/*

 * Copyright 2000-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

# include "incls/_precompiled.incl"

# include "incls/_genCollectedHeap.cpp.incl"

GenCollectedHeap* GenCollectedHeap::_gch;

NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)

// The set of potentially parallel tasks in strong root scanning.

enum GCH_process_strong_roots_tasks {

  // We probably want to parallelize both of these internally, but for now...

  GCH_PS_younger_gens,

  // Leave this one last.

  GCH_PS_NumElements

};

GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :

  SharedHeap(policy),

  _gen_policy(policy),

  _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),

  _full_collections_completed(0)

{

  if (_gen_process_strong_tasks == NULL ||

      !_gen_process_strong_tasks->valid()) {

    vm_exit_during_initialization("Failed necessary allocation.");

  }

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

  _preloading_shared_classes = false;

}

jint GenCollectedHeap::initialize() {

  int i;

  _n_gens = gen_policy()->number_of_generations();

  // While there are no constraints in the GC code that HeapWordSize

  // be any particular value, there are multiple other areas in the

  // system which believe this to be true (e.g. oop->object_size in some

  // cases incorrectly returns the size in wordSize units rather than

  // HeapWordSize).

  guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");

  // The heap must be at least as aligned as generations.

  size_t alignment = Generation::GenGrain;

  _gen_specs = gen_policy()->generations();

  PermanentGenerationSpec *perm_gen_spec =

                                collector_policy()->permanent_generation();

  // Make sure the sizes are all aligned.

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

    _gen_specs[i]->align(alignment);

  }

  perm_gen_spec->align(alignment);

  // If we are dumping the heap, then allocate a wasted block of address

  // space in order to push the heap to a lower address.  This extra

  // address range allows for other (or larger) libraries to be loaded

  // without them occupying the space required for the shared spaces.

  if (DumpSharedSpaces) {

    uintx reserved = 0;

    uintx block_size = 64*1024*1024;

    while (reserved < SharedDummyBlockSize) {

      char* dummy = os::reserve_memory(block_size);

      reserved += block_size;

    }

  }

  // Allocate space for the heap.

  char* heap_address;

  size_t total_reserved = 0;

  int n_covered_regions = 0;

  ReservedSpace heap_rs(0);

  heap_address = allocate(alignment, perm_gen_spec, &total_reserved,

                          &n_covered_regions, &heap_rs);

  if (UseSharedSpaces) {

    if (!heap_rs.is_reserved() || heap_address != heap_rs.base()) {

      if (heap_rs.is_reserved()) {

        heap_rs.release();

      }

      FileMapInfo* mapinfo = FileMapInfo::current_info();

      mapinfo->fail_continue("Unable to reserve shared region.");

      allocate(alignment, perm_gen_spec, &total_reserved, &n_covered_regions,

               &heap_rs);

    }

  }

  if (!heap_rs.is_reserved()) {

    vm_shutdown_during_initialization(

      "Could not reserve enough space for object heap");

    return JNI_ENOMEM;

  }

  _reserved = MemRegion((HeapWord*)heap_rs.base(),

                        (HeapWord*)(heap_rs.base() + heap_rs.size()));

  // It is important to do this in a way such that concurrent readers can't

  // temporarily think somethings in the heap.  (Seen this happen in asserts.)

  _reserved.set_word_size(0);

  _reserved.set_start((HeapWord*)heap_rs.base());

  size_t actual_heap_size = heap_rs.size() - perm_gen_spec->misc_data_size()

                                           - perm_gen_spec->misc_code_size();

  _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));

  _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);

  set_barrier_set(rem_set()->bs());

  _gch = this;

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

    ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(),

                                              UseSharedSpaces, UseSharedSpaces);

    _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());

    heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());

  }

  _perm_gen = perm_gen_spec->init(heap_rs, PermSize, rem_set());

  clear_incremental_collection_will_fail();

  clear_last_incremental_collection_failed();

#ifndef SERIALGC

  // If we are running CMS, create the collector responsible

  // for collecting the CMS generations.

  if (collector_policy()->is_concurrent_mark_sweep_policy()) {

    bool success = create_cms_collector();

    if (!success) return JNI_ENOMEM;

  }

#endif // SERIALGC

  return JNI_OK;

