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Java example source code file (memoryPool.cpp)

This example Java source code file (memoryPool.cpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

argument, check_null, collectedmemorypool, include_all_gcs, memorypool\:\:max_num_managers, memoryusage, metaspaceaux\:\:allocated_used_bytes, metaspaceaux\:\:committed_bytes, nonheap, null, pooltype, sensorinfo, symbol, thresholdsupport

The memoryPool.cpp Java example source code

/*
 * Copyright (c) 2003, 2013, 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/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "memory/metaspace.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/javaCalls.hpp"
#include "services/lowMemoryDetector.hpp"
#include "services/management.hpp"
#include "services/memoryManager.hpp"
#include "services/memoryPool.hpp"
#include "utilities/macros.hpp"
#include "utilities/globalDefinitions.hpp"

MemoryPool::MemoryPool(const char* name,
                       PoolType type,
                       size_t init_size,
                       size_t max_size,
                       bool support_usage_threshold,
                       bool support_gc_threshold) {
  _name = name;
  _initial_size = init_size;
  _max_size = max_size;
  (void)const_cast<instanceOop&>(_memory_pool_obj = NULL);
  _available_for_allocation = true;
  _num_managers = 0;
  _type = type;

  // initialize the max and init size of collection usage
  _after_gc_usage = MemoryUsage(_initial_size, 0, 0, _max_size);

  _usage_sensor = NULL;
  _gc_usage_sensor = NULL;
  // usage threshold supports both high and low threshold
  _usage_threshold = new ThresholdSupport(support_usage_threshold, support_usage_threshold);
  // gc usage threshold supports only high threshold
  _gc_usage_threshold = new ThresholdSupport(support_gc_threshold, support_gc_threshold);
}

void MemoryPool::add_manager(MemoryManager* mgr) {
  assert(_num_managers < MemoryPool::max_num_managers, "_num_managers exceeds the max");
  if (_num_managers < MemoryPool::max_num_managers) {
    _managers[_num_managers] = mgr;
    _num_managers++;
  }
}


// Returns an instanceHandle of a MemoryPool object.
// It creates a MemoryPool instance when the first time
// this function is called.
instanceOop MemoryPool::get_memory_pool_instance(TRAPS) {
  // Must do an acquire so as to force ordering of subsequent
  // loads from anything _memory_pool_obj points to or implies.
  instanceOop pool_obj = (instanceOop)OrderAccess::load_ptr_acquire(&_memory_pool_obj);
  if (pool_obj == NULL) {
    // It's ok for more than one thread to execute the code up to the locked region.
    // Extra pool instances will just be gc'ed.
    Klass* k = Management::sun_management_ManagementFactory_klass(CHECK_NULL);
    instanceKlassHandle ik(THREAD, k);

    Handle pool_name = java_lang_String::create_from_str(_name, CHECK_NULL);
    jlong usage_threshold_value = (_usage_threshold->is_high_threshold_supported() ? 0 : -1L);
    jlong gc_usage_threshold_value = (_gc_usage_threshold->is_high_threshold_supported() ? 0 : -1L);

    JavaValue result(T_OBJECT);
    JavaCallArguments args;
    args.push_oop(pool_name);           // Argument 1
    args.push_int((int) is_heap());     // Argument 2

    Symbol* method_name = vmSymbols::createMemoryPool_name();
    Symbol* signature = vmSymbols::createMemoryPool_signature();

    args.push_long(usage_threshold_value);    // Argument 3
    args.push_long(gc_usage_threshold_value); // Argument 4

    JavaCalls::call_static(&result,
                           ik,
                           method_name,
                           signature,
                           &args,
                           CHECK_NULL);

    instanceOop p = (instanceOop) result.get_jobject();
    instanceHandle pool(THREAD, p);

    {
      // Get lock since another thread may have create the instance
      MutexLocker ml(Management_lock);

      // Check if another thread has created the pool.  We reload
      // _memory_pool_obj here because some other thread may have
      // initialized it while we were executing the code before the lock.
      //
      // The lock has done an acquire, so the load can't float above it,
      // but we need to do a load_acquire as above.
      pool_obj = (instanceOop)OrderAccess::load_ptr_acquire(&_memory_pool_obj);
      if (pool_obj != NULL) {
         return pool_obj;
      }

      // Get the address of the object we created via call_special.
      pool_obj = pool();

      // Use store barrier to make sure the memory accesses associated
      // with creating the pool are visible before publishing its address.
      // The unlock will publish the store to _memory_pool_obj because
      // it does a release first.
      OrderAccess::release_store_ptr(&_memory_pool_obj, pool_obj);
    }
  }

  return pool_obj;
}

inline static size_t get_max_value(size_t val1, size_t val2) {
    return (val1 > val2 ? val1 : val2);
}

void MemoryPool::record_peak_memory_usage() {
  // Caller in JDK is responsible for synchronization -
  // acquire the lock for this memory pool before calling VM
  MemoryUsage usage = get_memory_usage();
  size_t peak_used = get_max_value(usage.used(), _peak_usage.used());
  size_t peak_committed = get_max_value(usage.committed(), _peak_usage.committed());
  size_t peak_max_size = get_max_value(usage.max_size(), _peak_usage.max_size());

