1 /*

     2  * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "jfr/jfrEvents.hpp"

    27 #include "jfr/leakprofiler/chains/edgeStore.hpp"

    28 #include "jfr/leakprofiler/chains/pathToGcRootsOperation.hpp"

    29 #include "jfr/leakprofiler/checkpoint/eventEmitter.hpp"

    30 #include "jfr/leakprofiler/checkpoint/objectSampleCheckpoint.hpp"

    31 #include "jfr/leakprofiler/sampling/objectSample.hpp"

    32 #include "jfr/leakprofiler/sampling/objectSampler.hpp"

    33 #include "logging/log.hpp"

    34 #include "memory/resourceArea.hpp"

    35 #include "oops/markOop.hpp"

    36 #include "oops/oop.inline.hpp"

    37 #include "runtime/thread.inline.hpp"

    38 #include "runtime/vmThread.hpp"

    39 

    40 EventEmitter::EventEmitter(const JfrTicks& start_time, const JfrTicks& end_time) :

    41   _start_time(start_time),

    42   _end_time(end_time),

    43   _thread(Thread::current()),

    44   _jfr_thread_local(_thread->jfr_thread_local()),

    45   _thread_id(_thread->jfr_thread_local()->thread_id()) {}

    46 

    47 EventEmitter::~EventEmitter() {

    48   // restore / reset thread local stack trace and thread id

    49   _jfr_thread_local->set_thread_id(_thread_id);

    50   _jfr_thread_local->clear_cached_stack_trace();

    51 }

    52 

    53 void EventEmitter::emit(ObjectSampler* sampler, int64_t cutoff_ticks, bool emit_all) {

    54   assert(sampler != NULL, "invariant");

    55 

    56   ResourceMark rm;

    57   EdgeStore edge_store;

    58   if (cutoff_ticks <= 0) {

    59     // no reference chains

    60     JfrTicks time_stamp = JfrTicks::now();

    61     EventEmitter emitter(time_stamp, time_stamp);

    62     emitter.write_events(sampler, &edge_store, emit_all);

    63     return;

    64   }

    65   // events emitted with reference chains require a safepoint operation

    66   PathToGcRootsOperation op(sampler, &edge_store, cutoff_ticks, emit_all);

    67   VMThread::execute(&op);

    68 }

    69 

    70 size_t EventEmitter::write_events(ObjectSampler* object_sampler, EdgeStore* edge_store, bool emit_all) {

    71   assert(_thread == Thread::current(), "invariant");

    72   assert(_thread->jfr_thread_local() == _jfr_thread_local, "invariant");

    73   assert(object_sampler != NULL, "invariant");

    74   assert(edge_store != NULL, "invariant");

    75 

    76   const jlong last_sweep = emit_all ? max_jlong : object_sampler->last_sweep().value();

    77   size_t count = 0;

    78 

    79   const ObjectSample* current = object_sampler->first();

    80   while (current != NULL) {

    81     ObjectSample* prev = current->prev();

    82     if (current->is_alive_and_older_than(last_sweep)) {

    83       write_event(current, edge_store);

    84       ++count;

    85     }

    86     current = prev;

    87   }

    88 

    89   if (count > 0) {

    90     // serialize associated checkpoints and potential chains

    91     ObjectSampleCheckpoint::write(object_sampler, edge_store, emit_all, _thread);

    92   }

    93   return count;

    94 }

    95 

    96 static int array_size(const oop object) {

    97   assert(object != NULL, "invariant");

    98   if (object->is_array()) {

    99     return arrayOop(object)->length();

   100   }

   101   return min_jint;

   102 }

   103 

   104 void EventEmitter::write_event(const ObjectSample* sample, EdgeStore* edge_store) {

   105   assert(sample != NULL, "invariant");

   106   assert(!sample->is_dead(), "invariant");

   107   assert(edge_store != NULL, "invariant");

   108   assert(_jfr_thread_local != NULL, "invariant");

   109 

   110   const oop* object_addr = sample->object_addr();

   111   traceid gc_root_id = 0;

   112   const Edge* edge = NULL;

   113   if (SafepointSynchronize::is_at_safepoint()) {

   114     edge = (const Edge*)(*object_addr)->mark();

   115   }

   116   if (edge == NULL) {

   117     // In order to dump out a representation of the event

   118     // even though it was not reachable / too long to reach,

   119     // we need to register a top level edge for this object.

   120     edge = edge_store->put(object_addr);

   121   } else {

   122     gc_root_id = edge_store->gc_root_id(edge);

   123   }

   124 

   125   assert(edge != NULL, "invariant");

   126   const traceid object_id = edge_store->get_id(edge);

   127   assert(object_id != 0, "invariant");

   128 

   129   EventOldObjectSample e(UNTIMED);

   130   e.set_starttime(_start_time);

   131   e.set_endtime(_end_time);

   132   e.set_allocationTime(sample->allocation_time());

   133   e.set_lastKnownHeapUsage(sample->heap_used_at_last_gc());

   134   e.set_object(object_id);

   135   e.set_arrayElements(array_size(edge->pointee()));

   136   e.set_root(gc_root_id);

   137 

   138   // Temporarily assigning both the stack trace id and thread id

   139   // onto the thread local data structure of the emitter thread (for the duration

   140   // of the commit() call). This trick provides a means to override

   141   // the event generation mechanism by injecting externally provided id's.

   142   // At this particular location, it allows us to emit an old object event

   143   // supplying information from where the actual sampling occurred.

   144   _jfr_thread_local->set_cached_stack_trace_id(sample->stack_trace_id());

   145   assert(sample->has_thread(), "invariant");

   146   _jfr_thread_local->set_thread_id(sample->thread_id());

   147   e.commit();

   148 }