--- /dev/null	2017-11-09 09:38:01.297999907 +0100
+++ new/src/hotspot/share/jfr/periodic/sampling/jfrThreadSampler.cpp	2018-04-09 14:52:59.222729300 +0200
@@ -0,0 +1,565 @@
+/*
+ * Copyright (c) 2012, 2018, 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.
+ *
+ * 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 "precompiled.hpp"
+#include "jfr/recorder/jfrRecorder.hpp"
+#include "jfr/periodic/sampling/jfrCallTrace.hpp"
+#include "jfr/periodic/sampling/jfrThreadSampler.hpp"
+#include "jfr/recorder/stacktrace/jfrStackTraceRepository.hpp"
+#include "jfr/recorder/access/jfrOptionSet.hpp"
+#include "jfr/utilities/jfrTraceTime.hpp"
+#include "logging/log.hpp"
+#include "runtime/frame.inline.hpp"
+#include "runtime/os.hpp"
+#include "runtime/thread.inline.hpp"
+#include "runtime/threadSMR.hpp"
+#include "trace/tracing.hpp"
+#include "tracefiles/traceEventIds.hpp"
+
+static bool in_java_sample(JavaThread* thread) {
+  switch (thread->thread_state()) {
+  case _thread_new:
+  case _thread_uninitialized:
+  case _thread_new_trans:
+  case _thread_in_vm_trans:
+  case _thread_blocked_trans:
+  case _thread_in_native_trans:
+  case _thread_blocked:
+  case _thread_in_vm:
+  case _thread_in_native:
+  case _thread_in_Java_trans:
+    break;
+  case _thread_in_Java:
+    return true;
+  default:
+    ShouldNotReachHere();
+    break;
+  }
+  return false;
+}
+
+static bool in_native_sample(JavaThread* thread) {
+  switch (thread->thread_state()) {
+  case _thread_new:
+  case _thread_uninitialized:
+  case _thread_new_trans:
+  case _thread_blocked_trans:
+  case _thread_blocked:
+  case _thread_in_vm:
+  case _thread_in_vm_trans:
+  case _thread_in_Java_trans:
+  case _thread_in_Java:
+  case _thread_in_native_trans:
+    break;
+  case _thread_in_native:
+    return true;
+  default:
+    ShouldNotReachHere();
+    break;
+  }
+  return false;
+}
+
+class JfrThreadSampleClosure {
+ public:
+  JfrThreadSampleClosure(EventExecutionSample* events, EventNativeMethodSample* events_native);
+  ~JfrThreadSampleClosure() {}
+  EventExecutionSample* next_event() { return &_events[_added_java++]; }
+  EventNativeMethodSample* next_event_native() { return &_events_native[_added_native++]; }
+  void commit_events();
+  int added() const { return _added_java; }
+  JfrSampleType do_sample_thread(JavaThread* thread, JfrStackFrame* frames, u4 max_frames, bool java_sample, bool native_sample);
+  int java_entries() { return _added_java; }
+  int native_entries() { return _added_native; }
+
+ private:
+  bool sample_thread_in_java(JavaThread* thread, JfrStackFrame* frames, u4 max_frames);
+  bool sample_thread_in_native(JavaThread* thread, JfrStackFrame* frames, u4 max_frames);
+  EventExecutionSample* _events;
+  EventNativeMethodSample* _events_native;
+  Thread* _self;
+  int _added_java;
+  int _added_native;
+};
+
+class OSThreadSampler : public os::SuspendedThreadTask {
+ public:
+  OSThreadSampler(JavaThread* thread,
+                  JfrThreadSampleClosure& closure,
+                  JfrStackFrame *frames,
+                  u4 max_frames) : os::SuspendedThreadTask((Thread*)thread),
+    _success(false),
+    _stacktrace(frames, max_frames),
+    _closure(closure),
+    _suspend_time(0) {}
+
+  void take_sample();
+  void do_task(const os::SuspendedThreadTaskContext& context);
+  void protected_task(const os::SuspendedThreadTaskContext& context);
+  bool success() const { return _success; }
+  const JfrStackTrace& stacktrace() const { return _stacktrace; }
+
+ private:
+  bool _success;
+  JfrStackTrace _stacktrace;
