1 files changed, 350 insertions, 0 deletions
diff --git a/libgo/runtime/mheap.c b/libgo/runtime/mheap.c
new file mode 100644
index 000000000..52c6d8c1b
--- /dev/null
+++ b/libgo/runtime/mheap.c
@@ -0,0 +1,350 @@
+// 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.
+
+// Page heap.
+//
+// See malloc.h for overview.
+//
+// When a MSpan is in the heap free list, state == MSpanFree
+// and heapmap(s->start) == span, heapmap(s->start+s->npages-1) == span.
+//
+// When a MSpan is allocated, state == MSpanInUse
+// and heapmap(i) == span for all s->start <= i < s->start+s->npages.
+
+#include "runtime.h"
+#include "malloc.h"
+
+static MSpan *MHeap_AllocLocked(MHeap*, uintptr, int32);
+static bool MHeap_Grow(MHeap*, uintptr);
+static void MHeap_FreeLocked(MHeap*, MSpan*);
+static MSpan *MHeap_AllocLarge(MHeap*, uintptr);
+static MSpan *BestFit(MSpan*, uintptr, MSpan*);
+
+static void
+RecordSpan(void *vh, byte *p)
+{
+	MHeap *h;
+	MSpan *s;
+
+	h = vh;
+	s = (MSpan*)p;
+	s->allnext = h->allspans;
+	h->allspans = s;
+}
+
+// Initialize the heap; fetch memory using alloc.
+void
+runtime_MHeap_Init(MHeap *h, void *(*alloc)(uintptr))
+{
+	uint32 i;
+
+	runtime_initlock(h);
+	runtime_FixAlloc_Init(&h->spanalloc, sizeof(MSpan), alloc, RecordSpan, h);
+	runtime_FixAlloc_Init(&h->cachealloc, sizeof(MCache), alloc, nil, nil);
+	runtime_MHeapMap_Init(&h->map, alloc);
+	// h->mapcache needs no init
+	for(i=0; i<nelem(h->free); i++)
+		runtime_MSpanList_Init(&h->free[i]);
+	runtime_MSpanList_Init(&h->large);
+	for(i=0; i<nelem(h->central); i++)
+		runtime_MCentral_Init(&h->central[i], i);
+}
+
+// Allocate a new span of npage pages from the heap
+// and record its size class in the HeapMap and HeapMapCache.
+MSpan*
+runtime_MHeap_Alloc(MHeap *h, uintptr npage, int32 sizeclass, int32 acct)
+{
+	MSpan *s;
+
+	runtime_lock(h);
+	mstats.heap_alloc += m->mcache->local_alloc;
+	m->mcache->local_alloc = 0;
+	mstats.heap_objects += m->mcache->local_objects;
+	m->mcache->local_objects = 0;
+	s = MHeap_AllocLocked(h, npage, sizeclass);
+	if(s != nil) {
+		mstats.heap_inuse += npage<<PageShift;
+		if(acct) {
+			mstats.heap_objects++;
+			mstats.heap_alloc += npage<<PageShift;
+		}
+	}
+	runtime_unlock(h);
+	return s;
+}
+
+static MSpan*
+MHeap_AllocLocked(MHeap *h, uintptr npage, int32 sizeclass)
+{
+	uintptr n;
+	MSpan *s, *t;
+
+	// Try in fixed-size lists up to max.
+	for(n=npage; n < nelem(h->free); n++) {
+		if(!runtime_MSpanList_IsEmpty(&h->free[n])) {
+			s = h->free[n].next;
+			goto HaveSpan;
+		}
+	}
+
+	// Best fit in list of large spans.
+	if((s = MHeap_AllocLarge(h, npage)) == nil) {
+		if(!MHeap_Grow(h, npage))
+			return nil;
+		if((s = MHeap_AllocLarge(h, npage)) == nil)
+			return nil;
+	}
+
+HaveSpan:
+	// Mark span in use.
+	if(s->state != MSpanFree)
+		runtime_throw("MHeap_AllocLocked - MSpan not free");
+	if(s->npages < npage)
+		runtime_throw("MHeap_AllocLocked - bad npages");
+	runtime_MSpanList_Remove(s);
+	s->state = MSpanInUse;
+
+	if(s->npages > npage) {
+		// Trim extra and put it back in the heap.
