/*

 * Copyright (c) 2018, 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 "logging/log.hpp"

#include "logging/logStream.hpp"

#include "memory/binaryTreeDictionary.inline.hpp"

#include "memory/freeList.inline.hpp"

#include "memory/metaspace/chunkManager.hpp"

#include "memory/metaspace/metachunk.hpp"

#include "memory/metaspace/metaspaceCommon.hpp"

#include "memory/metaspace/metaspaceStatistics.hpp"

#include "memory/metaspace/occupancyMap.hpp"

#include "memory/metaspace/virtualSpaceNode.hpp"

#include "runtime/mutexLocker.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

#include "utilities/ostream.hpp"

namespace metaspace {

void ChunkManager::remove_chunk(Metachunk* chunk) {

  size_t word_size = chunk->word_size();

  ChunkIndex index = list_index(word_size);

  if (index != HumongousIndex) {

    free_chunks(index)->remove_chunk(chunk);

  } else {

    humongous_dictionary()->remove_chunk(chunk);

  }

  // Chunk has been removed from the chunks free list, update counters.

  account_for_removed_chunk(chunk);

}

bool ChunkManager::attempt_to_coalesce_around_chunk(Metachunk* chunk, ChunkIndex target_chunk_type) {

  assert_lock_strong(MetaspaceExpand_lock);

  assert(chunk != NULL, "invalid chunk pointer");

  // Check for valid merge combinations.

  assert((chunk->get_chunk_type() == SpecializedIndex &&

          (target_chunk_type == SmallIndex || target_chunk_type == MediumIndex)) ||

         (chunk->get_chunk_type() == SmallIndex && target_chunk_type == MediumIndex),

        "Invalid chunk merge combination.");

  const size_t target_chunk_word_size =

    get_size_for_nonhumongous_chunktype(target_chunk_type, this->is_class());

  // [ prospective merge region )

  MetaWord* const p_merge_region_start =

    (MetaWord*) align_down(chunk, target_chunk_word_size * sizeof(MetaWord));

  MetaWord* const p_merge_region_end =

    p_merge_region_start + target_chunk_word_size;

  // We need the VirtualSpaceNode containing this chunk and its occupancy map.

  VirtualSpaceNode* const vsn = chunk->container();

  OccupancyMap* const ocmap = vsn->occupancy_map();

  // The prospective chunk merge range must be completely contained by the

  // committed range of the virtual space node.

  if (p_merge_region_start < vsn->bottom() || p_merge_region_end > vsn->top()) {

    return false;

  }

  // Only attempt to merge this range if at its start a chunk starts and at its end

  // a chunk ends. If a chunk (can only be humongous) straddles either start or end

  // of that range, we cannot merge.

  if (!ocmap->chunk_starts_at_address(p_merge_region_start)) {

    return false;

  }

  if (p_merge_region_end < vsn->top() &&

      !ocmap->chunk_starts_at_address(p_merge_region_end)) {

    return false;

  }

  // Now check if the prospective merge area contains live chunks. If it does we cannot merge.

  if (ocmap->is_region_in_use(p_merge_region_start, target_chunk_word_size)) {

    return false;

  }

  // Success! Remove all chunks in this region...

  log_trace(gc, metaspace, freelist)("%s: coalescing chunks in area [%p-%p)...",

    (is_class() ? "class space" : "metaspace"),

    p_merge_region_start, p_merge_region_end);

  const int num_chunks_removed =

    remove_chunks_in_area(p_merge_region_start, target_chunk_word_size);

  // ... and create a single new bigger chunk.

  Metachunk* const p_new_chunk =

      ::new (p_merge_region_start) Metachunk(target_chunk_type, is_class(), target_chunk_word_size, vsn);

  assert(p_new_chunk == (Metachunk*)p_merge_region_start, "Sanity");

  p_new_chunk->set_origin(origin_merge);

  log_trace(gc, metaspace, freelist)("%s: created coalesced chunk at %p, size " SIZE_FORMAT_HEX ".",

    (is_class() ? "class space" : "metaspace"),

    p_new_chunk, p_new_chunk->word_size() * sizeof(MetaWord));

  // Fix occupancy map: remove old start bits of the small chunks and set new start bit.

  ocmap->wipe_chunk_start_bits_in_region(p_merge_region_start, target_chunk_word_size);

  ocmap->set_chunk_starts_at_address(p_merge_region_start, true);

  // Mark chunk as free. Note: it is not necessary to update the occupancy

  // map in-use map, because the old chunks were also free, so nothing

  // should have changed.

  p_new_chunk->set_is_tagged_free(true);

  // Add new chunk to its freelist.

