qzdoom-gpl/src/memarena.h
Christoph Oelckers a60bdc2bfb use a memory arena for allocating code generation nodes.
- Since the number of small allocations here is extremely high this will help a lot to prevent fragmentation and since most nodes are collected up front and this is done when no large resources are being loaded it won't cause heap spikes.

let Emit methods delete FxExpression arrays when they are done.
- For some reason the deletion process does not work 100%, there are always some nodes left behind and so far I haven't found them. This ensures that these arrays do not live any longer than needed.
2016-11-10 15:13:31 +01:00

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/*
** memarena.h
**
**---------------------------------------------------------------------------
** Copyright 2010 Randy Heit
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in the
** documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
** derived from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
*/
#ifndef __MEMARENA_H
#define __MEMARENA_H
#include "zstring.h"
// A general purpose arena.
class FMemArena
{
public:
FMemArena(int blocksize = 10*1024);
~FMemArena();
void *Alloc(size_t size);
void FreeAll();
void FreeAllBlocks();
protected:
struct Block;
Block *AddBlock(size_t size);
void FreeBlockChain(Block *&top);
Block *TopBlock;
Block *FreeBlocks;
int BlockSize;
};
// An arena specializing in storage of FStrings. It knows how to free them,
// but this means it also should never be used for allocating anything else.
// Identical strings all return the same pointer.
class FSharedStringArena : public FMemArena
{
public:
FSharedStringArena();
~FSharedStringArena();
void FreeAll();
class FString *Alloc(const FString &source);
class FString *Alloc(const char *source);
class FString *Alloc(const char *source, size_t strlen);
protected:
struct Node
{
Node *Next;
FString String;
unsigned int Hash;
};
Node *Buckets[256];
Node *FindString(const char *str, size_t strlen, unsigned int &hash);
private:
void *Alloc(size_t size) { return NULL; } // No access to FMemArena::Alloc for outsiders.
};
#endif