+++ /dev/null
-/* Copyright (c) 2010-2020. The SimGrid Team. All rights reserved. */
-
-/* This program is free software; you can redistribute it and/or modify it
- * under the terms of the license (GNU LGPL) which comes with this package. */
-
-#include "node.hpp"
-#include "routing_table.hpp"
-
-XBT_LOG_NEW_DEFAULT_CATEGORY(kademlia_node, "Messages specific for this example");
-
-namespace kademlia {
-static void destroy(void* message)
-{
- const Message* msg = static_cast<Message*>(message);
- delete msg->answer_;
- delete msg;
-}
-
-/**
- * @brief Tries to join the network
- * @param known_id id of the node I know in the network.
- */
-bool Node::join(unsigned int known_id)
-{
- const Answer* node_list;
- unsigned int i;
- bool got_answer = false;
-
- /* Add the guy we know to our routing table and ourselves. */
- routingTableUpdate(id_);
- routingTableUpdate(known_id);
-
- /* First step: Send a "FIND_NODE" request to the node we know */
- sendFindNode(known_id, id_);
-
- simgrid::s4u::Mailbox* mailbox = simgrid::s4u::Mailbox::by_name(std::to_string(id_));
- do {
- if (receive_comm == nullptr)
- receive_comm = mailbox->get_async(&received_msg);
- if (receive_comm->test()) {
- XBT_DEBUG("Received an answer from the node I know.");
- got_answer = true;
- // retrieve the node list and ping them.
- const Message* msg = static_cast<Message*>(received_msg);
- node_list = msg->answer_;
- if (node_list) {
- for (auto const& contact : node_list->getNodes())
- routingTableUpdate(contact.first);
- } else {
- handleFindNode(msg);
- }
- delete msg->answer_;
- delete msg;
- receive_comm = nullptr;
- } else
- simgrid::s4u::this_actor::sleep_for(1);
- } while (not got_answer);
-
- /* Second step: Send a FIND_NODE to a a random node in buckets */
- unsigned int bucket_id = table.findBucket(known_id)->getId();
- xbt_assert(bucket_id <= IDENTIFIER_SIZE);
- for (i = 0; ((bucket_id > i) || (bucket_id + i) <= IDENTIFIER_SIZE) && i < JOIN_BUCKETS_QUERIES; i++) {
- if (bucket_id > i) {
- unsigned int id_in_bucket = get_id_in_prefix(id_, bucket_id - i);
- findNode(id_in_bucket, false);
- }
- if (bucket_id + i <= IDENTIFIER_SIZE) {
- unsigned int id_in_bucket = get_id_in_prefix(id_, bucket_id + i);
- findNode(id_in_bucket, false);
- }
- }
- return got_answer;
-}
-
-/** @brief Send a "FIND_NODE" to a node
- * @param id node we are querying
- * @param destination node we are trying to find.
- */
-void Node::sendFindNode(unsigned int id, unsigned int destination)
-{
- /* Gets the mailbox to send to */
- simgrid::s4u::Mailbox* mailbox = simgrid::s4u::Mailbox::by_name(std::to_string(id));
- /* Build the task */
-
- Message* msg = new Message(id_, destination, simgrid::s4u::Mailbox::by_name(std::to_string(id_)),
- simgrid::s4u::Host::current()->get_cname());
-
- /* Send the task */
- mailbox->put_init(msg, 1)->detach(kademlia::destroy);
- XBT_VERB("Asking %u for its closest nodes", id);
-}
-
-/**
- * Sends to the best "KADEMLIA_ALPHA" nodes in the "node_list" array a "FIND_NODE" request, to ask them for their best
- * nodes
- */
-unsigned int Node::sendFindNodeToBest(const Answer* node_list)
-{
- unsigned int i = 0;
- unsigned int j = 0;
- unsigned int destination = node_list->getDestinationId();
- for (auto const& node_to_query : node_list->getNodes()) {
- /* We need to have at most "KADEMLIA_ALPHA" requests each time, according to the protocol */
- /* Gets the node we want to send the query to */
- if (node_to_query.first != id_) { /* No need to query ourselves */
- sendFindNode(node_to_query.first, destination);
- j++;
- }
- i++;
- if (j == KADEMLIA_ALPHA)
- break;
- }
- return i;
-}
-
-/** @brief Updates/Puts the node id unsigned into our routing table
- * @param id The id of the node we need to add unsigned into our routing table
- */
-void Node::routingTableUpdate(unsigned int id)
-{
- // retrieval of the bucket in which the should be
- Bucket* bucket = table.findBucket(id);
-
- // check if the id is already in the bucket.
