/*

 * Copyright (c) 2000, 2010, 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_implementation/shared/cSpaceCounters.hpp"

#include "gc_implementation/shared/vmGCOperations.hpp"

#include "gc_interface/collectedHeap.inline.hpp"

#include "memory/blockOffsetTable.inline.hpp"

#include "memory/compactPermGen.hpp"

#include "memory/gcLocker.hpp"

#include "memory/gcLocker.inline.hpp"

#include "memory/genCollectedHeap.hpp"

#include "memory/generation.inline.hpp"

#include "memory/permGen.hpp"

#include "memory/universe.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/java.hpp"

#include "runtime/vmThread.hpp"

HeapWord* PermGen::request_expand_and_allocate(Generation* gen, size_t size,

                                               GCCause::Cause prev_cause) {

  if (gen->capacity() < _capacity_expansion_limit ||

      prev_cause != GCCause::_no_gc || UseG1GC) {  // last disjunct is a temporary hack for G1

    return gen->expand_and_allocate(size, false);

  }

  // We have reached the limit of capacity expansion where

  // we will not expand further until a GC is done; request denied.

  return NULL;

}

HeapWord* PermGen::mem_allocate_in_gen(size_t size, Generation* gen) {

  GCCause::Cause next_cause = GCCause::_permanent_generation_full;

  GCCause::Cause prev_cause = GCCause::_no_gc;

  unsigned int gc_count_before, full_gc_count_before;

  HeapWord* obj;

  for (;;) {

    {

      MutexLocker ml(Heap_lock);

      if ((obj = gen->allocate(size, false)) != NULL) {

        return obj;

      }

      // Attempt to expand and allocate the requested space:

      // specific subtypes may use specific policy to either expand

      // or not. The default policy (see above) is to expand until

      // _capacity_expansion_limit, and no further unless a GC is done.

      // Concurrent collectors may decide to kick off a concurrent

      // collection under appropriate conditions.

      obj = request_expand_and_allocate(gen, size, prev_cause);

      if (obj != NULL || prev_cause == GCCause::_last_ditch_collection) {

        return obj;

      }

      if (GC_locker::is_active_and_needs_gc()) {

        // If this thread is not in a jni critical section, we stall

        // the requestor until the critical section has cleared and

        // GC allowed. When the critical section clears, a GC is

        // initiated by the last thread exiting the critical section; so

        // we retry the allocation sequence from the beginning of the loop,

        // rather than causing more, now probably unnecessary, GC attempts.

        JavaThread* jthr = JavaThread::current();

        if (!jthr->in_critical()) {

          MutexUnlocker mul(Heap_lock);

          // Wait for JNI critical section to be exited

          GC_locker::stall_until_clear();

          continue;

        } else {

          if (CheckJNICalls) {

            fatal("Possible deadlock due to allocating while"

                  " in jni critical section");

          }

          return NULL;

        }

      }

      // Read the GC count while holding the Heap_lock

      gc_count_before      = SharedHeap::heap()->total_collections();

      full_gc_count_before = SharedHeap::heap()->total_full_collections();

    }

    // Give up heap lock above, VMThread::execute below gets it back

    VM_GenCollectForPermanentAllocation op(size, gc_count_before, full_gc_count_before,

                                           next_cause);

    VMThread::execute(&op);

    if (!op.prologue_succeeded() || op.gc_locked()) {

      assert(op.result() == NULL, "must be NULL if gc_locked() is true");

      continue;  // retry and/or stall as necessary

    }

    obj = op.result();

    assert(obj == NULL || SharedHeap::heap()->is_in_reserved(obj),

           "result not in heap");

    if (obj != NULL) {

      return obj;

    }

    prev_cause = next_cause;

    next_cause = GCCause::_last_ditch_collection;

  }

}

CompactingPermGen::CompactingPermGen(ReservedSpace rs,

                                     ReservedSpace shared_rs,

                                     size_t initial_byte_size,

                                     GenRemSet* remset,

                                     PermanentGenerationSpec* perm_spec)

{

  CompactingPermGenGen* g =

    new CompactingPermGenGen(rs, shared_rs, initial_byte_size, -1, remset,

                             NULL, perm_spec);

  if (g == NULL)

    vm_exit_during_initialization("Could not allocate a CompactingPermGen");

  _gen = g;

  g->initialize_performance_counters();

  _capacity_expansion_limit = g->capacity() + MaxPermHeapExpansion;

}

HeapWord* CompactingPermGen::mem_allocate(size_t size) {

  return mem_allocate_in_gen(size, _gen);

}

void CompactingPermGen::compute_new_size() {

  size_t desired_capacity = align_size_up(_gen->used(), MinPermHeapExpansion);

  if (desired_capacity < PermSize) {

    desired_capacity = PermSize;

  }

  if (_gen->capacity() > desired_capacity) {

    _gen->shrink(_gen->capacity() - desired_capacity);

  }

  set_capacity_expansion_limit(_gen->capacity() + MaxPermHeapExpansion);

}