);
echo '__destruct now:', php_eol;
gc_collect_cycles();
sleep(3);
echo 'no operation', php_eol;
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