141 lines
3.8 KiB
C++
141 lines
3.8 KiB
C++
/* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifndef MALLOC_ALLOCATOR_INCLUDED
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#define MALLOC_ALLOCATOR_INCLUDED
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#include "my_global.h"
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#include "my_sys.h"
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#include <new>
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#include <limits>
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/**
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Malloc_allocator is a C++ STL memory allocator based on my_malloc/my_free.
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This allows for P_S instrumentation of memory allocation done by
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internally by STL container classes.
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Example usage:
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vector<int, Malloc_allocator<int> >
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v((Malloc_allocator<int>(PSI_NOT_INSTRUMENTED)));
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@note allocate() throws std::bad_alloc() similarly to the default
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STL memory allocator. This is necessary - STL functions which allocates
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memory expects it. Otherwise these functions will try to use the memory,
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leading to seg faults if memory allocation was not successful.
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@note This allocator cannot be used for std::basic_string
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because of this libstd++ bug:
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56437
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"basic_string assumes that allocators are default-constructible"
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*/
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template <class T> class Malloc_allocator
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{
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// This cannot be const if we want to be able to swap.
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PSI_memory_key m_key;
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public:
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typedef T value_type;
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typedef size_t size_type;
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typedef ptrdiff_t difference_type;
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typedef T* pointer;
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typedef const T* const_pointer;
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typedef T& reference;
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typedef const T& const_reference;
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pointer address(reference r) const { return &r; }
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const_pointer address(const_reference r) const { return &r; }
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explicit Malloc_allocator(PSI_memory_key key) : m_key(key)
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{}
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template <class U> Malloc_allocator(const Malloc_allocator<U> &other)
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: m_key(other.psi_key())
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{}
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template <class U> Malloc_allocator & operator=
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(const Malloc_allocator<U> &other)
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{
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DBUG_ASSERT(m_key == other.psi_key()); // Don't swap key.
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}
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~Malloc_allocator()
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{}
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pointer allocate(size_type n, const_pointer hint= 0)
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{
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if (n == 0)
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return NULL;
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if (n > max_size())
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throw std::bad_alloc();
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pointer p= static_cast<pointer>(my_malloc(m_key, n * sizeof(T),
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MYF(MY_WME | ME_FATALERROR)));
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if (p == NULL)
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throw std::bad_alloc();
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return p;
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}
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void deallocate(pointer p, size_type n) { my_free(p); }
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void construct(pointer p, const T& val)
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{
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DBUG_ASSERT(p != NULL);
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try {
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new(p) T(val);
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} catch (...) {
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DBUG_ASSERT(false); // Constructor should not throw an exception.
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}
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}
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void destroy(pointer p)
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{
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DBUG_ASSERT(p != NULL);
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try {
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p->~T();
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} catch (...) {
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DBUG_ASSERT(false); // Destructor should not throw an exception
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}
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}
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size_type max_size() const
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{
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return std::numeric_limits<size_t>::max() / sizeof(T);
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}
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template <class U> struct rebind { typedef Malloc_allocator<U> other; };
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PSI_memory_key psi_key() const { return m_key; }
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};
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template <class T>
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bool operator== (const Malloc_allocator<T>& a1, const Malloc_allocator<T>& a2)
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{
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return a1.psi_key() == a2.psi_key();
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}
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template <class T>
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bool operator!= (const Malloc_allocator<T>& a1, const Malloc_allocator<T>& a2)
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{
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return a1.psi_key() != a2.psi_key();
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}
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#endif // MALLOC_ALLOCATOR_INCLUDED
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