implement Thread.yield

src/classpath-avian.cpp

@@ -579,6 +579,13 @@ Avian_java_lang_Thread_enumerate
   return count;
 }
 
+extern "C" JNIEXPORT void JNICALL
+Avian_java_lang_Thread_yield
+(Thread* t, object, uintptr_t*)
+{
+  t->m->system->yield();
+}
+
 extern "C" JNIEXPORT void JNICALL
 Avian_avian_Classes_acquireClassLock
 (Thread* t, object, uintptr_t*)

src/classpath-openjdk.cpp

@@ -2210,13 +2210,9 @@ EXPORT(JVM_SetThreadPriority)(Thread*, jobject, jint)
 }
 
 extern "C" JNIEXPORT void JNICALL
-EXPORT(JVM_Yield)(Thread*, jclass)
+EXPORT(JVM_Yield)(Thread* t, jclass)
 {
-#ifdef PLATFORM_WINDOWS
+  t->m->system->yield();
-  SwitchToThread();
-#else
-  sched_yield();
-#endif
 }
 
 uint64_t

src/posix.cpp

@@ -30,6 +30,7 @@
 #include "sys/ucontext.h"
 #include "stdint.h"
 #include "dirent.h"
+#include "sched.h"
 
 #include "arch.h"
 #include "system.h"
@@ -795,6 +796,10 @@ class MySystem: public System {
       (static_cast<int64_t>(tv.tv_usec) / 1000);
   }
 
+  virtual void yield() {
+    sched_yield();
+  }
+
   virtual void exit(int code) {
     ::exit(code);
   }

src/system.h

@@ -141,6 +141,7 @@ class System {
   virtual char pathSeparator() = 0;
   virtual char fileSeparator() = 0;
   virtual int64_t now() = 0;
+  virtual void yield() = 0;
   virtual void exit(int code) = 0;
   virtual void abort() = 0;
   virtual void dispose() = 0;

src/windows.cpp

@@ -807,6 +807,10 @@ class MySystem: public System {
              | time.dwLowDateTime) / 10000) - 11644473600000LL;
   }
 
+  virtual void yield() {
+    SwitchToThread();
+  }
+
   virtual void exit(int code) {
     ::exit(code);
   }