/*

 * 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/markWord.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().to_pointer();

  }

  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();

}