On Sun, 15 Apr 2007, Henrik Bengtsson wrote: > On 4/15/07, Prof Brian Ripley <[EMAIL PROTECTED]> wrote: > > On Sun, 15 Apr 2007, Henrik Bengtsson wrote: > > > > > are there any (cross-platform) specs on what the saved filed is if > > > save() is interrupted, e.g. by a user interrupt? It could be > > > non-existing, empty, partly written, or completed. > > > > My understanding is that you cannot user interrupt compiled code unless it > > is set up to check interrupts. Version 2 saves are done via the internal > > saveToConn, and I don't see any calls to R_CheckUserInterrupt there. So > > you only need to worry about user interrupts in the R code, and that has > > an on.exit action to close the connection (which should be executed even > > if you interrupt). Which suggests that the file will be > > > > non-existent > > empty > > complete > > > > and the first two depend on interrupting in the millisecond or less before > > the compiled code gets called. > > I'll put it on my todo list to investigate how to make save() more > robust against interrupts before calling the internal code. One > option is to use tryCatch(). However, that does not handle too > frequent user interrupts, e.g. if an interrupt is sent while in the > "interrupt" call, that will interrupt the function. So, tryCatch() > alone will only lower the risk for incomplete empty files. For data > written to files, one alternative is to check for files of zero size > in the on.exit() statement and remove such. > > /Henrik > > > > For other forms of interrupts, e.g. a Unix kill -9, the file state could > > be anything. > > > > Brian D. Ripley, [EMAIL PROTECTED] > > ...
You could change the code to write to a temporary file (in the directory you want the result in) and when you successfully finish writing to the file you rename it to the permanent name. (On an interrupt you remove the temp file, and on 'kill -9' the only bad effect is the space used by the partially written temp file.) This has the added advantage that you don't overwrite an existing save file by the given name until you know a suitable replacement is ready. Perhaps we need a connection type that encapsulates this. ---------------------------------------------------------------------------- Bill Dunlap Insightful Corporation bill at insightful dot com 360-428-8146 "All statements in this message represent the opinions of the author and do not necessarily reflect Insightful Corporation policy or position." ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