  ChunkList* const list = free_chunks(target_chunk_type);

  list->return_chunk_at_head(p_new_chunk);

  // And adjust ChunkManager:: _free_chunks_count (_free_chunks_total

  // should not have changed, because the size of the space should be the same)

  _free_chunks_count -= num_chunks_removed;

  _free_chunks_count ++;

  // VirtualSpaceNode::container_count does not have to be modified:

  // it means "number of active (non-free) chunks", so merging free chunks

  // should not affect that count.

  // At the end of a chunk merge, run verification tests.

  if (VerifyMetaspace) {

    DEBUG_ONLY(this->locked_verify());

    DEBUG_ONLY(vsn->verify());

  }

  return true;

}

// Remove all chunks in the given area - the chunks are supposed to be free -

// from their corresponding freelists. Mark them as invalid.

// - This does not correct the occupancy map.

// - This does not adjust the counters in ChunkManager.

// - Does not adjust container count counter in containing VirtualSpaceNode

// Returns number of chunks removed.

int ChunkManager::remove_chunks_in_area(MetaWord* p, size_t word_size) {

  assert(p != NULL && word_size > 0, "Invalid range.");

  const size_t smallest_chunk_size = get_size_for_nonhumongous_chunktype(SpecializedIndex, is_class());

  assert_is_aligned(word_size, smallest_chunk_size);

  Metachunk* const start = (Metachunk*) p;

  const Metachunk* const end = (Metachunk*)(p + word_size);

  Metachunk* cur = start;

  int num_removed = 0;

  while (cur < end) {

    Metachunk* next = (Metachunk*)(((MetaWord*)cur) + cur->word_size());

    DEBUG_ONLY(do_verify_chunk(cur));

    assert(cur->get_chunk_type() != HumongousIndex, "Unexpected humongous chunk found at %p.", cur);

    assert(cur->is_tagged_free(), "Chunk expected to be free (%p)", cur);

    log_trace(gc, metaspace, freelist)("%s: removing chunk %p, size " SIZE_FORMAT_HEX ".",

      (is_class() ? "class space" : "metaspace"),

      cur, cur->word_size() * sizeof(MetaWord));

    cur->remove_sentinel();

    // Note: cannot call ChunkManager::remove_chunk, because that

    // modifies the counters in ChunkManager, which we do not want. So

    // we call remove_chunk on the freelist directly (see also the

    // splitting function which does the same).

    ChunkList* const list = free_chunks(list_index(cur->word_size()));

    list->remove_chunk(cur);

    num_removed ++;

    cur = next;

  }

  return num_removed;

}

size_t ChunkManager::free_chunks_total_words() {

  return _free_chunks_total;

}

size_t ChunkManager::free_chunks_total_bytes() {

  return free_chunks_total_words() * BytesPerWord;

}

// Update internal accounting after a chunk was added

void ChunkManager::account_for_added_chunk(const Metachunk* c) {

  assert_lock_strong(MetaspaceExpand_lock);

  _free_chunks_count ++;

  _free_chunks_total += c->word_size();

}

// Update internal accounting after a chunk was removed

void ChunkManager::account_for_removed_chunk(const Metachunk* c) {

  assert_lock_strong(MetaspaceExpand_lock);

  assert(_free_chunks_count >= 1,

    "ChunkManager::_free_chunks_count: about to go negative (" SIZE_FORMAT ").", _free_chunks_count);

  assert(_free_chunks_total >= c->word_size(),

    "ChunkManager::_free_chunks_total: about to go negative"

     "(now: " SIZE_FORMAT ", decrement value: " SIZE_FORMAT ").", _free_chunks_total, c->word_size());

  _free_chunks_count --;

  _free_chunks_total -= c->word_size();

}

size_t ChunkManager::free_chunks_count() {

#ifdef ASSERT

  if (!UseConcMarkSweepGC && !MetaspaceExpand_lock->is_locked()) {

    MutexLockerEx cl(MetaspaceExpand_lock,

                     Mutex::_no_safepoint_check_flag);

