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/* <!-- copyright */
/*
* aria2 - The high speed download utility
*
* Copyright (C) 2010 Tatsuhiro Tsujikawa
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* In addition, as a special exception, the copyright holders give
* permission to link the code of portions of this program with the
* OpenSSL library under certain conditions as described in each
* individual source file, and distribute linked combinations
* including the two.
* You must obey the GNU General Public License in all respects
* for all of the code used other than OpenSSL. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you
* do not wish to do so, delete this exception statement from your
* version. If you delete this exception statement from all source
* files in the program, then also delete it here.
*/
/* copyright --> */
#ifndef D_DHT_BUCKET_TREE_H
#define D_DHT_BUCKET_TREE_H
#include "common.h"
#include <vector>
#include <memory>
#include "DHTConstants.h"
namespace aria2 {
class DHTBucket;
class DHTNode;
// This class represents Kademlia DHT routing tree. The leaf nodes
// have bucket which contains DHT node. The tree is binary tree but
// highly unbalanced.
class DHTBucketTreeNode {
public:
// Ctor for internal node
DHTBucketTreeNode(std::unique_ptr<DHTBucketTreeNode> left,
std::unique_ptr<DHTBucketTreeNode> right);
// Ctor for leaf node
DHTBucketTreeNode(std::shared_ptr<DHTBucket> bucket);
~DHTBucketTreeNode();
// Returns child node, left or right, which contains key. If dig is
// called against leaf node, then returns 0.
DHTBucketTreeNode* dig(const unsigned char* key);
bool isInRange(const unsigned char* key) const;
// Returns true iff this is a leaf node.
bool leaf() const { return bucket_.get(); }
const unsigned char* getMaxId() const { return maxId_; }
const unsigned char* getMinId() const { return minId_; }
DHTBucketTreeNode* getParent() const { return parent_; }
DHTBucketTreeNode* getLeft() const { return left_.get(); }
DHTBucketTreeNode* getRight() const { return right_.get(); }
const std::shared_ptr<DHTBucket>& getBucket() const { return bucket_; }
// Splits this object's bucket using DHTBucket::split() and create
// left and right child node to hold buckets. The bucket of current
// node is reset so this node becomes internal node after this
// call.
void split();
private:
// Do not allow copying
DHTBucketTreeNode(const DHTBucketTreeNode&);
DHTBucketTreeNode& operator=(const DHTBucketTreeNode&);
// Reset relation of children and minId_ and maxId_.
void resetRelation();
void setParent(DHTBucketTreeNode* parent) { parent_ = parent; }
DHTBucketTreeNode* parent_;
std::unique_ptr<DHTBucketTreeNode> left_;
std::unique_ptr<DHTBucketTreeNode> right_;
std::shared_ptr<DHTBucket> bucket_;
unsigned char minId_[DHT_ID_LENGTH];
unsigned char maxId_[DHT_ID_LENGTH];
};
namespace dht {
// Returns leaf node where key fits between node's min and max ID
// range.
DHTBucketTreeNode* findTreeNodeFor(DHTBucketTreeNode* root,
const unsigned char* key);
// Returns bucket where key fits between bucket's min and max ID
// range. This function first use findTreeNodeFor and returns its
// bucket_.
std::shared_ptr<DHTBucket> findBucketFor(DHTBucketTreeNode* root,
const unsigned char* key);
// Stores most closest K nodes against key in nodes. K is
// DHTBucket::K. This function may returns less than K nodes because
// the routing tree contains less than K nodes. The order of nodes is
// arbitrary. Caller must pass empty nodes.
void findClosestKNodes(std::vector<std::shared_ptr<DHTNode>>& nodes,
DHTBucketTreeNode* root, const unsigned char* key);
// Stores all buckets in buckets.
void enumerateBucket(std::vector<std::shared_ptr<DHTBucket>>& buckets,
DHTBucketTreeNode* root);
} // namespace dht
} // namespace aria2
#endif // D_DHT_BUCKET_TREE_H
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