/*

 * virtualSpaceList.cpp

 *

 *  Created on: May 6, 2018

 *      Author: thomas

 */

#include "precompiled.hpp"

#include "logging/log.hpp"

#include "logging/logStream.hpp"

#include "memory/metaspace.hpp"

#include "memory/metaspace/chunkManager.hpp"

#include "memory/metaspace/metachunk.hpp"

#include "memory/metaspace/metaspaceCommon.hpp"

#include "memory/metaspace/virtualSpaceList.hpp"

#include "memory/metaspace/virtualSpaceNode.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/safepoint.hpp"

namespace metaspace {

VirtualSpaceList::~VirtualSpaceList() {

  VirtualSpaceListIterator iter(virtual_space_list());

  while (iter.repeat()) {

    VirtualSpaceNode* vsl = iter.get_next();

    delete vsl;

  }

}

void VirtualSpaceList::inc_reserved_words(size_t v) {

  assert_lock_strong(MetaspaceExpand_lock);

  _reserved_words = _reserved_words + v;

}

void VirtualSpaceList::dec_reserved_words(size_t v) {

  assert_lock_strong(MetaspaceExpand_lock);

  _reserved_words = _reserved_words - v;

}

#define assert_committed_below_limit()                        \

  assert(MetaspaceUtils::committed_bytes() <= MaxMetaspaceSize, \

         "Too much committed memory. Committed: " SIZE_FORMAT \

         " limit (MaxMetaspaceSize): " SIZE_FORMAT,           \

          MetaspaceUtils::committed_bytes(), MaxMetaspaceSize);

void VirtualSpaceList::inc_committed_words(size_t v) {

  assert_lock_strong(MetaspaceExpand_lock);

  _committed_words = _committed_words + v;

  assert_committed_below_limit();

}

void VirtualSpaceList::dec_committed_words(size_t v) {

  assert_lock_strong(MetaspaceExpand_lock);

  _committed_words = _committed_words - v;

  assert_committed_below_limit();

}

void VirtualSpaceList::inc_virtual_space_count() {

  assert_lock_strong(MetaspaceExpand_lock);

  _virtual_space_count++;

}

void VirtualSpaceList::dec_virtual_space_count() {

  assert_lock_strong(MetaspaceExpand_lock);

  _virtual_space_count--;

}

// Walk the list of VirtualSpaceNodes and delete

// nodes with a 0 container_count.  Remove Metachunks in

// the node from their respective freelists.

void VirtualSpaceList::purge(ChunkManager* chunk_manager) {

  assert(SafepointSynchronize::is_at_safepoint(), "must be called at safepoint for contains to work");

  assert_lock_strong(MetaspaceExpand_lock);

  // Don't use a VirtualSpaceListIterator because this

  // list is being changed and a straightforward use of an iterator is not safe.

  VirtualSpaceNode* purged_vsl = NULL;

  VirtualSpaceNode* prev_vsl = virtual_space_list();

  VirtualSpaceNode* next_vsl = prev_vsl;

  while (next_vsl != NULL) {

    VirtualSpaceNode* vsl = next_vsl;

    DEBUG_ONLY(vsl->verify_container_count();)

    next_vsl = vsl->next();

    // Don't free the current virtual space since it will likely

    // be needed soon.

    if (vsl->container_count() == 0 && vsl != current_virtual_space()) {

      log_trace(gc, metaspace, freelist)("Purging VirtualSpaceNode " PTR_FORMAT " (capacity: " SIZE_FORMAT

                                         ", used: " SIZE_FORMAT ").", p2i(vsl), vsl->capacity_words_in_vs(), vsl->used_words_in_vs());

      DEBUG_ONLY(Atomic::inc(&g_internal_statistics.num_vsnodes_purged));

      // Unlink it from the list

      if (prev_vsl == vsl) {

        // This is the case of the current node being the first node.

        assert(vsl == virtual_space_list(), "Expected to be the first node");

        set_virtual_space_list(vsl->next());

      } else {

        prev_vsl->set_next(vsl->next());

      }

      vsl->purge(chunk_manager);

      dec_reserved_words(vsl->reserved_words());

      dec_committed_words(vsl->committed_words());

      dec_virtual_space_count();

      purged_vsl = vsl;

      delete vsl;

    } else {

      prev_vsl = vsl;

    }

  }

#ifdef ASSERT

  if (purged_vsl != NULL) {

    // List should be stable enough to use an iterator here.

    VirtualSpaceListIterator iter(virtual_space_list());

    while (iter.repeat()) {

      VirtualSpaceNode* vsl = iter.get_next();

      assert(vsl != purged_vsl, "Purge of vsl failed");

    }

  }

#endif

}

// This function looks at the mmap regions in the metaspace without locking.

