/*

 * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.

 *

 * 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/epsilon/epsilonHeap.hpp"

#include "gc/epsilon/epsilonMemoryPool.hpp"

#include "gc/epsilon/epsilonThreadLocalData.hpp"

#include "memory/allocation.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/resourceArea.hpp"

jint EpsilonHeap::initialize() {

  size_t init_byte_size = _policy->initial_heap_byte_size();

  size_t max_byte_size  = _policy->max_heap_byte_size();

  // Initialize backing storage

  ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size, _policy->heap_alignment());

  _virtual_space.initialize(heap_rs, init_byte_size);

  MemRegion committed_region((HeapWord*)_virtual_space.low(),          (HeapWord*)_virtual_space.high());

  MemRegion  reserved_region((HeapWord*)_virtual_space.low_boundary(), (HeapWord*)_virtual_space.high_boundary());

  initialize_reserved_region(reserved_region.start(), reserved_region.end());

  _space = new ContiguousSpace();

  _space->initialize(committed_region, /* clear_space = */ true, /* mangle_space = */ true);

  // Precompute hot fields

  _max_tlab_size = MIN2(CollectedHeap::max_tlab_size(), EpsilonMaxTLABSize / HeapWordSize);

  _step_counter_update = MIN2<size_t>(max_byte_size / 16, EpsilonUpdateCountersStep);

  _step_heap_print = (EpsilonPrintHeapStep == 0) ? SIZE_MAX : (max_byte_size / EpsilonPrintHeapStep);

  // Enable monitoring

  _monitoring_support = new EpsilonMonitoringSupport(this);

  _last_counter_update = 0;

  _last_heap_print = 0;

  // Install barrier set

  BarrierSet::set_barrier_set(new EpsilonBarrierSet());

  // All done, print out the configuration

  if (init_byte_size != max_byte_size) {

    log_info(gc)("Resizeable heap; starting at " SIZE_FORMAT "M, max: " SIZE_FORMAT "M, step: " SIZE_FORMAT "M",

                 init_byte_size / M, max_byte_size / M, EpsilonMinHeapExpand / M);

  } else {

    log_info(gc)("Non-resizeable heap; start/max: " SIZE_FORMAT "M", init_byte_size / M);

  }

  if (UseTLAB) {

    log_info(gc)("Using TLAB allocation; max: " SIZE_FORMAT "K", _max_tlab_size * HeapWordSize / K);

    if (EpsilonElasticTLAB) {

      log_info(gc)("Elastic TLABs enabled; elasticity: %.2fx", EpsilonTLABElasticity);

    }

    if (EpsilonElasticTLABDecay) {

      log_info(gc)("Elastic TLABs decay enabled; decay time: " SIZE_FORMAT "ms", EpsilonTLABDecayTime);

    }

  } else {

    log_info(gc)("Not using TLAB allocation");

  }

  return JNI_OK;

}

void EpsilonHeap::post_initialize() {

  CollectedHeap::post_initialize();

}

void EpsilonHeap::initialize_serviceability() {

  _pool = new EpsilonMemoryPool(this);

  _memory_manager.add_pool(_pool);

}

GrowableArray<GCMemoryManager*> EpsilonHeap::memory_managers() {

  GrowableArray<GCMemoryManager*> memory_managers(1);

  memory_managers.append(&_memory_manager);

  return memory_managers;

}

GrowableArray<MemoryPool*> EpsilonHeap::memory_pools() {

  GrowableArray<MemoryPool*> memory_pools(1);

  memory_pools.append(_pool);

  return memory_pools;

}

size_t EpsilonHeap::unsafe_max_tlab_alloc(Thread* thr) const {

  // Return max allocatable TLAB size, and let allocation path figure out

  // the actual TLAB allocation size.

  return _max_tlab_size;

}

EpsilonHeap* EpsilonHeap::heap() {

  CollectedHeap* heap = Universe::heap();

  assert(heap != NULL, "Uninitialized access to EpsilonHeap::heap()");

  assert(heap->kind() == CollectedHeap::Epsilon, "Not an Epsilon heap");

  return (EpsilonHeap*)heap;

}

HeapWord* EpsilonHeap::allocate_work(size_t size) {

  HeapWord* res = _space->par_allocate(size);

  while (res == NULL) {

    // Allocation failed, attempt expansion, and retry:

    MutexLockerEx ml(Heap_lock);

    size_t space_left = max_capacity() - capacity();

    size_t want_space = MAX2(size, EpsilonMinHeapExpand);

    if (want_space < space_left) {

      // Enough space to expand in bulk:

      bool expand = _virtual_space.expand_by(want_space);

      assert(expand, "Should be able to expand");

    } else if (size < space_left) {

      // No space to expand in bulk, and this allocation is still possible,

      // take all the remaining space:

      bool expand = _virtual_space.expand_by(space_left);

      assert(expand, "Should be able to expand");

    } else {

      // No space left:

      return NULL;

