src/hotspot/share/gc/parallel/spaceCounters.cpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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#include "precompiled.hpp"
#include "gc/parallel/spaceCounters.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "runtime/atomic.hpp"
#include "runtime/mutex.hpp"
#include "runtime/mutexLocker.hpp"
#include "utilities/debug.hpp"
#include "utilities/macros.hpp"

SpaceCounters::SpaceCounters(const char* name, int ordinal, size_t max_size,
                             MutableSpace* m, GenerationCounters* gc)
  : _last_used_in_bytes(0), _object_space(m)
{
  if (UsePerfData) {
    EXCEPTION_MARK;
    ResourceMark rm;

    const char* cns = PerfDataManager::name_space(gc->name_space(), "space",
                                                  ordinal);

    _name_space = NEW_C_HEAP_ARRAY(char, strlen(cns)+1, mtGC);
    strcpy(_name_space, cns);

    const char* cname = PerfDataManager::counter_name(_name_space, "name");
    PerfDataManager::create_string_constant(SUN_GC, cname, name, CHECK);

    cname = PerfDataManager::counter_name(_name_space, "maxCapacity");
    PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_Bytes,
                                     (jlong)max_size, CHECK);

    cname = PerfDataManager::counter_name(_name_space, "capacity");
    _capacity = PerfDataManager::create_variable(SUN_GC, cname,
                                                 PerfData::U_Bytes,
                                                 _object_space->capacity_in_bytes(),
                                                 CHECK);

    cname = PerfDataManager::counter_name(_name_space, "used");
    _used = PerfDataManager::create_variable(SUN_GC, cname, PerfData::U_Bytes,
                                             new UsedHelper(this),
                                             CHECK);

    cname = PerfDataManager::counter_name(_name_space, "initCapacity");
    PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_Bytes,
                                     _object_space->capacity_in_bytes(), CHECK);
  }
}

SpaceCounters::~SpaceCounters() {
  FREE_C_HEAP_ARRAY(char, _name_space);
}

void SpaceCounters::update_used() {
  size_t new_used = _object_space->used_in_bytes();
  Atomic::store(&_last_used_in_bytes, new_used);
  _used->set_value(new_used);
}

jlong SpaceCounters::UsedHelper::take_sample() {
  // Sampling may occur during GC, possibly while GC is updating the space.
  // The space can be in an inconsistent state during such an update.  We
  // don't want to block sampling for the duration of a GC.  Instead, skip
  // sampling in that case, using the last recorded value.
  assert(!Heap_lock->owned_by_self(), "precondition");
  if (Heap_lock->try_lock()) {
    size_t new_used = _counters->_object_space->used_in_bytes();
    Atomic::store(&_counters->_last_used_in_bytes, new_used);
    Heap_lock->unlock();
  }
  return Atomic::load(&_counters->_last_used_in_bytes);
}