//////////////////////////////////////////////////////////////////////////////
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//
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// (C) Copyright Ion Gaztanaga 2015-2015. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// See http://www.boost.org/libs/container for documentation.
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//
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//////////////////////////////////////////////////////////////////////////////
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#ifndef BOOST_CONTAINER_PMR_UNSYNCHRONIZED_POOL_RESOURCE_HPP
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#define BOOST_CONTAINER_PMR_UNSYNCHRONIZED_POOL_RESOURCE_HPP
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#if defined (_MSC_VER)
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# pragma once
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#endif
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#include <boost/container/detail/config_begin.hpp>
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#include <boost/container/detail/workaround.hpp>
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#include <boost/container/detail/auto_link.hpp>
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#include <boost/container/pmr/memory_resource.hpp>
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#include <boost/container/detail/pool_resource.hpp>
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#include <cstddef>
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namespace boost {
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namespace container {
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namespace pmr {
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//! A unsynchronized_pool_resource is a general-purpose memory resources having
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//! the following qualities:
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//!
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//! - Each resource owns the allocated memory, and frees it on destruction,
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//! even if deallocate has not been called for some of the allocated blocks.
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//!
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//! - A pool resource consists of a collection of pools, serving
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//! requests for different block sizes. Each individual pool manages a
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//! collection of chunks that are in turn divided into blocks of uniform size,
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//! returned via calls to do_allocate. Each call to do_allocate(size, alignment)
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//! is dispatched to the pool serving the smallest blocks accommodating at
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//! least size bytes.
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//!
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//! - When a particular pool is exhausted, allocating a block from that pool
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//! results in the allocation of an additional chunk of memory from the upstream
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//! allocator (supplied at construction), thus replenishing the pool. With
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//! each successive replenishment, the chunk size obtained increases
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//! geometrically. [ Note: By allocating memory in chunks, the pooling strategy
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//! increases the chance that consecutive allocations will be close together
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//! in memory. - end note ]
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//!
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//! - Allocation requests that exceed the largest block size of any pool are
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//! fulfilled directly from the upstream allocator.
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//!
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//! - A pool_options struct may be passed to the pool resource constructors to
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//! tune the largest block size and the maximum chunk size.
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//!
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//! An unsynchronized_pool_resource class may not be accessed from multiple threads
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//! simultaneously and thus avoids the cost of synchronization entirely in
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//! single-threaded applications.
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class BOOST_CONTAINER_DECL unsynchronized_pool_resource
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: public memory_resource
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{
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pool_resource m_resource;
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public:
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//! <b>Requires</b>: `upstream` is the address of a valid memory resource.
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//!
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//! <b>Effects</b>: Constructs a pool resource object that will obtain memory
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//! from upstream whenever the pool resource is unable to satisfy a memory
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//! request from its own internal data structures. The resulting object will hold
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//! a copy of upstream, but will not own the resource to which upstream points.
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//! [ Note: The intention is that calls to upstream->allocate() will be
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//! substantially fewer than calls to this->allocate() in most cases. - end note
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//! The behavior of the pooling mechanism is tuned according to the value of
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//! the opts argument.
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//!
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//! <b>Throws</b>: Nothing unless upstream->allocate() throws. It is unspecified if
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//! or under what conditions this constructor calls upstream->allocate().
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unsynchronized_pool_resource(const pool_options& opts, memory_resource* upstream) BOOST_NOEXCEPT;
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//! <b>Effects</b>: Same as
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//! `unsynchronized_pool_resource(pool_options(), get_default_resource())`.
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unsynchronized_pool_resource() BOOST_NOEXCEPT;
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//! <b>Effects</b>: Same as
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//! `unsynchronized_pool_resource(pool_options(), upstream)`.
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explicit unsynchronized_pool_resource(memory_resource* upstream) BOOST_NOEXCEPT;
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//! <b>Effects</b>: Same as
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//! `unsynchronized_pool_resource(opts, get_default_resource())`.
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explicit unsynchronized_pool_resource(const pool_options& opts) BOOST_NOEXCEPT;
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#if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS) || defined(BOOST_CONTAINER_DOXYGEN_INVOKED)
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unsynchronized_pool_resource(const unsynchronized_pool_resource&) = delete;
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unsynchronized_pool_resource operator=(const unsynchronized_pool_resource&) = delete;
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#else
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private:
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unsynchronized_pool_resource (const unsynchronized_pool_resource&);
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unsynchronized_pool_resource operator=(const unsynchronized_pool_resource&);
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public:
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#endif
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//! <b>Effects</b>: Calls
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//! `this->release()`.
