8026946: JvmtiEnv::SetBreakpoint and JvmtiEnv::ClearBreakpoint should use MethodHandle

8026948: JvmtiEnv::SetBreakpoint and JvmtiEnv::ClearBreakpoint might not work with anonymous classes

Walk methods in breakpoints for marking on stack so they aren't deallocated by redefine classes.  Use class_holder rather than class_loader to keep GC from reclaiming class owning the method.

Reviewed-by: sspitsyn, ehelin, sla

hotspot/src/share/vm/classfile/metadataOnStackMark.cpp

@@ -27,6 +27,7 @@
 #include "code/codeCache.hpp"
 #include "compiler/compileBroker.hpp"
 #include "oops/metadata.hpp"
+#include "prims/jvmtiImpl.hpp"
 #include "runtime/synchronizer.hpp"
 #include "runtime/thread.hpp"
 #include "utilities/growableArray.hpp"
@@ -48,6 +49,7 @@ MetadataOnStackMark::MetadataOnStackMark() {
   Threads::metadata_do(Metadata::mark_on_stack);
   CodeCache::alive_nmethods_do(nmethod::mark_on_stack);
   CompileBroker::mark_on_stack();
+  JvmtiCurrentBreakpoints::metadata_do(Metadata::mark_on_stack);
 }
 
 MetadataOnStackMark::~MetadataOnStackMark() {

hotspot/src/share/vm/prims/jvmtiImpl.cpp

@@ -210,6 +210,14 @@ void GrowableCache::oops_do(OopClosure* f) {
   }
 }
 
+void GrowableCache::metadata_do(void f(Metadata*)) {
+  int len = _elements->length();
+  for (int i=0; i<len; i++) {
+    GrowableElement *e = _elements->at(i);
+    e->metadata_do(f);
+  }
+}
+
 void GrowableCache::gc_epilogue() {
   int len = _elements->length();
   for (int i=0; i<len; i++) {
@@ -224,20 +232,20 @@ void GrowableCache::gc_epilogue() {
 JvmtiBreakpoint::JvmtiBreakpoint() {
   _method = NULL;
   _bci    = 0;
-  _class_loader = NULL;
+  _class_holder = NULL;
 }
 
 JvmtiBreakpoint::JvmtiBreakpoint(Method* m_method, jlocation location) {
   _method        = m_method;
-  _class_loader  = _method->method_holder()->class_loader_data()->class_loader();
+  _class_holder  = _method->method_holder()->klass_holder();
 #ifdef CHECK_UNHANDLED_OOPS
-  // _class_loader can't be wrapped in a Handle, because JvmtiBreakpoint:s are
-  // eventually allocated on the heap.
+  // _class_holder can't be wrapped in a Handle, because JvmtiBreakpoints are
+  // sometimes allocated on the heap.
   //
-  // The code handling JvmtiBreakpoint:s allocated on the stack can't be
-  // interrupted by a GC until _class_loader is reachable by the GC via the
+  // The code handling JvmtiBreakpoints allocated on the stack can't be
+  // interrupted by a GC until _class_holder is reachable by the GC via the
   // oops_do method.
-  Thread::current()->allow_unhandled_oop(&_class_loader);
+  Thread::current()->allow_unhandled_oop(&_class_holder);
 #endif // CHECK_UNHANDLED_OOPS
   assert(_method != NULL, "_method != NULL");
   _bci           = (int) location;
@@ -247,7 +255,7 @@ JvmtiBreakpoint::JvmtiBreakpoint(Method* m_method, jlocation location) {
 void JvmtiBreakpoint::copy(JvmtiBreakpoint& bp) {
   _method   = bp._method;
   _bci      = bp._bci;
-  _class_loader = bp._class_loader;
+  _class_holder = bp._class_holder;
 }
 
 bool JvmtiBreakpoint::lessThan(JvmtiBreakpoint& bp) {
@@ -365,6 +373,13 @@ void VM_ChangeBreakpoints::oops_do(OopClosure* f) {
   }
 }
 