+  JfrThreadSampleClosure& _closure;
+  JfrTraceTime _suspend_time;
+};
+
+class OSThreadSamplerCallback : public os::CrashProtectionCallback {
+ public:
+  OSThreadSamplerCallback(OSThreadSampler& sampler, const os::SuspendedThreadTaskContext &context) :
+    _sampler(sampler), _context(context) {
+  }
+  virtual void call() {
+    _sampler.protected_task(_context);
+  }
+ private:
+  OSThreadSampler& _sampler;
+  const os::SuspendedThreadTaskContext& _context;
+};
+
+void OSThreadSampler::do_task(const os::SuspendedThreadTaskContext& context) {
+#ifndef ASSERT
+  guarantee(JfrOptionSet::sample_protection(), "Sample Protection should be on in product builds");
+#endif
+  assert(0 == _suspend_time, "already timestamped!");
+  _suspend_time = JfrTraceTime::now();
+
+  if (JfrOptionSet::sample_protection()) {
+    OSThreadSamplerCallback cb(*this, context);
+    os::ThreadCrashProtection crash_protection;
+    if (!crash_protection.call(cb)) {
+      log_error(jfr)("Thread method sampler crashed");
+    }
+  } else {
+    protected_task(context);
+  }
+}
+
+/*
+* From this method and down the call tree we attempt to protect against crashes
+* using a signal handler / __try block. Don't take locks, rely on destructors or
+* leave memory (in case of signal / exception) in an inconsistent state. */
+void OSThreadSampler::protected_task(const os::SuspendedThreadTaskContext& context) {
+  JavaThread* jth = (JavaThread*)context.thread();
+  // Skip sample if we signaled a thread that moved to other state
+  if (!in_java_sample(jth)) {
+    return;
+  }
+  JfrGetCallTrace trace(true, jth);
+  frame topframe;
+  if (trace.get_topframe(context.ucontext(), topframe)) {
+    if (_stacktrace.record_thread(*jth, topframe)) {
+      /* If we managed to get a topframe and a stacktrace, create an event
+      * and put it into our array. We can't call Jfr::_stacktraces.add()
+      * here since it would allocate memory using malloc. Doing so while
+      * the stopped thread is inside malloc would deadlock. */
+      _success = true;
+      EventExecutionSample *ev = _closure.next_event();
+      ev->set_starttime(_suspend_time);
+      ev->set_endtime(JfrTraceTime(1)); // fake to not take an end time
+      ev->set_sampledThread(THREAD_TRACE_ID(jth));
+      ev->set_state(java_lang_Thread::get_thread_status(jth->threadObj()));
+    }
+  }
+}
+
+void OSThreadSampler::take_sample() {
+  run();
+}
+
+class JfrNativeSamplerCallback : public os::CrashProtectionCallback {
+ public:
+  JfrNativeSamplerCallback(JfrThreadSampleClosure& closure, JavaThread* jt, JfrStackFrame* frames, u4 max_frames) :
+    _closure(closure), _jt(jt), _stacktrace(frames, max_frames), _success(false) {
+  }
+  virtual void call();
+  bool success() { return _success; }
+  JfrStackTrace& stacktrace() { return _stacktrace; }
+
+ private:
+  JfrThreadSampleClosure& _closure;
+  JavaThread* _jt;
+  JfrStackTrace _stacktrace;
+  bool _success;
+};
+
+static void write_native_event(JfrThreadSampleClosure& closure, JavaThread* jt) {
+  EventNativeMethodSample *ev = closure.next_event_native();
+  ev->set_starttime(JfrTraceTime(0));
+  ev->set_sampledThread(THREAD_TRACE_ID(jt));
+  ev->set_state(java_lang_Thread::get_thread_status(jt->threadObj()));
+}
+
+void JfrNativeSamplerCallback::call() {
+  // When a thread is only attach it will be native without a last java frame
+  if (!_jt->has_last_Java_frame()) {
+    return;
+  }
+
+  frame topframe = _jt->last_frame();
+  frame first_java_frame;
+  Method* method = NULL;
+  JfrGetCallTrace gct(false, _jt);
