Carlo Wood wrote:
If not, then I think direct support for this has to be added. A signal handler can be called at almost any moment in the code and can therefore not use system resources, or shared resources, of any kind. You can't even have it wait for a mutex. Basically all a signal handler can do is set an atomic flag that there has been a signal.
The trouble here is that you lose information if two signals arrive back-to-back (which unfortunately POSIX allows the implementation to lose anyway, but that doesn't mean you can be as lazy as the laziest implementation!) Also, some signals will not interrupt select() on some POSIX-compliant UNIXes. I searched long and hard for a perfect generic signal handler, and unfortunately, concluded there was no such thing. The best implementation I came up with was using an atomic add to increment a counter in a table of signals, and then writing to a pipe (which can also be used as a hint) to signal select(). Specific operating systems, such as Linux, will still require something more to decode extra information within exceptions. Aaron W. LaFramboise