Print error message, restore default signal handler and re-raise signal when --single-threaded

* Fixes #2265
* TruffleLogger does not work when the context is not entered.
* Exceptions from SignalHandler seem ignored by the JVM.

Author: eregon

CHANGELOG.md

@@ -13,6 +13,7 @@ Bug fixes:
 * Fix `Thread.handle_interrupt` to defer non-pure interrupts until the end of the `handle_interrupt` block (#2219).
 * Clear and restore errinfo on entry and normal return from methods in C extensions (#2227).
 * Fix extra whitespace in squiggly heredoc with escaped newline (#2238, @wildmaples and @norswap).
+* Fix handling of signals with `--single-threaded` (#2265).
 
 Compatibility:
 

src/main/java/org/truffleruby/core/VMPrimitiveNodes.java

@@ -252,18 +252,17 @@ protected boolean restoreDefault(Object signalString, Object action,
         @Specialization(guards = "libSignalString.isRubyString(signalString)")
         protected boolean watchSignalProc(Object signalString, RubyProc action,
                 @CachedLibrary(limit = "2") RubyStringLibrary libSignalString) {
-            if (getContext().getThreadManager().getCurrentThread() != getContext().getThreadManager().getRootThread()) {
+            final RubyContext context = getContext();
+
+            if (context.getThreadManager().getCurrentThread() != context.getThreadManager().getRootThread()) {
                 // The proc will be executed on the main thread
                 SharedObjects.writeBarrier(getLanguage(), action);
             }
 
-            final RubyContext context = getContext();
-
-            String signalName = libSignalString.getJavaString(signalString);
+            final String signalName = libSignalString.getJavaString(signalString);
             return registerHandler(signalName, signal -> {
                 if (context.getOptions().SINGLE_THREADED) {
-                    RubyLanguage.LOGGER.severe(
-                            "signal " + signal + " caught but can't create a thread to handle it so ignoring");
+                    warnRestoreAndRaise(context, signalName, signal, "create a thread");
                     return;
                 }
 
@@ -276,16 +275,7 @@ protected boolean watchSignalProc(Object signalString, RubyProc action,
                 try {
                     prev = truffleContext.enter(this);
                 } catch (IllegalStateException e) { // Multi threaded access denied from Truffle
-                    // Not in a context, so we cannot use TruffleLogger
-                    context.getEnvErrStream().println(
-                            "[ruby] SEVERE: signal " + signal +
-                                    " caught but can't attach a thread to handle it so restoring the default handler and re-raising the signal");
-                    Signals.restoreDefaultHandler(signalName);
-                    try {
-                        Signal.raise(signal);
-                    } catch (IllegalArgumentException illegalArgumentException) {
-                        illegalArgumentException.printStackTrace(context.getEnvErrStream());
-                    }
+                    warnRestoreAndRaise(context, signalName, signal, "attach a thread");
                     return;
                 }
                 try {
@@ -299,6 +289,19 @@ protected boolean watchSignalProc(Object signalString, RubyProc action,
             });
         }
 
+        private static void warnRestoreAndRaise(RubyContext context, String signalName, Signal signal, String failure) {
+            // Not in a context, so we cannot use TruffleLogger
+            context.getEnvErrStream().println(
+                    "[ruby] SEVERE: signal " + signal + " caught but can't " + failure +
+                            " to handle it so restoring the default handler and re-raising the signal");
+            Signals.restoreDefaultHandler(signalName);
+            try {
+                Signal.raise(signal);
+            } catch (IllegalArgumentException illegalArgumentException) {
+                illegalArgumentException.printStackTrace(context.getEnvErrStream());
+            }
+        }
+
         @TruffleBoundary
         private boolean restoreDefaultHandler(String signalName) {
             if (getContext().getOptions().EMBEDDED) {