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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// See malloc.h for overview.
//
// TODO(rsc): double-check stats.
// TODO(rsc): solve "stack overflow during malloc" problem.
#include "runtime.h"
#include "malloc.h"
MHeap mheap;
MStats mstats;
// Allocate an object of at least size bytes.
// Small objects are allocated from the per-thread cache's free lists.
// Large objects (> 32 kB) are allocated straight from the heap.
void*
malloc(uintptr size)
{
int32 sizeclass;
MCache *c;
uintptr npages;
MSpan *s;
void *v;
if(size == 0)
size = 1;
if(size <= MaxSmallSize) {
// Allocate from mcache free lists.
sizeclass = SizeToClass(size);
size = class_to_size[sizeclass];
c = m->mcache;
v = MCache_Alloc(c, sizeclass, size);
if(v == nil)
return nil;
mstats.alloc += size;
return v;
}
// TODO(rsc): Report tracebacks for very large allocations.
// Allocate directly from heap.
npages = size >> PageShift;
if((size & PageMask) != 0)
npages++;
s = MHeap_Alloc(&mheap, npages, 0);
if(s == nil)
return nil;
mstats.alloc += npages<<PageShift;
return (void*)(s->start << PageShift);
}
// Free the object whose base pointer is v.
void
free(void *v)
{
int32 sizeclass, size;
uintptr page, tmp;
MSpan *s;
MCache *c;
// Find size class for v.
page = (uintptr)v >> PageShift;
sizeclass = MHeapMapCache_GET(&mheap.mapcache, page, tmp);
if(sizeclass == 0) {
// Missed in cache.
s = MHeap_Lookup(&mheap, page);
if(s == nil)
throw("free - invalid pointer");
sizeclass = s->sizeclass;
if(sizeclass == 0) {
// Large object.
mstats.alloc -= s->npages<<PageShift;
sys·memclr(v, s->npages<<PageShift);
MHeap_Free(&mheap, s);
return;
}
MHeapMapCache_SET(&mheap.mapcache, page, sizeclass);
}
// Small object.
c = m->mcache;
size = class_to_size[sizeclass];
sys·memclr(v, size);
mstats.alloc -= size;
MCache_Free(c, v, sizeclass, size);
}
MCache*
allocmcache(void)
{
return FixAlloc_Alloc(&mheap.cachealloc);
}
void
mallocinit(void)
{
InitSizes();
MHeap_Init(&mheap, SysAlloc);
m->mcache = allocmcache();
// See if it works.
free(malloc(1));
}
// TODO(rsc): Move elsewhere.
enum
{
NHUNK = 20<<20,
PROT_NONE = 0x00,
PROT_READ = 0x01,
PROT_WRITE = 0x02,
PROT_EXEC = 0x04,
MAP_FILE = 0x0000,
MAP_SHARED = 0x0001,
MAP_PRIVATE = 0x0002,
MAP_FIXED = 0x0010,
MAP_ANON = 0x1000, // not on Linux - TODO(rsc)
};
void*
SysAlloc(uintptr n)
{
mstats.sys += n;
return sys·mmap(nil, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 0, 0);
}
void
SysUnused(void *v, uintptr n)
{
// TODO(rsc): call madvise MADV_DONTNEED
}
void
SysFree(void *v, uintptr n)
{
USED(v);
USED(n);
// TODO(rsc): call munmap
}
// Go function stubs.
void
malloc·Alloc(uintptr n, byte *p)
{
p = malloc(n);
FLUSH(&p);
}
void
malloc·Free(byte *p)
{
free(p);
}
void
malloc·GetStats(MStats *s)
{
s = &mstats;
FLUSH(&s);
}
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