test,util: fix flaky test-util-sigint-watchdog

Fix parallel/test-util-sigint-watchdog by polling until the
signal has definitely been received instead of just using a timeout.

Fixes: https://github.com/nodejs/node/issues/7919
PR-URL: https://github.com/nodejs/node/pull/7933
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/node_util.cc

@@ -113,6 +113,13 @@ void StopSigintWatchdog(const FunctionCallbackInfo<Value>& args) {
   args.GetReturnValue().Set(had_pending_signals);
 }
 
+
+void WatchdogHasPendingSigint(const FunctionCallbackInfo<Value>& args) {
+  bool ret = SigintWatchdogHelper::GetInstance()->HasPendingSignal();
+  args.GetReturnValue().Set(ret);
+}
+
+
 void Initialize(Local<Object> target,
                 Local<Value> unused,
                 Local<Context> context) {
@@ -138,6 +145,7 @@ void Initialize(Local<Object> target,
 
   env->SetMethod(target, "startSigintWatchdog", StartSigintWatchdog);
   env->SetMethod(target, "stopSigintWatchdog", StopSigintWatchdog);
+  env->SetMethod(target, "watchdogHasPendingSigint", WatchdogHasPendingSigint);
 }
 
 }  // namespace util

src/node_watchdog.cc

@@ -258,6 +258,13 @@ bool SigintWatchdogHelper::Stop() {
 }
 
 
+bool SigintWatchdogHelper::HasPendingSignal() {
+  Mutex::ScopedLock lock(list_mutex_);
+
+  return has_pending_signal_;
+}
+
+
 void SigintWatchdogHelper::Register(SigintWatchdog* wd) {
   Mutex::ScopedLock lock(list_mutex_);
 

src/node_watchdog.h

@@ -63,6 +63,7 @@ class SigintWatchdogHelper {
   static SigintWatchdogHelper* GetInstance() { return &instance; }
   void Register(SigintWatchdog* watchdog);
   void Unregister(SigintWatchdog* watchdog);
+  bool HasPendingSignal();
 
   int Start();
   bool Stop();

test/parallel/test-util-sigint-watchdog.js

@@ -20,24 +20,24 @@ if (common.isWindows) {
   // Test with one call to the watchdog, one signal.
   binding.startSigintWatchdog();
   process.kill(process.pid, 'SIGINT');
-  setTimeout(common.mustCall(() => {
+  waitForPendingSignal(common.mustCall(() => {
     const hadPendingSignals = binding.stopSigintWatchdog();
     assert.strictEqual(hadPendingSignals, true);
     next();
-  }), common.platformTimeout(100));
+  }));
 },
 (next) => {
   // Nested calls are okay.
   binding.startSigintWatchdog();
   binding.startSigintWatchdog();
   process.kill(process.pid, 'SIGINT');
-  setTimeout(common.mustCall(() => {
+  waitForPendingSignal(common.mustCall(() => {
     const hadPendingSignals1 = binding.stopSigintWatchdog();
     const hadPendingSignals2 = binding.stopSigintWatchdog();
     assert.strictEqual(hadPendingSignals1, true);
     assert.strictEqual(hadPendingSignals2, false);
     next();
-  }), common.platformTimeout(100));
+  }));
 },
 () => {
   // Signal comes in after first call to stop.
@@ -45,9 +45,16 @@ if (common.isWindows) {
   binding.startSigintWatchdog();
   const hadPendingSignals1 = binding.stopSigintWatchdog();
   process.kill(process.pid, 'SIGINT');
-  setTimeout(common.mustCall(() => {
+  waitForPendingSignal(common.mustCall(() => {
     const hadPendingSignals2 = binding.stopSigintWatchdog();
     assert.strictEqual(hadPendingSignals1, false);
     assert.strictEqual(hadPendingSignals2, true);
-  }), common.platformTimeout(100));
+  }));
 }].reduceRight((a, b) => common.mustCall(b).bind(null, a))();
+
+function waitForPendingSignal(cb) {
+  if (binding.watchdogHasPendingSigint())
+    cb();
+  else
+    setTimeout(waitForPendingSignal, 10, cb);
+}