/*

 * Copyright (c) 2001, 2011, 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/g1/g1CollectedHeap.inline.hpp"

#include "gc_implementation/g1/heapRegionSeq.hpp"

#include "memory/allocation.hpp"

// Local to this file.

static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {

  if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;

  else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;

  else if (*hr1p == *hr2p) return 0;

  else {

    assert(false, "We should never compare distinct overlapping regions.");

  }

  return 0;

}

HeapRegionSeq::HeapRegionSeq(const size_t max_size) :

  _alloc_search_start(0),

  // The line below is the worst bit of C++ hackery I've ever written

  // (Detlefs, 11/23).  You should think of it as equivalent to

  // "_regions(100, true)": initialize the growable array and inform it

  // that it should allocate its elem array(s) on the C heap.

  //

  // The first argument, however, is actually a comma expression

  // (set_allocation_type(this, C_HEAP), 100). The purpose of the

  // set_allocation_type() call is to replace the default allocation

  // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will

  // allow to pass the assert in GenericGrowableArray() which checks

  // that a growable array object must be on C heap if elements are.

  //

  // Note: containing object is allocated on C heap since it is CHeapObj.

  //

  _regions((ResourceObj::set_allocation_type((address)&_regions,

                                             ResourceObj::C_HEAP),

            (int)max_size),

           true),

  _next_rr_candidate(0),

  _seq_bottom(NULL)

{}

// Private methods.

void HeapRegionSeq::print_empty_runs() {

  int empty_run = 0;

  int n_empty = 0;

  int empty_run_start;

  for (int i = 0; i < _regions.length(); i++) {

    HeapRegion* r = _regions.at(i);

    if (r->continuesHumongous()) continue;

    if (r->is_empty()) {

      assert(!r->isHumongous(), "H regions should not be empty.");

      if (empty_run == 0) empty_run_start = i;

      empty_run++;

      n_empty++;

    } else {

      if (empty_run > 0) {

        gclog_or_tty->print("  %d:%d", empty_run_start, empty_run);

        empty_run = 0;

      }

    }

  }

  if (empty_run > 0) {

    gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);

  }

  gclog_or_tty->print_cr(" [tot = %d]", n_empty);

}

int HeapRegionSeq::find(HeapRegion* hr) {

  // FIXME: optimized for adjacent regions of fixed size.

  int ind = hr->hrs_index();

  if (ind != -1) {

    assert(_regions.at(ind) == hr, "Mismatch");

  }

  return ind;

}

// Public methods.

void HeapRegionSeq::insert(HeapRegion* hr) {

  assert(!_regions.is_full(), "Too many elements in HeapRegionSeq");

  if (_regions.length() == 0

      || _regions.top()->end() <= hr->bottom()) {

    hr->set_hrs_index(_regions.length());

    _regions.append(hr);

  } else {

    _regions.append(hr);

    _regions.sort(orderRegions);

    for (int i = 0; i < _regions.length(); i++) {

      _regions.at(i)->set_hrs_index(i);

    }

  }

  char* bot = (char*)_regions.at(0)->bottom();

  if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;

}

size_t HeapRegionSeq::length() {

  return _regions.length();

}

size_t HeapRegionSeq::free_suffix() {

  size_t res = 0;

  int first = _regions.length() - 1;

  int cur = first;

  while (cur >= 0 &&

         (_regions.at(cur)->is_empty()

          && (first == cur

              || (_regions.at(cur+1)->bottom() ==

                  _regions.at(cur)->end())))) {

      res++;

      cur--;

  }

  return res;

}

int HeapRegionSeq::find_contiguous_from(int from, size_t num) {

  assert(num > 1, "pre-condition");

  assert(0 <= from && from <= _regions.length(),

         err_msg("from: %d should be valid and <= than %d",

                 from, _regions.length()));

  int curr = from;

  int first = -1;

  size_t num_so_far = 0;

  while (curr < _regions.length() && num_so_far < num) {

    HeapRegion* curr_hr = _regions.at(curr);

    if (curr_hr->is_empty()) {

      if (first == -1) {

        first = curr;

        num_so_far = 1;

      } else {

        num_so_far += 1;

      }

    } else {

      first = -1;

      num_so_far = 0;

    }

    curr += 1;

  }

  assert(num_so_far <= num, "post-condition");

  if (num_so_far == num) {

    assert(from <= first && first < _regions.length(), "post-condition");

    assert(first < curr && (curr - first) == (int) num, "post-condition");

    for (int i = first; i < first + (int) num; ++i) {

      assert(_regions.at(i)->is_empty(), "post-condition");