+void VM_ChangeBreakpoints::metadata_do(void f(Metadata*)) {
+  // Walk metadata in breakpoints to keep from being deallocated with RedefineClasses
+  if (_bp != NULL) {
+    _bp->metadata_do(f);
+  }
+}
+
 //
 // class JvmtiBreakpoints
 //
@@ -381,6 +396,10 @@ void  JvmtiBreakpoints::oops_do(OopClosure* f) {
   _bps.oops_do(f);
 }
 
+void  JvmtiBreakpoints::metadata_do(void f(Metadata*)) {
+  _bps.metadata_do(f);
+}
+
 void JvmtiBreakpoints::gc_epilogue() {
   _bps.gc_epilogue();
 }
@@ -499,6 +518,12 @@ void JvmtiCurrentBreakpoints::oops_do(OopClosure* f) {
   }
 }
 
+void JvmtiCurrentBreakpoints::metadata_do(void f(Metadata*)) {
+  if (_jvmti_breakpoints != NULL) {
+    _jvmti_breakpoints->metadata_do(f);
+  }
+}
+
 void JvmtiCurrentBreakpoints::gc_epilogue() {
   if (_jvmti_breakpoints != NULL) {
     _jvmti_breakpoints->gc_epilogue();

hotspot/src/share/vm/prims/jvmtiImpl.hpp

@@ -69,6 +69,7 @@ public:
   virtual bool lessThan(GrowableElement *e)=0;
   virtual GrowableElement *clone()         =0;
   virtual void oops_do(OopClosure* f)      =0;
+  virtual void metadata_do(void f(Metadata*)) =0;
 };
 
 class GrowableCache VALUE_OBJ_CLASS_SPEC {
@@ -115,6 +116,8 @@ public:
   void clear();
   // apply f to every element and update the cache
   void oops_do(OopClosure* f);
+  // walk metadata to preserve for RedefineClasses
+  void metadata_do(void f(Metadata*));
   // update the cache after a full gc
   void gc_epilogue();
 };
@@ -148,6 +151,7 @@ public:
   void remove (int index)               { _cache.remove(index); }
   void clear()                          { _cache.clear(); }
   void oops_do(OopClosure* f)           { _cache.oops_do(f); }
+  void metadata_do(void f(Metadata*))   { _cache.metadata_do(f); }
   void gc_epilogue()                    { _cache.gc_epilogue(); }
 };
 
@@ -169,7 +173,7 @@ private:
   Method*               _method;
   int                   _bci;
   Bytecodes::Code       _orig_bytecode;
-  oop                   _class_loader;
+  oop                   _class_holder;  // keeps _method memory from being deallocated
 
 public:
   JvmtiBreakpoint();
@@ -191,9 +195,15 @@ public:
   bool lessThan(GrowableElement* e) { Unimplemented(); return false; }
   bool equals(GrowableElement* e) { return equals((JvmtiBreakpoint&) *e); }
   void oops_do(OopClosure* f)     {
-    // Mark the method loader as live
-    f->do_oop(&_class_loader);
+    // Mark the method loader as live so the Method* class loader doesn't get
+    // unloaded and Method* memory reclaimed.
+    f->do_oop(&_class_holder);
   }
+  void metadata_do(void f(Metadata*)) {
+    // walk metadata to preserve for RedefineClasses
+    f(_method);
+  }
+
   GrowableElement *clone()        {
     JvmtiBreakpoint *bp = new JvmtiBreakpoint();
     bp->copy(*this);
@@ -239,6 +249,7 @@ public:
 
   int length();
   void oops_do(OopClosure* f);
+  void metadata_do(void f(Metadata*));
   void print();
 
   int  set(JvmtiBreakpoint& bp);
@@ -288,6 +299,7 @@ public:
   static inline bool is_breakpoint(address bcp);
 
   static void oops_do(OopClosure* f);
+  static void metadata_do(void f(Metadata*));
   static void gc_epilogue();
 };
 
@@ -332,6 +344,7 @@ public:
   VMOp_Type type() const { return VMOp_ChangeBreakpoints; }
   void doit();
   void oops_do(OopClosure* f);
+  void metadata_do(void f(Metadata*));
 };