  _peak_usage = MemoryUsage(initial_size(), peak_used, peak_committed, peak_max_size);
}

static void set_sensor_obj_at(SensorInfo** sensor_ptr, instanceHandle sh) {
  assert(*sensor_ptr == NULL, "Should be called only once");
  SensorInfo* sensor = new SensorInfo();
  sensor->set_sensor(sh());
  *sensor_ptr = sensor;
}

void MemoryPool::set_usage_sensor_obj(instanceHandle sh) {
  set_sensor_obj_at(&_usage_sensor, sh);
}

void MemoryPool::set_gc_usage_sensor_obj(instanceHandle sh) {
  set_sensor_obj_at(&_gc_usage_sensor, sh);
}

void MemoryPool::oops_do(OopClosure* f) {
  f->do_oop((oop*) &_memory_pool_obj);
  if (_usage_sensor != NULL) {
    _usage_sensor->oops_do(f);
  }
  if (_gc_usage_sensor != NULL) {
    _gc_usage_sensor->oops_do(f);
  }
}

ContiguousSpacePool::ContiguousSpacePool(ContiguousSpace* space,
                                         const char* name,
                                         PoolType type,
                                         size_t max_size,
                                         bool support_usage_threshold) :
  CollectedMemoryPool(name, type, space->capacity(), max_size,
                      support_usage_threshold), _space(space) {
}

MemoryUsage ContiguousSpacePool::get_memory_usage() {
  size_t maxSize   = (available_for_allocation() ? max_size() : 0);
  size_t used      = used_in_bytes();
  size_t committed = _space->capacity();

  return MemoryUsage(initial_size(), used, committed, maxSize);
}

SurvivorContiguousSpacePool::SurvivorContiguousSpacePool(DefNewGeneration* gen,
                                                         const char* name,
                                                         PoolType type,
                                                         size_t max_size,
                                                         bool support_usage_threshold) :
  CollectedMemoryPool(name, type, gen->from()->capacity(), max_size,
                      support_usage_threshold), _gen(gen) {
}

MemoryUsage SurvivorContiguousSpacePool::get_memory_usage() {
  size_t maxSize = (available_for_allocation() ? max_size() : 0);
  size_t used    = used_in_bytes();
  size_t committed = committed_in_bytes();

  return MemoryUsage(initial_size(), used, committed, maxSize);
}

#if INCLUDE_ALL_GCS
CompactibleFreeListSpacePool::CompactibleFreeListSpacePool(CompactibleFreeListSpace* space,
                                                           const char* name,
                                                           PoolType type,
                                                           size_t max_size,
                                                           bool support_usage_threshold) :
  CollectedMemoryPool(name, type, space->capacity(), max_size,
                      support_usage_threshold), _space(space) {
}

MemoryUsage CompactibleFreeListSpacePool::get_memory_usage() {
  size_t maxSize   = (available_for_allocation() ? max_size() : 0);
  size_t used      = used_in_bytes();
  size_t committed = _space->capacity();

  return MemoryUsage(initial_size(), used, committed, maxSize);
}
#endif // INCLUDE_ALL_GCS

GenerationPool::GenerationPool(Generation* gen,
                               const char* name,
                               PoolType type,
                               bool support_usage_threshold) :
  CollectedMemoryPool(name, type, gen->capacity(), gen->max_capacity(),
                      support_usage_threshold), _gen(gen) {
}

MemoryUsage GenerationPool::get_memory_usage() {
  size_t used      = used_in_bytes();
  size_t committed = _gen->capacity();
  size_t maxSize   = (available_for_allocation() ? max_size() : 0);

  return MemoryUsage(initial_size(), used, committed, maxSize);
}

CodeHeapPool::CodeHeapPool(CodeHeap* codeHeap, const char* name, bool support_usage_threshold) :
  MemoryPool(name, NonHeap, codeHeap->capacity(), codeHeap->max_capacity(),
             support_usage_threshold, false), _codeHeap(codeHeap) {
}

MemoryUsage CodeHeapPool::get_memory_usage() {
  size_t used      = used_in_bytes();
  size_t committed = _codeHeap->capacity();
  size_t maxSize   = (available_for_allocation() ? max_size() : 0);

  return MemoryUsage(initial_size(), used, committed, maxSize);
}

MetaspacePool::MetaspacePool() :
  MemoryPool("Metaspace", NonHeap, 0, calculate_max_size(), true, false) { }

MemoryUsage MetaspacePool::get_memory_usage() {
  size_t committed = MetaspaceAux::committed_bytes();
  return MemoryUsage(initial_size(), used_in_bytes(), committed, max_size());
}

size_t MetaspacePool::used_in_bytes() {
  return MetaspaceAux::allocated_used_bytes();
}

size_t MetaspacePool::calculate_max_size() const {
  return FLAG_IS_CMDLINE(MaxMetaspaceSize) ? MaxMetaspaceSize :
                                             MemoryUsage::undefined_size();
}

CompressedKlassSpacePool::CompressedKlassSpacePool() :
  MemoryPool("Compressed Class Space", NonHeap, 0, CompressedClassSpaceSize, true, false) { }

size_t CompressedKlassSpacePool::used_in_bytes() {
  return MetaspaceAux::allocated_used_bytes(Metaspace::ClassType);
}

MemoryUsage CompressedKlassSpacePool::get_memory_usage() {
  size_t committed = MetaspaceAux::committed_bytes(Metaspace::ClassType);
  return MemoryUsage(initial_size(), used_in_bytes(), committed, max_size());
}

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