Add rudimentary signal workaround.

This is the best we can do considering the mechanism of supporting signal() on
the JVM. The supported signals could probably be expanded to "everything that
ends the receiving process", but I don't know enough about POSIX signals to
decide which signals belong into that group.

Author: peschwa

src/vm/jvm/QAST/Compiler.nqp

@@ -2014,6 +2014,10 @@ my %const_map := nqp::hash(
     'PIPE_IGNORE_ERR',          128,
     'PIPE_CAPTURE_ERR',         256,
 
+    # could probably support a few more...
+    'SIG_INT',                  2,
+    'SIG_KILL',                 9,
+
     'TYPE_CHECK_CACHE_DEFINITIVE',  0,
     'TYPE_CHECK_CACHE_THEN_METHOD', 1,
     'TYPE_CHECK_NEEDS_ACCEPTS',     2,
@@ -2723,7 +2727,7 @@ QAST::OperationsJAST.map_classlib_core_op('queuepoll', $TYPE_OPS, 'queuepoll', [
 # asynchrony related ops
 QAST::OperationsJAST.map_classlib_core_op('timer', $TYPE_OPS, 'timer', [$RT_OBJ, $RT_OBJ, $RT_INT, $RT_INT, $RT_OBJ], $RT_OBJ, :tc);
 QAST::OperationsJAST.map_classlib_core_op('cancel', $TYPE_OPS, 'cancel', [$RT_OBJ], $RT_OBJ, :tc);
-QAST::OperationsJAST.map_classlib_core_op('signal', $TYPE_IO_OPS, 'signal', [$RT_OBJ, $RT_OBJ, $RT_INT, $RT_INT, $RT_OBJ], $RT_OBJ, :tc);
+QAST::OperationsJAST.map_classlib_core_op('signal', $TYPE_IO_OPS, 'signal', [$RT_OBJ, $RT_OBJ, $RT_INT, $RT_OBJ], $RT_OBJ, :tc);
 QAST::OperationsJAST.map_classlib_core_op('watchfile', $TYPE_IO_OPS, 'watchfile', [$RT_OBJ, $RT_OBJ, $RT_STR, $RT_OBJ], $RT_OBJ, :tc);
 QAST::OperationsJAST.map_classlib_core_op('asyncconnect', $TYPE_IO_OPS, 'asyncconnect', [$RT_OBJ, $RT_OBJ, $RT_STR, $RT_INT, $RT_OBJ], $RT_OBJ, :tc);
 QAST::OperationsJAST.map_classlib_core_op('asynclisten', $TYPE_IO_OPS, 'asynclisten', [$RT_OBJ, $RT_OBJ, $RT_STR, $RT_INT, $RT_INT, $RT_OBJ], $RT_OBJ, :tc);

src/vm/jvm/runtime/org/perl6/nqp/runtime/IOOps.java

@@ -5,12 +5,44 @@
 import org.perl6.nqp.sixmodel.SixModelObject;
 import org.perl6.nqp.sixmodel.reprs.AsyncTaskInstance;
 import org.perl6.nqp.sixmodel.reprs.IOHandleInstance;
+import org.perl6.nqp.runtime.Ops;
 
 public final class IOOps {
 
+    private static class SigRunnable implements Runnable {
+        public static ThreadContext tc;
+        public static SixModelObject schedulee;
+        public static long signum;
+
+        public SigRunnable(ThreadContext tc, SixModelObject schedulee, long signum) {
+            this.tc = tc;
+            this.schedulee = schedulee;
+            this.signum = signum;
+        }
+
+        public void run() {
+            Ops.invokeDirect(tc, schedulee, Ops.invocantCallSite, 
+                new Object[] { Ops.box_i(signum, tc.curFrame.codeRef.staticInfo.compUnit.hllConfig.intBoxType, tc) });
+        }
+    }
     public static SixModelObject signal(SixModelObject queue, SixModelObject schedulee,
             long signalNum, SixModelObject asyncType, ThreadContext tc) {
-        throw new UnsupportedOperationException("signal is not available on JVM.");
+        switch((int)signalNum) {
+            case 2: // INT
+                break;
+            case 9: // KILL
+                break;
+            default:
+                ExceptionHandling.dieInternal(tc, "Unsupported signal " + signalNum);
+        }
+        AsyncTaskInstance task = (AsyncTaskInstance) asyncType.st.REPR.allocate(tc, asyncType.st);
+        task.queue = queue;
+        task.schedulee = schedulee;
+
+        Runnable sigrun = new SigRunnable(tc, schedulee, signalNum);
+        Runtime.getRuntime().addShutdownHook(new Thread(sigrun));
+        return task;
+        // throw new UnsupportedOperationException("signal is not available on JVM.");
     }
 
     public static SixModelObject watchfile(SixModelObject queue, SixModelObject schedulee,