/*

 * 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

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 */

#include "precompiled.hpp"

#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

#include "gc_implementation/g1/g1CollectorPolicy.hpp"

#include "gc_implementation/g1/vm_operations_g1.hpp"

#include "gc_implementation/shared/isGCActiveMark.hpp"

#include "gc_implementation/g1/vm_operations_g1.hpp"

#include "runtime/interfaceSupport.hpp"

VM_G1CollectForAllocation::VM_G1CollectForAllocation(

                                                  unsigned int gc_count_before,

                                                  size_t word_size)

  : VM_G1OperationWithAllocRequest(gc_count_before, word_size) {

  guarantee(word_size > 0, "an allocation should always be requested");

}

void VM_G1CollectForAllocation::doit() {

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  _result = g1h->satisfy_failed_allocation(_word_size, &_pause_succeeded);

  assert(_result == NULL || _pause_succeeded,

         "if we get back a result, the pause should have succeeded");

}

void VM_G1CollectFull::doit() {

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  GCCauseSetter x(g1h, _gc_cause);

  g1h->do_full_collection(false /* clear_all_soft_refs */);

}

VM_G1IncCollectionPause::VM_G1IncCollectionPause(

                                      unsigned int   gc_count_before,

                                      size_t         word_size,

                                      bool           should_initiate_conc_mark,

                                      double         target_pause_time_ms,

                                      GCCause::Cause gc_cause)

  : VM_G1OperationWithAllocRequest(gc_count_before, word_size),

    _should_initiate_conc_mark(should_initiate_conc_mark),

    _target_pause_time_ms(target_pause_time_ms),

    _full_collections_completed_before(0) {

  guarantee(target_pause_time_ms > 0.0,

            err_msg("target_pause_time_ms = %1.6lf should be positive",

                    target_pause_time_ms));

  guarantee(word_size == 0 || gc_cause == GCCause::_g1_inc_collection_pause,

            "we can only request an allocation if the GC cause is for "

            "an incremental GC pause");

  _gc_cause = gc_cause;

}

void VM_G1IncCollectionPause::doit() {

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  assert(!_should_initiate_conc_mark ||

  ((_gc_cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||

   (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)),

         "only a GC locker or a System.gc() induced GC should start a cycle");

  if (_word_size > 0) {

    // An allocation has been requested. So, try to do that first.

    _result = g1h->attempt_allocation_at_safepoint(_word_size,

                                     false /* expect_null_cur_alloc_region */);

    if (_result != NULL) {

      // If we can successfully allocate before we actually do the

      // pause then we will consider this pause successful.

      _pause_succeeded = true;

      return;

    }

  }

  GCCauseSetter x(g1h, _gc_cause);

  if (_should_initiate_conc_mark) {

    // It's safer to read full_collections_completed() here, given

    // that noone else will be updating it concurrently. Since we'll

    // only need it if we're initiating a marking cycle, no point in

    // setting it earlier.

    _full_collections_completed_before = g1h->full_collections_completed();

    // At this point we are supposed to start a concurrent cycle. We

    // will do so if one is not already in progress.

    bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle();

  }

  _pause_succeeded =

    g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);

  if (_pause_succeeded && _word_size > 0) {

    // An allocation had been requested.

    _result = g1h->attempt_allocation_at_safepoint(_word_size,

                                      true /* expect_null_cur_alloc_region */);

  } else {

    assert(_result == NULL, "invariant");

  }

}

void VM_G1IncCollectionPause::doit_epilogue() {

  VM_GC_Operation::doit_epilogue();

  // If the pause was initiated by a System.gc() and

  // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle

  // that just started (or maybe one that was already in progress) to

  // finish.

  if (_gc_cause == GCCause::_java_lang_system_gc &&

      _should_initiate_conc_mark) {

    assert(ExplicitGCInvokesConcurrent,

           "the only way to be here is if ExplicitGCInvokesConcurrent is set");

    G1CollectedHeap* g1h = G1CollectedHeap::heap();

    // In the doit() method we saved g1h->full_collections_completed()

    // in the _full_collections_completed_before field. We have to

    // wait until we observe that g1h->full_collections_completed()

    // has increased by at least one. This can happen if a) we started

    // a cycle and it completes, b) a cycle already in progress

    // completes, or c) a Full GC happens.

    // If the condition has already been reached, there's no point in

    // actually taking the lock and doing the wait.

    if (g1h->full_collections_completed() <=

                                          _full_collections_completed_before) {

      // The following is largely copied from CMS

      Thread* thr = Thread::current();

      assert(thr->is_Java_thread(), "invariant");

      JavaThread* jt = (JavaThread*)thr;

      ThreadToNativeFromVM native(jt);

      MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);

      while (g1h->full_collections_completed() <=

                                          _full_collections_completed_before) {

        FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);

      }

    }

  }

}

void VM_CGC_Operation::doit() {

  gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);

  TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);

  TraceTime t(_printGCMessage, PrintGC, true, gclog_or_tty);

  SharedHeap* sh = SharedHeap::heap();

  // This could go away if CollectedHeap gave access to _gc_is_active...

  if (sh != NULL) {

    IsGCActiveMark x;

    _cl->do_void();

  } else {

    _cl->do_void();

  }

}

bool VM_CGC_Operation::doit_prologue() {

  Heap_lock->lock();

  SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;

  return true;

}

void VM_CGC_Operation::doit_epilogue() {

  SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;

  Heap_lock->unlock();

}