    }

    return first;

  } else {

    // we failed to find enough space for the humongous object

    return -1;

  }

}

int HeapRegionSeq::find_contiguous(size_t num) {

  assert(num > 1, "otherwise we should not be calling this");

  assert(0 <= _alloc_search_start && _alloc_search_start <= _regions.length(),

         err_msg("_alloc_search_start: %d should be valid and <= than %d",

                 _alloc_search_start, _regions.length()));

  int start = _alloc_search_start;

  int res = find_contiguous_from(start, num);

  if (res == -1 && start != 0) {

    // Try starting from the beginning. If _alloc_search_start was 0,

    // no point in doing this again.

    res = find_contiguous_from(0, num);

  }

  if (res != -1) {

    assert(0 <= res && res < _regions.length(),

           err_msg("res: %d should be valid", res));

    _alloc_search_start = res + (int) num;

    assert(0 < _alloc_search_start && _alloc_search_start <= _regions.length(),

           err_msg("_alloc_search_start: %d should be valid",

                   _alloc_search_start));

  }

  return res;

}

void HeapRegionSeq::iterate(HeapRegionClosure* blk) {

  iterate_from((HeapRegion*)NULL, blk);

}

// The first argument r is the heap region at which iteration begins.

// This operation runs fastest when r is NULL, or the heap region for

// which a HeapRegionClosure most recently returned true, or the

// heap region immediately to its right in the sequence.  In all

// other cases a linear search is required to find the index of r.

void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) {

  // :::: FIXME ::::

  // Static cache value is bad, especially when we start doing parallel

  // remembered set update. For now just don't cache anything (the

  // code in the def'd out blocks).

#if 0

  static int cached_j = 0;

#endif

  int len = _regions.length();

  int j = 0;

  // Find the index of r.

  if (r != NULL) {

#if 0

    assert(cached_j >= 0, "Invariant.");

    if ((cached_j < len) && (r == _regions.at(cached_j))) {

      j = cached_j;

    } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {

      j = cached_j + 1;

    } else {

      j = find(r);

#endif

      if (j < 0) {

        j = 0;

      }

#if 0

    }

#endif

  }

  int i;

  for (i = j; i < len; i += 1) {

    int res = blk->doHeapRegion(_regions.at(i));

    if (res) {

#if 0

      cached_j = i;

#endif

      blk->incomplete();

      return;

    }

  }

  for (i = 0; i < j; i += 1) {

    int res = blk->doHeapRegion(_regions.at(i));

    if (res) {

#if 0

      cached_j = i;

#endif

      blk->incomplete();

      return;

    }

  }

}

void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {

  int len = _regions.length();

  int i;

  for (i = idx; i < len; i++) {

    if (blk->doHeapRegion(_regions.at(i))) {

      blk->incomplete();

      return;

    }

  }

  for (i = 0; i < idx; i++) {

    if (blk->doHeapRegion(_regions.at(i))) {

      blk->incomplete();

      return;

    }

  }

}

MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,

                                   size_t& num_regions_deleted) {

  // Reset this in case it's currently pointing into the regions that

  // we just removed.

  _alloc_search_start = 0;

  assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");

  assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");

  if (_regions.length() == 0) {

    num_regions_deleted = 0;

    return MemRegion();

  }

  int j = _regions.length() - 1;

  HeapWord* end = _regions.at(j)->end();

  HeapWord* last_start = end;

  while (j >= 0 && shrink_bytes > 0) {

    HeapRegion* cur = _regions.at(j);

    // We have to leave humongous regions where they are,

    // and work around them.

    if (cur->isHumongous()) {

      return MemRegion(last_start, end);

    }

    assert(cur == _regions.top(), "Should be top");

    if (!cur->is_empty()) break;

    shrink_bytes -= cur->capacity();

    num_regions_deleted++;

    _regions.pop();

    last_start = cur->bottom();

    // We need to delete these somehow, but can't currently do so here: if

    // we do, the ZF thread may still access the deleted region.  We'll

    // leave this here as a reminder that we have to do something about

    // this.

    // delete cur;

    j--;

  }

  return MemRegion(last_start, end);

}

class PrintHeapRegionClosure : public  HeapRegionClosure {

public:

  bool doHeapRegion(HeapRegion* r) {

    gclog_or_tty->print(PTR_FORMAT ":", r);

    r->print();

    return false;

  }

};

void HeapRegionSeq::print() {

  PrintHeapRegionClosure cl;

  iterate(&cl);

}