+  if (!gct.find_top_frame(topframe, &method, first_java_frame)) {
+    return;
+  }
+  if (method == NULL) {
+    return;
+  }
+  topframe = first_java_frame;
+  _success = _stacktrace.record_thread(*_jt, topframe);
+  if (_success) {
+    write_native_event(_closure, _jt);
+  }
+}
+
+bool JfrThreadSampleClosure::sample_thread_in_java(JavaThread* thread, JfrStackFrame* frames, u4 max_frames) {
+  OSThreadSampler sampler(thread, *this, frames, max_frames);
+  sampler.take_sample();
+  /* We don't want to allocate any memory using malloc/etc while the thread
+  * is stopped, so everything is stored in stack allocated memory until this
+  * point where the thread has been resumed again, if the sampling was a success
+  * we need to store the stacktrace in the stacktrace repository and update
+  * the event with the id that was returned. */
+  if (!sampler.success()) {
+    return false;
+  }
+  EventExecutionSample *event = &_events[_added_java - 1];
+  traceid id = JfrStackTraceRepository::add(sampler.stacktrace());
+  assert(id != 0, "Stacktrace id should not be 0");
+  event->set_stackTrace(id);
+  return true;
+}
+
+bool JfrThreadSampleClosure::sample_thread_in_native(JavaThread* thread, JfrStackFrame* frames, u4 max_frames) {
+  JfrNativeSamplerCallback cb(*this, thread, frames, max_frames);
+  if (JfrOptionSet::sample_protection()) {
+    os::ThreadCrashProtection crash_protection;
+    if (!crash_protection.call(cb)) {
+      log_error(jfr)("Thread method sampler crashed for native");
+    }
+  } else {
+    cb.call();
+  }
+  if (!cb.success()) {
+    return false;
+  }
+  EventNativeMethodSample *event = &_events_native[_added_native - 1];
+  traceid id = JfrStackTraceRepository::add(cb.stacktrace());
+  assert(id != 0, "Stacktrace id should not be 0");
+  event->set_stackTrace(id);
+  return true;
+}
+
+void JfrThreadSampleClosure::commit_events() {
+  for (int i = 0; i < _added_java; ++i) {
+    _events[i].commit();
+  }
+  for (int i = 0; i < _added_native; ++i) {
+    _events_native[i].commit();
+  }
+}
+
+JfrThreadSampleClosure::JfrThreadSampleClosure(EventExecutionSample* events, EventNativeMethodSample* events_native) :
+  _events(events),
+  _events_native(events_native),
+  _self(Thread::current()),
+  _added_java(0),
+  _added_native(0) {
+}
+
+static void clear_transition_block(JavaThread* jt) {
+  jt->clear_trace_flag();
+  JfrThreadData* jtd = jt->trace_data();
+  if (jtd->is_trace_block()) {
+    MutexLockerEx ml(JfrThreadSampler::transition_block(), Mutex::_no_safepoint_check_flag);
+    JfrThreadSampler::transition_block()->notify_all();
+  }
+}
+
+JfrSampleType JfrThreadSampleClosure::do_sample_thread(JavaThread* thread, JfrStackFrame* frames, u4 max_frames, bool java_sample, bool native_sample) {
+  assert(Threads_lock->owned_by_self(), "Holding the thread table lock.");
+  if (thread->is_hidden_from_external_view()) {
+    return NO_SAMPLE;
+  }
+  if (thread->in_deopt_handler()) {
+    return NO_SAMPLE;
+  }
+  JfrSampleType ret = NO_SAMPLE;
+  thread->set_trace_flag();
+  if (!UseMembar) {
+    os::serialize_thread_states();
+  }
+  if (in_java_sample(thread) && java_sample) {
+    ret = sample_thread_in_java(thread, frames, max_frames) ? JAVA_SAMPLE : NO_SAMPLE;
+  } else if (in_native_sample(thread) && native_sample) {
+    ret = sample_thread_in_native(thread, frames, max_frames) ? NATIVE_SAMPLE : NO_SAMPLE;
+  }
+  clear_transition_block(thread);
+  return ret;
+}
+
+Monitor* JfrThreadSampler::_transition_block_lock = new Monitor(Mutex::leaf, "Trace block", true, Monitor::_safepoint_check_never);
