Hot code replacement

[mictadlo]

Hi I watched this http://www.youtube.com/watch?v=apZYqHPqzYo and thought it would be nice to have hot code replacement in Rust as well.

In Java, you have the OSGi project ( http://www.osgi.org/Main/HomePage ) and hotswap ( http://code.google.com/p/hotswap/ ), which facilitates upgrading and changing modules of your application without touching other modules.

[alexrp]

It is really, extremely hard to do this with native code, especially in a cross-platform fashion. VMs have an easier time because they have full control over bytecode loading, code generation, code placement, etc.

[sanxiyn]

I am not up-to-date on the latest research on the topic, but I found Kitsune: Efficient, General-purpose Dynamic Software Updating for C (OOPSLA 2012) interesting.

[pnkfelix]

visited for triage, 17 July 2013. Hot-swapping is indeed tricky, though some of the things necessary to support it (e.g. marking pages as executable; I-cache flushing, etc) would also be necessary to support a JIT compiler.

I suspect we'd also need position-independent code (PIC). The Kitsune paper actually covers even more aggressive transformations, e.g. migrating the data layouts between versions. (I have only skimmed that paper at this point.)

[catamorphism]

This would be cool, but I feel comfortable saying it's probably not going to happen. I think there are many other difficult problems that are more compelling.

[lilianmoraru]

It was done a few times with compiled code through LLVM and its JIT. Which throws it into a VM and allows to do the same stuff Erlang can do inside its VM...
Inspiration: http://vimeo.com/36579366
Examples with C++:

• https://www.youtube.com/watch?v=BrjV1ZgYbbA
• https://www.youtube.com/watch?v=imkVkRg-geI

If somebody wants to use a Low Level VM I guess they can do it in Rust too... For something like that to work you need to add the VM behavior anyway...

[tyoc213]

I will add this only for reference http://runtimecompiledcplusplus.blogspot.co.uk/ and the code https://github.com/RuntimeCompiledCPlusPlus/RuntimeCompiledCPlusPlus

and https://bentheelder.github.io/blog/rust-hotswap.html