}

char* GenCollectedHeap::allocate(size_t alignment,

                                 PermanentGenerationSpec* perm_gen_spec,

                                 size_t* _total_reserved,

                                 int* _n_covered_regions,

                                 ReservedSpace* heap_rs){

  const char overflow_msg[] = "The size of the object heap + VM data exceeds "

    "the maximum representable size";

  // Now figure out the total size.

  size_t total_reserved = 0;

  int n_covered_regions = 0;

  const size_t pageSize = UseLargePages ?

      os::large_page_size() : os::vm_page_size();

  for (int i = 0; i < _n_gens; i++) {

    total_reserved += _gen_specs[i]->max_size();

    if (total_reserved < _gen_specs[i]->max_size()) {

      vm_exit_during_initialization(overflow_msg);

    }

    n_covered_regions += _gen_specs[i]->n_covered_regions();

  }

  assert(total_reserved % pageSize == 0, "Gen size");

  total_reserved += perm_gen_spec->max_size();

  assert(total_reserved % pageSize == 0, "Perm Gen size");

  if (total_reserved < perm_gen_spec->max_size()) {

    vm_exit_during_initialization(overflow_msg);

  }

  n_covered_regions += perm_gen_spec->n_covered_regions();

  // Add the size of the data area which shares the same reserved area

  // as the heap, but which is not actually part of the heap.

  size_t s = perm_gen_spec->misc_data_size() + perm_gen_spec->misc_code_size();

  total_reserved += s;

  if (total_reserved < s) {

    vm_exit_during_initialization(overflow_msg);

  }

  if (UseLargePages) {

    assert(total_reserved != 0, "total_reserved cannot be 0");

    total_reserved = round_to(total_reserved, os::large_page_size());

    if (total_reserved < os::large_page_size()) {

      vm_exit_during_initialization(overflow_msg);

    }

  }

  // Calculate the address at which the heap must reside in order for

  // the shared data to be at the required address.

  char* heap_address;

  if (UseSharedSpaces) {

    // Calculate the address of the first word beyond the heap.

    FileMapInfo* mapinfo = FileMapInfo::current_info();

    int lr = CompactingPermGenGen::n_regions - 1;

    size_t capacity = align_size_up(mapinfo->space_capacity(lr), alignment);

    heap_address = mapinfo->region_base(lr) + capacity;

    // Calculate the address of the first word of the heap.

    heap_address -= total_reserved;

  } else {

    heap_address = NULL;  // any address will do.

  }

  *_total_reserved = total_reserved;

  *_n_covered_regions = n_covered_regions;

  *heap_rs = ReservedHeapSpace(total_reserved, alignment,

                               UseLargePages, heap_address);

  return heap_address;

}

void GenCollectedHeap::post_initialize() {

  SharedHeap::post_initialize();

  TwoGenerationCollectorPolicy *policy =

    (TwoGenerationCollectorPolicy *)collector_policy();

  guarantee(policy->is_two_generation_policy(), "Illegal policy type");

  DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);

  assert(def_new_gen->kind() == Generation::DefNew ||

         def_new_gen->kind() == Generation::ParNew ||

         def_new_gen->kind() == Generation::ASParNew,

         "Wrong generation kind");

  Generation* old_gen = get_gen(1);

  assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||

         old_gen->kind() == Generation::ASConcurrentMarkSweep ||

         old_gen->kind() == Generation::MarkSweepCompact,

    "Wrong generation kind");

  policy->initialize_size_policy(def_new_gen->eden()->capacity(),

                                 old_gen->capacity(),

                                 def_new_gen->from()->capacity());

  policy->initialize_gc_policy_counters();

}

void GenCollectedHeap::ref_processing_init() {

  SharedHeap::ref_processing_init();

  for (int i = 0; i < _n_gens; i++) {

    _gens[i]->ref_processor_init();

  }

}

size_t GenCollectedHeap::capacity() const {

  size_t res = 0;

  for (int i = 0; i < _n_gens; i++) {

    res += _gens[i]->capacity();

  }

  return res;

}

size_t GenCollectedHeap::used() const {

  size_t res = 0;

  for (int i = 0; i < _n_gens; i++) {

    res += _gens[i]->used();

  }

  return res;

}

// Save the "used_region" for generations level and lower,

// and, if perm is true, for perm gen.

