Chris Lu
3 years ago
6 changed files with 193 additions and 28 deletions
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60weed/util/bptree/README.md
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4weed/util/bptree/bpmap.go
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12weed/util/bptree/bptree.go
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43weed/util/bptree/bptree_node.go
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34weed/util/bptree/bptree_store_test.go
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44weed/util/bptree/getter_setter.go
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This adapts one b+ tree implementation |
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https://sourcegraph.com/github.com/timtadh/data-structures@master/-/tree/tree/bptree |
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to persist changes to on disk. |
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# When a node needs to persist itself? |
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* A node changed its key or value |
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* When an item is added. |
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* When an item is updated. |
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* When an item is deleted. |
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* When a node is split. |
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* 2 new nodes are created (they shoud persist themselves). |
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* Parent node need to point to the new nodes. |
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* When a node is merged. |
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* delete one node |
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* persist the merged node |
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In general, if one node is returned from a function, the node should have already been persisted. |
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The parent node may need to delete the old node. |
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BpTree |
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Add(key ItemKey, value ItemValue) |
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new_root = self.getRoot().put(key,value) |
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a, b, err := self.insert(key, value) |
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self.internal_insert(key, value) |
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self.internal_split(q.keys[0], q) |
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persist(a,b) |
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self.persist() // child add q node |
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self.maybePersist(child == p) |
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self.leaf_insert(key, value) |
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self.persist() // if dedup |
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self.leaf_split(key, value) |
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self.pure_leaf_split(key, value) |
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persist(a,b) |
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a.persist() |
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persist(a,b) |
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self.put_kv(key, value) |
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new_root.persist() |
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self.setRoot(new_root) |
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oldroot.destroy() |
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// maybe persist BpTree new root |
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Replace(key ItemKey, where WhereFunc, value ItemValue) |
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leaf.persist() |
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RemoveWhere(key ItemKey, where WhereFunc) |
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self.getRoot().remove(key, where) |
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self.internal_remove(key, nil, where) |
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child.leaf_remove(key, nil, where) |
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child.leaf_remove(key, sibling.keys[0], where) |
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l.destroy() // when the node is empty |
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a.maybePersist(hasChange) |
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self.destroy() // when no keys left |
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self.persist() // when some keys are left |
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self.leaf_remove(key, self.keys[len(self.keys)-1], where) |
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new_root.persist() // when new root is added |
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// maybe persist BpTree new root |
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@ -0,0 +1,34 @@ |
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package bptree |
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import ( |
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"fmt" |
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"testing" |
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) |
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func TestAddRemove(t *testing.T) { |
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tree := NewBpTree(32) |
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PersistFn = func(node *BpNode) error { |
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println("saving", node.protoNodeId) |
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return nil |
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} |
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DestroyFn = func(node *BpNode) error { |
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println("delete", node.protoNodeId) |
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return nil |
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} |
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for i:=0;i<1024;i++{ |
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println("++++++++++", i) |
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tree.Add(String(fmt.Sprintf("%02d", i)), String(fmt.Sprintf("%02d", i))) |
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printTree(tree.root, "") |
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} |
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} |
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func printTree(node *BpNode, prefix string) { |
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fmt.Printf("%sNode %d\n", prefix, node.protoNodeId) |
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prefix += " " |
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for i:=0;i<len(node.keys);i++{ |
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fmt.Printf("%skey %s\n", prefix, node.keys[i]) |
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if i < len(node.pointers) && node.pointers[i] != nil { |
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printTree(node.pointers[i], prefix+" ") |
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} |
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} |
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} |
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