/*
 * Copyright (c) 2013, 2015, Red Hat, Inc. and/or its affiliates.
 *
 * 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 "memory/allocation.hpp"
#include "gc/shenandoah/brooksPointer.hpp"
#include "gc/shenandoah/shenandoahConnectionMatrix.hpp"
#include "gc/shenandoah/shenandoahHeap.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.hpp"
#include "gc/shared/space.inline.hpp"
#include "memory/universe.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/os.hpp"
#include "runtime/safepoint.hpp"

Monitor ShenandoahHeapRegion::_mem_protect_lock(Mutex::special, "ShenandoahMemProtect_lock", true, Monitor::_safepoint_check_never);
size_t ShenandoahHeapRegion::RegionSizeShift = 0;
size_t ShenandoahHeapRegion::RegionSizeBytes = 0;

ShenandoahHeapRegion::ShenandoahHeapRegion(ShenandoahHeap* heap, HeapWord* start,
                                           size_t regionSizeWords, size_t index) :
#ifdef ASSERT
  _mem_protection_level(0),
#endif
  _heap(heap),
  _region_number(index),
  _live_data(0),
  reserved(MemRegion(start, regionSizeWords)),
  _humongous_start(false),
  _humongous_continuation(false),
  _recycled(true),
  _new_top(NULL),
  _critical_pins(0) {

  ContiguousSpace::initialize(reserved, true, false);
}

size_t ShenandoahHeapRegion::region_number() const {
  return _region_number;
}

bool ShenandoahHeapRegion::rollback_allocation(uint size) {
  set_top(top() - size);
  return true;
}

void ShenandoahHeapRegion::clear_live_data() {
  assert(Thread::current()->is_VM_thread(), "by VM thread");
  _live_data = 0;
}

void ShenandoahHeapRegion::set_recently_allocated(bool value) {
  _recycled = value;
}

bool ShenandoahHeapRegion::is_recently_allocated() const {
  return _recycled && used() > 0;
}

void ShenandoahHeapRegion::set_live_data(size_t s) {
  assert(Thread::current()->is_VM_thread(), "by VM thread");
  _live_data = (jint) (s / HeapWordSize);
}

size_t ShenandoahHeapRegion::get_live_data_words() const {
  return (size_t)OrderAccess::load_acquire((volatile jint*)&_live_data);
}

size_t ShenandoahHeapRegion::get_live_data_bytes() const {
  return get_live_data_words() * HeapWordSize;
}

bool ShenandoahHeapRegion::has_live() const {
  return get_live_data_words() != 0;
}

size_t ShenandoahHeapRegion::garbage() const {
  assert(used() >= get_live_data_bytes() || is_humongous(), "Live Data must be a subset of used() live: "SIZE_FORMAT" used: "SIZE_FORMAT,
         get_live_data_bytes(), used());
  size_t result = used() - get_live_data_bytes();
  return result;
}

bool ShenandoahHeapRegion::in_collection_set() const {
  return _heap->region_in_collection_set(_region_number);
}

void ShenandoahHeapRegion::set_in_collection_set(bool b) {
  assert(! (is_humongous() && b), "never ever enter a humongous region into the collection set");

  _heap->set_region_in_collection_set(_region_number, b);

#ifdef ASSERT
  if (ShenandoahVerifyWritesToFromSpace || ShenandoahVerifyReadsToFromSpace) {
    if (b) {
      memProtectionOn();
      assert(_mem_protection_level == 0, "need to be protected here");
    } else {
      assert(_mem_protection_level == 0, "need to be protected here");
      memProtectionOff();
    }
  }
#endif
}

