text: /*
   * Copyright (c) 2003, 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/systemDictionary.hpp"
  #include "classfile/vmSymbols.hpp"
  #include "memory/allocation.inline.hpp"
  #include "oops/oop.inline.hpp"
  #include "runtime/handles.inline.hpp"
  #include "runtime/javaCalls.hpp"
  #include "runtime/orderAccess.hpp"
  #include "services/lowMemoryDetector.hpp"
  #include "services/management.hpp"
  #include "services/memoryManager.hpp"
  #include "services/memoryPool.hpp"
  #include "services/memoryService.hpp"
  #include "services/gcNotifier.hpp"
  #include "utilities/dtrace.hpp"
  
  MemoryManager::MemoryManager(const char* name) : _name(name) {
    _num_pools = 0;
    (void)const_cast<instanceOop&>(_memory_mgr_obj = instanceOop(NULL));
  }
  
  void MemoryManager::add_pool(MemoryPool* pool) {
    assert(_num_pools < MemoryManager::max_num_pools, "_num_pools exceeds the max");
    if (_num_pools < MemoryManager::max_num_pools) {
      _pools[_num_pools] = pool;
      _num_pools++;
    }
    pool->add_manager(this);
  }
  
  MemoryManager* MemoryManager::get_code_cache_memory_manager() {
    return new MemoryManager("CodeCacheManager");
  }
  
  MemoryManager* MemoryManager::get_metaspace_memory_manager() {
    return new MemoryManager("Metaspace Manager");
  }
  
  instanceOop MemoryManager::get_memory_manager_instance(TRAPS) {
    // Must do an acquire so as to force ordering of subsequent
    // loads from anything _memory_mgr_obj points to or implies.
    instanceOop mgr_obj = OrderAccess::load_acquire(&_memory_mgr_obj);
    if (mgr_obj == NULL) {
      // It's ok for more than one thread to execute the code up to the locked region.
      // Extra manager instances will just be gc'ed.
      Klass* k = Management::sun_management_ManagementFactoryHelper_klass(CHECK_0);
  
      Handle mgr_name = java_lang_String::create_from_str(name(), CHECK_0);
  
      JavaValue result(T_OBJECT);
      JavaCallArguments args;
      args.push_oop(mgr_name);    // Argument 1
  
      Symbol* method_name = NULL;
      Symbol* signature = NULL;
      if (is_gc_memory_manager()) {
        Klass* extKlass = Management::com_sun_management_internal_GarbageCollectorExtImpl_klass(CHECK_0);
        // com.sun.management.GarbageCollectorMXBean is in jdk.management module which may not be present.
        if (extKlass != NULL) {
          k = extKlass;
        }
  
        method_name = vmSymbols::createGarbageCollector_name();
  
        signature = vmSymbols::createGarbageCollector_signature();
        args.push_oop(Handle());      // Argument 2 (for future extension)
      } else {
        method_name = vmSymbols::createMemoryManager_name();
        signature = vmSymbols::createMemoryManager_signature();
      }
  
      InstanceKlass* ik = InstanceKlass::cast(k);
  
      JavaCalls::call_static(&result,
                             ik,
                             method_name,
                             signature,
                             &args,
                             CHECK_0);
  
      instanceOop m = (instanceOop) result.get_jobject();
      instanceHandle mgr(THREAD, m);
  
      {
        // Get lock before setting _memory_mgr_obj
        // since another thread may have created the instance
        MutexLocker ml(Management_lock);
  
        // Check if another thread has created the management object.  We reload
        // _memory_mgr_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.
        mgr_obj = OrderAccess::load_acquire(&_memory_mgr_obj);
        if (mgr_obj != NULL) {
           return mgr_obj;
        }
  
        // Get the address of the object we created via call_special.
        mgr_obj = mgr();
  
        // Use store barrier to make sure the memory accesses associated
        // with creating the management object are visible before publishing
        // its address.  The unlock will publish the store to _memory_mgr_obj
        // because it does a release first.
        OrderAccess::release_store(&_memory_mgr_obj, mgr_obj);
      }
    }
  
    return mgr_obj;
  }
  
  void MemoryManager::oops_do(OopClosure* f) {
    f->do_oop((oop*) &_memory_mgr_obj);
  }
  
  GCStatInfo::GCStatInfo(int num_pools) {
    // initialize the arrays for memory usage
    _before_gc_usage_array = (MemoryUsage*) NEW_C_HEAP_ARRAY(MemoryUsage, num_pools, mtInternal);
    _after_gc_usage_array  = (MemoryUsage*) NEW_C_HEAP_ARRAY(MemoryUsage, num_pools, mtInternal);
    _usage_array_size = num_pools;
    clear();
  }
  
  GCStatInfo::~GCStatInfo() {
    FREE_C_HEAP_ARRAY(MemoryUsage*, _before_gc_usage_array);
    FREE_C_HEAP_ARRAY(MemoryUsage*, _after_gc_usage_array);
  }
  
  void GCStatInfo::set_gc_usage(int pool_index, MemoryUsage usage, bool before_gc) {
    MemoryUsage* gc_usage_array;
    if (before_gc) {
      gc_usage_array = _before_gc_usage_array;
    } else {
      gc_usage_array = _after_gc_usage_array;
    }
    gc_usage_array[pool_index] = usage;
  }
  
  void GCStatInfo::clear() {
    _index = 0;
    _start_time = 0L;
    _end_time = 0L;
    size_t len = _usage_array_size * sizeof(MemoryUsage);
    memset(_before_gc_usage_array, 0, len);
    memset(_after_gc_usage_array, 0, len);
  }
  