    }

    _space->set_end((HeapWord *) _virtual_space.high());

    res = _space->par_allocate(size);

  }

  // Allocation successful, update counters

  size_t used = _space->used();

  if (used - _last_counter_update >= _step_counter_update) {

    _last_counter_update = used;

    _monitoring_support->update_counters();

  }

  // ...and print the occupancy line, if needed

  if (used - _last_heap_print >= _step_heap_print) {

    log_info(gc)("Heap: " SIZE_FORMAT "M reserved, " SIZE_FORMAT "M committed, " SIZE_FORMAT "M used",

                 max_capacity() / M, capacity() / M, used / M);

    _last_heap_print = used;

  }

  return res;

}

HeapWord* EpsilonHeap::allocate_new_tlab(size_t min_size,

                                         size_t requested_size,

                                         size_t* actual_size) {

  Thread* thread = Thread::current();

  // Defaults in case elastic paths are not taken

  bool fits = true;

  size_t size = requested_size;

  size_t ergo_tlab = requested_size;

  int64_t time = 0;

  if (EpsilonElasticTLAB) {

    ergo_tlab = EpsilonThreadLocalData::ergo_tlab_size(thread);

    if (EpsilonElasticTLABDecay) {

      int64_t last_time = EpsilonThreadLocalData::last_tlab_time(thread);

      time = (int64_t) os::javaTimeNanos();

      assert(last_time <= time, "time should be monotonic");

      // If the thread had not allocated recently, retract the ergonomic size.

      // This conserves memory when the thread had initial burst of allocations,

      // and then started allocating only sporadically.

      if (last_time != 0 && (time - last_time > _decay_time_ns)) {

        ergo_tlab = 0;

        EpsilonThreadLocalData::set_ergo_tlab_size(thread, 0);

      }

    }

    // If we can fit the allocation under current TLAB size, do so.

    // Otherwise, we want to elastically increase the TLAB size.

    fits = (requested_size <= ergo_tlab);

    if (!fits) {

      size = (size_t) (ergo_tlab * EpsilonTLABElasticity);

    }

  }

  // Always honor boundaries

  size = MAX2(min_size, MIN2(_max_tlab_size, size));

  if (log_is_enabled(Trace, gc)) {

    ResourceMark rm;

    log_trace(gc)("TLAB size for \"%s\" (Requested: " SIZE_FORMAT "K, Min: " SIZE_FORMAT

                          "K, Max: " SIZE_FORMAT "K, Ergo: " SIZE_FORMAT "K) -> " SIZE_FORMAT "K",

                  thread->name(),

                  requested_size * HeapWordSize / K,

                  min_size * HeapWordSize / K,

                  _max_tlab_size * HeapWordSize / K,

                  ergo_tlab * HeapWordSize / K,

                  size * HeapWordSize / K);

  }

  // All prepared, let's do it!

  HeapWord* res = allocate_work(size);

  if (res != NULL) {

    // Allocation successful

    *actual_size = size;

    if (EpsilonElasticTLABDecay) {

      EpsilonThreadLocalData::set_last_tlab_time(thread, time);

    }

    if (EpsilonElasticTLAB && !fits) {

      // If we requested expansion, this is our new ergonomic TLAB size

      EpsilonThreadLocalData::set_ergo_tlab_size(thread, size);

    }

  } else {

    // Allocation failed, reset ergonomics to try and fit smaller TLABs

    if (EpsilonElasticTLAB) {

      EpsilonThreadLocalData::set_ergo_tlab_size(thread, 0);

    }

  }

  return res;

}

HeapWord* EpsilonHeap::mem_allocate(size_t size, bool *gc_overhead_limit_was_exceeded) {

  *gc_overhead_limit_was_exceeded = false;

  return allocate_work(size);

}

void EpsilonHeap::collect(GCCause::Cause cause) {

  log_info(gc)("GC request for \"%s\" is ignored", GCCause::to_string(cause));

  _monitoring_support->update_counters();

}

void EpsilonHeap::do_full_collection(bool clear_all_soft_refs) {

  log_info(gc)("Full GC request for \"%s\" is ignored", GCCause::to_string(gc_cause()));

  _monitoring_support->update_counters();

}

void EpsilonHeap::safe_object_iterate(ObjectClosure *cl) {

  _space->safe_object_iterate(cl);

}

void EpsilonHeap::print_on(outputStream *st) const {

  st->print_cr("Epsilon Heap");

  // Cast away constness:

  ((VirtualSpace)_virtual_space).print_on(st);

  st->print_cr("Allocation space:");

  _space->print_on(st);

}

void EpsilonHeap::print_tracing_info() const {

  Log(gc) log;

  size_t allocated_kb = used() / K;

  log.info("Total allocated: " SIZE_FORMAT " KB",

           allocated_kb);

  log.info("Average allocation rate: " SIZE_FORMAT " KB/sec",

           (size_t)(allocated_kb * NANOSECS_PER_SEC / os::elapsed_counter()));

}