/*

 * 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 "classfile/javaClasses.hpp"

#include "gc/shared/allocTracer.hpp"

#include "gc/shared/collectedHeap.hpp"

#include "gc/shared/memAllocator.hpp"

#include "gc/shared/threadLocalAllocBuffer.inline.hpp"

#include "memory/universe.hpp"

#include "oops/arrayOop.hpp"

#include "oops/oop.inline.hpp"

#include "prims/jvmtiExport.hpp"

#include "runtime/sharedRuntime.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/thread.inline.hpp"

#include "services/lowMemoryDetector.hpp"

#include "utilities/align.hpp"

#include "utilities/copy.hpp"

class MemAllocator::Allocation: StackObj {

  friend class MemAllocator;

  const MemAllocator& _allocator;

  Thread*             _thread;

  oop*                _obj_ptr;

  bool                _overhead_limit_exceeded;

  bool                _allocated_outside_tlab;

  size_t              _allocated_tlab_size;

  bool                _tlab_end_reset_for_sample;

  bool check_out_of_memory();

  void verify_before();

  void verify_after();

  void notify_allocation();

  void notify_allocation_jvmti_allocation_event();

  void notify_allocation_jvmti_sampler();

  void notify_allocation_low_memory_detector();

  void notify_allocation_jfr_sampler();

  void notify_allocation_dtrace_sampler();

  void check_for_bad_heap_word_value() const;

#ifdef ASSERT

  void check_for_valid_allocation_state() const;

#endif

  class PreserveObj;

public:

  Allocation(const MemAllocator& allocator, oop* obj_ptr)

    : _allocator(allocator),

      _thread(Thread::current()),

      _obj_ptr(obj_ptr),

      _overhead_limit_exceeded(false),

      _allocated_outside_tlab(false),

      _allocated_tlab_size(0),

      _tlab_end_reset_for_sample(false)

  {

    verify_before();

  }

  ~Allocation() {

    if (!check_out_of_memory()) {

      verify_after();

      notify_allocation();

    }

  }

  oop obj() const { return *_obj_ptr; }

};

class MemAllocator::Allocation::PreserveObj: StackObj {

  HandleMark _handle_mark;

  Handle     _handle;

  oop* const _obj_ptr;

public:

  PreserveObj(Thread* thread, oop* obj_ptr)

    : _handle_mark(thread),

      _handle(thread, *obj_ptr),

      _obj_ptr(obj_ptr)

  {

    *obj_ptr = NULL;

  }

  ~PreserveObj() {

    *_obj_ptr = _handle();

  }

  oop operator()() const {

    return _handle();

  }

};

bool MemAllocator::Allocation::check_out_of_memory() {

  Thread* THREAD = _thread;

  assert(!HAS_PENDING_EXCEPTION, "Unexpected exception, will result in uninitialized storage");

  if (obj() != NULL) {

    return false;

  }

  if (!_overhead_limit_exceeded) {

    // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support

    report_java_out_of_memory("Java heap space");

    if (JvmtiExport::should_post_resource_exhausted()) {

      JvmtiExport::post_resource_exhausted(

        JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR | JVMTI_RESOURCE_EXHAUSTED_JAVA_HEAP,

        "Java heap space");

    }

    THROW_OOP_(Universe::out_of_memory_error_java_heap(), true);

  } else {

    // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support

    report_java_out_of_memory("GC overhead limit exceeded");

    if (JvmtiExport::should_post_resource_exhausted()) {

      JvmtiExport::post_resource_exhausted(

        JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR | JVMTI_RESOURCE_EXHAUSTED_JAVA_HEAP,

        "GC overhead limit exceeded");

    }

    THROW_OOP_(Universe::out_of_memory_error_gc_overhead_limit(), true);

  }

}

void MemAllocator::Allocation::verify_before() {

  // Clear unhandled oops for memory allocation.  Memory allocation might

  // not take out a lock if from tlab, so clear here.

