# limitations under the License.
# Module to manage standard C signals
+#
+# Common usage imply 5 steps:
+#
+# 1. Implement the `SignalHandler` interface
+# 2. `redef receive_signal_unsafe` to handle `sigsegv`
+# 3. `redef receive_signal` to handle other signals safely
+# 4, Notify what signals to handle with `handle_signal`
+# 5. If using the safe handler method, routinely call `check_signals`
+#
+# Usage example:
+#
+# ~~~~
+# class MyReceiver
+# super SignalHandler
+#
+# redef fun receive_signal(signal)
+# do
+# print "received safely {signal}"
+# if signal == sigalarm then print "Alarm!"
+# end
+# redef fun receive_signal_unsafe( signal ) do print "received unsafely {signal}"
+# end
+#
+# var r = new MyReceiver
+#
+# # Handle `sigsegv` signal unsafely (the only way for this one)
+# r.handle_signal(sigsegv, false)
+#
+# # Handle `sigint` and `sigalarm` safely
+# r.handle_signal(sigint, true)
+# r.handle_signal(sigalarm, true)
+#
+# # Ask system to receive a `sigalarm` signal in 1 second
+# set_alarm(1)
+#
+# loop
+# # Check signals and callback `receive_signal`
+# var hit = check_signals
+#
+# if hit then break
+# end
+# ~~~~
module signals
`{
#include <stdio.h>
/*
+ This guard prevents errors by the C compiler when the Nit code imports this
+ module but do not use handle_signal. When it is _not_ used, the C type
+ SignalHandler and C function SignalHandler_receive_signal are not generated.
+ Which does not please the C compiler. This guard ensure that we compile this
+ code only if the type SignalHandler has been defined.
+
+ This is a HACK, FIXME by:
+ * Adding the macro to the FFI spec, or
+ * Attach the callbacks to this code block (or the module itself)
+ * Avoid using Nit types and callbacks or use them only in the C implementation
+ of Nit method.
+ */
+ #ifdef NIT_TYPE_SignalHandler
+
+ /*
Structure to manage each possible signals
are used in an array of 32 maximum signals.
This array is global to the software.
}
}
}
+
+ #endif
`}
# Receives the callback from system when a given signal arise
# r.handle_signal(sigint, true) # will call back when "check_signals" is called
# # ...
# check_signals # if a signal was received, it will invoke `r.receive_signal`
- fun receive_signal(signal: Int) `{
- `}
+ fun receive_signal(signal: Int) do end
# Called immediatly on receiving an unsafe signal (should be redefed by subclasses)
#
#
# var r = new MyReceiver
# r.handle_signal(sigsegv, false) # `r.receive_signal_unsafe` will be invoked on sigsegv
- fun receive_signal_unsafe(signal: Int) `{
- `}
+ fun receive_signal_unsafe(signal: Int) do end
# Set the receiver as the handler of the signal
#