fix windows build and refactor last addition to EventQueue

src/lib/base/EventQueue.cpp

@@ -201,14 +201,20 @@ EventQueue::adoptBuffer(IEventQueueBuffer* buffer)
     }
 }
 
+bool
+EventQueue::parent_requests_shutdown() const
+{
+    char ch;
+    return m_parentStream.try_read_char(ch) && ch == ShutdownCh;
+}
+
 bool
 EventQueue::getEvent(Event& event, double timeout)
 {
     Stopwatch timer(true);
 retry:
-    // check to see if parent wants us to shutdown now
-    char ch;
-    if (m_parentStream.try_read_char(ch) && ch == ShutdownCh) {
+    // before handling any events make sure we don't need to shutdown
+    if (parent_requests_shutdown()) {
         event = Event(Event::kQuit);
         return false;
     }

src/lib/base/EventQueue.h

@@ -73,6 +73,7 @@ private:
     bool                hasTimerExpired(Event& event);
     double                getNextTimerTimeout() const;
     void                addEventToBuffer(const Event& event);
+    bool                parent_requests_shutdown() const;
     
 private:
     class Timer {

src/lib/base/NonBlockingStream.cpp

@@ -15,6 +15,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#if !defined(_WIN32)
+
 #include "base/NonBlockingStream.h"
 
 #include <unistd.h> // tcgetattr/tcsetattr, read
@@ -46,7 +48,7 @@ NonBlockingStream::~NonBlockingStream()
     delete _p_ta_previous;
 }
 
-bool NonBlockingStream::try_read_char(char &ch)
+bool NonBlockingStream::try_read_char(char &ch) const
 {
     int result = read(_fd, &ch, 1);
     if (result == 1)
@@ -54,3 +56,5 @@ bool NonBlockingStream::try_read_char(char &ch)
     assert(result == -1 && (errno == EAGAIN || errno == EWOULDBLOCK));
     return false;
 }
+
+#endif // !defined(_WIN32)

src/lib/base/NonBlockingStream.h

@@ -17,6 +17,19 @@
 
 #pragma once
 
+// windows doesn't have a unistd.h so this class won't work as-written.
+// at the moment barrier doesn't need this functionality on windows so
+// it's left as a stub to be optimized out
+#if defined(_WIN32)
+
+class NonBlockingStream
+{
+public:
+    bool try_read_char(char &ch) const { return false; };
+};
+
+#else // non-windows platforms
+
 struct termios;
 
 class NonBlockingStream
@@ -25,10 +38,12 @@ public:
     explicit NonBlockingStream(int fd = 0);
     ~NonBlockingStream();
 
-    bool try_read_char(char &ch);
+    bool try_read_char(char &ch) const;
 
 private:
     int _fd;
     termios * _p_ta_previous;
     int _cntl_previous;
 };
+
+#endif