cocos-engine/native/cocos/base/Ref.cpp

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#include "base/Ref.h"
#include "base/AutoreleasePool.h"
#include "base/Macros.h"

#if CC_REF_LEAK_DETECTION
    #include <algorithm> // std::find
#endif

namespace cc {

#if CC_REF_LEAK_DETECTION
static void trackRef(Ref *ref);
static void untrackRef(Ref *ref);
#endif

Ref::Ref()
: _referenceCount(1) // when the Ref is created, the reference count of it is 1
{
#if CC_REF_LEAK_DETECTION
    trackRef(this);
#endif
}

Ref::~Ref() {
#if CC_REF_LEAK_DETECTION
    if (_referenceCount != 0)
        untrackRef(this);
#endif
}

void Ref::retain() {
    CCASSERT(_referenceCount > 0, "reference count should be greater than 0");
    ++_referenceCount;
}

void Ref::release() {
    CCASSERT(_referenceCount > 0, "reference count should be greater than 0");
    --_referenceCount;

    if (_referenceCount == 0) {
#if defined(CC_DEBUG) && (CC_DEBUG > 0)
        auto *poolManager = PoolManager::getInstance();
        auto *currentPool = poolManager->getCurrentPool();
        if (currentPool && !currentPool->isClearing() && poolManager->isObjectInPools(this)) {
            // Trigger an assert if the reference count is 0 but the Ref is still in autorelease pool.
            // This happens when 'autorelease/release' were not used in pairs with 'new/retain'.
            //
            // Wrong usage (1):
            //
            // auto obj = Node::create();   // Ref = 1, but it's an autorelease Ref which means it was in the autorelease pool.
            // obj->autorelease();   // Wrong: If you wish to invoke autorelease several times, you should retain `obj` first.
            //
            // Wrong usage (2):
            //
            // auto obj = Node::create();
            // obj->release();   // Wrong: obj is an autorelease Ref, it will be released when clearing current pool.
            //
            // Correct usage (1):
            //
            // auto obj = Node::create();
            //                     |-   new Node();     // `new` is the pair of the `autorelease` of next line
            //                     |-   autorelease();  // The pair of `new Node`.
            //
            // obj->retain();
            // obj->autorelease();  // This `autorelease` is the pair of `retain` of previous line.
            //
            // Correct usage (2):
            //
            // auto obj = Node::create();
            // obj->retain();
            // obj->release();   // This `release` is the pair of `retain` of previous line.
            CCASSERT(false, "The reference shouldn't be 0 because it is still in autorelease pool.");
        }
#endif

#if CC_REF_LEAK_DETECTION
        untrackRef(this);
#endif
        delete this;
    }
}

Ref *Ref::autorelease() {
    PoolManager::getInstance()->getCurrentPool()->addObject(this);
    return this;
}

unsigned int Ref::getReferenceCount() const {
    return _referenceCount;
}

#if CC_REF_LEAK_DETECTION

static std::list<Ref *> __refAllocationList;

void Ref::printLeaks() {
    // Dump Ref object memory leaks
    if (__refAllocationList.empty()) {
        log("[memory] All Ref objects successfully cleaned up (no leaks detected).\n");
    } else {
        log("[memory] WARNING: %d Ref objects still active in memory.\n", (int)__refAllocationList.size());

        for (const auto &ref : __refAllocationList) {
            CC_ASSERT(ref);
            const char *type = typeid(*ref).name();
            log("[memory] LEAK: Ref object '%s' still active with reference count %d.\n", (type ? type : ""), ref->getReferenceCount());
        }
    }
}

static void trackRef(Ref *ref) {
    CCASSERT(ref, "Invalid parameter, ref should not be null!");

    // Create memory allocation record.
    __refAllocationList.push_back(ref);
}

static void untrackRef(Ref *ref) {
    auto iter = std::find(__refAllocationList.begin(), __refAllocationList.end(), ref);
    if (iter == __refAllocationList.end()) {
        log("[memory] CORRUPTION: Attempting to free (%s) with invalid ref tracking record.\n", typeid(*ref).name());
        return;
    }

    __refAllocationList.erase(iter);
}

#endif // #if CC_REF_LEAK_DETECTION

} // namespace cc