Is there a way to increase the efficiency of shared_ptr by storing the reference count inside the co
- by BillyONeal
Hello everyone :)
This is becoming a common pattern in my code, for when I need to manage an object that needs to be noncopyable because either A. it is "heavy" or B. it is an operating system resource, such as a critical section:
class Resource;
class Implementation : public boost::noncopyable
{
friend class Resource;
HANDLE someData;
Implementation(HANDLE input) : someData(input) {};
void SomeMethodThatActsOnHandle() {
//Do stuff
};
public:
~Implementation() { FreeHandle(someData) };
};
class Resource
{
boost::shared_ptr<Implementation> impl;
public:
Resource(int argA) explicit {
HANDLE handle =
SomeLegacyCApiThatMakesSomething(argA);
if (handle == INVALID_HANDLE_VALUE)
throw SomeTypeOfException();
impl.reset(new Implementation(handle));
};
void SomeMethodThatActsOnTheResource() {
impl->SomeMethodThatActsOnTheHandle();
};
};
This way, shared_ptr takes care of the reference counting headaches, allowing Resource to be copyable, even though the underlying handle should only be closed once all references to it are destroyed.
However, it seems like we could save the overhead of allocating shared_ptr's reference counts and such separately if we could move that data inside Implementation somehow, like boost's intrusive containers do.
If this is making the premature optimization hackles nag some people, I actually agree that I don't need this for my current project. But I'm curious if it is possible.
