Re: [libvirt] Redesigning Libvirt: Adopting use of a safe language

On Tue, Nov 28, 2017 at 10:22:21AM +0000, Daniel P. Berrange wrote: > On Tue, Nov 28, 2017 at 08:43:54AM +0100, Martin Kletzander wrote: > > Just a quick note on what I've found out after I dedicated half day to go > > through the tour of go and some other tutorials. The learning curve of Go is > > even less steep than I though (for some unknown reason) it is. So that's in > > favor of Go. However I haven't found out how is it possible to avoid some > > SIGSEGVs or aborts since Go doesn't have many recoverable errors. And in some > > cases they are not easy to spot immediately. Or making sure struct fields are > > initialized. Since libvirt strives to go for recoverable errors, I see this as > > a downside. > > Either I'm mis-understanding what you mean, or you missed the 'recover' > function. In normal operation, error reporting is dealt with by having > functions return a value that implements the 'error' interface. Functions > can have multiple return values, so typically you would return a pair of > values, the first being the data, the second being the error indicator. > You check & deal with those errors with normal control flow statements. > > For cases where the code triggered a runtime panic() (eg dereference a > Nil pointer), ordinarily that will terminate the program. At point in > the callstack, however, can catch that panic using the recover() method > which avoids termination, and resumes normal execution. Typically in an > RPC server, the RPC dispatch method would use recover() so that if any > RPC method execution panic()s the server carries on running normally, > only that one method is terminated. > > The only thing that you can't catch is when you call into C code and > that crashes. The C code can obviously arbitrarily corrupt memory, so > there's no safe way to recover that. Only the Go can be recover()d from. Opps, meant to include this link https://blog.golang.org/defer-panic-and-recover

Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|