jdk/src/java.base/share/native/libjava/VM.c

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2015, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this

@@ -31,10 +31,15 @@
 #include "jvm.h"
 #include "jdk_util.h"
 
 #include "sun_misc_VM.h"
 
+/* Only register the performance-critical methods */
+static JNINativeMethod methods[] = {
+    {"getNanoTimeAdjustment", "(J)J", (void *)&JVM_GetNanoTimeAdjustment}
+};
+
 JNIEXPORT jobject JNICALL
 Java_sun_misc_VM_latestUserDefinedLoader(JNIEnv *env, jclass cls) {
     return JVM_LatestUserDefinedLoader(env);
 }
 

@@ -47,10 +52,18 @@
     if (!JDK_InitJvmHandle()) {
         JNU_ThrowInternalError(env, "Handle for JVM not found for symbol lookup");
         return;
     }
 
+    // Registers implementations of native methods described in methods[]
+    // above.
+    // In particular, registers JVM_GetNanoTimeAdjustment as the implementation
+    // of the native sun.misc.VM.getNanoTimeAdjustment - avoiding the cost of
+    // introducing a Java_sun_misc_VM_getNanoTimeAdjustment  wrapper
+    (*env)->RegisterNatives(env, cls,
+                            methods, sizeof(methods)/sizeof(methods[0]));
+
     func_p = (GetJvmVersionInfo_fp) JDK_FindJvmEntry("JVM_GetVersionInfo");
      if (func_p != NULL) {
         jvm_version_info info;
 
         memset(&info, 0, sizeof(info));