1 /*
   2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/javaClasses.hpp"
  27 #include "classfile/symbolTable.hpp"
  28 #include "jfr/jni/jfrGetAllEventClasses.hpp"
  29 #include "jfr/jni/jfrJavaSupport.hpp"
  30 #include "jfr/support/jfrEventClass.hpp"
  31 #include "oops/instanceKlass.hpp"
  32 #include "memory/allocation.inline.hpp"
  33 #include "memory/resourceArea.hpp"
  34 #include "runtime/handles.inline.hpp"
  35 #include "runtime/mutexLocker.hpp"
  36 #include "runtime/safepoint.hpp"
  37 #include "runtime/thread.inline.hpp"
  38 #include "utilities/growableArray.hpp"
  39 #include "utilities/stack.inline.hpp"
  40 
  41  // incremented during class unloading (safepoint) for each unloaded event class
  42 static jlong unloaded_event_classes = 0;
  43 
  44 jlong JfrEventClasses::unloaded_event_classes_count() {
  45   return unloaded_event_classes;
  46 }
  47 
  48 void JfrEventClasses::increment_unloaded_event_class() {
  49   // incremented during class unloading (safepoint) for each unloaded event class
  50   assert(SafepointSynchronize::is_at_safepoint(), "invariant");
  51   ++unloaded_event_classes;
  52 }
  53 
  54 static jobject empty_java_util_arraylist = NULL;
  55 
  56 static oop new_java_util_arraylist(TRAPS) {
  57   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
  58   JavaValue result(T_OBJECT);
  59   JfrJavaArguments args(&result, "java/util/ArrayList", "<init>", "()V", CHECK_NULL);
  60   JfrJavaSupport::new_object(&args, CHECK_NULL);
  61   return (oop)result.get_jobject();
  62 }
  63 
  64 static bool initialize(TRAPS) {
  65   static bool initialized = false;
  66   if (!initialized) {
  67     unloaded_event_classes = 0;
  68     assert(NULL == empty_java_util_arraylist, "invariant");
  69     const oop array_list = new_java_util_arraylist(CHECK_false);
  70     empty_java_util_arraylist = JfrJavaSupport::global_jni_handle(array_list, THREAD);
  71     initialized = empty_java_util_arraylist != NULL;
  72   }
  73   return initialized;
  74 }
  75 
  76 /*
  77  * Abstract klasses are filtered out unconditionally.
  78  * If a klass is not yet initialized, i.e yet to run its <clinit>
  79  * it is also filtered out so we don't accidentally
  80  * trigger initialization.
  81  */
  82 static bool is_whitelisted(const Klass* k) {
  83   assert(k != NULL, "invariant");
  84   return !(k->is_abstract() || k->should_be_initialized());
  85 }
  86 
  87 static void fill_klasses(GrowableArray<const void*>& event_subklasses, const Klass* event_klass, Thread* thread) {
  88   assert(event_subklasses.length() == 0, "invariant");
  89   assert(event_klass != NULL, "invariant");
  90   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(thread));
  91 
  92   Stack<const Klass*, mtTracing> mark_stack;
  93   MutexLocker ml(Compile_lock, thread);
  94   mark_stack.push(event_klass->subklass());
  95 
  96   while (!mark_stack.is_empty()) {
  97     const Klass* const current = mark_stack.pop();
  98     assert(current != NULL, "null element in stack!");
  99 
 100     if (is_whitelisted(current)) {
 101       event_subklasses.append(current);
 102     }
 103 
 104     // subclass (depth)
 105     const Klass* next_klass = current->subklass();
 106     if (next_klass != NULL) {
 107       mark_stack.push(next_klass);
 108     }
 109 
 110     // siblings (breadth)
 111     next_klass = current->next_sibling();
 112     if (next_klass != NULL) {
 113       mark_stack.push(next_klass);
 114     }
 115   }
 116   assert(mark_stack.is_empty(), "invariant");
 117 }
 118 
 119  static void transform_klasses_to_local_jni_handles(GrowableArray<const void*>& event_subklasses, Thread* thread) {
 120   assert(event_subklasses.is_nonempty(), "invariant");
 121   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(thread));
 122 
 123   for (int i = 0; i < event_subklasses.length(); ++i) {
 124     const InstanceKlass* k = static_cast<const InstanceKlass*>(event_subklasses.at(i));
 125     assert(is_whitelisted(k), "invariant");
 126     event_subklasses.at_put(i, JfrJavaSupport::local_jni_handle(k->java_mirror(), thread));
 127   }
 128 }
 129 
 130 static const int initial_size_growable_array = 64;
 131 
 132 jobject JfrEventClasses::get_all_event_classes(TRAPS) {
 133   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
 134   initialize(THREAD);
 135   assert(empty_java_util_arraylist != NULL, "should have been setup already!");
 136   static const char jdk_jfr_event_name[] = "jdk/jfr/Event";
 137   unsigned int unused_hash = 0;
 138   Symbol* const event_klass_name = SymbolTable::lookup_only(jdk_jfr_event_name, sizeof jdk_jfr_event_name - 1, unused_hash);
 139 
 140   if (NULL == event_klass_name) {
 141     // not loaded yet
 142     return empty_java_util_arraylist;
 143   }
 144 
 145   const Klass* const klass = SystemDictionary::resolve_or_null(event_klass_name, THREAD);
 146   assert(klass != NULL, "invariant");
 147   assert(JdkJfrEvent::is(klass), "invariant");
 148 
 149   if (klass->subklass() == NULL) {
 150     return empty_java_util_arraylist;
 151   }
 152 
 153   ResourceMark rm(THREAD);
 154   GrowableArray<const void*> event_subklasses(THREAD, initial_size_growable_array);
 155   fill_klasses(event_subklasses, klass, THREAD);
 156 
 157   if (event_subklasses.is_empty()) {
 158     return empty_java_util_arraylist;
 159   }
 160 
 161   transform_klasses_to_local_jni_handles(event_subklasses, THREAD);
 162 
 163   Handle h_array_list(THREAD, new_java_util_arraylist(THREAD));
 164   assert(h_array_list.not_null(), "invariant");
 165 
 166   static const char add_method_name[] = "add";
 167   static const char add_method_signature[] = "(Ljava/lang/Object;)Z";
 168   const Klass* const array_list_klass = JfrJavaSupport::klass(empty_java_util_arraylist);
 169   assert(array_list_klass != NULL, "invariant");
 170 
 171   const Symbol* const add_method_sym = SymbolTable::lookup(add_method_name, sizeof add_method_name - 1, THREAD);
 172   assert(add_method_sym != NULL, "invariant");
 173 
 174   const Symbol* const add_method_sig_sym = SymbolTable::lookup(add_method_signature, sizeof add_method_signature - 1, THREAD);
 175   assert(add_method_signature != NULL, "invariant");
 176 
 177   JavaValue result(T_BOOLEAN);
 178   for (int i = 0; i < event_subklasses.length(); ++i) {
 179     const jclass clazz = (const jclass)event_subklasses.at(i);
 180     assert(JdkJfrEvent::is_subklass(clazz), "invariant");
 181     JfrJavaArguments args(&result, array_list_klass, add_method_sym, add_method_sig_sym);
 182     args.set_receiver(h_array_list());
 183     args.push_jobject(clazz);
 184     JfrJavaSupport::call_virtual(&args, THREAD);
 185     if (HAS_PENDING_EXCEPTION || JNI_FALSE == result.get_jboolean()) {
 186       return empty_java_util_arraylist;
 187     }
 188   }
 189   return JfrJavaSupport::local_jni_handle(h_array_list(), THREAD);
 190 }