8275775: Add jcmd VM.classes to print details of all classes

Reviewed-by: dholmes, iklam, stuefe

src/hotspot/share/oops/instanceKlass.cpp

@@ -2074,6 +2074,52 @@ Method* InstanceKlass::lookup_method_in_all_interfaces(Symbol* name,
   return NULL;
 }
 
+PrintClassClosure::PrintClassClosure(outputStream* st, bool verbose)
+  :_st(st), _verbose(verbose) {
+  ResourceMark rm;
+  _st->print("%-18s  ", "KlassAddr");
+  _st->print("%-4s  ", "Size");
+  _st->print("%-20s  ", "State");
+  _st->print("%-7s  ", "Flags");
+  _st->print("%-5s  ", "ClassName");
+  _st->cr();
+}
+
+void PrintClassClosure::do_klass(Klass* k)  {
+  ResourceMark rm;
+  // klass pointer
+  _st->print(INTPTR_FORMAT "  ", p2i(k));
+  // klass size
+  _st->print("%4d  ", k->size());
+  // initialization state
+  if (k->is_instance_klass()) {
+    _st->print("%-20s  ",InstanceKlass::cast(k)->init_state_name());
+  } else {
+    _st->print("%-20s  ","");
+  }
+  // misc flags(Changes should synced with ClassesDCmd::ClassesDCmd help doc)
+  char buf[10];
+  int i = 0;
+  if (k->has_finalizer()) buf[i++] = 'F';
+  if (k->has_final_method()) buf[i++] = 'f';
+  if (k->is_instance_klass()) {
+    InstanceKlass* ik = InstanceKlass::cast(k);
+    if (ik->is_rewritten()) buf[i++] = 'W';
+    if (ik->is_contended()) buf[i++] = 'C';
+    if (ik->has_been_redefined()) buf[i++] = 'R';
+    if (ik->is_shared()) buf[i++] = 'S';
+  }
+  buf[i++] = '\0';
+  _st->print("%-7s  ", buf);
+  // klass name
+  _st->print("%-5s  ", k->external_name());
+  // end
+  _st->cr();
+  if (_verbose) {
+    k->print_on(_st);
+  }
+}
+
 /* jni_id_for for jfieldIds only */
 JNIid* InstanceKlass::jni_id_for(int offset) {
   MutexLocker ml(JfieldIdCreation_lock);
@@ -3393,6 +3439,10 @@ static void print_vtable(vtableEntry* start, int len, outputStream* st) {
   return print_vtable(reinterpret_cast<intptr_t*>(start), len, st);
 }
 
+const char* InstanceKlass::init_state_name() const {
+  return state_names[_init_state];
+}
+
 void InstanceKlass::print_on(outputStream* st) const {
   assert(is_klass(), "must be klass");
   Klass::print_on(st);
@@ -3400,7 +3450,7 @@ void InstanceKlass::print_on(outputStream* st) const {
   st->print(BULLET"instance size:     %d", size_helper());                        st->cr();
   st->print(BULLET"klass size:        %d", size());                               st->cr();
   st->print(BULLET"access:            "); access_flags().print_on(st);            st->cr();
-  st->print(BULLET"state:             "); st->print_cr("%s", state_names[_init_state]);
+  st->print(BULLET"state:             "); st->print_cr("%s", init_state_name());
   st->print(BULLET"name:              "); name()->print_value_on(st);             st->cr();
   st->print(BULLET"super:             "); Metadata::print_value_on_maybe_null(st, super()); st->cr();
   st->print(BULLET"sub:               ");

src/hotspot/share/oops/instanceKlass.hpp

@@ -547,6 +547,7 @@ public:
   bool is_in_error_state() const           { return _init_state == initialization_error; }
   bool is_reentrant_initialization(Thread *thread)  { return thread == _init_thread; }
   ClassState  init_state()                 { return (ClassState)_init_state; }
+  const char* init_state_name() const;
   bool is_rewritten() const                { return (_misc_flags & _misc_rewritten) != 0; }
 
   // is this a sealed class
@@ -1277,6 +1278,15 @@ inline u2 InstanceKlass::next_method_idnum() {
   }
 }
 
+class PrintClassClosure : public KlassClosure {
+private:
+  outputStream* _st;
+  bool _verbose;
+public:
+  PrintClassClosure(outputStream* st, bool verbose);
+
+  void do_klass(Klass* k);
+};
 