  Thread* THREAD = _thread;

  CHECK_UNHANDLED_OOPS_ONLY(THREAD->clear_unhandled_oops();)

  assert(!HAS_PENDING_EXCEPTION, "Should not allocate with exception pending");

  debug_only(check_for_valid_allocation_state());

  assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");

}

void MemAllocator::Allocation::verify_after() {

  NOT_PRODUCT(check_for_bad_heap_word_value();)

}

void MemAllocator::Allocation::check_for_bad_heap_word_value() const {

  MemRegion obj_range = _allocator.obj_memory_range(obj());

  HeapWord* addr = obj_range.start();

  size_t size = obj_range.word_size();

  if (CheckMemoryInitialization && ZapUnusedHeapArea) {

    for (size_t slot = 0; slot < size; slot += 1) {

      assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),

             "Found badHeapWordValue in post-allocation check");

    }

  }

}

#ifdef ASSERT

void MemAllocator::Allocation::check_for_valid_allocation_state() const {

  // How to choose between a pending exception and a potential

  // OutOfMemoryError?  Don't allow pending exceptions.

  // This is a VM policy failure, so how do we exhaustively test it?

  assert(!_thread->has_pending_exception(),

         "shouldn't be allocating with pending exception");

  if (StrictSafepointChecks) {

    assert(_thread->allow_allocation(),

           "Allocation done by thread for which allocation is blocked "

           "by No_Allocation_Verifier!");

    // Allocation of an oop can always invoke a safepoint,

    // hence, the true argument

    _thread->check_for_valid_safepoint_state(true);

  }

}

#endif

void MemAllocator::Allocation::notify_allocation_jvmti_sampler() {

  // support for JVMTI VMObjectAlloc event (no-op if not enabled)

  JvmtiExport::vm_object_alloc_event_collector(obj());

  if (!ThreadHeapSampler::enabled()) {

    // Sampling disabled

    return;

  }

  if (!_allocated_outside_tlab && _allocated_tlab_size == 0 && !_tlab_end_reset_for_sample) {

    // Sample if it's a non-TLAB allocation, or a TLAB allocation that either refills the TLAB

    // or expands it due to taking a sampler induced slow path.

    return;

  }

  assert(JavaThread::current()->heap_sampler().add_sampling_collector(),

         "Should never return false.");

  // Only check if the sampler could actually sample something in this path.

  assert(!JvmtiExport::should_post_sampled_object_alloc() ||

         !JvmtiSampledObjectAllocEventCollector::object_alloc_is_safe_to_sample() ||

         _thread->heap_sampler().sampling_collector_present(),

         "Sampling collector not present.");

  if (JvmtiExport::should_post_sampled_object_alloc()) {

    // If we want to be sampling, protect the allocated object with a Handle

    // before doing the callback. The callback is done in the destructor of

    // the JvmtiSampledObjectAllocEventCollector.

    PreserveObj obj_h(_thread, _obj_ptr);

    JvmtiSampledObjectAllocEventCollector collector;

    size_t size_in_bytes = _allocator._word_size * HeapWordSize;

    ThreadLocalAllocBuffer& tlab = _thread->tlab();

    size_t bytes_since_last = _allocated_outside_tlab ? 0 : tlab.bytes_since_last_sample_point();

    _thread->heap_sampler().check_for_sampling(obj_h(), size_in_bytes, bytes_since_last);

  }

  assert(JavaThread::current()->heap_sampler().remove_sampling_collector(), "Should never return false.");

  if (_tlab_end_reset_for_sample || _allocated_tlab_size != 0) {

    _thread->tlab().set_sample_end();

  }

}

void MemAllocator::Allocation::notify_allocation_low_memory_detector() {

  // support low memory notifications (no-op if not enabled)

  LowMemoryDetector::detect_low_memory_for_collected_pools();

