ART: Add ThreadGroup API support

Add support for GetThreadGroupInfo, GetThreadGroupChildren and
GetTopThreadGroups. Add tests.

Bug: 31455788
Test: m test-art-host-run-test-925-threadgroups
Change-Id: I56809c95dfd2666c2e18769a8960d6b1604274b4
diff --git a/runtime/openjdkjvmti/ti_threadgroup.cc b/runtime/openjdkjvmti/ti_threadgroup.cc
new file mode 100644
index 0000000..31c7582
--- /dev/null
+++ b/runtime/openjdkjvmti/ti_threadgroup.cc
@@ -0,0 +1,284 @@
+/* Copyright (C) 2017 The Android Open Source Project
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This file implements interfaces from the file jvmti.h. This implementation
+ * is licensed under the same terms as the file jvmti.h.  The
+ * copyright and license information for the file jvmti.h follows.
+ *
+ * Copyright (c) 2003, 2011, 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
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+#include "ti_threadgroup.h"
+
+#include "art_field.h"
+#include "art_jvmti.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/mutex.h"
+#include "handle_scope-inl.h"
+#include "jni_internal.h"
+#include "mirror/class.h"
+#include "mirror/object-inl.h"
+#include "mirror/string.h"
+#include "obj_ptr.h"
+#include "runtime.h"
+#include "scoped_thread_state_change-inl.h"
+#include "thread-inl.h"
+#include "thread_list.h"
+#include "well_known_classes.h"
+
+namespace openjdkjvmti {
+
+
+jvmtiError ThreadGroupUtil::GetTopThreadGroups(jvmtiEnv* env,
+                                               jint* group_count_ptr,
+                                               jthreadGroup** groups_ptr) {
+  // We only have a single top group. So we can take the current thread and move upwards.
+  if (group_count_ptr == nullptr || groups_ptr == nullptr) {
+    return ERR(NULL_POINTER);
+  }
+
+  art::Runtime* runtime = art::Runtime::Current();
+  if (runtime == nullptr) {
+    // Must be starting the runtime, or dying.
+    return ERR(WRONG_PHASE);
+  }
+
+  jobject sys_thread_group = runtime->GetSystemThreadGroup();
+  if (sys_thread_group == nullptr) {
+    // Seems we're still starting up.
+    return ERR(WRONG_PHASE);
+  }
+
+  unsigned char* data;
+  jvmtiError result = env->Allocate(sizeof(jthreadGroup), &data);
+  if (result != ERR(NONE)) {
+    return result;
+  }
+
+  jthreadGroup* groups = reinterpret_cast<jthreadGroup*>(data);
+  *groups =
+      reinterpret_cast<JNIEnv*>(art::Thread::Current()->GetJniEnv())->NewLocalRef(sys_thread_group);
+  *groups_ptr = groups;
+  *group_count_ptr = 1;
+
+  return ERR(NONE);
+}
+
+jvmtiError ThreadGroupUtil::GetThreadGroupInfo(jvmtiEnv* env,
+                                               jthreadGroup group,
+                                               jvmtiThreadGroupInfo* info_ptr) {
+  if (group == nullptr) {
+    return ERR(INVALID_THREAD_GROUP);
+  }
+
+  art::ScopedObjectAccess soa(art::Thread::Current());
+  if (soa.Env()->IsInstanceOf(group, art::WellKnownClasses::java_lang_ThreadGroup) == JNI_FALSE) {
+    return ERR(INVALID_THREAD_GROUP);
+  }
+
+  art::ObjPtr<art::mirror::Object> obj = soa.Decode<art::mirror::Object>(group);
+
+  // Do the name first. It's the only thing that can fail.
+  {
+    art::ArtField* name_field =
+        art::jni::DecodeArtField(art::WellKnownClasses::java_lang_ThreadGroup_name);
+    CHECK(name_field != nullptr);
+    art::ObjPtr<art::mirror::String> name_obj =
+        art::ObjPtr<art::mirror::String>::DownCast(name_field->GetObject(obj));
+    std::string tmp_str;
+    const char* tmp_cstr;
+    if (name_obj == nullptr) {
+      tmp_cstr = "";
+    } else {
+      tmp_str = name_obj->ToModifiedUtf8();
+      tmp_cstr = tmp_str.c_str();
+    }
+    jvmtiError result =
+        CopyString(env, tmp_cstr, reinterpret_cast<unsigned char**>(&info_ptr->name));
+    if (result != ERR(NONE)) {
+      return result;
+    }
+  }
+
+  // Parent.
+  {
+    art::ArtField* parent_field =
+        art::jni::DecodeArtField(art::WellKnownClasses::java_lang_ThreadGroup_parent);
+    CHECK(parent_field != nullptr);
+    art::ObjPtr<art::mirror::Object> parent_group = parent_field->GetObject(obj);
+    info_ptr->parent = parent_group == nullptr
+                           ? nullptr
+                           : soa.AddLocalReference<jthreadGroup>(parent_group);
+  }
+
+  // Max priority.
+  {
+    art::ArtField* prio_field = obj->GetClass()->FindDeclaredInstanceField("maxPriority", "I");
+    CHECK(prio_field != nullptr);
+    info_ptr->max_priority = static_cast<jint>(prio_field->GetInt(obj));
+  }
+
+  // Daemon.
