Quelle  cSpaceCounters.cpp

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 *
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 * accompanied this code).
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#include "precompiled.hpp"
#include "gc/serial/cSpaceCounters.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"

CSpaceCounters::CSpaceCounters(const char* name, int ordinal, size_t max_size,
                               ContiguousSpace* s, GenerationCounters* gc) :
   _space(s) {

  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");
    _max_capacity = PerfDataManager::create_variable(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,
                                                 _space->capacity(), CHECK);

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

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

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

void CSpaceCounters::update_capacity() {
  _capacity->set_value(_space->capacity());
}

static volatile size_t last_used_in_bytes = 0;

void CSpaceCounters::update_used() {
  size_t new_used = _space->used();
  Atomic::store(&last_used_in_bytes, new_used);
  _used->set_value(new_used);
}

void CSpaceCounters::update_all() {
  update_used();
  update_capacity();
}

jlong ContiguousSpaceUsedHelper::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()) {
    Atomic::store(&last_used_in_bytes, _space->used());
    Heap_lock->unlock();
  }
  return Atomic::load(&last_used_in_bytes);
}