ART: Add GetAllThreads

Add support for GetAllThreads. Add a test.

Bug: 31684593
Test: m test-art-host-run-test-924-threads
Change-Id: I7068dd4d3700a32a87a44d38590e53df0bd238c7
diff --git a/runtime/openjdkjvmti/OpenjdkJvmTi.cc b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
index 4334ca3..e41f074 100644
--- a/runtime/openjdkjvmti/OpenjdkJvmTi.cc
+++ b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
@@ -127,7 +127,7 @@
   }
 
   static jvmtiError GetAllThreads(jvmtiEnv* env, jint* threads_count_ptr, jthread** threads_ptr) {
-    return ERR(NOT_IMPLEMENTED);
+    return ThreadUtil::GetAllThreads(env, threads_count_ptr, threads_ptr);
   }
 
   static jvmtiError SuspendThread(jvmtiEnv* env, jthread thread) {
diff --git a/runtime/openjdkjvmti/ti_thread.cc b/runtime/openjdkjvmti/ti_thread.cc
index e20f560..f7f63bd 100644
--- a/runtime/openjdkjvmti/ti_thread.cc
+++ b/runtime/openjdkjvmti/ti_thread.cc
@@ -42,6 +42,7 @@
 #include "obj_ptr.h"
 #include "scoped_thread_state_change-inl.h"
 #include "thread-inl.h"
+#include "thread_list.h"
 #include "well_known_classes.h"
 
 namespace openjdkjvmti {
@@ -354,4 +355,53 @@
   return ERR(NONE);
 }
 
+jvmtiError ThreadUtil::GetAllThreads(jvmtiEnv* env,
+                                     jint* threads_count_ptr,
+                                     jthread** threads_ptr) {
+  if (threads_count_ptr == nullptr || threads_ptr == nullptr) {
+    return ERR(NULL_POINTER);
+  }
+
+  art::Thread* current = art::Thread::Current();
+
+  art::ScopedObjectAccess soa(current);
+
+  art::MutexLock mu(current, *art::Locks::thread_list_lock_);
+  std::list<art::Thread*> thread_list = art::Runtime::Current()->GetThreadList()->GetList();
+
+  std::vector<art::ObjPtr<art::mirror::Object>> peers;
+
+  for (art::Thread* thread : thread_list) {
+    // Skip threads that are still starting.
+    if (thread->IsStillStarting()) {
+      continue;
+    }
+
+    art::ObjPtr<art::mirror::Object> peer = thread->GetPeer();
+    if (peer != nullptr) {
+      peers.push_back(peer);
+    }
+  }
+
+  if (peers.empty()) {
+    *threads_count_ptr = 0;
+    *threads_ptr = nullptr;
+  } else {
+    unsigned char* data;
+    jvmtiError data_result = env->Allocate(peers.size() * sizeof(jthread), &data);
+    if (data_result != ERR(NONE)) {
+      return data_result;
+    }
+    jthread* threads = reinterpret_cast<jthread*>(data);
+    for (size_t i = 0; i != peers.size(); ++i) {
+      threads[i] = soa.AddLocalReference<jthread>(peers[i]);
+    }
+
+    *threads_count_ptr = static_cast<jint>(peers.size());
+    *threads_ptr = threads;
+  }
+
+  return ERR(NONE);
+}
+
 }  // namespace openjdkjvmti
diff --git a/runtime/openjdkjvmti/ti_thread.h b/runtime/openjdkjvmti/ti_thread.h
index b6ffbb5..fca42ad 100644
--- a/runtime/openjdkjvmti/ti_thread.h
+++ b/runtime/openjdkjvmti/ti_thread.h
@@ -39,6 +39,8 @@
 
 class ThreadUtil {
  public:
+  static jvmtiError GetAllThreads(jvmtiEnv* env, jint* threads_count_ptr, jthread** threads_ptr);
+
   static jvmtiError GetCurrentThread(jvmtiEnv* env, jthread* thread_ptr);
 
   static jvmtiError GetThreadInfo(jvmtiEnv* env, jthread thread, jvmtiThreadInfo* info_ptr);
diff --git a/test/924-threads/expected.txt b/test/924-threads/expected.txt
index 5406522..32e3368 100644
--- a/test/924-threads/expected.txt
+++ b/test/924-threads/expected.txt
@@ -28,3 +28,4 @@
 e1 = ALIVE|WAITING_WITH_TIMEOUT|SLEEPING|WAITING
 5 = ALIVE|RUNNABLE
 2 = TERMINATED
+[Thread[FinalizerDaemon,5,system], Thread[FinalizerWatchdogDaemon,5,system], Thread[HeapTaskDaemon,5,system], Thread[ReferenceQueueDaemon,5,system], Thread[Signal Catcher,5,system], Thread[main,5,main]]
diff --git a/test/924-threads/src/Main.java b/test/924-threads/src/Main.java
index 0487666..492a7ac 100644
--- a/test/924-threads/src/Main.java
+++ b/test/924-threads/src/Main.java
@@ -17,6 +17,7 @@
 import java.util.Arrays;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.concurrent.CountDownLatch;
 import java.util.HashMap;
 import java.util.List;
@@ -53,6 +54,8 @@
     printThreadInfo(t3);
 
     doStateTests();
+
+    doAllThreadsTests();
   }
 
   private static class Holder {
@@ -155,6 +158,18 @@
     printThreadState(t);
   }
 
+  private static void doAllThreadsTests() {
+    Thread[] threads = getAllThreads();
+    Arrays.sort(threads, THREAD_COMP);
+    System.out.println(Arrays.toString(threads));
+  }
+
+  private final static Comparator<Thread> THREAD_COMP = new Comparator<Thread>() {
+    public int compare(Thread o1, Thread o2) {
+      return o1.getName().compareTo(o2.getName());
+    }
+  };
+
   private final static Map<Integer, String> STATE_NAMES = new HashMap<Integer, String>();
   private final static List<Integer> STATE_KEYS = new ArrayList<Integer>();
   static {
@@ -213,4 +228,5 @@
   private static native Thread getCurrentThread();
   private static native Object[] getThreadInfo(Thread t);
   private static native int getThreadState(Thread t);
+  private static native Thread[] getAllThreads();
 }
diff --git a/test/924-threads/threads.cc b/test/924-threads/threads.cc
index 4abf8fc..1487b7c 100644
--- a/test/924-threads/threads.cc
+++ b/test/924-threads/threads.cc
@@ -100,5 +100,25 @@
   return state;
 }
 
+extern "C" JNIEXPORT jobjectArray JNICALL Java_Main_getAllThreads(
+    JNIEnv* env, jclass Main_klass ATTRIBUTE_UNUSED) {
+  jint thread_count;
+  jthread* threads;
+
+  jvmtiError result = jvmti_env->GetAllThreads(&thread_count, &threads);
+  if (JvmtiErrorToException(env, result)) {
+    return nullptr;
+  }
+
+  auto callback = [&](jint index) {
+    return threads[index];
+  };
+  jobjectArray ret = CreateObjectArray(env, thread_count, "java/lang/Thread", callback);
+
+  jvmti_env->Deallocate(reinterpret_cast<unsigned char*>(threads));
+
+  return ret;
+}
+
 }  // namespace Test924Threads
 }  // namespace art