}

void MemAllocator::Allocation::notify_allocation_jfr_sampler() {

  HeapWord* mem = (HeapWord*)obj();

  size_t size_in_bytes = _allocator._word_size * HeapWordSize;

  if (_allocated_outside_tlab) {

    AllocTracer::send_allocation_outside_tlab(_allocator._klass, mem, size_in_bytes, _thread);

  } else if (_allocated_tlab_size != 0) {

    // TLAB was refilled

    AllocTracer::send_allocation_in_new_tlab(_allocator._klass, mem, _allocated_tlab_size * HeapWordSize,

                                             size_in_bytes, _thread);

  }

}

void MemAllocator::Allocation::notify_allocation_dtrace_sampler() {

  if (DTraceAllocProbes) {

    // support for Dtrace object alloc event (no-op most of the time)

    Klass* klass = _allocator._klass;

    size_t word_size = _allocator._word_size;

    if (klass != NULL && klass->name() != NULL) {

      SharedRuntime::dtrace_object_alloc(obj(), (int)word_size);

    }

  }

}

void MemAllocator::Allocation::notify_allocation() {

  notify_allocation_low_memory_detector();

  notify_allocation_jfr_sampler();

  notify_allocation_dtrace_sampler();

  notify_allocation_jvmti_sampler();

}

HeapWord* MemAllocator::allocate_outside_tlab(Allocation& allocation) const {

  allocation._allocated_outside_tlab = true;

  HeapWord* mem = _heap->mem_allocate(_word_size, &allocation._overhead_limit_exceeded);

  if (mem == NULL) {

    return mem;

  }

  NOT_PRODUCT(_heap->check_for_non_bad_heap_word_value(mem, _word_size));

  size_t size_in_bytes = _word_size * HeapWordSize;

  _thread->incr_allocated_bytes(size_in_bytes);

  return mem;

}

HeapWord* MemAllocator::allocate_inside_tlab(Allocation& allocation) const {

  assert(UseTLAB, "should use UseTLAB");

  // Try allocating from an existing TLAB.

  HeapWord* mem = _thread->tlab().allocate(_word_size);

  if (mem != NULL) {

    return mem;

  }

  // Try refilling the TLAB and allocating the object in it.

  return allocate_inside_tlab_slow(allocation);

}

HeapWord* MemAllocator::allocate_inside_tlab_slow(Allocation& allocation) const {

  HeapWord* mem = NULL;

  ThreadLocalAllocBuffer& tlab = _thread->tlab();

  if (ThreadHeapSampler::enabled()) {

    // Try to allocate the sampled object from TLAB, it is possible a sample

    // point was put and the TLAB still has space.

    tlab.set_back_allocation_end();

    mem = tlab.allocate(_word_size);

    if (mem != NULL) {

      allocation._tlab_end_reset_for_sample = true;

      return mem;

    }

  }

  // Retain tlab and allocate object in shared space if

  // the amount free in the tlab is too large to discard.

  if (tlab.free() > tlab.refill_waste_limit()) {

    tlab.record_slow_allocation(_word_size);

    return NULL;

  }

  // Discard tlab and allocate a new one.

  // To minimize fragmentation, the last TLAB may be smaller than the rest.

  size_t new_tlab_size = tlab.compute_size(_word_size);

  tlab.clear_before_allocation();

  if (new_tlab_size == 0) {

    return NULL;

  }

  // Allocate a new TLAB requesting new_tlab_size. Any size

  // between minimal and new_tlab_size is accepted.

  size_t min_tlab_size = ThreadLocalAllocBuffer::compute_min_size(_word_size);

  mem = _heap->allocate_new_tlab(min_tlab_size, new_tlab_size, &allocation._allocated_tlab_size);

  if (mem == NULL) {

    assert(allocation._allocated_tlab_size == 0,

           "Allocation failed, but actual size was updated. min: " SIZE_FORMAT

           ", desired: " SIZE_FORMAT ", actual: " SIZE_FORMAT,

           min_tlab_size, new_tlab_size, allocation._allocated_tlab_size);

    return NULL;

  }

  assert(allocation._allocated_tlab_size != 0, "Allocation succeeded but actual size not updated. mem at: "

         PTR_FORMAT " min: " SIZE_FORMAT ", desired: " SIZE_FORMAT,

         p2i(mem), min_tlab_size, new_tlab_size);

  if (ZeroTLAB) {

    // ..and clear it.

