Bug 1370644 - Part 1: Only use NS_ERROR for an imminent failure. r=froydnj

This modifies the logic in |CheckAcquisition| to only call |NS_ERROR| if we're
really going to deadlock. Instead, if we detect a suspicious cycle, we just use
an |NS_WARNING|. This means that we'll still output warning text in debug
builds, but we won't cause the process to abort.

MozReview-Commit-ID: 71mFInWwbDY

xpcom/tests/gtest/TestDeadlockDetector.cpp

@@ -136,6 +136,8 @@ TEST_F(TESTNAME(DeadlockDetectorTest), TESTNAME(Sanity2DeathTest))
     ASSERT_DEATH_IF_SUPPORTED(Sanity2_Child(), regex);
 }
 
+#if 0
+// Temporarily disabled, see bug 1370644.
 int
 Sanity3_Child()
 {
@@ -173,6 +175,7 @@ TEST_F(TESTNAME(DeadlockDetectorTest), TESTNAME(Sanity3DeathTest))
 
     ASSERT_DEATH_IF_SUPPORTED(Sanity3_Child(), regex);
 }
+#endif
 
 int
 Sanity4_Child()
@@ -219,6 +222,8 @@ struct ThreadState
   int id;
 };
 
+#if 0
+// Temporarily disabled, see bug 1370644.
 static void
 TwoThreads_thread(void* arg)
 {
@@ -277,6 +282,7 @@ TEST_F(TESTNAME(DeadlockDetectorTest), TESTNAME(TwoThreadsDeathTest))
 
     ASSERT_DEATH_IF_SUPPORTED(TwoThreads_Child(), regex);
 }
+#endif
 
 static void
 ContentionNoDeadlock_thread(void* arg)

xpcom/threads/BlockingResourceBase.cpp

@@ -301,11 +301,12 @@ BlockingResourceBase::CheckAcquire()
     out.AppendLiteral("\nDeadlock may happen for some other execution\n\n");
   }
 
-  // XXX can customize behavior on whether we /think/ deadlock is
-  // XXX about to happen.  for example:
-  // XXX   if (maybeImminent)
-  //           NS_RUNTIMEABORT(out.get());
-  NS_ERROR(out.get());
+  // Only error out if we think a deadlock is imminent.
+  if (maybeImminent) {
+    NS_ERROR(out.get());
+  } else {
+    NS_WARNING(out.get());
+  }
 }