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 /*

  * 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 "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();

 }