commit 71c55c57183420b91f7769438ffb0274f0212635
author Brian Silverman <brians> Tue Aug 19 14:31:59 2014 -0400
committer Brian Silverman <brians> Sat Dec 26 18:41:11 2015 -0800
tree 6acdadd1f2be92ca84c4d07e5b91eb1ef985ab28
parent 97aae2656fbcf04fb3eb8b4fd077cfb320e3e40f

implement robust mutex support

This allows making everything in shared memory robust to
processes dying at any point in time (not actually done yet in this
commit).

This includes using FUTEX_REQUEUE_PI, but currently only on ARM because
that's the only place we can rely on the kernel not corrupting random
memory due to a bug (fix has been merged upstream).

Change-Id: Id5bda1dc3185a1aac759510934bce6fd9121ad3f

aos/common/condition_test.cc

diff --git a/aos/common/condition_test.cc b/aos/common/condition_test.cc
index dbaa546..0e7bfe4 100644
--- a/aos/common/condition_test.cc
+++ b/aos/common/condition_test.cc
@@ -5,6 +5,7 @@
 #include <sys/wait.h>
 
 #include <atomic>
+#include <thread>
 
 #include "gtest/gtest.h"
 
@@ -75,6 +76,22 @@
   EXPECT_TRUE(child_finished.load());
 }
 
+// Tests that contention on the associated mutex doesn't break anything.
+// This seems likely to cause issues with AddressSanitizer in particular.
+TEST_F(SimpleConditionTest, MutexContention) {
+  for (int i = 0; i < 1000; ++i) {
+    ASSERT_FALSE(mutex_.Lock());
+    ::std::thread thread([this]() {
+      ASSERT_FALSE(mutex_.Lock());
+      condition_.Signal();
+      mutex_.Unlock();
+    });
+    ASSERT_FALSE(condition_.Wait());
+    mutex_.Unlock();
+    thread.join();
+  }
+}
+
 class ConditionTest : public ConditionTestCommon {
  public:
   struct Shared {
@@ -307,7 +324,8 @@
   Settle();
   shared_->condition.Signal();
   EXPECT_FALSE(child.Hung());
-  EXPECT_EQ(Mutex::State::kLockFailed, shared_->mutex.TryLock());
+  EXPECT_EQ(Mutex::State::kOwnerDied, shared_->mutex.TryLock());
+  shared_->mutex.Unlock();
 }
 
 // Tests that Signal() stops exactly 1 Wait()er.