+
+JfrThreadSampler::JfrThreadSampler(size_t interval_java, size_t interval_native, u4 max_frames) :
+  _frames(JfrCHeapObj::new_array<JfrStackFrame>(max_frames)),
+  _last_thread_java(NULL),
+  _last_thread_native(NULL),
+  _interval_java(interval_java),
+  _interval_native(interval_native),
+  _cur_index(-1),
+  _max_frames(max_frames),
+  _should_terminate(false) {
+}
+
+JfrThreadSampler::~JfrThreadSampler() {
+  JfrCHeapObj::free(_frames, sizeof(JfrStackFrame) * _max_frames);
+}
+
+void JfrThreadSampler::on_javathread_suspend(JavaThread* thread) {
+  JfrThreadData* jtd = thread->trace_data();
+  jtd->set_trace_block();
+  {
+    MutexLockerEx ml(transition_block(), Mutex::_no_safepoint_check_flag);
+    while (thread->is_trace_suspend()) {
+      transition_block()->wait(true);
+    }
+    jtd->clear_trace_block();
+  }
+}
+
+JavaThread* JfrThreadSampler::next_thread(ThreadsList* t_list, JavaThread* first_sampled, JavaThread* current) {
+  assert(Threads_lock->owned_by_self(), "Holding the thread table lock.");
+  if (current == NULL) {
+    _cur_index = 0;
+    return t_list->thread_at(_cur_index);
+  }
+
+  if (_cur_index == -1 || t_list->thread_at(_cur_index) != current) {
+    // 'current' is not at '_cur_index' so find it:
+    _cur_index = t_list->find_index_of_JavaThread(current);
+    assert(_cur_index != -1, "current JavaThread should be findable.");
+  }
+  _cur_index++;
+
+  JavaThread* next = NULL;
+  // wrap
+  if ((uint)_cur_index >= t_list->length()) {
+    _cur_index = 0;
+  }
+  next = t_list->thread_at(_cur_index);
+
+  // sample wrap
+  if (next == first_sampled) {
+    return NULL;
+  }
+  return next;
+}
+
+void JfrThreadSampler::enroll() {
+  if (os::create_thread(this, os::os_thread)) {
+    os::start_thread(this);
+  } else {
+    log_error(jfr)("Failed to create thread for thread sampling");
+  }
+}
+
+void JfrThreadSampler::disenroll() {
+  _should_terminate = true;
+}
+
+static jlong get_monotonic_ms() {
+  return os::javaTimeNanos() / 1000000;
+}
+
+void JfrThreadSampler::run() {
+  jlong last_java_ms = get_monotonic_ms();
+  jlong last_native_ms = last_java_ms;
+  while (!_should_terminate) {
+    jlong java_interval = _interval_java == 0 ? max_jlong : MAX2<jlong>(_interval_java, 10);
+    jlong native_interval = _interval_native == 0 ? max_jlong : MAX2<jlong>(_interval_native, 10);
+
+    jlong now_ms = get_monotonic_ms();
+
+    jlong next_j = java_interval + last_java_ms - now_ms;
+    jlong next_n = native_interval + last_native_ms - now_ms;
+
+    jlong sleep_to_next = MIN2<jlong>(next_j, next_n);
+
+    if (sleep_to_next > 0) {
+      os::naked_short_sleep(sleep_to_next);
+    }
+
+    if ((next_j - sleep_to_next) <= 0) {
+      task_stacktrace(JAVA_SAMPLE, &_last_thread_java);
+      last_java_ms = get_monotonic_ms();
+    }
+    if ((next_n - sleep_to_next) <= 0) {
+      task_stacktrace(NATIVE_SAMPLE, &_last_thread_native);
+      last_native_ms = get_monotonic_ms();
+    }
+  }
+  delete this;
+}
+
+static const int MAX_NR_OF_SAMPLES = 5;
+
+void JfrThreadSampler::task_stacktrace(JfrSampleType type, JavaThread** last_thread) {
+  ResourceMark rm;
+  EventExecutionSample samples[MAX_NR_OF_SAMPLES];
+  EventNativeMethodSample samples_native[MAX_NR_OF_SAMPLES];
+  JfrThreadSampleClosure sample_task(samples, samples_native);
+
+  int num_samples = 0;
+  {
+    elapsedTimer sample_time;
+    sample_time.start();
+
+    {
+      MonitorLockerEx tlock(Threads_lock, Mutex::_allow_vm_block_flag);
+      ThreadsListHandle tlh;
