Re:The Linux kernel's inability to gracefully handle low mem...
by la_barba on Tuesday August 06, 2019 @12:16PM
(#20626564)
> No RAII, so you have to explicitly handle cleanup at every point you may have to early-return an error (goto fail etc...).
I think RAII can be useful, but I've never found any use for it in systems level code that I write. Most of the time I'm dealing with resources that were allocated inside a systems library or an external component which just gives me a handle to the resource. I think this is a common enough scenario in systems code that I don't think its just me.
e.g.
1. X = CreateResource()
2. Y = TransformResource(X)
3. ProcessNewResource(Y)
4. Z = TransformResource(Y)
5. etc. etc.
And so as you transform that resource, you will have multiple ways to unwind the resource depending on where the failure occurs. Even if you wrap X in some RAII container, you don't know what your destructor is going to look like.
Another con to RAII, especially when paired with shared-ownership smart pointers, is you lose predictability over your resource deallocs. You never know when the last pointer is going go out of scope, and if its a 'heavy' resource with a complicated unwind, you're going to get a CPU spike at an indeterminate time. I deal primarily with industrial automation code and I much prefer to have a smooth/even CPU graph. I think this issue is more relevant to systems code which is the context of this thread.
I think RAII can be useful, but I've never found any use for it in systems level code that I write. Most of the time I'm dealing with resources that were allocated inside a systems library or an external component which just gives me a handle to the resource. I think this is a common enough scenario in systems code that I don't think its just me.
e.g.
And so as you transform that resource, you will have multiple ways to unwind the resource depending on where the failure occurs. Even if you wrap X in some RAII container, you don't know what your destructor is going to look like.Another con to RAII, especially when paired with shared-ownership smart pointers, is you lose predictability over your resource deallocs. You never know when the last pointer is going go out of scope, and if its a 'heavy' resource with a complicated unwind, you're going to get a CPU spike at an indeterminate time. I deal primarily with industrial automation code and I much prefer to have a smooth/even CPU graph. I think this issue is more relevant to systems code which is the context of this thread.