/*

 * Copyright (c) 2002, 2016, 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 "gc/parallel/gcTaskManager.hpp"

#include "gc/parallel/gcTaskThread.hpp"

#include "gc/shared/gcId.hpp"

#include "logging/log.hpp"

#include "memory/allocation.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/resourceArea.hpp"

#include "runtime/atomic.inline.hpp"

#include "runtime/handles.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/os.hpp"

#include "runtime/thread.hpp"

GCTaskThread::GCTaskThread(GCTaskManager* manager,

                           uint           which,

                           uint           processor_id) :

  _manager(manager),

  _processor_id(processor_id),

  _time_stamps(NULL),

  _time_stamp_index(0)

{

  set_id(which);

}

GCTaskThread::~GCTaskThread() {

  if (_time_stamps != NULL) {

    FREE_C_HEAP_ARRAY(GCTaskTimeStamp, _time_stamps);

  }

}

GCTaskTimeStamp* GCTaskThread::time_stamp_at(uint index) {

  guarantee(index < GCTaskTimeStampEntries, "increase GCTaskTimeStampEntries");

  if (_time_stamps == NULL) {

    // We allocate the _time_stamps array lazily since logging can be enabled dynamically

    GCTaskTimeStamp* time_stamps = NEW_C_HEAP_ARRAY(GCTaskTimeStamp, GCTaskTimeStampEntries, mtGC);

    void* old = Atomic::cmpxchg_ptr(time_stamps, &_time_stamps, NULL);

    if (old != NULL) {

      // Someone already setup the time stamps

      FREE_C_HEAP_ARRAY(GCTaskTimeStamp, time_stamps);

    }

  }

  return &(_time_stamps[index]);

}

void GCTaskThread::print_task_time_stamps() {

  assert(log_is_enabled(Debug, gc, task, time), "Sanity");

  // Since _time_stamps is now lazily allocated we need to check that it

  // has in fact been allocated when calling this function.

  if (_time_stamps != NULL) {

    log_debug(gc, task, time)("GC-Thread %u entries: %d", id(), _time_stamp_index);

    for(uint i=0; i<_time_stamp_index; i++) {

      GCTaskTimeStamp* time_stamp = time_stamp_at(i);

      log_debug(gc, task, time)("\t[ %s " JLONG_FORMAT " " JLONG_FORMAT " ]",

                                time_stamp->name(),

                                time_stamp->entry_time(),

                                time_stamp->exit_time());

    }

    // Reset after dumping the data

    _time_stamp_index = 0;

  }

}

// GC workers get tasks from the GCTaskManager and execute

// them in this method.  If there are no tasks to execute,

// the GC workers wait in the GCTaskManager's get_task()

// for tasks to be enqueued for execution.

void GCTaskThread::run() {

  // Set up the thread for stack overflow support

  this->record_stack_base_and_size();

  this->initialize_named_thread();

  // Bind yourself to your processor.

  if (processor_id() != GCTaskManager::sentinel_worker()) {

    log_trace(gc, task, thread)("GCTaskThread::run: binding to processor %u", processor_id());

    if (!os::bind_to_processor(processor_id())) {

      DEBUG_ONLY(

        log_warning(gc)("Couldn't bind GCTaskThread %u to processor %u",

                        which(), processor_id());

      )

    }

  }

  // Part of thread setup.

  // ??? Are these set up once here to make subsequent ones fast?

  HandleMark   hm_outer;

  ResourceMark rm_outer;

  TimeStamp timer;

  for (;/* ever */;) {

    // These are so we can flush the resources allocated in the inner loop.

    HandleMark   hm_inner;

    ResourceMark rm_inner;

    for (; /* break */; ) {

      // This will block until there is a task to be gotten.

      GCTask* task = manager()->get_task(which());

      GCIdMark gc_id_mark(task->gc_id());

      // Record if this is an idle task for later use.

      bool is_idle_task = task->is_idle_task();

      // In case the update is costly

      if (log_is_enabled(Debug, gc, task, time)) {

        timer.update();

      }

      jlong entry_time = timer.ticks();

      char* name = task->name();

      // If this is the barrier task, it can be destroyed

      // by the GC task manager once the do_it() executes.

      task->do_it(manager(), which());

      // Use the saved value of is_idle_task because references

      // using "task" are not reliable for the barrier task.

      if (!is_idle_task) {

        manager()->note_completion(which());

        if (log_is_enabled(Debug, gc, task, time)) {

          timer.update();

          GCTaskTimeStamp* time_stamp = time_stamp_at(_time_stamp_index);

          time_stamp->set_name(name);

          time_stamp->set_entry_time(entry_time);

          time_stamp->set_exit_time(timer.ticks());

          // Update the index after we have set up the entry correctly since

          // GCTaskThread::print_task_time_stamps() may read this value concurrently.

          _time_stamp_index++;

        }

      } else {

        // idle tasks complete outside the normal accounting

        // so that a task can complete without waiting for idle tasks.

        // They have to be terminated separately.

        IdleGCTask::destroy((IdleGCTask*)task);

        set_is_working(true);

      }

      // Check if we should release our inner resources.

      if (manager()->should_release_resources(which())) {

        manager()->note_release(which());

        break;

      }

    }

  }

}