  
  GCMemoryManager::GCMemoryManager(const char* name, const char* gc_end_message) :
    MemoryManager(name), _gc_end_message(gc_end_message) {
    _num_collections = 0;
    _last_gc_stat = NULL;
    _last_gc_lock = new Mutex(Mutex::leaf, "_last_gc_lock", true,
                              Monitor::_safepoint_check_never);
    _current_gc_stat = NULL;
    _num_gc_threads = 1;
    _notification_enabled = false;
  }
  
  GCMemoryManager::~GCMemoryManager() {
    delete _last_gc_stat;
    delete _last_gc_lock;
    delete _current_gc_stat;
  }
  
  void GCMemoryManager::initialize_gc_stat_info() {
    assert(MemoryService::num_memory_pools() > 0, "should have one or more memory pools");
    _last_gc_stat = new(ResourceObj::C_HEAP, mtGC) GCStatInfo(MemoryService::num_memory_pools());
    _current_gc_stat = new(ResourceObj::C_HEAP, mtGC) GCStatInfo(MemoryService::num_memory_pools());
    // tracking concurrent collections we need two objects: one to update, and one to
    // hold the publicly available "last (completed) gc" information.
  }
  
  void GCMemoryManager::gc_begin(bool recordGCBeginTime, bool recordPreGCUsage,
                                 bool recordAccumulatedGCTime) {
    assert(_last_gc_stat != NULL && _current_gc_stat != NULL, "Just checking");
    if (recordAccumulatedGCTime) {
      _accumulated_timer.start();
    }
    // _num_collections now increases in gc_end, to count completed collections
    if (recordGCBeginTime) {
      _current_gc_stat->set_index(_num_collections+1);
      _current_gc_stat->set_start_time(Management::timestamp());
    }
  
    if (recordPreGCUsage) {
      // Keep memory usage of all memory pools
      for (int i = 0; i < MemoryService::num_memory_pools(); i++) {
        MemoryPool* pool = MemoryService::get_memory_pool(i);
        MemoryUsage usage = pool->get_memory_usage();
        _current_gc_stat->set_before_gc_usage(i, usage);
        HOTSPOT_MEM_POOL_GC_BEGIN(
          (char *) name(), strlen(name()),
          (char *) pool->name(), strlen(pool->name()),
          usage.init_size(), usage.used(),
          usage.committed(), usage.max_size());
      }
    }
  }
  
  // A collector MUST, even if it does not complete for some reason,
  // make a TraceMemoryManagerStats object where countCollection is true,
  // to ensure the current gc stat is placed in _last_gc_stat.
  void GCMemoryManager::gc_end(bool recordPostGCUsage,
                               bool recordAccumulatedGCTime,
                               bool recordGCEndTime, bool countCollection,
                               GCCause::Cause cause) {
    if (recordAccumulatedGCTime) {
      _accumulated_timer.stop();
    }
    if (recordGCEndTime) {
      _current_gc_stat->set_end_time(Management::timestamp());
    }
  
    if (recordPostGCUsage) {
      int i;
      // keep the last gc statistics for all memory pools
      for (i = 0; i < MemoryService::num_memory_pools(); i++) {
        MemoryPool* pool = MemoryService::get_memory_pool(i);
        MemoryUsage usage = pool->get_memory_usage();
  
        HOTSPOT_MEM_POOL_GC_END(
          (char *) name(), strlen(name()),
          (char *) pool->name(), strlen(pool->name()),
          usage.init_size(), usage.used(),
          usage.committed(), usage.max_size());
  
        _current_gc_stat->set_after_gc_usage(i, usage);
      }
  
      // Set last collection usage of the memory pools managed by this collector
      for (i = 0; i < num_memory_pools(); i++) {
        MemoryPool* pool = get_memory_pool(i);
        MemoryUsage usage = pool->get_memory_usage();
  
        // Compare with GC usage threshold
        pool->set_last_collection_usage(usage);
        LowMemoryDetector::detect_after_gc_memory(pool);
      }
    }
  
    if (countCollection) {
      _num_collections++;
      // alternately update two objects making one public when complete
      {
        MutexLockerEx ml(_last_gc_lock, Mutex::_no_safepoint_check_flag);
        GCStatInfo *tmp = _last_gc_stat;
        _last_gc_stat = _current_gc_stat;
        _current_gc_stat = tmp;
        // reset the current stat for diagnosability purposes
        _current_gc_stat->clear();
      }
  
      if (is_notification_enabled()) {
        GCNotifier::pushNotification(this, _gc_end_message, GCCause::to_string(cause));
      }
    }
  }
  
  size_t GCMemoryManager::get_last_gc_stat(GCStatInfo* dest) {
    MutexLockerEx ml(_last_gc_lock, Mutex::_no_safepoint_check_flag);
    if (_last_gc_stat->gc_index() != 0) {
      dest->set_index(_last_gc_stat->gc_index());
      dest->set_start_time(_last_gc_stat->start_time());
      dest->set_end_time(_last_gc_stat->end_time());
      assert(dest->usage_array_size() == _last_gc_stat->usage_array_size(),
             "Must have same array size");
      size_t len = dest->usage_array_size() * sizeof(MemoryUsage);
      memcpy(dest->before_gc_usage_array(), _last_gc_stat->before_gc_usage_array(), len);
      memcpy(dest->after_gc_usage_array(), _last_gc_stat->after_gc_usage_array(), len);
    }
    return _last_gc_stat->gc_index();
  }
  