+		t = runtime_FixAlloc_Alloc(&h->spanalloc);
+		mstats.mspan_inuse = h->spanalloc.inuse;
+		mstats.mspan_sys = h->spanalloc.sys;
+		runtime_MSpan_Init(t, s->start + npage, s->npages - npage);
+		s->npages = npage;
+		runtime_MHeapMap_Set(&h->map, t->start - 1, s);
+		runtime_MHeapMap_Set(&h->map, t->start, t);
+		runtime_MHeapMap_Set(&h->map, t->start + t->npages - 1, t);
+		t->state = MSpanInUse;
+		MHeap_FreeLocked(h, t);
+	}
+
+	// Record span info, because gc needs to be
+	// able to map interior pointer to containing span.
+	s->sizeclass = sizeclass;
+	for(n=0; n<npage; n++)
+		runtime_MHeapMap_Set(&h->map, s->start+n, s);
+	return s;
+}
+
+// Allocate a span of exactly npage pages from the list of large spans.
+static MSpan*
+MHeap_AllocLarge(MHeap *h, uintptr npage)
+{
+	return BestFit(&h->large, npage, nil);
+}
+
+// Search list for smallest span with >= npage pages.
+// If there are multiple smallest spans, take the one
+// with the earliest starting address.
+static MSpan*
+BestFit(MSpan *list, uintptr npage, MSpan *best)
+{
+	MSpan *s;
+
+	for(s=list->next; s != list; s=s->next) {
+		if(s->npages < npage)
+			continue;
+		if(best == nil
+		|| s->npages < best->npages
+		|| (s->npages == best->npages && s->start < best->start))
+			best = s;
+	}
+	return best;
+}
+
+// Try to add at least npage pages of memory to the heap,
+// returning whether it worked.
+static bool
+MHeap_Grow(MHeap *h, uintptr npage)
+{
+	uintptr ask;
+	void *v;
+	MSpan *s;
+
+	// Ask for a big chunk, to reduce the number of mappings
+	// the operating system needs to track; also amortizes
+	// the overhead of an operating system mapping.
+	// Allocate a multiple of 64kB (16 pages).
+	npage = (npage+15)&~15;
+	ask = npage<<PageShift;
+	if(ask < HeapAllocChunk)
+		ask = HeapAllocChunk;
+
+	v = runtime_SysAlloc(ask);
+	if(v == nil) {
+		if(ask > (npage<<PageShift)) {
+			ask = npage<<PageShift;
+			v = runtime_SysAlloc(ask);
+		}
+		if(v == nil)
+			return false;
+	}
+	mstats.heap_sys += ask;
+
+	if((byte*)v < h->min || h->min == nil)
+		h->min = v;
+	if((byte*)v+ask > h->max)
+		h->max = (byte*)v+ask;
+
+	// NOTE(rsc): In tcmalloc, if we've accumulated enough
+	// system allocations, the heap map gets entirely allocated
+	// in 32-bit mode.  (In 64-bit mode that's not practical.)
+	if(!runtime_MHeapMap_Preallocate(&h->map, ((uintptr)v>>PageShift) - 1, (ask>>PageShift) + 2)) {
+		runtime_SysFree(v, ask);
+		return false;
+	}
+
+	// Create a fake "in use" span and free it, so that the
+	// right coalescing happens.
+	s = runtime_FixAlloc_Alloc(&h->spanalloc);
+	mstats.mspan_inuse = h->spanalloc.inuse;
+	mstats.mspan_sys = h->spanalloc.sys;
+	runtime_MSpan_Init(s, (uintptr)v>>PageShift, ask>>PageShift);
+	runtime_MHeapMap_Set(&h->map, s->start, s);
+	runtime_MHeapMap_Set(&h->map, s->start + s->npages - 1, s);
+	s->state = MSpanInUse;
+	MHeap_FreeLocked(h, s);
+	return true;
+}
+
+// Look up the span at the given page number.
+// Page number is guaranteed to be in map
+// and is guaranteed to be start or end of span.
+MSpan*
+runtime_MHeap_Lookup(MHeap *h, PageID p)
+{
+	return runtime_MHeapMap_Get(&h->map, p);
+}
+
+// Look up the span at the given page number.
+// Page number is *not* guaranteed to be in map
+// and may be anywhere in the span.
+// Map entries for the middle of a span are only
+// valid for allocated spans.  Free spans may have
+// other garbage in their middles, so we have to
+// check for that.