    // This lock is only needed in debug because the verification

    // of the _free_chunks_totals walks the list of free chunks

    slow_locked_verify_free_chunks_count();

  }

#endif

  return _free_chunks_count;

}

ChunkIndex ChunkManager::list_index(size_t size) {

  return get_chunk_type_by_size(size, is_class());

}

size_t ChunkManager::size_by_index(ChunkIndex index) const {

  index_bounds_check(index);

  assert(index != HumongousIndex, "Do not call for humongous chunks.");

  return get_size_for_nonhumongous_chunktype(index, is_class());

}

void ChunkManager::locked_verify_free_chunks_total() {

  assert_lock_strong(MetaspaceExpand_lock);

  assert(sum_free_chunks() == _free_chunks_total,

         "_free_chunks_total " SIZE_FORMAT " is not the"

         " same as sum " SIZE_FORMAT, _free_chunks_total,

         sum_free_chunks());

}

void ChunkManager::locked_verify_free_chunks_count() {

  assert_lock_strong(MetaspaceExpand_lock);

  assert(sum_free_chunks_count() == _free_chunks_count,

         "_free_chunks_count " SIZE_FORMAT " is not the"

         " same as sum " SIZE_FORMAT, _free_chunks_count,

         sum_free_chunks_count());

}

void ChunkManager::verify() {

  MutexLockerEx cl(MetaspaceExpand_lock,

                     Mutex::_no_safepoint_check_flag);

  locked_verify();

}

void ChunkManager::locked_verify() {

  locked_verify_free_chunks_count();

  locked_verify_free_chunks_total();

  for (ChunkIndex i = ZeroIndex; i < NumberOfFreeLists; i = next_chunk_index(i)) {

    ChunkList* list = free_chunks(i);

    if (list != NULL) {

      Metachunk* chunk = list->head();

      while (chunk) {

        DEBUG_ONLY(do_verify_chunk(chunk);)

        assert(chunk->is_tagged_free(), "Chunk should be tagged as free.");

        chunk = chunk->next();

      }

    }

  }

}

void ChunkManager::locked_print_free_chunks(outputStream* st) {

  assert_lock_strong(MetaspaceExpand_lock);

  st->print_cr("Free chunk total " SIZE_FORMAT "  count " SIZE_FORMAT,

                _free_chunks_total, _free_chunks_count);

}

void ChunkManager::locked_print_sum_free_chunks(outputStream* st) {

  assert_lock_strong(MetaspaceExpand_lock);

  st->print_cr("Sum free chunk total " SIZE_FORMAT "  count " SIZE_FORMAT,

                sum_free_chunks(), sum_free_chunks_count());

}

ChunkList* ChunkManager::free_chunks(ChunkIndex index) {

  assert(index == SpecializedIndex || index == SmallIndex || index == MediumIndex,

         "Bad index: %d", (int)index);

  return &_free_chunks[index];

}

// These methods that sum the free chunk lists are used in printing

// methods that are used in product builds.

size_t ChunkManager::sum_free_chunks() {

  assert_lock_strong(MetaspaceExpand_lock);

  size_t result = 0;

  for (ChunkIndex i = ZeroIndex; i < NumberOfFreeLists; i = next_chunk_index(i)) {

    ChunkList* list = free_chunks(i);

    if (list == NULL) {

      continue;

    }

    result = result + list->count() * list->size();

  }

  result = result + humongous_dictionary()->total_size();

  return result;

}

size_t ChunkManager::sum_free_chunks_count() {

  assert_lock_strong(MetaspaceExpand_lock);

  size_t count = 0;

  for (ChunkIndex i = ZeroIndex; i < NumberOfFreeLists; i = next_chunk_index(i)) {

    ChunkList* list = free_chunks(i);

    if (list == NULL) {

      continue;

    }

    count = count + list->count();

  }

  count = count + humongous_dictionary()->total_free_blocks();

  return count;

}

ChunkList* ChunkManager::find_free_chunks_list(size_t word_size) {

  ChunkIndex index = list_index(word_size);

  assert(index < HumongousIndex, "No humongous list");

  return free_chunks(index);

}

// Helper for chunk splitting: given a target chunk size and a larger free chunk,

// split up the larger chunk into n smaller chunks, at least one of which should be

// the target chunk of target chunk size. The smaller chunks, including the target

// chunk, are returned to the freelist. The pointer to the target chunk is returned.