void GenCollectedHeap::save_used_regions(int level, bool perm) {

  assert(level < _n_gens, "Illegal level parameter");

  for (int i = level; i >= 0; i--) {

    _gens[i]->save_used_region();

  }

  if (perm) {

    perm_gen()->save_used_region();

  }

}

size_t GenCollectedHeap::max_capacity() const {

  size_t res = 0;

  for (int i = 0; i < _n_gens; i++) {

    res += _gens[i]->max_capacity();

  }

  return res;

}

// Update the _full_collections_completed counter

// at the end of a stop-world full GC.

unsigned int GenCollectedHeap::update_full_collections_completed() {

  MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);

  assert(_full_collections_completed <= _total_full_collections,

         "Can't complete more collections than were started");

  _full_collections_completed = _total_full_collections;

  ml.notify_all();

  return _full_collections_completed;

}

// Update the _full_collections_completed counter, as appropriate,

// at the end of a concurrent GC cycle. Note the conditional update

// below to allow this method to be called by a concurrent collector

// without synchronizing in any manner with the VM thread (which

// may already have initiated a STW full collection "concurrently").

unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {

  MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);

  assert((_full_collections_completed <= _total_full_collections) &&

         (count <= _total_full_collections),

         "Can't complete more collections than were started");

  if (count > _full_collections_completed) {

    _full_collections_completed = count;

    ml.notify_all();

  }

  return _full_collections_completed;

}

#ifndef PRODUCT

// Override of memory state checking method in CollectedHeap:

// Some collectors (CMS for example) can't have badHeapWordVal written

// in the first two words of an object. (For instance , in the case of

// CMS these words hold state used to synchronize between certain

// (concurrent) GC steps and direct allocating mutators.)

// The skip_header_HeapWords() method below, allows us to skip

// over the requisite number of HeapWord's. Note that (for

// generational collectors) this means that those many words are

// skipped in each object, irrespective of the generation in which

// that object lives. The resultant loss of precision seems to be

// harmless and the pain of avoiding that imprecision appears somewhat

// higher than we are prepared to pay for such rudimentary debugging

// support.

void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,

                                                         size_t size) {

  if (CheckMemoryInitialization && ZapUnusedHeapArea) {

    // We are asked to check a size in HeapWords,

    // but the memory is mangled in juint words.

    juint* start = (juint*) (addr + skip_header_HeapWords());

    juint* end   = (juint*) (addr + size);

    for (juint* slot = start; slot < end; slot += 1) {

      assert(*slot == badHeapWordVal,

             "Found non badHeapWordValue in pre-allocation check");

    }

  }

}

#endif

HeapWord* GenCollectedHeap::attempt_allocation(size_t size,

                                               bool is_tlab,

                                               bool first_only) {

  HeapWord* res;

  for (int i = 0; i < _n_gens; i++) {

    if (_gens[i]->should_allocate(size, is_tlab)) {

      res = _gens[i]->allocate(size, is_tlab);

      if (res != NULL) return res;

      else if (first_only) break;

    }

  }

  // Otherwise...

  return NULL;

}

HeapWord* GenCollectedHeap::mem_allocate(size_t size,

                                         bool is_large_noref,

                                         bool is_tlab,

                                         bool* gc_overhead_limit_was_exceeded) {

  return collector_policy()->mem_allocate_work(size,

                                               is_tlab,

                                               gc_overhead_limit_was_exceeded);

}

bool GenCollectedHeap::must_clear_all_soft_refs() {

  return _gc_cause == GCCause::_last_ditch_collection;

}

bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {

  return (cause == GCCause::_java_lang_system_gc ||

          cause == GCCause::_gc_locker) &&

         UseConcMarkSweepGC && ExplicitGCInvokesConcurrent;

}

void GenCollectedHeap::do_collection(bool  full,

                                     bool   clear_all_soft_refs,

                                     size_t size,

                                     bool   is_tlab,

                                     int    max_level) {

  bool prepared_for_verification = false;

  ResourceMark rm;

  DEBUG_ONLY(Thread* my_thread = Thread::current();)

  assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");

  assert(my_thread->is_VM_thread() ||

         my_thread->is_ConcurrentGC_thread(),

         "incorrect thread type capability");

  assert(Heap_lock->is_locked(), "the requesting thread should have the Heap_lock");

  guarantee(!is_gc_active(), "collection is not reentrant");

  assert(max_level < n_gens(), "sanity check");

  if (GC_locker::check_active_before_gc()) {

    return; // GC is disabled (e.g. JNI GetXXXCritical operation)