+MSpan*
+runtime_MHeap_LookupMaybe(MHeap *h, PageID p)
+{
+	MSpan *s;
+
+	s = runtime_MHeapMap_GetMaybe(&h->map, p);
+	if(s == nil || p < s->start || p - s->start >= s->npages)
+		return nil;
+	if(s->state != MSpanInUse)
+		return nil;
+	return s;
+}
+
+// Free the span back into the heap.
+void
+runtime_MHeap_Free(MHeap *h, MSpan *s, int32 acct)
+{
+	runtime_lock(h);
+	mstats.heap_alloc += m->mcache->local_alloc;
+	m->mcache->local_alloc = 0;
+	mstats.heap_objects += m->mcache->local_objects;
+	m->mcache->local_objects = 0;
+	mstats.heap_inuse -= s->npages<<PageShift;
+	if(acct) {
+		mstats.heap_alloc -= s->npages<<PageShift;
+		mstats.heap_objects--;
+	}
+	MHeap_FreeLocked(h, s);
+	runtime_unlock(h);
+}
+
+static void
+MHeap_FreeLocked(MHeap *h, MSpan *s)
+{
+	MSpan *t;
+
+	if(s->state != MSpanInUse || s->ref != 0) {
+		// runtime_printf("MHeap_FreeLocked - span %p ptr %p state %d ref %d\n", s, s->start<<PageShift, s->state, s->ref);
+		runtime_throw("MHeap_FreeLocked - invalid free");
+	}
+	s->state = MSpanFree;
+	runtime_MSpanList_Remove(s);
+
+	// Coalesce with earlier, later spans.
+	if((t = runtime_MHeapMap_Get(&h->map, s->start - 1)) != nil && t->state != MSpanInUse) {
+		s->start = t->start;
+		s->npages += t->npages;
+		runtime_MHeapMap_Set(&h->map, s->start, s);
+		runtime_MSpanList_Remove(t);
+		t->state = MSpanDead;
+		runtime_FixAlloc_Free(&h->spanalloc, t);
+		mstats.mspan_inuse = h->spanalloc.inuse;
+		mstats.mspan_sys = h->spanalloc.sys;
+	}
+	if((t = runtime_MHeapMap_Get(&h->map, s->start + s->npages)) != nil && t->state != MSpanInUse) {
+		s->npages += t->npages;
+		runtime_MHeapMap_Set(&h->map, s->start + s->npages - 1, s);
+		runtime_MSpanList_Remove(t);
+		t->state = MSpanDead;
+		runtime_FixAlloc_Free(&h->spanalloc, t);
+		mstats.mspan_inuse = h->spanalloc.inuse;
+		mstats.mspan_sys = h->spanalloc.sys;
+	}
+
+	// Insert s into appropriate list.
+	if(s->npages < nelem(h->free))
+		runtime_MSpanList_Insert(&h->free[s->npages], s);
+	else
+		runtime_MSpanList_Insert(&h->large, s);
+
+	// TODO(rsc): IncrementalScavenge() to return memory to OS.
+}
+
+// Initialize a new span with the given start and npages.
+void
+runtime_MSpan_Init(MSpan *span, PageID start, uintptr npages)
+{
+	span->next = nil;
+	span->prev = nil;
+	span->start = start;
+	span->npages = npages;
+	span->freelist = nil;
+	span->ref = 0;
+	span->sizeclass = 0;
+	span->state = 0;
+}
+
+// Initialize an empty doubly-linked list.
+void
+runtime_MSpanList_Init(MSpan *list)
+{
+	list->state = MSpanListHead;
+	list->next = list;
+	list->prev = list;
+}
+
+void
+runtime_MSpanList_Remove(MSpan *span)
+{
+	if(span->prev == nil && span->next == nil)
+		return;
+	span->prev->next = span->next;
+	span->next->prev = span->prev;
+	span->prev = nil;
+	span->next = nil;
+}
+
+bool
+runtime_MSpanList_IsEmpty(MSpan *list)
+{
+	return list->next == list;
+}
+
+void
+runtime_MSpanList_Insert(MSpan *list, MSpan *span)
+{
+	if(span->next != nil || span->prev != nil)
+		runtime_throw("MSpanList_Insert");
+	span->next = list->next;
+	span->prev = list;
+	span->next->prev = span;
+	span->prev->next = span;
+}