// The chunks are added with store ordering and not deleted except for at

// unloading time during a safepoint.

bool VirtualSpaceList::contains(const void* ptr) {

  // List should be stable enough to use an iterator here because removing virtual

  // space nodes is only allowed at a safepoint.

  VirtualSpaceListIterator iter(virtual_space_list());

  while (iter.repeat()) {

    VirtualSpaceNode* vsn = iter.get_next();

    if (vsn->contains(ptr)) {

      return true;

    }

  }

  return false;

}

void VirtualSpaceList::retire_current_virtual_space() {

  assert_lock_strong(MetaspaceExpand_lock);

  VirtualSpaceNode* vsn = current_virtual_space();

  ChunkManager* cm = is_class() ? Metaspace::chunk_manager_class() :

                                  Metaspace::chunk_manager_metadata();

  vsn->retire(cm);

}

VirtualSpaceList::VirtualSpaceList(size_t word_size) :

                                   _is_class(false),

                                   _virtual_space_list(NULL),

                                   _current_virtual_space(NULL),

                                   _reserved_words(0),

                                   _committed_words(0),

                                   _virtual_space_count(0) {

  MutexLockerEx cl(MetaspaceExpand_lock,

                   Mutex::_no_safepoint_check_flag);

  create_new_virtual_space(word_size);

}

VirtualSpaceList::VirtualSpaceList(ReservedSpace rs) :

                                   _is_class(true),

                                   _virtual_space_list(NULL),

                                   _current_virtual_space(NULL),

                                   _reserved_words(0),

                                   _committed_words(0),

                                   _virtual_space_count(0) {

  MutexLockerEx cl(MetaspaceExpand_lock,

                   Mutex::_no_safepoint_check_flag);

  VirtualSpaceNode* class_entry = new VirtualSpaceNode(is_class(), rs);

  bool succeeded = class_entry->initialize();

  if (succeeded) {

    link_vs(class_entry);

  }

}

size_t VirtualSpaceList::free_bytes() {

  return current_virtual_space()->free_words_in_vs() * BytesPerWord;

}

// Allocate another meta virtual space and add it to the list.

bool VirtualSpaceList::create_new_virtual_space(size_t vs_word_size) {

  assert_lock_strong(MetaspaceExpand_lock);

  if (is_class()) {

    assert(false, "We currently don't support more than one VirtualSpace for"

                  " the compressed class space. The initialization of the"

                  " CCS uses another code path and should not hit this path.");

    return false;

  }

  if (vs_word_size == 0) {

    assert(false, "vs_word_size should always be at least _reserve_alignment large.");

    return false;

  }

  // Reserve the space

  size_t vs_byte_size = vs_word_size * BytesPerWord;

  assert_is_aligned(vs_byte_size, Metaspace::reserve_alignment());

  // Allocate the meta virtual space and initialize it.

  VirtualSpaceNode* new_entry = new VirtualSpaceNode(is_class(), vs_byte_size);

  if (!new_entry->initialize()) {

    delete new_entry;

    return false;

  } else {

    assert(new_entry->reserved_words() == vs_word_size,

        "Reserved memory size differs from requested memory size");

    // ensure lock-free iteration sees fully initialized node

    OrderAccess::storestore();

    link_vs(new_entry);

    DEBUG_ONLY(Atomic::inc(&g_internal_statistics.num_vsnodes_created));

    return true;

  }

}

void VirtualSpaceList::link_vs(VirtualSpaceNode* new_entry) {

  if (virtual_space_list() == NULL) {

      set_virtual_space_list(new_entry);

  } else {

    current_virtual_space()->set_next(new_entry);

  }

  set_current_virtual_space(new_entry);

  inc_reserved_words(new_entry->reserved_words());

  inc_committed_words(new_entry->committed_words());

  inc_virtual_space_count();

#ifdef ASSERT

  new_entry->mangle();

#endif

  LogTarget(Trace, gc, metaspace) lt;

  if (lt.is_enabled()) {

    LogStream ls(lt);

    VirtualSpaceNode* vsl = current_virtual_space();

    ResourceMark rm;

    vsl->print_on(&ls);

  }

}

bool VirtualSpaceList::expand_node_by(VirtualSpaceNode* node,

                                      size_t min_words,

                                      size_t preferred_words) {

  size_t before = node->committed_words();

  bool result = node->expand_by(min_words, preferred_words);

  size_t after = node->committed_words();

  // after and before can be the same if the memory was pre-committed.

  assert(after >= before, "Inconsistency");

  inc_committed_words(after - before);

  return result;