    Copy::zero_to_words(mem, allocation._allocated_tlab_size);

  } else {

    // ...and zap just allocated object.

#ifdef ASSERT

    // Skip mangling the space corresponding to the object header to

    // ensure that the returned space is not considered parsable by

    // any concurrent GC thread.

    size_t hdr_size = oopDesc::header_size();

    Copy::fill_to_words(mem + hdr_size, allocation._allocated_tlab_size - hdr_size, badHeapWordVal);

#endif // ASSERT

  }

  tlab.fill(mem, mem + _word_size, allocation._allocated_tlab_size);

  return mem;

}

HeapWord* MemAllocator::mem_allocate(Allocation& allocation) const {

  if (UseTLAB) {

    HeapWord* result = allocate_inside_tlab(allocation);

    if (result != NULL) {

      return result;

    }

  }

  return allocate_outside_tlab(allocation);

}

oop MemAllocator::allocate() const {

  oop obj = NULL;

  {

    Allocation allocation(*this, &obj);

    HeapWord* mem = mem_allocate(allocation);

    if (mem != NULL) {

      obj = initialize(mem);

    }

  }

  return obj;

}

void MemAllocator::mem_clear(HeapWord* mem) const {

  assert(mem != NULL, "cannot initialize NULL object");

  const size_t hs = oopDesc::header_size();

  assert(_word_size >= hs, "unexpected object size");

  oopDesc::set_klass_gap(mem, 0);

  Copy::fill_to_aligned_words(mem + hs, _word_size - hs);

}

oop MemAllocator::finish(HeapWord* mem) const {

  assert(mem != NULL, "NULL object pointer");

  if (UseBiasedLocking) {

    oopDesc::set_mark_raw(mem, _klass->prototype_header());

  } else {

    // May be bootstrapping

    oopDesc::set_mark_raw(mem, markOopDesc::prototype());

  }

  // Need a release store to ensure array/class length, mark word, and

  // object zeroing are visible before setting the klass non-NULL, for

  // concurrent collectors.

  oopDesc::release_set_klass(mem, _klass);

  return oop(mem);

}

oop ObjAllocator::initialize(HeapWord* mem) const {

  mem_clear(mem);

  return finish(mem);

}

MemRegion ObjArrayAllocator::obj_memory_range(oop obj) const {

  if (_do_zero) {

    return MemAllocator::obj_memory_range(obj);

  }

  ArrayKlass* array_klass = ArrayKlass::cast(_klass);

  const size_t hs = arrayOopDesc::header_size(array_klass->element_type());

  return MemRegion(((HeapWord*)obj) + hs, _word_size - hs);

}

oop ObjArrayAllocator::initialize(HeapWord* mem) const {

  // Set array length before setting the _klass field because a

  // non-NULL klass field indicates that the object is parsable by

  // concurrent GC.

  assert(_length >= 0, "length should be non-negative");

  if (_do_zero) {

    mem_clear(mem);

  }

  arrayOopDesc::set_length(mem, _length);

  return finish(mem);

}

oop ClassAllocator::initialize(HeapWord* mem) const {

  // Set oop_size field before setting the _klass field because a

  // non-NULL _klass field indicates that the object is parsable by

  // concurrent GC.

  assert(_word_size > 0, "oop_size must be positive.");

  mem_clear(mem);

  java_lang_Class::set_oop_size(mem, (int)_word_size);

  return finish(mem);

}