 /* JNIid class for jfieldIDs only */
 class JNIid: public CHeapObj<mtClass> {

src/hotspot/share/runtime/vmOperation.hpp

@@ -95,6 +95,7 @@
   template(CleanClassLoaderDataMetaspaces)        \
   template(PrintCompileQueue)                     \
   template(PrintClassHierarchy)                   \
+  template(PrintClasses)                          \
   template(ICBufferFull)                          \
   template(PrintMetadata)                         \
   template(GTestExecuteAtSafepoint)               \

src/hotspot/share/services/diagnosticCommand.cpp

@@ -26,6 +26,7 @@
 #include "jvm.h"
 #include "classfile/classLoaderHierarchyDCmd.hpp"
 #include "classfile/classLoaderStats.hpp"
+#include "classfile/classLoaderDataGraph.hpp"
 #include "classfile/javaClasses.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmClasses.hpp"
@@ -102,6 +103,7 @@ void DCmdRegistrant::register_dcmds(){
   DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<ClassHistogramDCmd>(full_export, true, false));
   DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<SystemDictionaryDCmd>(full_export, true, false));
   DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<ClassHierarchyDCmd>(full_export, true, false));
+  DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<ClassesDCmd>(full_export, true, false));
   DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<SymboltableDCmd>(full_export, true, false));
   DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<StringtableDCmd>(full_export, true, false));
   DCmdFactory::register_DCmdFactory(new DCmdFactoryImpl<metaspace::MetaspaceDCmd>(full_export, true, false));
@@ -954,6 +956,41 @@ void TouchedMethodsDCmd::execute(DCmdSource source, TRAPS) {
   VMThread::execute(&dumper);
 }
 
+ClassesDCmd::ClassesDCmd(outputStream* output, bool heap) :
+                                     DCmdWithParser(output, heap),
+  _verbose("-verbose",
+           "Dump the detailed content of a Java class. "
+           "Some classes are annotated with flags: "
+           "F = has, or inherits, a non-empty finalize method, "
+           "f = has final method, "
+           "W = methods rewritten, "
+           "C = marked with @Contended annotation, "
+           "R = has been redefined, "
+           "S = is shared class",
+           "BOOLEAN", false, "false") {
+  _dcmdparser.add_dcmd_option(&_verbose);
+}
+
+class VM_PrintClasses : public VM_Operation {
+private:
+  outputStream* _out;
+  bool _verbose;
+public:
+  VM_PrintClasses(outputStream* out, bool verbose) : _out(out), _verbose(verbose) {}
+
+  virtual VMOp_Type type() const { return VMOp_PrintClasses; }
+
+  virtual void doit() {
+    PrintClassClosure closure(_out, _verbose);
+    ClassLoaderDataGraph::classes_do(&closure);
+  }
+};
+
+void ClassesDCmd::execute(DCmdSource source, TRAPS) {
+  VM_PrintClasses vmop(output(), _verbose.is_set());
+  VMThread::execute(&vmop);
+}
+
 #if INCLUDE_CDS
 DumpSharedArchiveDCmd::DumpSharedArchiveDCmd(outputStream* output, bool heap) :
                                      DCmdWithParser(output, heap),

src/hotspot/share/services/diagnosticCommand.hpp

@@ -858,6 +858,28 @@ public:
   virtual void execute(DCmdSource source, TRAPS);
 };
 
+class ClassesDCmd : public DCmdWithParser {
+protected:
+  DCmdArgument<bool> _verbose;
+public:
+  ClassesDCmd(outputStream* output, bool heap);
+  static const char* name() {
+    return "VM.classes";
+  }
+  static const char* description() {
+    return "Print all loaded classes";
+  }
+  static const char* impact() {
+      return "Medium: Depends on number of loaded classes.";
+  }
+  static const JavaPermission permission() {
+    JavaPermission p = {"java.lang.management.ManagementPermission",
+                        "monitor", NULL};
+    return p;
+  }
+  virtual void execute(DCmdSource source, TRAPS);
+};
+
 #if INCLUDE_JVMTI
 class DebugOnCmdStartDCmd : public DCmd {
 public:

test/hotspot/jtreg/runtime/CommandLine/PrintClasses.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2022, Alibaba Group Holding Limited. 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.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+
+/*
+ * @test
+ * @bug 8275775
+ * @summary Test jcmd VM.classes
+ * @library /test/lib
+ * @run main/othervm PrintClasses
+ */
+
+import jdk.test.lib.process.OutputAnalyzer;
+import jdk.test.lib.JDKToolFinder;
+
+public class PrintClasses {
+  public static void main(String args[]) throws Exception {
+    var pid = Long.toString(ProcessHandle.current().pid());
+    var pb = new ProcessBuilder();
+
+    pb.command(new String[] { JDKToolFinder.getJDKTool("jcmd"), pid, "VM.classes"});
+    var output = new OutputAnalyzer(pb.start());
+    output.shouldNotContain("instance size");
+    output.shouldContain(PrintClasses.class.getSimpleName());
+
+    pb.command(new String[] { JDKToolFinder.getJDKTool("jcmd"), pid, "VM.classes", "-verbose"});
+    output = new OutputAnalyzer(pb.start());
+    output.shouldContain("instance size");
+    output.shouldContain(PrintClasses.class.getSimpleName());
+  }
+}