#include <sys/mman.h>

#ifdef ASSERT

void ShenandoahHeapRegion::memProtectionOn() {
  /*
  log_develop_trace(gc)("Protect memory on region level: "INT32_FORMAT, _mem_protection_level);
  print(tty);
  */
  MutexLockerEx ml(&_mem_protect_lock, true);
  assert(_mem_protection_level >= 1, "invariant");

  if (--_mem_protection_level == 0) {
    if (ShenandoahVerifyWritesToFromSpace) {
      assert(! ShenandoahVerifyReadsToFromSpace, "can't verify from-space reads when verifying from-space writes");
      os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_READ);
    } else {
      assert(ShenandoahVerifyReadsToFromSpace, "need to be verifying reads here");
      os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_NONE);
    }
  }
}

void ShenandoahHeapRegion::memProtectionOff() {
  /*
  tty->print_cr("unprotect memory on region level: "INT32_FORMAT, _mem_protection_level);
  print(tty);
  */
  MutexLockerEx ml(&_mem_protect_lock, true);
  assert(_mem_protection_level >= 0, "invariant");
  if (_mem_protection_level++ == 0) {
    os::protect_memory((char*) bottom(), end() - bottom(), os::MEM_PROT_RW);
  }
}

#endif

void ShenandoahHeapRegion::print_on(outputStream* st) const {
  st->print("ShenandoahHeapRegion: "PTR_FORMAT"/"SIZE_FORMAT, p2i(this), _region_number);

  if (in_collection_set())
    st->print("C");
  if (is_humongous_start()) {
    st->print("H");
  }
  if (is_humongous_continuation()) {
    st->print("h");
  }
  //else
    st->print(" ");

  st->print_cr("live = "SIZE_FORMAT" garbage = "SIZE_FORMAT" bottom = "PTR_FORMAT" end = "PTR_FORMAT" top = "PTR_FORMAT,
               get_live_data_bytes(), garbage(), p2i(bottom()), p2i(end()), p2i(top()));
}


void ShenandoahHeapRegion::object_iterate_interruptible(ObjectClosure* blk, bool allow_cancel) {
  HeapWord* p = bottom() + BrooksPointer::word_size();
  while (p < top() && !(allow_cancel && _heap->cancelled_concgc())) {
    blk->do_object(oop(p));
#ifdef ASSERT
    if (ShenandoahVerifyReadsToFromSpace) {
      memProtectionOff();
      p += oop(p)->size() + BrooksPointer::word_size();
      memProtectionOn();
    } else {
      p += oop(p)->size() + BrooksPointer::word_size();
    }
#else
      p += oop(p)->size() + BrooksPointer::word_size();
#endif
  }
}

HeapWord* ShenandoahHeapRegion::object_iterate_careful(ObjectClosureCareful* blk) {
  HeapWord * limit = concurrent_iteration_safe_limit();
  assert(limit <= top(), "sanity check");
  for (HeapWord* p = bottom() + BrooksPointer::word_size(); p < limit;) {
    size_t size = blk->do_object_careful(oop(p));
    if (size == 0) {
      return p;  // failed at p
    } else {
      p += size + BrooksPointer::word_size();
    }
  }
  return NULL; // all done
}

void ShenandoahHeapRegion::fill_region() {
  ShenandoahHeap* sh = (ShenandoahHeap*) Universe::heap();

  if (free() > (BrooksPointer::word_size() + CollectedHeap::min_fill_size())) {
    HeapWord* filler = allocate(BrooksPointer::word_size());
    HeapWord* obj = allocate(end() - top());
    sh->fill_with_object(obj, end() - obj);
    BrooksPointer::initialize(oop(obj));
  }
}

void ShenandoahHeapRegion::set_humongous_start(bool start) {
  _humongous_start = start;
}

void ShenandoahHeapRegion::set_humongous_continuation(bool continuation) {
  _humongous_continuation = continuation;
}

bool ShenandoahHeapRegion::is_humongous() const {
  return _humongous_start || _humongous_continuation;
}

bool ShenandoahHeapRegion::is_humongous_start() const {
  return _humongous_start;
}

