[NFC][DirectoryWatchedTests] Unlocking mutexes before signaling condition variable.

[plotfi]

Summary

This should not affect actual behavior, but should pessimize the threading less by avoiding the situation where:

• mutex is still locked
• T1 notifies on condition variable
• T2 wakes to check mutex
• T2 sees mutex is still locked
• T2 waits
• T1 unlocks mutex
• T2 tries again, acquires mutex.

[jkorous]

LGTM. Thanks!

clang/unittests/DirectoryWatcher/DirectoryWatcherTest.cpp

struct VerifyingConsumer {
   void consumeInitial(DirectoryWatcher::Event E) {
     std::unique_lock<std::mutex> L(Mtx);
     auto It = std::find(ExpectedInitial.begin(), ExpectedInitial.end(), E);
     if (It == ExpectedInitial.end()) {
       UnexpectedInitial.push_back(E);
     } else {
       ExpectedInitial.erase(It);
     }
-    if (result())
+    if (result()) {
+      L.unlock();
       ResultIsReady.notify_one();
     }
+  }
 
   void consumeNonInitial(DirectoryWatcher::Event E) {
     std::unique_lock<std::mutex> L(Mtx);
     auto It =
         std::find(ExpectedNonInitial.begin(), ExpectedNonInitial.end(), E);
     if (It == ExpectedNonInitial.end()) {
       auto OptIt =
           std::find(OptionalNonInitial.begin(), OptionalNonInitial.end(), E);
       if (OptIt != OptionalNonInitial.end()) {
         OptionalNonInitial.erase(OptIt);
       } else {
         UnexpectedNonInitial.push_back(E);
       }
     } else {
       ExpectedNonInitial.erase(It);
     }
-    if (result())
+    if (result()) {
+      L.unlock();
       ResultIsReady.notify_one();
     }
+  }
 
   // This method is used by DirectoryWatcher.
   void consume(llvm::ArrayRef<DirectoryWatcher::Event> Es, bool IsInitial) {
     for (const auto &E : Es)
       consume(E, IsInitial);
   }
 
   // Not locking - caller has to lock Mtx.
auto DW = DirectoryWatcher::create(
                         bool IsInitial) {
           TestConsumer.consume(Events, IsInitial);
         },
         /*waitForInitialSync=*/true);
   } // DW is destructed here.
 
   checkEventualResultWithTimeout(TestConsumer);
 }
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