On Wed, 23 Aug 2006 11:45:29 -0700 Travis Oliphant <[EMAIL PROTECTED]> wrote:
> > I'm working on some macros that will allow extensions to be > "interruptable" (i.e. with Ctrl-C). The idea came from SAGE but the > implementation is complicated by the possibility of threads and making > sure to handle clean-up code correctly when the interrupt returns. > For writing clean-up code, here's some prior art on adding exceptions to C: http://www.ossp.org/pkg/lib/ex/ (BSD license) http://adomas.org/excc/ (GPL'd, so no good) http://ldeniau.web.cern.ch/ldeniau/html/exception/exception.html (no license given) The last one has functions that allow you to add pointers (and their deallocation functions) to a list so that they can be deallocated when an exception is thrown. (You don't necessarily need something like these libraries, but I thought I'd throw it in here, because it's along the same lines) > Step 2: > > Implementation. I have the idea to have a single interrupt handler > (defined globally in NumPy) that basically uses longjmp to return to the > section of code corresponding to the thread that is handling the > interrupt. I had thought to use a global variable containing a linked > list of jmp_buf structures with a thread-id attached > (PyThread_get_thread_ident()) so that the interrupt handler can search > it to see if the thread has registered a return location. If it has > not, then the intterupt handler will just return normally. In this way > a thread that calls setjmpbuf will be sure to return to the correct > place when it handles the interrupt. Signals and threads don't mix well at *all*. With POSIX semantics, synchronous signals (ones caused by the thread itself) should be sent to the handler for that thread. Asynchronous ones (like SIGINT for Ctrl-C) will be sent to an *arbitrary* thread. (Apple, for instance, doesn't make any guarantees on which thread gets it: http://developer.apple.com/qa/qa2001/qa1184.html) Best way I can see this is to have a SIGINT handler installed that sets a global variable, and check that every so often. It's such a good way that Python already does this -- Parser/intrcheck.c sets the handler, and you can use PyOS_InterruptOccurred() to check if one happened. So something like while (long running loop) { if (PyOS_InterruptOccurred()) goto error: ... useful stuff ... } error: This could be abstracted to a set of macros (with Perry's syntax): NPY_SIG_INTERRUPTABLE while (long loop) { NPY_CHECK_SIGINT; .. more stuff .. } NPY_SIG_END_INTERRUPTABLE where NPY_CHECK_SIGINT would do a longjmp(). Or come up with a good (fast) way to run stuff in another process :-) -- |>|\/|< /--------------------------------------------------------------------------\ |David M. Cooke http://arbutus.physics.mcmaster.ca/dmc/ |[EMAIL PROTECTED] ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion
