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/*
* Licensed to Elasticsearch B.V. under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch B.V. licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
* This project is based on a modification of https://github.com/tdunning/t-digest which is licensed under the Apache 2.0 License.
*/
package org.elasticsearch.tdigest;
import org.apache.lucene.util.Accountable;
import org.apache.lucene.util.RamUsageEstimator;
import org.elasticsearch.core.Releasable;
import org.elasticsearch.core.Releasables;
import org.elasticsearch.tdigest.arrays.TDigestArrays;
import org.elasticsearch.tdigest.arrays.TDigestByteArray;
import org.elasticsearch.tdigest.arrays.TDigestIntArray;
/**
* An AVL-tree structure stored in parallel arrays.
* This class only stores the tree structure, so you need to extend it if you
* want to add data to the nodes, typically by using arrays and node
* identifiers as indices.
*/
abstract class IntAVLTree implements Releasable, Accountable {
static final long SHALLOW_SIZE = RamUsageEstimator.shallowSizeOfInstance(IntAVLTree.class);
/**
* We use 0 instead of -1 so that left(NIL) works without
* condition.
*/
protected static final int NIL = 0;
/** Grow a size by 1/8. */
static int oversize(int size) {
return size + (size >>> 3);
}
private final TDigestArrays arrays;
private boolean closed = false;
private final NodeAllocator nodeAllocator;
private int root;
private final TDigestIntArray parent;
private final TDigestIntArray left;
private final TDigestIntArray right;
private final TDigestByteArray depth;
IntAVLTree(TDigestArrays arrays, int initialCapacity) {
this.arrays = arrays;
root = NIL;
NodeAllocator nodeAllocator = null;
TDigestIntArray parent = null;
TDigestIntArray left = null;
TDigestIntArray right = null;
TDigestByteArray depth = null;
try {
this.nodeAllocator = nodeAllocator = NodeAllocator.create(arrays);
this.parent = parent = arrays.newIntArray(initialCapacity);
this.left = left = arrays.newIntArray(initialCapacity);
this.right = right = arrays.newIntArray(initialCapacity);
this.depth = depth = arrays.newByteArray(initialCapacity);
nodeAllocator = null;
parent = null;
left = null;
right = null;
depth = null;
} finally {
Releasables.close(nodeAllocator, parent, left, right, depth);
}
}
IntAVLTree(TDigestArrays arrays) {
this(arrays, 16);
}
@Override
public long ramBytesUsed() {
return SHALLOW_SIZE + nodeAllocator.ramBytesUsed() + parent.ramBytesUsed() + left.ramBytesUsed() + right.ramBytesUsed() + depth
.ramBytesUsed();
}
/**
* Return the current root of the tree.
*/
public int root() {
return root;
}
/**
* Return the current capacity, which is the number of nodes that this tree
* can hold.
*/
public int capacity() {
return parent.size();
}
/**
* Resize internal storage in order to be able to store data for nodes up to
* newCapacity (excluded).
*/
protected void resize(int newCapacity) {
parent.resize(newCapacity);
left.resize(newCapacity);
right.resize(newCapacity);
depth.resize(newCapacity);
}
/**
* Return the size of this tree.
*/
public int size() {
return nodeAllocator.size();
}
/**
* Return the parent of the provided node.
*/
public int parent(int node) {
return parent.get(node);
}
/**
* Return the left child of the provided node.
*/
public int left(int node) {
return left.get(node);
}
/**
* Return the right child of the provided node.
*/
public int right(int node) {
return right.get(node);
}
/**
* Return the depth nodes that are stored below node including itself.
*/
public int depth(int node) {
return depth.get(node);
}
/**
* Return the least node under node.
*/
public int first(int node) {
if (node == NIL) {
return NIL;
}
while (true) {
final int left = left(node);
if (left == NIL) {
break;
}
node = left;
}
return node;
}
/**
* Return the largest node under node.
*/
public int last(int node) {
while (true) {
final int right = right(node);
if (right == NIL) {
break;
}
node = right;
}
return node;
}
/**
* Return the least node that is strictly greater than node.
*/
public final int next(int node) {
final int right = right(node);
if (right != NIL) {
return first(right);
} else {
int parent = parent(node);
while (parent != NIL && node == right(parent)) {
node = parent;
parent = parent(parent);
}
return parent;
}
}
/**
* Return the highest node that is strictly less than node.
*/
public final int prev(int node) {
final int left = left(node);
if (left != NIL) {
return last(left);
} else {
int parent = parent(node);
while (parent != NIL && node == left(parent)) {
node = parent;
parent = parent(parent);
}
return parent;
}
}
/**
* Compare data against data which is stored in node.
*/
protected abstract int compare(int node);
/**
* Compare data into node.
*/
protected abstract void copy(int node);
/**
* Merge data into node.
*/
protected abstract void merge(int node);
/**
* Add current data to the tree and return true if a new node was added
* to the tree or false if the node was merged into an existing node.
*/
public boolean add() {
if (root == NIL) {
root = nodeAllocator.newNode();
copy(root);
fixAggregates(root);
return true;
} else {
int node = root;
assert parent(root) == NIL;
int parent;
int cmp;
do {
cmp = compare(node);
if (cmp < 0) {
parent = node;
node = left(node);
} else if (cmp > 0) {
parent = node;
node = right(node);
} else {
merge(node);
return false;
}
} while (node != NIL);
node = nodeAllocator.newNode();
if (node >= capacity()) {
resize(oversize(node + 1));
}
copy(node);
parent(node, parent);
if (cmp < 0) {
left(parent, node);
} else {
right(parent, node);
}
rebalance(node);
return true;
}
}
/**
* Find a node in this tree.
*/
public int find() {
for (int node = root; node != NIL;) {
final int cmp = compare(node);
if (cmp < 0) {
node = left(node);
} else if (cmp > 0) {
node = right(node);
} else {
return node;
}
}
return NIL;
}
/**
* Update node with the current data.
*/
public void update(int node) {
final int prev = prev(node);
final int next = next(node);
if ((prev == NIL || compare(prev) > 0) && (next == NIL || compare(next) < 0)) {
// Update can be done in-place
copy(node);
for (int n = node; n != NIL; n = parent(n)) {
fixAggregates(n);
}
} else {
// TODO: it should be possible to find the new node position without
// starting from scratch
remove(node);
add();
}
}
/**
* Remove the specified node from the tree.
*/
public void remove(int node) {
if (node == NIL) {
throw new IllegalArgumentException();
}
if (left(node) != NIL && right(node) != NIL) {
// inner node
final int next = next(node);
assert next != NIL;
swap(node, next);
}
assert left(node) == NIL || right(node) == NIL;
final int parent = parent(node);
int child = left(node);
if (child == NIL) {
child = right(node);
}
if (child == NIL) {
// no children
if (node == root) {
assert size() == 1 : size();
root = NIL;
} else {
if (node == left(parent)) {
left(parent, NIL);
} else {
assert node == right(parent);
right(parent, NIL);
}
}
} else {
// one single child
if (node == root) {
assert size() == 2;
root = child;
} else if (node == left(parent)) {
left(parent, child);
} else {
assert node == right(parent);
right(parent, child);
}
parent(child, parent);
}
release(node);
rebalance(parent);
}
private void release(int node) {
left(node, NIL);
right(node, NIL);
parent(node, NIL);
nodeAllocator.release(node);
}
private void swap(int node1, int node2) {
final int parent1 = parent(node1);
final int parent2 = parent(node2);
if (parent1 != NIL) {
if (node1 == left(parent1)) {
left(parent1, node2);
} else {
assert node1 == right(parent1);
right(parent1, node2);
}
} else {
assert root == node1;
root = node2;
}
if (parent2 != NIL) {
if (node2 == left(parent2)) {
left(parent2, node1);
} else {
assert node2 == right(parent2);
right(parent2, node1);
}
} else {
assert root == node2;
root = node1;
}
parent(node1, parent2);
parent(node2, parent1);
final int left1 = left(node1);
final int left2 = left(node2);
left(node1, left2);
if (left2 != NIL) {
parent(left2, node1);
}
left(node2, left1);
if (left1 != NIL) {
parent(left1, node2);
}
final int right1 = right(node1);
final int right2 = right(node2);
right(node1, right2);
if (right2 != NIL) {
parent(right2, node1);
}
right(node2, right1);
if (right1 != NIL) {
parent(right1, node2);
}
final int depth1 = depth(node1);
final int depth2 = depth(node2);
depth(node1, depth2);
depth(node2, depth1);
}
private int balanceFactor(int node) {
return depth(left(node)) - depth(right(node));
}
private void rebalance(int node) {
for (int n = node; n != NIL;) {
final int p = parent(n);
fixAggregates(n);
switch (balanceFactor(n)) {
case -2:
final int right = right(n);
if (balanceFactor(right) == 1) {
rotateRight(right);
}
rotateLeft(n);
break;
case 2:
