1 /*
   2  * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_JFR_UTILITIES_JFRALLOCATION_HPP
  26 #define SHARE_VM_JFR_UTILITIES_JFRALLOCATION_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "services/memTracker.hpp"
  30 #include "utilities/exceptions.hpp"
  31 
  32 /*
  33  * A subclass to the CHeapObj<mtTracing> allocator, useful for critical
  34  * Jfr subsystems. Critical in this context means subsystems for which
  35  * allocations are crucial to the bootstrap and initialization of Jfr.
  36  * The default behaviour by a CHeapObj is to call vm_exit_out_of_memory()
  37  * on allocation failure and this is problematic in combination with the
  38  * Jfr on-demand, dynamic start at runtime, capability.
  39  * We would not like a user dynamically starting Jfr to
  40  * tear down the VM she is about to inspect as a side effect.
  41  *
  42  * This allocator uses the RETURN_NULL capabilities
  43  * instead of calling vm_exit_out_of_memory() until Jfr is properly started.
  44  * This allows for controlled behaviour on allocation failures during startup,
  45  * which means we can take actions on failure, such as transactional rollback
  46  * (deallocations and restorations).
  47  * In addition, this allocator allows for easy hooking of memory
  48  * allocations / deallocations for debugging purposes.
  49  */
  50 
  51 class JfrCHeapObj : public CHeapObj<mtTracing> {
  52  private:
  53   static void on_memory_allocation(const void* allocation, size_t size);
  54   static char* allocate_array_noinline(size_t elements, size_t element_size);
  55 
  56  public:
  57   NOINLINE void* operator new(size_t size) throw();
  58   NOINLINE void* operator new (size_t size, const std::nothrow_t&  nothrow_constant) throw();
  59   NOINLINE void* operator new [](size_t size) throw();
  60   NOINLINE void* operator new [](size_t size, const std::nothrow_t&  nothrow_constant) throw();
  61   void  operator delete(void* p, size_t size);
  62   void  operator delete [] (void* p, size_t size);
  63   static char* realloc_array(char* old, size_t size);
  64   static void free(void* p, size_t size = 0);
  65 
  66   template <class T>
  67   static T* new_array(size_t size) {
  68     T* const memory = (T*)allocate_array_noinline(size, sizeof(T));
  69     on_memory_allocation(memory, sizeof(T) * size);
  70     return memory;
  71   }
  72 };
  73 
  74 #endif // SHARE_VM_JFR_UTILITIES_JFRALLOCATION_HPP