diff -r 1e95931e7d8f -r 49102ba8cf14 src/hotspot/share/jfr/leakprofiler/checkpoint/eventEmitter.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/jfr/leakprofiler/checkpoint/eventEmitter.cpp	Wed Jul 03 11:34:46 2019 +0200
@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2019, 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/jfrEvents.hpp"
+#include "jfr/leakprofiler/chains/edgeStore.hpp"
+#include "jfr/leakprofiler/chains/pathToGcRootsOperation.hpp"
+#include "jfr/leakprofiler/checkpoint/eventEmitter.hpp"
+#include "jfr/leakprofiler/checkpoint/objectSampleCheckpoint.hpp"
+#include "jfr/leakprofiler/sampling/objectSample.hpp"
+#include "jfr/leakprofiler/sampling/objectSampler.hpp"
+#include "logging/log.hpp"
+#include "memory/resourceArea.hpp"
+#include "oops/markOop.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/thread.inline.hpp"
+#include "runtime/vmThread.hpp"
+
+EventEmitter::EventEmitter(const JfrTicks& start_time, const JfrTicks& end_time) :
+  _start_time(start_time),
+  _end_time(end_time),
+  _thread(Thread::current()),
+  _jfr_thread_local(_thread->jfr_thread_local()),
+  _thread_id(_thread->jfr_thread_local()->thread_id()) {}
+
+EventEmitter::~EventEmitter() {
+  // restore / reset thread local stack trace and thread id
+  _jfr_thread_local->set_thread_id(_thread_id);
+  _jfr_thread_local->clear_cached_stack_trace();
+}
+
+void EventEmitter::emit(ObjectSampler* sampler, int64_t cutoff_ticks, bool emit_all) {
+  assert(sampler != NULL, "invariant");
+
+  ResourceMark rm;
+  EdgeStore edge_store;
+  if (cutoff_ticks <= 0) {
+    // no reference chains
+    JfrTicks time_stamp = JfrTicks::now();
+    EventEmitter emitter(time_stamp, time_stamp);
+    emitter.write_events(sampler, &edge_store, emit_all);
+    return;
+  }
+  // events emitted with reference chains require a safepoint operation
+  PathToGcRootsOperation op(sampler, &edge_store, cutoff_ticks, emit_all);
+  VMThread::execute(&op);
+}
+
+size_t EventEmitter::write_events(ObjectSampler* object_sampler, EdgeStore* edge_store, bool emit_all) {
+  assert(_thread == Thread::current(), "invariant");
+  assert(_thread->jfr_thread_local() == _jfr_thread_local, "invariant");
+  assert(object_sampler != NULL, "invariant");
+  assert(edge_store != NULL, "invariant");
+
+  const jlong last_sweep = emit_all ? max_jlong : object_sampler->last_sweep().value();
+  size_t count = 0;
+
+  const ObjectSample* current = object_sampler->first();
+  while (current != NULL) {
+    ObjectSample* prev = current->prev();
+    if (current->is_alive_and_older_than(last_sweep)) {
+      write_event(current, edge_store);
+      ++count;
+    }
+    current = prev;
+  }
+
+  if (count > 0) {
+    // serialize associated checkpoints and potential chains
+    ObjectSampleCheckpoint::write(object_sampler, edge_store, emit_all, _thread);
+  }
+  return count;
+}
+
+static int array_size(const oop object) {
+  assert(object != NULL, "invariant");
+  if (object->is_array()) {
+    return arrayOop(object)->length();
+  }
+  return min_jint;
+}
+
+void EventEmitter::write_event(const ObjectSample* sample, EdgeStore* edge_store) {
+  assert(sample != NULL, "invariant");
+  assert(!sample->is_dead(), "invariant");
+  assert(edge_store != NULL, "invariant");
+  assert(_jfr_thread_local != NULL, "invariant");
+
+  const oop* object_addr = sample->object_addr();
+  traceid gc_root_id = 0;
+  const Edge* edge = NULL;
+  if (SafepointSynchronize::is_at_safepoint()) {
+    edge = (const Edge*)(*object_addr)->mark();
+  }
+  if (edge == NULL) {
+    // In order to dump out a representation of the event
+    // even though it was not reachable / too long to reach,
+    // we need to register a top level edge for this object.
+    edge = edge_store->put(object_addr);
+  } else {
+    gc_root_id = edge_store->gc_root_id(edge);
+  }
+
+  assert(edge != NULL, "invariant");
+  const traceid object_id = edge_store->get_id(edge);
+  assert(object_id != 0, "invariant");
+
+  EventOldObjectSample e(UNTIMED);
+  e.set_starttime(_start_time);
+  e.set_endtime(_end_time);
+  e.set_allocationTime(sample->allocation_time());
+  e.set_lastKnownHeapUsage(sample->heap_used_at_last_gc());
+  e.set_object(object_id);
+  e.set_arrayElements(array_size(edge->pointee()));
+  e.set_root(gc_root_id);
+
+  // Temporarily assigning both the stack trace id and thread id
+  // onto the thread local data structure of the emitter thread (for the duration
+  // of the commit() call). This trick provides a means to override
+  // the event generation mechanism by injecting externally provided id's.
+  // At this particular location, it allows us to emit an old object event
+  // supplying information from where the actual sampling occurred.
+  _jfr_thread_local->set_cached_stack_trace_id(sample->stack_trace_id());
+  assert(sample->has_thread(), "invariant");
+  _jfr_thread_local->set_thread_id(sample->thread_id());
+  e.commit();
+}