+  {
+    art::ArtField* daemon_field = obj->GetClass()->FindDeclaredInstanceField("daemon", "Z");
+    CHECK(daemon_field != nullptr);
+    info_ptr->is_daemon = daemon_field->GetBoolean(obj) == 0 ? JNI_FALSE : JNI_TRUE;
+  }
+
+  return ERR(NONE);
+}
+
+
+static bool IsInDesiredThreadGroup(art::ObjPtr<art::mirror::Object> desired_thread_group,
+                                   art::ObjPtr<art::mirror::Object> peer)
+    REQUIRES_SHARED(art::Locks::mutator_lock_) {
+  CHECK(desired_thread_group != nullptr);
+
+  art::ArtField* thread_group_field =
+      art::jni::DecodeArtField(art::WellKnownClasses::java_lang_Thread_group);
+  DCHECK(thread_group_field != nullptr);
+  art::ObjPtr<art::mirror::Object> group = thread_group_field->GetObject(peer);
+  return (group == desired_thread_group);
+}
+
+static void GetThreads(art::ObjPtr<art::mirror::Object> thread_group,
+                       std::vector<art::ObjPtr<art::mirror::Object>>* thread_peers)
+    REQUIRES_SHARED(art::Locks::mutator_lock_) REQUIRES(!art::Locks::thread_list_lock_) {
+  CHECK(thread_group != nullptr);
+
+  std::list<art::Thread*> all_threads_list;
+  {
+    art::MutexLock mu(art::Thread::Current(), *art::Locks::thread_list_lock_);
+    all_threads_list = art::Runtime::Current()->GetThreadList()->GetList();
+  }
+  for (art::Thread* t : all_threads_list) {
+    if (t->IsStillStarting()) {
+      continue;
+    }
+    art::ObjPtr<art::mirror::Object> peer = t->GetPeer();
+    if (peer == nullptr) {
+      continue;
+    }
+    if (IsInDesiredThreadGroup(thread_group, peer)) {
+      thread_peers->push_back(peer);
+    }
+  }
+}
+
+static void GetChildThreadGroups(art::ObjPtr<art::mirror::Object> thread_group,
+                                 std::vector<art::ObjPtr<art::mirror::Object>>* thread_groups)
+    REQUIRES_SHARED(art::Locks::mutator_lock_) {
+  CHECK(thread_group != nullptr);
+
+  // Get the ThreadGroup[] "groups" out of this thread group...
+  art::ArtField* groups_field =
+      art::jni::DecodeArtField(art::WellKnownClasses::java_lang_ThreadGroup_groups);
+  art::ObjPtr<art::mirror::Object> groups_array = groups_field->GetObject(thread_group);
+
+  if (groups_array == nullptr) {
+    return;
+  }
+  CHECK(groups_array->IsObjectArray());
+
+  art::ObjPtr<art::mirror::ObjectArray<art::mirror::Object>> groups_array_as_array =
+      groups_array->AsObjectArray<art::mirror::Object>();
+
+  // Copy all non-null elements.
+  for (int32_t i = 0; i < groups_array_as_array->GetLength(); ++i) {
+    art::ObjPtr<art::mirror::Object> entry = groups_array_as_array->Get(i);
+    if (entry != nullptr) {
+      thread_groups->push_back(entry);
+    }
+  }
+}
+
+jvmtiError ThreadGroupUtil::GetThreadGroupChildren(jvmtiEnv* env,
+                                                   jthreadGroup group,
+                                                   jint* thread_count_ptr,
+                                                   jthread** threads_ptr,
+                                                   jint* group_count_ptr,
+                                                   jthreadGroup** groups_ptr) {
+  if (group == nullptr) {
+    return ERR(INVALID_THREAD_GROUP);
+  }
+
+  art::ScopedObjectAccess soa(art::Thread::Current());
+
+  if (!soa.Env()->IsInstanceOf(group, art::WellKnownClasses::java_lang_ThreadGroup)) {
+    return ERR(INVALID_THREAD_GROUP);
+  }
+
+  art::ObjPtr<art::mirror::Object> thread_group = soa.Decode<art::mirror::Object>(group);
+
+  std::vector<art::ObjPtr<art::mirror::Object>> thread_peers;
+  GetThreads(thread_group, &thread_peers);
+
+  std::vector<art::ObjPtr<art::mirror::Object>> thread_groups;
+  GetChildThreadGroups(thread_group, &thread_groups);
+
+  jthread* thread_data = nullptr;
+  JvmtiUniquePtr peers_uptr;
+  if (!thread_peers.empty()) {
+    unsigned char* data;
+    jvmtiError res = env->Allocate(sizeof(jthread) * thread_peers.size(), &data);
+    if (res != ERR(NONE)) {
+      return res;
+    }
+    thread_data = reinterpret_cast<jthread*>(data);
+    peers_uptr = MakeJvmtiUniquePtr(env, data);
+  }
+
+  jthreadGroup* group_data = nullptr;
+  if (!thread_groups.empty()) {
+    unsigned char* data;
+    jvmtiError res = env->Allocate(sizeof(jthreadGroup) * thread_groups.size(), &data);
+    if (res != ERR(NONE)) {
+      return res;
+    }
+    group_data = reinterpret_cast<jthreadGroup*>(data);
+  }
+
+  // Can't fail anymore from here on.
+
+  // Copy data into out buffers.
+  for (size_t i = 0; i != thread_peers.size(); ++i) {
+    thread_data[i] = soa.AddLocalReference<jthread>(thread_peers[i]);
+  }
+  for (size_t i = 0; i != thread_groups.size(); ++i) {
+    group_data[i] = soa.AddLocalReference<jthreadGroup>(thread_groups[i]);
+  }
+
+  *thread_count_ptr = static_cast<jint>(thread_peers.size());
+  *threads_ptr = thread_data;
+  *group_count_ptr = static_cast<jint>(thread_groups.size());
+  *groups_ptr = group_data;
+
+  // Everything's fine.
+  peers_uptr.release();
+
+  return ERR(NONE);
+}
+
+}  // namespace openjdkjvmti