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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,229 @@ | ||
| // Package rstree provides a datatype that supports building a space-efficient summary of networks | ||
| // and IPs. | ||
| package rstree | ||
|
|
||
| import ( | ||
| "container/list" | ||
| "unsafe" | ||
|
|
||
| "github.com/PatrickCronin/routesum/pkg/routesum/bitslice" | ||
| ) | ||
|
|
||
| type node struct { | ||
| children *[2]*node | ||
| } | ||
|
|
||
| func (n *node) isLeaf() bool { | ||
| return n.children == nil | ||
| } | ||
|
|
||
| // RSTree is a binary tree that supports the storage and retrieval of networks and IPs for the | ||
| // purpose of route summarization. | ||
| type RSTree struct { | ||
| root *node | ||
| } | ||
|
|
||
| // NewRSTree returns an initialized RSTree for use | ||
| func NewRSTree() *RSTree { | ||
| return &RSTree{ | ||
| root: nil, | ||
| } | ||
| } | ||
|
|
||
| // InsertRoute inserts a new BitSlice into the tree. Each insert results in a space-optimized tree | ||
| // structure. If a route being inserted is already covered by an existing route, it's simply | ||
| // ignored. If a route being inserted covers one or more routes already stored, those routes are | ||
| // replaced. | ||
| func (t *RSTree) InsertRoute(routeBits bitslice.BitSlice) { | ||
| // If the tree has no root node, create one. | ||
| if t.root == nil { | ||
| t.root = &node{children: nil} | ||
|
|
||
| if len(routeBits) > 0 { | ||
| t.root.children = new([2]*node) | ||
| } | ||
| } | ||
|
|
||
| t.root.insertRoute(routeBits) | ||
| } | ||
|
|
||
| // insertRoute returns whether or not a change was made to the tree that might require upwards | ||
| // optimization. | ||
| func (n *node) insertRoute(remainingRouteBits bitslice.BitSlice) bool { | ||
| // Does the current node cover the requested route? If so, we're done. | ||
| if n.isLeaf() { | ||
| return false | ||
| } | ||
|
|
||
| // Does the requested route cover the current node? If so, update the current node. | ||
| remainingRouteBitsLen := len(remainingRouteBits) | ||
| if remainingRouteBitsLen == 0 { | ||
| n.children = nil | ||
| return true | ||
| } | ||
|
|
||
| // Otherwise the requested route diverges from the current node. | ||
| nextBit := remainingRouteBits[0] | ||
| if n.children[nextBit] == nil { | ||
| // As an optimization, if we would create a node only to realize it is redundant, just | ||
| // trim the rundundant child now and return. | ||
| if remainingRouteBitsLen == 1 && | ||
| n.children[^nextBit&1] != nil && | ||
| n.children[^nextBit&1].isLeaf() { | ||
| n.children = nil | ||
| return true | ||
| } | ||
|
|
||
| // Otherwise we add a node | ||
| n.children[nextBit] = new(node) | ||
| if remainingRouteBitsLen > 1 { | ||
| n.children[nextBit].children = new([2]*node) | ||
| } | ||
| } | ||
|
|
||
| // Traverse to the new node | ||
| if n.children[nextBit].insertRoute(remainingRouteBits[1:]) { | ||
| return n.maybeRemoveRedundantChildren() | ||
| } | ||
|
|
||
| return false | ||
| } | ||
|
|
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| // A node's children are redundant if they, taken together, represent a complete subtree from the | ||
| // node's perspective. This situation can be represented more simply as the node having a nil | ||
| // children pointer. | ||
| func (n *node) maybeRemoveRedundantChildren() bool { | ||
| if n.isLeaf() { | ||
| return false | ||
| } | ||
|
|
||
| if n.children[0] == nil || | ||
| !n.children[0].isLeaf() || | ||
| n.children[1] == nil || | ||
| !n.children[1].isLeaf() { | ||
| return false | ||
| } | ||
|
|
||
| n.children = nil | ||
| return true | ||
| } | ||
|
|
||
| type traversalStep struct { | ||
| n *node | ||
| precedingRouteBits bitslice.BitSlice | ||
