mirror of
https://github.com/golang/go
synced 2024-10-03 06:31:22 -06:00
170 lines
2.9 KiB
C
170 lines
2.9 KiB
C
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// See malloc.h for overview.
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//
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// TODO(rsc): double-check stats.
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// TODO(rsc): solve "stack overflow during malloc" problem.
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#include "runtime.h"
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#include "malloc.h"
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MHeap mheap;
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MStats mstats;
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// Allocate an object of at least size bytes.
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// Small objects are allocated from the per-thread cache's free lists.
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// Large objects (> 32 kB) are allocated straight from the heap.
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void*
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malloc(uintptr size)
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{
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int32 sizeclass;
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MCache *c;
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uintptr npages;
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MSpan *s;
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void *v;
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if(size == 0)
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size = 1;
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if(size <= MaxSmallSize) {
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// Allocate from mcache free lists.
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sizeclass = SizeToClass(size);
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size = class_to_size[sizeclass];
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c = m->mcache;
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v = MCache_Alloc(c, sizeclass, size);
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if(v == nil)
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return nil;
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mstats.alloc += size;
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return v;
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}
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// TODO(rsc): Report tracebacks for very large allocations.
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// Allocate directly from heap.
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npages = size >> PageShift;
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if((size & PageMask) != 0)
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npages++;
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s = MHeap_Alloc(&mheap, npages, 0);
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if(s == nil)
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return nil;
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mstats.alloc += npages<<PageShift;
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return (void*)(s->start << PageShift);
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}
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// Free the object whose base pointer is v.
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void
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free(void *v)
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{
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int32 sizeclass, size;
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uintptr page, tmp;
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MSpan *s;
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MCache *c;
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// Find size class for v.
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page = (uintptr)v >> PageShift;
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sizeclass = MHeapMapCache_GET(&mheap.mapcache, page, tmp);
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if(sizeclass == 0) {
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// Missed in cache.
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s = MHeap_Lookup(&mheap, page);
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if(s == nil)
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throw("free - invalid pointer");
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sizeclass = s->sizeclass;
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if(sizeclass == 0) {
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// Large object.
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mstats.alloc -= s->npages<<PageShift;
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sys·memclr(v, s->npages<<PageShift);
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MHeap_Free(&mheap, s);
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return;
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}
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MHeapMapCache_SET(&mheap.mapcache, page, sizeclass);
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}
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// Small object.
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c = m->mcache;
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size = class_to_size[sizeclass];
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sys·memclr(v, size);
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mstats.alloc -= size;
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MCache_Free(c, v, sizeclass, size);
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}
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MCache*
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allocmcache(void)
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{
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return FixAlloc_Alloc(&mheap.cachealloc);
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}
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void
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mallocinit(void)
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{
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InitSizes();
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MHeap_Init(&mheap, SysAlloc);
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m->mcache = allocmcache();
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// See if it works.
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free(malloc(1));
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}
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// TODO(rsc): Move elsewhere.
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enum
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{
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NHUNK = 20<<20,
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PROT_NONE = 0x00,
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PROT_READ = 0x01,
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PROT_WRITE = 0x02,
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PROT_EXEC = 0x04,
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MAP_FILE = 0x0000,
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MAP_SHARED = 0x0001,
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MAP_PRIVATE = 0x0002,
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MAP_FIXED = 0x0010,
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MAP_ANON = 0x1000, // not on Linux - TODO(rsc)
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};
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void*
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SysAlloc(uintptr n)
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{
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mstats.sys += n;
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return sys·mmap(nil, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 0, 0);
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}
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void
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SysUnused(void *v, uintptr n)
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{
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// TODO(rsc): call madvise MADV_DONTNEED
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}
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void
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SysFree(void *v, uintptr n)
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{
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USED(v);
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USED(n);
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// TODO(rsc): call munmap
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}
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// Go function stubs.
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void
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malloc·Alloc(uintptr n, byte *p)
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{
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p = malloc(n);
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FLUSH(&p);
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}
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void
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malloc·Free(byte *p)
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{
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free(p);
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}
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void
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malloc·GetStats(MStats *s)
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{
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s = &mstats;
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FLUSH(&s);
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}
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