Clarification on refcounting behavior of object handlers/get_gc

Description

When implementing https://github.com/mongodb/mongo-php-driver/pull/1850, I have encountered some strange refcounting behavior within the garbage collector; specifically, when working with the hashtable returned by get_gc in https://github.com/php/php-src/blob/master/Zend/zend_gc.c#L892 and https://github.com/php/php-src/blob/master/Zend/zend_gc.c#L1516 the refcount is incremented and then seemingly not decremented again (leading to the leaks I'm fighting in https://github.com/mongodb/mongo-php-driver/pull/1850), but in https://github.com/php/php-src/blob/master/Zend/zend_gc.c#L1068, the refcount is decremented correctly.

This brings the question: what should be the refcount of the hashtables returned by get_gc, get_properties_for (in all of the various modes), get_properties, get_debug_info, and all other object handlers?

This detail is not documented anywhere, and specifically for get_gc, it's especially not clear given that returning a refcount of 0 would cause a negative refcount in one place, and returning 1 causes a leak in other two places (though that may be due to an issue in my implementation in the https://github.com/mongodb/mongo-php-driver/pull/1850 PR, though it's not immediately obvious what it is to me).

It would be super nice to have it documented at least inside of the source code as comments too...

PHP Version

8.4.10

Operating System

No response

从 Zend/zend_gc.c 中第 892、1068 和 1516 行附近引用的部分开始，然后将 get_gc 的行为与 get_properties_for、get_properties 和 get_debug_info 进行比较。检查链接的 mongo-php-driver pull request 中报告的泄漏；当每个 handler 预期的 refcount 所有权得到确定，并记录在相关源代码注释中时，即视为完成。