| } | ||
|
|
||
| // Contents returns the BitSlices contained in the RSTree. | ||
| func (t *RSTree) Contents() []bitslice.BitSlice { | ||
| // If the tree is empty | ||
| if t.root == nil { | ||
| return []bitslice.BitSlice{} | ||
| } | ||
|
|
||
| // Otherwise | ||
| remainingSteps := list.New() | ||
| remainingSteps.PushFront(traversalStep{ | ||
| n: t.root, | ||
| precedingRouteBits: bitslice.BitSlice{}, | ||
| }) | ||
|
|
||
| contents := []bitslice.BitSlice{} | ||
| for remainingSteps.Len() > 0 { | ||
| step := remainingSteps.Remove(remainingSteps.Front()).(traversalStep) | ||
|
|
||
| if step.n.isLeaf() { | ||
| contents = append(contents, step.precedingRouteBits) | ||
| } else { | ||
| lenPrecedingRouteBits := len(step.precedingRouteBits) | ||
|
|
||
| if step.n.children[1] != nil { | ||
| highChildBits := make([]byte, lenPrecedingRouteBits+1) | ||
| copy(highChildBits, step.precedingRouteBits) | ||
| highChildBits[lenPrecedingRouteBits] = 1 | ||
| remainingSteps.PushFront(traversalStep{ | ||
| n: step.n.children[1], | ||
| precedingRouteBits: highChildBits, | ||
| }) | ||
| } | ||
|
|
||
| if step.n.children[0] != nil { | ||
| lowChildBits := make([]byte, lenPrecedingRouteBits+1) | ||
| copy(lowChildBits, step.precedingRouteBits) | ||
| lowChildBits[lenPrecedingRouteBits] = 0 | ||
| remainingSteps.PushFront(traversalStep{ | ||
| n: step.n.children[0], | ||
| precedingRouteBits: lowChildBits, | ||
| }) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| return contents | ||
| } | ||
|
|
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| func (t *RSTree) visitAll(cb func(*node)) { | ||
| // If the trie is empty | ||
| if t.root == nil { | ||
| return | ||
| } | ||
|
|
||
| // Otherwise | ||
| remainingSteps := list.New() | ||
| remainingSteps.PushFront(traversalStep{ | ||
| n: t.root, | ||
| precedingRouteBits: bitslice.BitSlice{}, | ||
| }) | ||
|
|
||
| for remainingSteps.Len() > 0 { | ||
| curNode := remainingSteps.Remove(remainingSteps.Front()).(traversalStep) | ||
|
|
||
| // Act on this node | ||
| cb(curNode.n) | ||
|
|
||
| // Traverse the remainder of the nodes | ||
| if !curNode.n.isLeaf() { | ||
| lenPrecedingRouteBits := len(curNode.precedingRouteBits) | ||
|
|
||
| if curNode.n.children[1] != nil { | ||
| highChildBits := make([]byte, lenPrecedingRouteBits+1) | ||
| copy(highChildBits, curNode.precedingRouteBits) | ||
| highChildBits[lenPrecedingRouteBits] = 1 | ||
| remainingSteps.PushFront(traversalStep{ | ||
| n: curNode.n.children[1], | ||
| precedingRouteBits: highChildBits, | ||
| }) | ||
| } | ||
|
|
||
| if curNode.n.children[0] != nil { | ||
| lowChildBits := make([]byte, lenPrecedingRouteBits+1) | ||
| copy(lowChildBits, curNode.precedingRouteBits) | ||
| lowChildBits[lenPrecedingRouteBits] = 0 | ||
| remainingSteps.PushFront(traversalStep{ | ||
| n: curNode.n.children[0], | ||
| precedingRouteBits: lowChildBits, | ||
| }) | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // MemUsage returns information about an RSTrie's current size in memory. | ||
| func (t *RSTree) MemUsage() (uint, uint, uintptr, uintptr) { | ||
| var numInternalNodes, numLeafNodes uint | ||
| var internalNodesTotalSize, leafNodesTotalSize uintptr | ||
|
|
||
| tallyNode := func(n *node) { | ||
| baseNodeSize := unsafe.Sizeof(node{}) //nolint: exhaustruct, gosec | ||
| if n.isLeaf() { | ||
| numLeafNodes++ | ||
| leafNodesTotalSize += baseNodeSize | ||
| return | ||
| } | ||
|
|
||
| numInternalNodes++ | ||
| internalNodesTotalSize += baseNodeSize + unsafe.Sizeof([2]*node{}) //nolint: gosec | ||
| } | ||
| t.visitAll(tallyNode) | ||
|
|
||
| return numInternalNodes, numLeafNodes, internalNodesTotalSize, leafNodesTotalSize | ||
| } |
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