bool ShenandoahHeapRegion::is_humongous_continuation() const {
  return _humongous_continuation;
}

void ShenandoahHeapRegion::recycle() {
  ContiguousSpace::initialize(reserved, true, false);
  clear_live_data();
  _humongous_start = false;
  _humongous_continuation = false;
  _recycled = true;
  set_in_collection_set(false);
  // Reset C-TAMS pointer to ensure size-based iteration, everything
  // in that regions is going to be new objects.
  _heap->set_complete_top_at_mark_start(bottom(), bottom());
  // We can only safely reset the C-TAMS pointer if the bitmap is clear for that region.
  assert(_heap->is_complete_bitmap_clear_range(bottom(), end()), "must be clear");
  _heap->connection_matrix()->clear_region(region_number());
}

HeapWord* ShenandoahHeapRegion::block_start_const(const void* p) const {
  assert(MemRegion(bottom(), end()).contains(p),
         "p ("PTR_FORMAT") not in space ["PTR_FORMAT", "PTR_FORMAT")",
         p2i(p), p2i(bottom()), p2i(end()));
  if (p >= top()) {
    return top();
  } else {
    HeapWord* last = bottom() + BrooksPointer::word_size();
    HeapWord* cur = last;
    while (cur <= p) {
      last = cur;
      cur += oop(cur)->size() + BrooksPointer::word_size();
    }
    assert(oop(last)->is_oop(),
           PTR_FORMAT" should be an object start", p2i(last));
    return last;
  }
}

void ShenandoahHeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {
  // Absolute minimums we should not ever break:
  static const size_t MIN_REGION_SIZE = 256*K;
  static const size_t MIN_NUM_REGIONS = 10;

  uintx region_size;
  if (FLAG_IS_DEFAULT(ShenandoahHeapRegionSize)) {
    if (ShenandoahMinRegionSize > initial_heap_size / MIN_NUM_REGIONS) {
      err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number "
                      "of regions (" SIZE_FORMAT ") of minimum region size (" SIZE_FORMAT "K).",
                      initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahMinRegionSize/K);
      vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
    }
    if (ShenandoahMinRegionSize < MIN_REGION_SIZE) {
      err_msg message("" SIZE_FORMAT "K should not be lower than minimum region size (" SIZE_FORMAT "K).",
                      ShenandoahMinRegionSize/K,  MIN_REGION_SIZE/K);
      vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
    }
    if (ShenandoahMinRegionSize < MinTLABSize) {
      err_msg message("" SIZE_FORMAT "K should not be lower than TLAB size size (" SIZE_FORMAT "K).",
                      ShenandoahMinRegionSize/K,  MinTLABSize/K);
      vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize option", message);
    }
    if (ShenandoahMaxRegionSize < MIN_REGION_SIZE) {
      err_msg message("" SIZE_FORMAT "K should not be lower than min region size (" SIZE_FORMAT "K).",
                      ShenandoahMaxRegionSize/K,  MIN_REGION_SIZE/K);
      vm_exit_during_initialization("Invalid -XX:ShenandoahMaxRegionSize option", message);
    }
    if (ShenandoahMinRegionSize > ShenandoahMaxRegionSize) {
      err_msg message("Minimum (" SIZE_FORMAT "K) should be larger than maximum (" SIZE_FORMAT "K).",
                      ShenandoahMinRegionSize/K, ShenandoahMaxRegionSize/K);
      vm_exit_during_initialization("Invalid -XX:ShenandoahMinRegionSize or -XX:ShenandoahMaxRegionSize", message);
    }
    size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;
    region_size = MAX2(average_heap_size / ShenandoahTargetNumRegions,
                       ShenandoahMinRegionSize);

    // Now make sure that we don't go over or under our limits.
    region_size = MAX2(ShenandoahMinRegionSize, region_size);
    region_size = MIN2(ShenandoahMaxRegionSize, region_size);

