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authorRob Pike <r@golang.org>2009-06-09 09:53:44 -0700
committerRob Pike <r@golang.org>2009-06-09 09:53:44 -0700
commit7249ea4df2b4f12a4e7ed446f270cea87e4ffd34 (patch)
tree7032a11d0cac2ae4d3e90f7a189b575b5a50f848 /src/pkg/runtime/malloc.c
parentacf6ef7a82b3fe61516a1bac4563706552bdf078 (diff)
downloadgolang-7249ea4df2b4f12a4e7ed446f270cea87e4ffd34.tar.gz
mv src/lib to src/pkg
tests: all.bash passes, gobuild still works, godoc still works. R=rsc OCL=30096 CL=30102
Diffstat (limited to 'src/pkg/runtime/malloc.c')
-rw-r--r--src/pkg/runtime/malloc.c308
1 files changed, 308 insertions, 0 deletions
diff --git a/src/pkg/runtime/malloc.c b/src/pkg/runtime/malloc.c
new file mode 100644
index 000000000..81cdfb300
--- /dev/null
+++ b/src/pkg/runtime/malloc.c
@@ -0,0 +1,308 @@
+// 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"
+#include "defs.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;
+ uint32 *ref;
+
+ if(m->mallocing)
+ throw("malloc/free - deadlock");
+ m->mallocing = 1;
+
+ 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)
+ throw("out of memory");
+ mstats.alloc += size;
+ } else {
+ // 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)
+ throw("out of memory");
+ mstats.alloc += npages<<PageShift;
+ v = (void*)(s->start << PageShift);
+ }
+
+ // setup for mark sweep
+ if(!mlookup(v, nil, nil, &ref)) {
+ printf("malloc %D; mlookup failed\n", (uint64)size);
+ throw("malloc mlookup");
+ }
+ *ref = RefNone;
+
+ m->mallocing = 0;
+ return v;
+}
+
+void*
+mallocgc(uintptr size)
+{
+ void *v;
+
+ v = malloc(size);
+ if(mstats.inuse_pages > mstats.next_gc)
+ gc(0);
+ return v;
+}
+
+// Free the object whose base pointer is v.
+void
+free(void *v)
+{
+ int32 sizeclass, size;
+ uintptr page, tmp;
+ MSpan *s;
+ MCache *c;
+ uint32 *ref;
+
+ if(v == nil)
+ return;
+
+ if(m->mallocing)
+ throw("malloc/free - deadlock");
+ m->mallocing = 1;
+
+ if(!mlookup(v, nil, nil, &ref))
+ throw("free mlookup");
+ *ref = RefFree;
+
+ // 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);
+ goto out;
+ }
+ 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);
+
+out:
+ m->mallocing = 0;
+}
+
+int32
+mlookup(void *v, byte **base, uintptr *size, uint32 **ref)
+{
+ uintptr n, nobj, i;
+ byte *p;
+ MSpan *s;
+
+ s = MHeap_LookupMaybe(&mheap, (uintptr)v>>PageShift);
+ if(s == nil) {
+ if(base)
+ *base = nil;
+ if(size)
+ *size = 0;
+ if(ref)
+ *ref = 0;
+ return 0;
+ }
+
+ p = (byte*)((uintptr)s->start<<PageShift);
+ if(s->sizeclass == 0) {
+ // Large object.
+ if(base)
+ *base = p;
+ if(size)
+ *size = s->npages<<PageShift;
+ if(ref)
+ *ref = &s->gcref0;
+ return 1;
+ }
+
+ if((byte*)v >= (byte*)s->gcref) {
+ // pointers into the gc ref counts
+ // do not count as pointers.
+ return 0;
+ }
+
+ n = class_to_size[s->sizeclass];
+ i = ((byte*)v - p)/n;
+ if(base)
+ *base = p + i*n;
+ if(size)
+ *size = n;
+ nobj = (s->npages << PageShift) / (n + RefcountOverhead);
+ if((byte*)s->gcref < p || (byte*)(s->gcref+nobj) > p+(s->npages<<PageShift)) {
+ printf("odd span state=%d span=%p base=%p sizeclass=%d n=%D size=%D npages=%D\n",
+ s->state, s, p, s->sizeclass, (uint64)nobj, (uint64)n, (uint64)s->npages);
+ printf("s->base sizeclass %d v=%p base=%p gcref=%p blocksize=%D nobj=%D size=%D end=%p end=%p\n",
+ s->sizeclass, v, p, s->gcref, (uint64)s->npages<<PageShift,
+ (uint64)nobj, (uint64)n, s->gcref + nobj, p+(s->npages<<PageShift));
+ throw("bad gcref");
+ }
+ if(ref)
+ *ref = &s->gcref[i];
+
+ return 1;
+}
+
+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));
+}
+
+void*
+SysAlloc(uintptr n)
+{
+ mstats.sys += n;
+ return sys_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
+}
+
+void
+SysUnused(void *v, uintptr n)
+{
+ USED(v);
+ USED(n);
+ // TODO(rsc): call madvise MADV_DONTNEED
+}
+
+void
+SysFree(void *v, uintptr n)
+{
+ USED(v);
+ USED(n);
+ // TODO(rsc): call munmap
+}
+
+// Runtime stubs.
+
+extern void *oldmal(uint32);
+
+void*
+mal(uint32 n)
+{
+//return oldmal(n);
+ void *v;
+
+ v = mallocgc(n);
+
+ if(0) {
+ byte *p;
+ uint32 i;
+ p = v;
+ for(i=0; i<n; i++) {
+ if(p[i] != 0) {
+ printf("mal %d => %p: byte %d is non-zero\n", n, v, i);
+ throw("mal");
+ }
+ }
+ }
+
+//printf("mal %d %p\n", n, v); // |checkmal to check for overlapping returns.
+ return v;
+}
+
+// Stack allocator uses malloc/free most of the time,
+// but if we're in the middle of malloc and need stack,
+// we have to do something else to avoid deadlock.
+// In that case, we fall back on a fixed-size free-list
+// allocator, assuming that inside malloc all the stack
+// frames are small, so that all the stack allocations
+// will be a single size, the minimum (right now, 5k).
+struct {
+ Lock;
+ FixAlloc;
+} stacks;
+
+void*
+stackalloc(uint32 n)
+{
+ void *v;
+ uint32 *ref;
+
+//return oldmal(n);
+ if(m->mallocing) {
+ lock(&stacks);
+ if(stacks.size == 0)
+ FixAlloc_Init(&stacks, n, SysAlloc, nil, nil);
+ if(stacks.size != n) {
+ printf("stackalloc: in malloc, size=%D want %d", (uint64)stacks.size, n);
+ throw("stackalloc");
+ }
+ v = FixAlloc_Alloc(&stacks);
+ unlock(&stacks);
+ return v;
+ }
+ v = malloc(n);
+ if(!mlookup(v, nil, nil, &ref))
+ throw("stackalloc mlookup");
+ *ref = RefStack;
+ return v;
+}
+
+void
+stackfree(void *v)
+{
+//return;
+
+ if(m->mallocing) {
+ lock(&stacks);
+ FixAlloc_Free(&stacks, v);
+ unlock(&stacks);
+ return;
+ }
+ free(v);
+}