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C++ Boost

Singleton Pool


singleton_pool.hpp provides a template class singleton_pool, which provides access to a pool as a singleton object. For information on other pool-based interfaces, see the other pool interfaces.


template <typename Tag, unsigned RequestedSize,
    typename UserAllocator = default_user_allocator_new_delete>
struct singleton_pool
    typedef Tag tag;
    typedef UserAllocator user_allocator;
    typedef typename pool<UserAllocator>::size_type size_type;
    typedef typename pool<UserAllocator>::difference_type difference_type;

    static const unsigned requested_size = RequestedSize;

    static pool<size_type> p; // exposition only!


    static bool is_from(void * ptr);

    static void * malloc();
    static void * ordered_malloc();
    static void * ordered_malloc(size_type n);

    static void free(void * ptr);
    static void ordered_free(void * ptr);
    static void free(void * ptr, std::size_t n);
    static void ordered_free(void * ptr, size_type n);

    static bool release_memory();
    static bool purge_memory();


The underlying pool p referenced by the static functions in singleton_pool is actually declared in a way that it is:

Note that a different underlying pool p exists for each different set of template parameters, including implementation-specific ones.

Template Parameters


The Tag template parameter allows different unbounded sets of singleton pools to exist. For example, the pool allocators use two tag classes to ensure that the two different allocator types never share the same underlying singleton pool.

Tag is never actually used by singleton_pool.


The requested size of memory chunks to allocate. This is passed as a constructor parameter to the underlying pool. Must be greater than 0.


Defines the method that the underlying pool will use to allocate memory from the system. See User Allocators for details.


Symbol Table
Symbol Meaning
SingletonPool singleton_pool<Tag, RequestedSize, UserAllocator>
chunk value of type void *
n value of type size_type

Typedefs/Static Const Values
Expression Type/Value
SingletonPool::tag Tag
SingletonPool::user_allocator UserAllocator
SingletonPool::size_type pool<UserAllocator>::size_type
SingletonPool::difference_type pool<UserAllocator>::difference_type
SingletonPool::requested_size RequestedSize

Expression Return Type Semantic Equivalent
SingletonPool::is_from(chunk) bool SingletonPool::p.is_from(chunk); synchronized
SingletonPool::malloc() void * SingletonPool::p.malloc(); synchronized
SingletonPool::ordered_malloc(n) void * SingletonPool::p.ordered_malloc(n); synchronized
SingletonPool::free(chunk) void; synchronized
SingletonPool::ordered_free(chunk) void SingletonPool::p.ordered_free(chunk); synchronized
SingletonPool::free(chunk, n) void, n); synchronized
SingletonPool::ordered_free(chunk, n) void SingletonPool::p.ordered_free(chunk, n); synchronized
SingletonPool::release_memory() bool SingletonPool::p.release_memory(); synchronized
SingletonPool::purge_memory() bool SingletonPool::p.purge_memory(); synchronized

For more information on the semantics of these functions, see the pool interface.


Implementation Details

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Revised 05 December, 2006

Copyright © 2000, 2001 Stephen Cleary (scleary AT jerviswebb DOT com)

Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at