final int left = left(n);
if (balanceFactor(left) == -1) {
rotateLeft(left);
}
rotateRight(n);
break;
case -1:
case 0:
case 1:
break; // ok
default:
throw new AssertionError();
}
n = p;
}
}
protected void fixAggregates(int node) {
depth(node, 1 + Math.max(depth(left(node)), depth(right(node))));
}
/** Rotate left the subtree under n */
private void rotateLeft(int n) {
final int r = right(n);
final int lr = left(r);
right(n, lr);
if (lr != NIL) {
parent(lr, n);
}
final int p = parent(n);
parent(r, p);
if (p == NIL) {
root = r;
} else if (left(p) == n) {
left(p, r);
} else {
assert right(p) == n;
right(p, r);
}
left(r, n);
parent(n, r);
fixAggregates(n);
fixAggregates(parent(n));
}
/** Rotate right the subtree under n */
private void rotateRight(int n) {
final int l = left(n);
final int rl = right(l);
left(n, rl);
if (rl != NIL) {
parent(rl, n);
}
final int p = parent(n);
parent(l, p);
if (p == NIL) {
root = l;
} else if (right(p) == n) {
right(p, l);
} else {
assert left(p) == n;
left(p, l);
}
right(l, n);
parent(n, l);
fixAggregates(n);
fixAggregates(parent(n));
}
private void parent(int node, int parent) {
assert node != NIL;
this.parent.set(node, parent);
}
private void left(int node, int left) {
assert node != NIL;
this.left.set(node, left);
}
private void right(int node, int right) {
assert node != NIL;
this.right.set(node, right);
}
private void depth(int node, int depth) {
assert node != NIL;
assert depth >= 0 && depth <= Byte.MAX_VALUE;
this.depth.set(node, (byte) depth);
}
void checkBalance(int node) {
if (node == NIL) {
assert depth(node) == 0;
} else {
assert depth(node) == 1 + Math.max(depth(left(node)), depth(right(node)));
assert Math.abs(depth(left(node)) - depth(right(node))) <= 1;
checkBalance(left(node));
checkBalance(right(node));
}
}
/**
* A stack of int values.
*/
private static class IntStack implements Releasable, Accountable {
private static final long SHALLOW_SIZE = RamUsageEstimator.shallowSizeOfInstance(IntStack.class);
private final TDigestArrays arrays;
private boolean closed = false;
private final TDigestIntArray stack;
private int size;
IntStack(TDigestArrays arrays) {
this.arrays = arrays;
stack = arrays.newIntArray(0);
size = 0;
}
@Override
public long ramBytesUsed() {
return SHALLOW_SIZE + stack.ramBytesUsed();
}
int size() {
return size;
}
int pop() {
int value = stack.get(--size);
stack.resize(size);
return value;
}
void push(int v) {
stack.resize(++size);
stack.set(size - 1, v);
}
@Override
public void close() {
if (closed == false) {
closed = true;
arrays.adjustBreaker(-SHALLOW_SIZE);
stack.close();
}
}
}
private static class NodeAllocator implements Releasable, Accountable {
private static final long SHALLOW_SIZE = RamUsageEstimator.shallowSizeOfInstance(NodeAllocator.class);
private final TDigestArrays arrays;
private boolean closed = false;
private int nextNode;
private final IntStack releasedNodes;
static NodeAllocator create(TDigestArrays arrays) {
arrays.adjustBreaker(SHALLOW_SIZE);
try {
return new NodeAllocator(arrays);
} catch (Exception e) {
arrays.adjustBreaker(-SHALLOW_SIZE);
throw e;
}
}
private NodeAllocator(TDigestArrays arrays) {
this.arrays = arrays;
nextNode = NIL + 1;
arrays.adjustBreaker(IntStack.SHALLOW_SIZE);
try {
releasedNodes = new IntStack(arrays);
} catch (Exception e) {
arrays.adjustBreaker(-IntStack.SHALLOW_SIZE);
throw e;
}
}
@Override
public long ramBytesUsed() {
return SHALLOW_SIZE + releasedNodes.ramBytesUsed();
}
int newNode() {
if (releasedNodes.size() > 0) {
return releasedNodes.pop();
} else {
return nextNode++;
}
}
void release(int node) {
assert node < nextNode;
releasedNodes.push(node);
}
int size() {
return nextNode - releasedNodes.size() - 1;
}
@Override
public void close() {
if (closed == false) {
closed = true;
arrays.adjustBreaker(-SHALLOW_SIZE);
releasedNodes.close();
}
}
}
@Override
public void close() {
if (closed == false) {
closed = true;
arrays.adjustBreaker(-SHALLOW_SIZE);
Releasables.close(nodeAllocator, parent, left, right, depth);
}
}
}
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