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forked from 0ad/0ad
0ad/source/lib/allocators/headerless.h
janwas 2e5d9452aa part2: misc source/lib fixes/improvements
move all except user-specified config choices out of config.h and into
appropriate headers
CPU_IA32 -> ARCH_IA32
wsdl: disable use of ddraw (will soon be replaced by WMI)

use shared_ptr without namespace qualifier (it's in tr1)
debug_warn -> debug_assert(0)
LIB_API to allow building as DLL
smart pointers: reduce use of .get()
cache_adt: use map instead of hash_map (avoids needing a hashCompare
class). also remove spurious warning
code_annotation.h: better cassert implementation
move FPS measuring portion of timer.cpp into frequency_filter
move include of memory headers into mmgr.h (to avoid errors, we must
ensure they are included if mmgr is used)
posix_filesystem.h: move definition of mkdir to wfilesystem
stl: disable iterator checks in release mode
wmi: fix COM init bug, use smart pointers
wutil: add code to get DLL module handle (if compiled as such), add
WinScopedLock
timer: fix handling of raw ticks

This was SVN commit r5517.
2007-12-20 20:09:19 +00:00

73 lines
2.2 KiB
C++

/**
* =========================================================================
* File : headerless.h
* Project : 0 A.D.
* Description : (header-less) pool-based heap allocator
* =========================================================================
*/
// license: GPL; see lib/license.txt
#ifndef INCLUDED_HEADERLESS
#define INCLUDED_HEADERLESS
/**
* (header-less) pool-based heap allocator
* provides Allocate and Deallocate without requiring in-band headers;
* this is useful when allocating page-aligned I/O buffers
* (headers would waste an entire page per buffer)
*
* policy:
* - allocation: first exhaust the freelist, then allocate more
* - freelist: address-ordered good fit, always split blocks
* - coalescing: immediate
* mechanism:
* - coalescing: boundary tags in freed memory with distinct bit patterns
* - freelist: segregated range lists of power-of-two size classes
*
* note: this module basically implements a (rather complex) freelist and
* could be made independent of the Pool allocation scheme. however, reading
* neighboring boundary tags may cause segmentation violations; knowing the
* bounds of valid committed memory (i.e. Pool extents) avoids this.
**/
class HeaderlessAllocator
{
public:
/**
* @param poolSize maximum amount of memory that can be allocated.
* this much virtual address space is reserved up-front (see Pool).
**/
HeaderlessAllocator(size_t poolSize);
/**
* restore the original state (as if newly constructed).
* this includes reclaiming all extant allocations.
**/
void Reset();
/**
* @param size [bytes] must be a multiple of the minimum alignment and
* enough to store a block header. (this allocator is designed for
* page-aligned requests but can handle smaller amounts.)
* @return allocated memory or 0 if the pool is too fragmented or full.
**/
void* Allocate(size_t size) throw();
/**
* deallocate memory.
* @param size must be exactly as specified to Allocate.
**/
void Deallocate(void* p, size_t size);
/**
* perform sanity checks; ensure allocator state is consistent.
**/
void Validate() const;
private:
class Impl;
shared_ptr<Impl> impl;
};
#endif // #ifndef INCLUDED_HEADERLESS