// Note that this chunk is supposed to be removed from the freelist right away.

Metachunk* ChunkManager::split_chunk(size_t target_chunk_word_size, Metachunk* larger_chunk) {

  assert(larger_chunk->word_size() > target_chunk_word_size, "Sanity");

  const ChunkIndex larger_chunk_index = larger_chunk->get_chunk_type();

  const ChunkIndex target_chunk_index = get_chunk_type_by_size(target_chunk_word_size, is_class());

  MetaWord* const region_start = (MetaWord*)larger_chunk;

  const size_t region_word_len = larger_chunk->word_size();

  MetaWord* const region_end = region_start + region_word_len;

  VirtualSpaceNode* const vsn = larger_chunk->container();

  OccupancyMap* const ocmap = vsn->occupancy_map();

  // Any larger non-humongous chunk size is a multiple of any smaller chunk size.

  // Since non-humongous chunks are aligned to their chunk size, the larger chunk should start

  // at an address suitable to place the smaller target chunk.

  assert_is_aligned(region_start, target_chunk_word_size);

  // Remove old chunk.

  free_chunks(larger_chunk_index)->remove_chunk(larger_chunk);

  larger_chunk->remove_sentinel();

  // Prevent access to the old chunk from here on.

  larger_chunk = NULL;

  // ... and wipe it.

  DEBUG_ONLY(memset(region_start, 0xfe, region_word_len * BytesPerWord));

  // In its place create first the target chunk...

  MetaWord* p = region_start;

  Metachunk* target_chunk = ::new (p) Metachunk(target_chunk_index, is_class(), target_chunk_word_size, vsn);

  assert(target_chunk == (Metachunk*)p, "Sanity");

  target_chunk->set_origin(origin_split);

  // Note: we do not need to mark its start in the occupancy map

  // because it coincides with the old chunk start.

  // Mark chunk as free and return to the freelist.

  do_update_in_use_info_for_chunk(target_chunk, false);

  free_chunks(target_chunk_index)->return_chunk_at_head(target_chunk);

  // This chunk should now be valid and can be verified.

  DEBUG_ONLY(do_verify_chunk(target_chunk));

  // In the remaining space create the remainder chunks.

  p += target_chunk->word_size();

  assert(p < region_end, "Sanity");

  while (p < region_end) {

    // Find the largest chunk size which fits the alignment requirements at address p.

    ChunkIndex this_chunk_index = prev_chunk_index(larger_chunk_index);

    size_t this_chunk_word_size = 0;

    for(;;) {

      this_chunk_word_size = get_size_for_nonhumongous_chunktype(this_chunk_index, is_class());

      if (is_aligned(p, this_chunk_word_size * BytesPerWord)) {

        break;

      } else {

        this_chunk_index = prev_chunk_index(this_chunk_index);

        assert(this_chunk_index >= target_chunk_index, "Sanity");

      }

    }

    assert(this_chunk_word_size >= target_chunk_word_size, "Sanity");

    assert(is_aligned(p, this_chunk_word_size * BytesPerWord), "Sanity");

    assert(p + this_chunk_word_size <= region_end, "Sanity");

    // Create splitting chunk.

    Metachunk* this_chunk = ::new (p) Metachunk(this_chunk_index, is_class(), this_chunk_word_size, vsn);

    assert(this_chunk == (Metachunk*)p, "Sanity");

    this_chunk->set_origin(origin_split);

    ocmap->set_chunk_starts_at_address(p, true);

    do_update_in_use_info_for_chunk(this_chunk, false);

    // This chunk should be valid and can be verified.

