145 lines
3.4 KiB
C++
145 lines
3.4 KiB
C++
/* Copyright (C) 2009 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. 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, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. 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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*
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* You should have received a copy of the GNU General Public License
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* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* bucket allocator
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*/
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#include "precompiled.h"
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#include "bucket.h"
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#include "lib/bits.h"
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#include "mem_util.h"
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// power-of-2 isn't required; value is arbitrary.
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const size_t bucketSize = 4000;
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LibError bucket_create(Bucket* b, size_t el_size)
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{
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b->freelist = 0;
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b->el_size = mem_RoundUpToAlignment(el_size);
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// note: allocating here avoids the is-this-the-first-time check
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// in bucket_alloc, which speeds things up.
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b->bucket = (u8*)malloc(bucketSize);
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if(!b->bucket)
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{
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// cause next bucket_alloc to retry the allocation
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b->pos = bucketSize;
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b->num_buckets = 0;
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WARN_RETURN(ERR::NO_MEM);
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}
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*(u8**)b->bucket = 0; // terminate list
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b->pos = mem_RoundUpToAlignment(sizeof(u8*));
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b->num_buckets = 1;
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return INFO::OK;
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}
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void bucket_destroy(Bucket* b)
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{
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while(b->bucket)
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{
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u8* prev_bucket = *(u8**)b->bucket;
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free(b->bucket);
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b->bucket = prev_bucket;
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b->num_buckets--;
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}
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debug_assert(b->num_buckets == 0);
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// poison pill: cause subsequent alloc and free to fail
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b->freelist = 0;
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b->el_size = bucketSize;
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}
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void* bucket_alloc(Bucket* b, size_t size)
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{
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size_t el_size = b->el_size? b->el_size : mem_RoundUpToAlignment(size);
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// must fit in a bucket
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debug_assert(el_size <= bucketSize-sizeof(u8*));
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// try to satisfy alloc from freelist
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void* el = mem_freelist_Detach(b->freelist);
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if(el)
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return el;
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// if there's not enough space left, close current bucket and
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// allocate another.
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if(b->pos+el_size > bucketSize)
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{
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u8* bucket = (u8*)malloc(bucketSize);
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if(!bucket)
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return 0;
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*(u8**)bucket = b->bucket;
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b->bucket = bucket;
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// skip bucket list field and align (note: malloc already
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// aligns to at least 8 bytes, so don't take b->bucket into account)
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b->pos = mem_RoundUpToAlignment(sizeof(u8*));;
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b->num_buckets++;
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}
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void* ret = b->bucket+b->pos;
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b->pos += el_size;
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return ret;
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}
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void* bucket_fast_alloc(Bucket* b)
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{
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// try to satisfy alloc from freelist
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void* el = mem_freelist_Detach(b->freelist);
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if(el)
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return el;
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// if there's not enough space left, close current bucket and
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// allocate another.
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if(b->pos+b->el_size > bucketSize)
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{
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u8* bucket = (u8*)malloc(bucketSize);
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*(u8**)bucket = b->bucket;
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b->bucket = bucket;
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// skip bucket list field (alignment is only pointer-size)
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b->pos = sizeof(u8*);
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b->num_buckets++;
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}
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void* ret = b->bucket+b->pos;
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b->pos += b->el_size;
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return ret;
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}
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void bucket_free(Bucket* b, void* el)
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{
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if(b->el_size == 0)
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{
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DEBUG_WARN_ERR(ERR::LOGIC); // cannot free variable-size items
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return;
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}
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mem_freelist_AddToFront(b->freelist, el);
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// note: checking if <el> was actually allocated from <b> is difficult:
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// it may not be in the currently open bucket, so we'd have to
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// iterate over the list - too much work.
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}
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