4 files changed, 45 insertions, 5 deletions
diff --git a/src/rt/sync/condition_variable.cpp b/src/rt/sync/condition_variable.cpp
index d4032572..c34ab7f4 100644
--- a/src/rt/sync/condition_variable.cpp
+++ b/src/rt/sync/condition_variable.cpp
@@ -9,14 +9,16 @@
 
 // #define TRACE
 
-condition_variable::condition_variable() {
 #if defined(__WIN32__)
+condition_variable::condition_variable() {
     _event = CreateEvent(NULL, FALSE, FALSE, NULL);
+}
 #else
+condition_variable::condition_variable() {
     pthread_cond_init(&_cond, NULL);
     pthread_mutex_init(&_mutex, NULL);
-#endif
 }
+#endif
 
 condition_variable::~condition_variable() {
 #if defined(__WIN32__)
@@ -31,15 +33,31 @@ condition_variable::~condition_variable() {
  * Wait indefinitely until condition is signaled.
  */
 void condition_variable::wait() {
+    timed_wait(0);
+}
+
+void condition_variable::timed_wait(size_t timeout_in_ns) {
 #ifdef TRACE
-    printf("waiting on condition_variable: 0x%" PRIxPTR "\n",
-           (uintptr_t)this);
+    printf("waiting on condition_variable: 0x%" PRIxPTR " for %d ns. \n",
+           (uintptr_t) this, (int) timeout_in_ns);
 #endif
 #if defined(__WIN32__)
     WaitForSingleObject(_event, INFINITE);
 #else
     pthread_mutex_lock(&_mutex);
-    pthread_cond_wait(&_cond, &_mutex);
+    // wait() automatically releases the mutex while it waits, and acquires
+    // it right before exiting. This allows signal() to acquire the mutex
+    // when signaling.)
+    if (timeout_in_ns == 0) {
+        pthread_cond_wait(&_cond, &_mutex);
+    } else {
+        timeval time_val;
+        gettimeofday(&time_val, NULL);
+        timespec time_spec;
+        time_spec.tv_sec = time_val.tv_sec + 0;
+        time_spec.tv_nsec = time_val.tv_usec * 1000 + timeout_in_ns;
+        pthread_cond_timedwait(&_cond, &_mutex, &time_spec);
+    }
     pthread_mutex_unlock(&_mutex);
 #endif
 #ifdef TRACE
diff --git a/src/rt/sync/condition_variable.h b/src/rt/sync/condition_variable.h
index f847ef99..f336a7f2 100644
--- a/src/rt/sync/condition_variable.h
+++ b/src/rt/sync/condition_variable.h
@@ -13,6 +13,7 @@ public:
     virtual ~condition_variable();
 
     void wait();
+    void timed_wait(size_t timeout_in_ns);
     void signal();
 };
 
diff --git a/src/rt/sync/sync.cpp b/src/rt/sync/sync.cpp
new file mode 100644
index 00000000..eba51a49
--- /dev/null
+++ b/src/rt/sync/sync.cpp
@@ -0,0 +1,12 @@
+#include "../globals.h"
+#include "sync.h"
+
+void sync::yield() {
+#ifdef __APPLE__
+    pthread_yield_np();
+#elif __WIN32__
+
+#else
+    pthread_yield();
+#endif
+}
diff --git a/src/rt/sync/sync.h b/src/rt/sync/sync.h
new file mode 100644
index 00000000..902b5661
--- /dev/null
+++ b/src/rt/sync/sync.h
@@ -0,0 +1,9 @@
+#ifndef SYNC_H
+#define SYNC_H
+
+class sync {
+public:
+    static void yield();
+};
+
+#endif /* SYNC_H */