  } else {
    if (ShenandoahHeapRegionSize > initial_heap_size / MIN_NUM_REGIONS) {
      err_msg message("Initial heap size (" SIZE_FORMAT "K) is too low to afford the minimum number "
                              "of regions (" SIZE_FORMAT ") of requested size (" SIZE_FORMAT "K).",
                      initial_heap_size/K, MIN_NUM_REGIONS, ShenandoahHeapRegionSize/K);
      vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
    }
    if (ShenandoahHeapRegionSize < ShenandoahMinRegionSize) {
      err_msg message("Heap region size (" SIZE_FORMAT "K) should be larger than min region size (" SIZE_FORMAT "K).",
                      ShenandoahHeapRegionSize/K, ShenandoahMinRegionSize/K);
      vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
    }
    if (ShenandoahHeapRegionSize > ShenandoahMaxRegionSize) {
      err_msg message("Heap region size (" SIZE_FORMAT "K) should be lower than max region size (" SIZE_FORMAT "K).",
                      ShenandoahHeapRegionSize/K, ShenandoahMaxRegionSize/K);
      vm_exit_during_initialization("Invalid -XX:ShenandoahHeapRegionSize option", message);
    }
    region_size = ShenandoahHeapRegionSize;
  }

  // Make sure region size is at least one large page, if enabled.
  // Otherwise, mem-protecting one region may falsely protect the adjacent
  // regions too.
  if (UseLargePages) {
    region_size = MAX2(region_size, os::large_page_size());
  }

  int region_size_log = log2_long((jlong) region_size);
  // Recalculate the region size to make sure it's a power of
  // 2. This means that region_size is the largest power of 2 that's
  // <= what we've calculated so far.
  region_size = ((uintx)1 << region_size_log);

  // Now, set up the globals.
  guarantee(RegionSizeShift == 0, "we should only set it once");
  RegionSizeShift = region_size_log;

  guarantee(RegionSizeBytes == 0, "we should only set it once");
  RegionSizeBytes = (size_t)region_size;

  log_info(gc, heap)("Heap region size: " SIZE_FORMAT "M", RegionSizeBytes / M);
  log_info(gc, init)("Region size in bytes: "SIZE_FORMAT, RegionSizeBytes);
  log_info(gc, init)("Region size shift: "SIZE_FORMAT, RegionSizeShift);
  log_info(gc, init)("Initial number of regions: "SIZE_FORMAT, initial_heap_size / RegionSizeBytes);
  log_info(gc, init)("Maximum number of regions: "SIZE_FORMAT, max_heap_size / RegionSizeBytes);
}

CompactibleSpace* ShenandoahHeapRegion::next_compaction_space() const {
  return _heap->next_compaction_region(this);
}

void ShenandoahHeapRegion::prepare_for_compaction(CompactPoint* cp) {
  scan_and_forward(this, cp);
}

void ShenandoahHeapRegion::adjust_pointers() {
  // Check first is there is any work to do.
  if (used() == 0) {
    return;   // Nothing to do.
  }

  scan_and_adjust_pointers(this);
}

void ShenandoahHeapRegion::compact() {
  assert(!is_humongous(), "Shouldn't be compacting humongous regions");
  scan_and_compact(this);
}

void ShenandoahHeapRegion::pin() {
  assert(! SafepointSynchronize::is_at_safepoint(), "only outside safepoints");
  assert(_critical_pins >= 0, "sanity");
  Atomic::inc(&_critical_pins);
}

void ShenandoahHeapRegion::unpin() {
  assert(! SafepointSynchronize::is_at_safepoint(), "only outside safepoints");
  Atomic::dec(&_critical_pins);
  assert(_critical_pins >= 0, "sanity");
}

bool ShenandoahHeapRegion::is_pinned() {
  jint v = OrderAccess::load_acquire(&_critical_pins);
  assert(v >= 0, "sanity");
  return v > 0;
}