  }

  const size_t perm_prev_used = perm_gen()->used();

  if (PrintHeapAtGC) {

    Universe::print_heap_before_gc();

    if (Verbose) {

      gclog_or_tty->print_cr("GC Cause: %s", GCCause::to_string(gc_cause()));

    }

  }

  {

    FlagSetting fl(_is_gc_active, true);

    bool complete = full && (max_level == (n_gens()-1));

    const char* gc_cause_str = "GC ";

    if (complete) {

      GCCause::Cause cause = gc_cause();

      if (cause == GCCause::_java_lang_system_gc) {

        gc_cause_str = "Full GC (System) ";

      } else {

        gc_cause_str = "Full GC ";

      }

    }

    gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);

    TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);

    TraceTime t(gc_cause_str, PrintGCDetails, false, gclog_or_tty);

    gc_prologue(complete);

    increment_total_collections(complete);

    size_t gch_prev_used = used();

    int starting_level = 0;

    if (full) {

      // Search for the oldest generation which will collect all younger

      // generations, and start collection loop there.

      for (int i = max_level; i >= 0; i--) {

        if (_gens[i]->full_collects_younger_generations()) {

          starting_level = i;

          break;

        }

      }

    }

    bool must_restore_marks_for_biased_locking = false;

    int max_level_collected = starting_level;

    for (int i = starting_level; i <= max_level; i++) {

      if (_gens[i]->should_collect(full, size, is_tlab)) {

        // Timer for individual generations. Last argument is false: no CR

        TraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, gclog_or_tty);

        TraceCollectorStats tcs(_gens[i]->counters());

        TraceMemoryManagerStats tmms(_gens[i]->kind());

        size_t prev_used = _gens[i]->used();

        _gens[i]->stat_record()->invocations++;

        _gens[i]->stat_record()->accumulated_time.start();

        // Must be done anew before each collection because

        // a previous collection will do mangling and will

        // change top of some spaces.

        record_gen_tops_before_GC();

        if (PrintGC && Verbose) {

          gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,

                     i,

                     _gens[i]->stat_record()->invocations,

                     size*HeapWordSize);

        }

        if (VerifyBeforeGC && i >= VerifyGCLevel &&

            total_collections() >= VerifyGCStartAt) {

          HandleMark hm;  // Discard invalid handles created during verification

          if (!prepared_for_verification) {

            prepare_for_verify();

            prepared_for_verification = true;

          }

          gclog_or_tty->print(" VerifyBeforeGC:");

          Universe::verify(true);

        }

        COMPILER2_PRESENT(DerivedPointerTable::clear());

        if (!must_restore_marks_for_biased_locking &&

            _gens[i]->performs_in_place_marking()) {

          // We perform this mark word preservation work lazily

          // because it's only at this point that we know whether we

          // absolutely have to do it; we want to avoid doing it for

          // scavenge-only collections where it's unnecessary

          must_restore_marks_for_biased_locking = true;

          BiasedLocking::preserve_marks();

        }

        // Do collection work

        {

          // Note on ref discovery: For what appear to be historical reasons,

          // GCH enables and disabled (by enqueing) refs discovery.

          // In the future this should be moved into the generation's

          // collect method so that ref discovery and enqueueing concerns

          // are local to a generation. The collect method could return

          // an appropriate indication in the case that notification on

          // the ref lock was needed. This will make the treatment of

          // weak refs more uniform (and indeed remove such concerns

          // from GCH). XXX

          HandleMark hm;  // Discard invalid handles created during gc

          save_marks();   // save marks for all gens

          // We want to discover references, but not process them yet.

          // This mode is disabled in process_discovered_references if the

          // generation does some collection work, or in

          // enqueue_discovered_references if the generation returns

          // without doing any work.

          ReferenceProcessor* rp = _gens[i]->ref_processor();

          // If the discovery of ("weak") refs in this generation is

          // atomic wrt other collectors in this configuration, we

          // are guaranteed to have empty discovered ref lists.

          if (rp->discovery_is_atomic()) {

            rp->verify_no_references_recorded();

            rp->enable_discovery();