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runtime: use iterator instead of raw node for treap find
Right now the mTreap structure exposes the treapNode structure through only one interface: find. There's no reason (performance or otherwise) for exposing this, and we get a cleaner abstraction through the iterators this way. This change also makes it easier to make changes to the mTreap implementation without violating its interface. Change-Id: I5ef86b8ac81a47d05d8404df65af9ec5f419dc40 Reviewed-on: https://go-review.googlesource.com/c/go/+/164098 Reviewed-by: Austin Clements <austin@google.com>
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@ -295,13 +295,13 @@ func (root *mTreap) removeNode(t *treapNode) {
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mheap_.treapalloc.free(unsafe.Pointer(t))
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}
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// find searches for, finds, and returns the treap node containing the
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// smallest span that can hold npages. If no span has at least npages
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// it returns nil.
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// find searches for, finds, and returns the treap iterator representing
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// the position of the smallest span that can hold npages. If no span has
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// at least npages it returns an invalid iterator.
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// This is slightly more complicated than a simple binary tree search
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// since if an exact match is not found the next larger node is
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// returned.
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func (root *mTreap) find(npages uintptr) *treapNode {
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func (root *mTreap) find(npages uintptr) treapIter {
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t := root.treap
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for t != nil {
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if t.spanKey == nil {
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@ -312,10 +312,10 @@ func (root *mTreap) find(npages uintptr) *treapNode {
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} else if t.left != nil && t.left.npagesKey >= npages {
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t = t.left
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} else {
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return t
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return treapIter{t}
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}
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}
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return nil
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return treapIter{}
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}
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// removeSpan searches for, finds, deletes span along with
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@ -1126,12 +1126,12 @@ func (h *mheap) pickFreeSpan(npage uintptr) *mspan {
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// Note that we want the _smaller_ free span, i.e. the free span
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// closer in size to the amount we requested (npage).
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var s *mspan
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if tf != nil && (ts == nil || tf.spanKey.npages <= ts.spanKey.npages) {
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s = tf.spanKey
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h.free.removeNode(tf)
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} else if ts != nil && (tf == nil || tf.spanKey.npages > ts.spanKey.npages) {
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s = ts.spanKey
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h.scav.removeNode(ts)
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if tf.valid() && (!ts.valid() || tf.span().npages <= ts.span().npages) {
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s = tf.span()
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h.free.erase(tf)
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} else if ts.valid() && (!tf.valid() || tf.span().npages > ts.span().npages) {
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s = ts.span()
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h.scav.erase(ts)
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}
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return s
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}
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