+      JavaThread* current = tlh.includes(*last_thread) ? *last_thread : NULL;
+      JavaThread* start = NULL;
+
+      while (num_samples < MAX_NR_OF_SAMPLES) {
+        current = next_thread(tlh.list(), start, current);
+        if (current == NULL) {
+          break;
+        }
+        if (start == NULL) {
+          start = current;  // remember thread where we started sampling
+        }
+        if (current->is_Compiler_thread()) {
+          continue;
+        }
+        *last_thread = current;  // remember thread we last sampled
+        JfrSampleType ret = sample_task.do_sample_thread(current, _frames, _max_frames, type == JAVA_SAMPLE, type == NATIVE_SAMPLE);
+        switch (type) {
+        case JAVA_SAMPLE:
+        case NATIVE_SAMPLE:
+          ++num_samples;
+          break;
+        default:
+          break;
+        }
+      }
+    }
+    sample_time.stop();
+    log_trace(jfr)("JFR thread sampling done in %3.7f secs with %d java %d native samples",
+      sample_time.seconds(), sample_task.java_entries(), sample_task.native_entries());
+  }
+  if (num_samples>0) {
+    sample_task.commit_events();
+  }
+}
+
+static JfrThreadSampling* _instance = NULL;
+
+JfrThreadSampling& JfrThreadSampling::instance() {
+  return *_instance;
+}
+
+JfrThreadSampling* JfrThreadSampling::create() {
+  assert(_instance == NULL, "invariant");
+  _instance = new JfrThreadSampling();
+  return _instance;
+}
+
+void JfrThreadSampling::destroy() {
+  if (_instance != NULL) {
+    delete _instance;
+    _instance = NULL;
+  }
+}
+
+JfrThreadSampling::JfrThreadSampling() : _sampler(NULL) {}
+
+JfrThreadSampling::~JfrThreadSampling() {
+  log_info(jfr)("Disrolling thread sampler");
+  stop_sampler();
+}
+
+static void log(size_t interval_java, size_t interval_native) {
+  log_info(jfr)("Updated thread sampler for java: " SIZE_FORMAT"  ms, native " SIZE_FORMAT " ms", interval_java, interval_native);
+}
+
+void JfrThreadSampling::start_sampler(size_t interval_java, size_t interval_native) {
+  assert(_sampler == NULL, "invariant");
+  log_info(jfr)("Enrolling thread sampler");
+  _sampler = new JfrThreadSampler(interval_java, interval_native, JfrOptionSet::stackdepth());
+  _sampler->enroll();
+}
+
+void JfrThreadSampling::stop_sampler() {
+  if (_sampler != NULL) {
+    _sampler->disenroll();
+    _sampler = NULL;
+  }
+}
+
+void JfrThreadSampling::set_sampling_interval(bool java_interval, size_t period) {
+  size_t interval_java = 0;
+  size_t interval_native = 0;
+  if (_sampler != NULL) {
+    interval_java = _sampler->get_java_interval();
+    interval_native = _sampler->get_native_interval();
+  }
+
+  if (java_interval) {
+    interval_java = period;
+  } else {
+    interval_native = period;
+  }
+
+  if (interval_java > 0 || interval_native > 0) {
+    if (_sampler == NULL) {
+      start_sampler(interval_java, interval_native);
+    } else {
+      _sampler->set_java_interval(interval_java);
+      _sampler->set_native_interval(interval_native);
+    }
+    assert(_sampler != NULL, "invariant");
+    log(interval_java, interval_native);
+  } else if (_sampler != NULL) {
+    log_info(jfr)("Disrolling thread sampler");
+    stop_sampler();
+  }
+}
+
+void JfrThreadSampling::set_java_sample_interval(size_t period) {
+  if (_instance == NULL && 0 == period) {
+    return;
+  }
+  instance().set_sampling_interval(true, period);
+}
+
+void JfrThreadSampling::set_native_sample_interval(size_t period) {
+  if (_instance == NULL && 0 == period) {
+    return;
+  }
+  instance().set_sampling_interval(false, period);
+}
+