}

bool VirtualSpaceList::expand_by(size_t min_words, size_t preferred_words) {

  assert_is_aligned(min_words,       Metaspace::commit_alignment_words());

  assert_is_aligned(preferred_words, Metaspace::commit_alignment_words());

  assert(min_words <= preferred_words, "Invalid arguments");

  const char* const class_or_not = (is_class() ? "class" : "non-class");

  if (!MetaspaceGC::can_expand(min_words, this->is_class())) {

    log_trace(gc, metaspace, freelist)("Cannot expand %s virtual space list.",

              class_or_not);

    return  false;

  }

  size_t allowed_expansion_words = MetaspaceGC::allowed_expansion();

  if (allowed_expansion_words < min_words) {

    log_trace(gc, metaspace, freelist)("Cannot expand %s virtual space list (must try gc first).",

              class_or_not);

    return false;

  }

  size_t max_expansion_words = MIN2(preferred_words, allowed_expansion_words);

  // Commit more memory from the the current virtual space.

  bool vs_expanded = expand_node_by(current_virtual_space(),

                                    min_words,

                                    max_expansion_words);

  if (vs_expanded) {

     log_trace(gc, metaspace, freelist)("Expanded %s virtual space list.",

               class_or_not);

     return true;

  }

  log_trace(gc, metaspace, freelist)("%s virtual space list: retire current node.",

            class_or_not);

  retire_current_virtual_space();

  // Get another virtual space.

  size_t grow_vs_words = MAX2((size_t)VirtualSpaceSize, preferred_words);

  grow_vs_words = align_up(grow_vs_words, Metaspace::reserve_alignment_words());

  if (create_new_virtual_space(grow_vs_words)) {

    if (current_virtual_space()->is_pre_committed()) {

      // The memory was pre-committed, so we are done here.

      assert(min_words <= current_virtual_space()->committed_words(),

          "The new VirtualSpace was pre-committed, so it"

          "should be large enough to fit the alloc request.");

      return true;

    }

    return expand_node_by(current_virtual_space(),

                          min_words,

                          max_expansion_words);

  }

  return false;

}

// Given a chunk, calculate the largest possible padding space which

// could be required when allocating it.

static size_t largest_possible_padding_size_for_chunk(size_t chunk_word_size, bool is_class) {

  const ChunkIndex chunk_type = get_chunk_type_by_size(chunk_word_size, is_class);

  if (chunk_type != HumongousIndex) {

    // Normal, non-humongous chunks are allocated at chunk size

    // boundaries, so the largest padding space required would be that

    // minus the smallest chunk size.

    const size_t smallest_chunk_size = is_class ? ClassSpecializedChunk : SpecializedChunk;

    return chunk_word_size - smallest_chunk_size;

  } else {

    // Humongous chunks are allocated at smallest-chunksize

    // boundaries, so there is no padding required.

    return 0;

  }

}

Metachunk* VirtualSpaceList::get_new_chunk(size_t chunk_word_size, size_t suggested_commit_granularity) {

  // Allocate a chunk out of the current virtual space.

  Metachunk* next = current_virtual_space()->get_chunk_vs(chunk_word_size);

  if (next != NULL) {

    return next;

  }

  // The expand amount is currently only determined by the requested sizes

  // and not how much committed memory is left in the current virtual space.

  // We must have enough space for the requested size and any

  // additional reqired padding chunks.

  const size_t size_for_padding = largest_possible_padding_size_for_chunk(chunk_word_size, this->is_class());

  size_t min_word_size       = align_up(chunk_word_size + size_for_padding, Metaspace::commit_alignment_words());

  size_t preferred_word_size = align_up(suggested_commit_granularity, Metaspace::commit_alignment_words());

  if (min_word_size >= preferred_word_size) {

    // Can happen when humongous chunks are allocated.

    preferred_word_size = min_word_size;

  }

  bool expanded = expand_by(min_word_size, preferred_word_size);

  if (expanded) {

    next = current_virtual_space()->get_chunk_vs(chunk_word_size);

    assert(next != NULL, "The allocation was expected to succeed after the expansion");

  }

   return next;

}

void VirtualSpaceList::print_on(outputStream* st, size_t scale) const {

  st->print_cr(SIZE_FORMAT " nodes, current node: " PTR_FORMAT,

      _virtual_space_count, p2i(_current_virtual_space));

  VirtualSpaceListIterator iter(virtual_space_list());

  while (iter.repeat()) {

    st->cr();

    VirtualSpaceNode* node = iter.get_next();

    node->print_on(st, scale);

  }

}

void VirtualSpaceList::print_map(outputStream* st) const {

  VirtualSpaceNode* list = virtual_space_list();

  VirtualSpaceListIterator iter(list);

  unsigned i = 0;

  while (iter.repeat()) {

    st->print_cr("Node %u:", i);

    VirtualSpaceNode* node = iter.get_next();

    node->print_map(st, this->is_class());

    i ++;

  }

}

} // namespace metaspace