    DEBUG_ONLY(do_verify_chunk(this_chunk));

    // Return this chunk to freelist and correct counter.

    free_chunks(this_chunk_index)->return_chunk_at_head(this_chunk);

    _free_chunks_count ++;

    log_trace(gc, metaspace, freelist)("Created chunk at " PTR_FORMAT ", word size "

      SIZE_FORMAT_HEX " (%s), in split region [" PTR_FORMAT "..." PTR_FORMAT ").",

      p2i(this_chunk), this_chunk->word_size(), chunk_size_name(this_chunk_index),

      p2i(region_start), p2i(region_end));

    p += this_chunk_word_size;

  }

  return target_chunk;

}

Metachunk* ChunkManager::free_chunks_get(size_t word_size) {

  assert_lock_strong(MetaspaceExpand_lock);

  slow_locked_verify();

  Metachunk* chunk = NULL;

  bool we_did_split_a_chunk = false;

  if (list_index(word_size) != HumongousIndex) {

    ChunkList* free_list = find_free_chunks_list(word_size);

    assert(free_list != NULL, "Sanity check");

    chunk = free_list->head();

    if (chunk == NULL) {

      // Split large chunks into smaller chunks if there are no smaller chunks, just large chunks.

      // This is the counterpart of the coalescing-upon-chunk-return.

      ChunkIndex target_chunk_index = get_chunk_type_by_size(word_size, is_class());

      // Is there a larger chunk we could split?

      Metachunk* larger_chunk = NULL;

      ChunkIndex larger_chunk_index = next_chunk_index(target_chunk_index);

      while (larger_chunk == NULL && larger_chunk_index < NumberOfFreeLists) {

        larger_chunk = free_chunks(larger_chunk_index)->head();

        if (larger_chunk == NULL) {

          larger_chunk_index = next_chunk_index(larger_chunk_index);

        }

      }

      if (larger_chunk != NULL) {

        assert(larger_chunk->word_size() > word_size, "Sanity");

        assert(larger_chunk->get_chunk_type() == larger_chunk_index, "Sanity");

        // We found a larger chunk. Lets split it up:

        // - remove old chunk

        // - in its place, create new smaller chunks, with at least one chunk

        //   being of target size, the others sized as large as possible. This

        //   is to make sure the resulting chunks are "as coalesced as possible"

        //   (similar to VirtualSpaceNode::retire()).

        // Note: during this operation both ChunkManager and VirtualSpaceNode

        //  are temporarily invalid, so be careful with asserts.

        log_trace(gc, metaspace, freelist)("%s: splitting chunk " PTR_FORMAT

           ", word size " SIZE_FORMAT_HEX " (%s), to get a chunk of word size " SIZE_FORMAT_HEX " (%s)...",

          (is_class() ? "class space" : "metaspace"), p2i(larger_chunk), larger_chunk->word_size(),

          chunk_size_name(larger_chunk_index), word_size, chunk_size_name(target_chunk_index));

        chunk = split_chunk(word_size, larger_chunk);

        // This should have worked.

        assert(chunk != NULL, "Sanity");

        assert(chunk->word_size() == word_size, "Sanity");

        assert(chunk->is_tagged_free(), "Sanity");

        we_did_split_a_chunk = true;

      }

    }

    if (chunk == NULL) {

      return NULL;

    }

    // Remove the chunk as the head of the list.

    free_list->remove_chunk(chunk);

    log_trace(gc, metaspace, freelist)("ChunkManager::free_chunks_get: free_list: " PTR_FORMAT " chunks left: " SSIZE_FORMAT ".",

                                       p2i(free_list), free_list->count());

  } else {

    chunk = humongous_dictionary()->get_chunk(word_size);

    if (chunk == NULL) {

      return NULL;

    }

    log_debug(gc, metaspace, alloc)("Free list allocate humongous chunk size " SIZE_FORMAT " for requested size " SIZE_FORMAT " waste " SIZE_FORMAT,

                                    chunk->word_size(), word_size, chunk->word_size() - word_size);

  }

  // Chunk has been removed from the chunk manager; update counters.

  account_for_removed_chunk(chunk);

  do_update_in_use_info_for_chunk(chunk, true);

  chunk->container()->inc_container_count();

  chunk->inc_use_count();

  // Remove it from the links to this freelist

  chunk->set_next(NULL);

  chunk->set_prev(NULL);

  // Run some verifications (some more if we did a chunk split)

#ifdef ASSERT

  if (VerifyMetaspace) {

    locked_verify();

    VirtualSpaceNode* const vsn = chunk->container();

    vsn->verify();

    if (we_did_split_a_chunk) {

      vsn->verify_free_chunks_are_ideally_merged();

    }

  }

#endif