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~unsynchronized_pool_resource() BOOST_OVERRIDE;
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//! <b>Effects</b>: Calls Calls `upstream_resource()->deallocate()` as necessary
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//! to release all allocated memory. [ Note: memory is released back to
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//! `upstream_resource()` even if deallocate has not been called for some
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//! of the allocated blocks. - end note ]
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void release();
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//! <b>Returns</b>: The value of the upstream argument provided to the
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//! constructor of this object.
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memory_resource* upstream_resource() const;
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//! <b>Returns</b>: The options that control the pooling behavior of this resource.
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//! The values in the returned struct may differ from those supplied to the pool
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//! resource constructor in that values of zero will be replaced with
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//! implementation-defined defaults and sizes may be rounded to unspecified granularity.
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pool_options options() const;
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protected:
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//! <b>Returns</b>: A pointer to allocated storage with a size of at least `bytes`.
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//! The size and alignment of the allocated memory shall meet the requirements for
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//! a class derived from `memory_resource`.
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//!
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//! <b>Effects</b>: If the pool selected for a block of size bytes is unable to
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//! satisfy the memory request from its own internal data structures, it will call
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//! `upstream_resource()->allocate()` to obtain more memory. If `bytes` is larger
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//! than that which the largest pool can handle, then memory will be allocated
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//! using `upstream_resource()->allocate()`.
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//!
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//! <b>Throws</b>: Nothing unless `upstream_resource()->allocate()` throws.
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void* do_allocate(std::size_t bytes, std::size_t alignment) BOOST_OVERRIDE;
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//! <b>Effects</b>: Return the memory at p to the pool. It is unspecified if or under
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//! what circumstances this operation will result in a call to
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//! `upstream_resource()->deallocate()`.
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//!
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//! <b>Throws</b>: Nothing.
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void do_deallocate(void* p, std::size_t bytes, std::size_t alignment) BOOST_OVERRIDE;
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//! <b>Returns</b>:
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//! `this == dynamic_cast<const unsynchronized_pool_resource*>(&other)`.
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bool do_is_equal(const memory_resource& other) const BOOST_NOEXCEPT BOOST_OVERRIDE;
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//Non-standard observers
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public:
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//! <b>Returns</b>: The number of pools that will be used in the pool resource.
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//!
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//! <b>Note</b>: Non-standard extension.
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std::size_t pool_count() const;
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//! <b>Returns</b>: The index of the pool that will be used to serve the allocation of `bytes`.
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//! Returns `pool_count()` if `bytes` is bigger
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//! than `options().largest_required_pool_block` (no pool will be used to serve this).
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//!
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//! <b>Note</b>: Non-standard extension.
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std::size_t pool_index(std::size_t bytes) const;
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//! <b>Requires</b>: `pool_idx < pool_index()`
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//!
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//! <b>Returns</b>: The number blocks that will be allocated in the next chunk
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//! from the pool specified by `pool_idx`.
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//!
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//! <b>Note</b>: Non-standard extension.
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std::size_t pool_next_blocks_per_chunk(std::size_t pool_idx) const;
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//! <b>Requires</b>: `pool_idx < pool_index()`
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//!
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//! <b>Returns</b>: The number of bytes of the block that the specified `pool_idx` pool manages.
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//!
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//! <b>Note</b>: Non-standard extension.
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std::size_t pool_block(std::size_t pool_idx) const;
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//! <b>Requires</b>: `pool_idx < pool_index()`
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//!
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//! <b>Returns</b>: The number of blocks that the specified `pool_idx` pool has cached
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//! and will be served without calling the upstream_allocator.
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//!
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//! <b>Note</b>: Non-standard extension.
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std::size_t pool_cached_blocks(std::size_t pool_idx) const;
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};
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} //namespace pmr {
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} //namespace container {
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} //namespace boost {
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#include <boost/container/detail/config_end.hpp>
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#endif //BOOST_CONTAINER_PMR_UNSYNCHRONIZED_POOL_RESOURCE_HPP
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