/*

 * Copyright (c) 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

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 */

#ifndef SHARE_VM_GC_SHARED_WORKERMANAGER_HPP

#define SHARE_VM_GC_SHARED_WORKERMANAGER_HPP

#include "gc/shared/adaptiveSizePolicy.hpp"

class WorkerManager : public AllStatic {

 public:

  // Create additional workers as needed.

  //   active_workers - number of workers being requested for an upcoming

  // parallel task.

  //   total_workers - total number of workers.  This is the maximum

  // number possible.

  //   created_workers - number of workers already created.  This maybe

  // less than, equal to, or greater than active workers.  If greater than

  // or equal to active_workers, nothing is done.

  //   worker_type - type of thread.

  //   initializing - true if this is called to get the initial number of

  // GC workers.

  // If initializing is true, do a vm exit if the workers cannot be created.

  // The initializing = true case is for JVM start up and failing to

  // create all the worker at start should considered a problem so exit.

  // If initializing = false, there are already some number of worker

  // threads and a failure would not be optimal but should not be fatal.

  template <class WorkerType>

  static uint add_workers (WorkerType* holder,

                           uint active_workers,

                           uint total_workers,

                           uint created_workers,

                           os::ThreadType worker_type,

                           bool initializing) {

    uint start = created_workers;

    uint end = MIN2(active_workers, total_workers);

    for (uint worker_id = start; worker_id < end; worker_id += 1) {

      WorkerThread* new_worker = NULL;

      if (initializing || !InjectGCWorkerCreationFailure) {

        new_worker = holder->install_worker(worker_id);

      }

      if (new_worker == NULL || !os::create_thread(new_worker, worker_type)) {

        log_trace(gc, task)("WorkerManager::add_workers() : "

                            "creation failed due to failed allocation of native %s",

                            new_worker == NULL ?  "memory" : "thread");

        if (new_worker != NULL) {

           delete new_worker;

        }

        if (initializing) {

          vm_exit_out_of_memory(0, OOM_MALLOC_ERROR, "Cannot create worker GC thread. Out of system resources.");

        }

        break;

      }

      created_workers++;

      os::start_thread(new_worker);

    }

    log_trace(gc, task)("WorkerManager::add_workers() : "

                        "created_workers: %u", created_workers);

    return created_workers;

  }

  // Log (at trace level) a change in the number of created workers.

  template <class WorkerType>

  static void log_worker_creation(WorkerType* holder,

                                  uint previous_created_workers,

                                  uint active_workers,

                                  uint created_workers,

                                  bool initializing) {

    if (previous_created_workers < created_workers) {

      const char* initializing_msg =  initializing ? "Adding initial" : "Creating additional";

      log_trace(gc, task)("%s %s(s) previously created workers %u active workers %u total created workers %u",

                          initializing_msg, holder->group_name(), previous_created_workers, active_workers, created_workers);

    }

  }

};

#endif // SHARE_VM_GC_SHARED_WORKERMANAGER_HPP