- auto id_pos = std::find(bucket->nodes.begin(), bucket->nodes.end(), id);
-
- if (id_pos == bucket->nodes.end()) {
- /* We check if the bucket is full or not. If it is, we evict an old element */
- if (bucket->nodes.size() >= BUCKET_SIZE) {
- bucket->nodes.pop_back();
- }
- bucket->nodes.push_front(id);
- XBT_VERB("I'm adding to my routing table %08x", id);
- } else {
- // We push the element to the front
- bucket->nodes.erase(id_pos);
- bucket->nodes.push_front(id);
- XBT_VERB("I'm updating %08x", id);
- }
-}
-
-/** @brief Finds the closest nodes to the node given.
- * @param node : our node
- * @param destination_id : the id of the guy we are trying to find
- */
-Answer* Node::findClosest(unsigned int destination_id)
-{
- Answer* answer = new Answer(destination_id);
- /* We find the corresponding bucket for the id */
- const Bucket* bucket = table.findBucket(destination_id);
- int bucket_id = bucket->getId();
- xbt_assert((bucket_id <= IDENTIFIER_SIZE), "Bucket found has a wrong identifier");
- /* So, we copy the contents of the bucket unsigned into our answer */
- answer->addBucket(bucket);
-
- /* However, if we don't have enough elements in our bucket, we NEED to include at least "BUCKET_SIZE" elements
- * (if, of course, we know at least "BUCKET_SIZE" elements. So we're going to look unsigned into the other buckets.
- */
- for (int i = 1; answer->getSize() < BUCKET_SIZE && ((bucket_id - i > 0) || (bucket_id + i < IDENTIFIER_SIZE)); i++) {
- /* We check the previous buckets */
- if (bucket_id - i >= 0) {
- const Bucket* bucket_p = &table.buckets[bucket_id - i];
- answer->addBucket(bucket_p);
- }
- /* We check the next buckets */
- if (bucket_id + i <= IDENTIFIER_SIZE) {
- const Bucket* bucket_n = &table.buckets[bucket_id + i];
- answer->addBucket(bucket_n);
- }
- }
- /* We trim the array to have only BUCKET_SIZE or less elements */
- answer->trim();
-
- return answer;
-}
-
-/** @brief Send a request to find a node in the node routing table.
- * @param id_to_find the id of the node we are trying to find
- */
-bool Node::findNode(unsigned int id_to_find, bool count_in_stats)
-{
- unsigned int queries;
- unsigned int answers;
- bool destination_found = false;
- unsigned int nodes_added = 0;
- double global_timeout = simgrid::s4u::Engine::get_clock() + FIND_NODE_GLOBAL_TIMEOUT;
- unsigned int steps = 0;
-
- /* First we build a list of who we already know */
- Answer* node_list = findClosest(id_to_find);
- xbt_assert((node_list != nullptr), "node_list incorrect");
- XBT_DEBUG("Doing a FIND_NODE on %08x", id_to_find);
-
- /* Ask the nodes on our list if they have information about the node we are trying to find */
- do {
- answers = 0;
- queries = sendFindNodeToBest(node_list);
- nodes_added = 0;
- double timeout = simgrid::s4u::Engine::get_clock() + FIND_NODE_TIMEOUT;
- steps++;
- double time_beginreceive = simgrid::s4u::Engine::get_clock();
-
- simgrid::s4u::Mailbox* mailbox = simgrid::s4u::Mailbox::by_name(std::to_string(id_));
- do {
- if (receive_comm == nullptr)
- receive_comm = mailbox->get_async(&received_msg);
-
- if (receive_comm->test()) {
- const Message* msg = static_cast<Message*>(received_msg);
- // Check if what we have received is what we are looking for.
- if (msg->answer_ && msg->answer_->getDestinationId() == id_to_find) {
- routingTableUpdate(msg->sender_id_);
- // Handle the answer
- for (auto const& contact : node_list->getNodes())
- routingTableUpdate(contact.first);
- answers++;
-
- nodes_added = node_list->merge(msg->answer_);
- XBT_DEBUG("Received an answer from %s (%s) with %zu nodes on it", msg->answer_to_->get_cname(),
- msg->issuer_host_name_.c_str(), msg->answer_->getSize());
- } else {
- if (msg->answer_) {
- routingTableUpdate(msg->sender_id_);
- XBT_DEBUG("Received a wrong answer for a FIND_NODE");
- } else {
- handleFindNode(msg);
- }
- // Update the timeout if we didn't have our answer
- timeout += simgrid::s4u::Engine::get_clock() - time_beginreceive;
- time_beginreceive = simgrid::s4u::Engine::get_clock();
- }
- delete msg->answer_;
- delete msg;
- receive_comm = nullptr;
- } else {
- simgrid::s4u::this_actor::sleep_for(1);
- }
- } while (simgrid::s4u::Engine::get_clock() < timeout && answers < queries);
- destination_found = node_list->destinationFound();
- } while (not destination_found && (nodes_added > 0 || answers == 0) &&
- simgrid::s4u::Engine::get_clock() < global_timeout && steps < MAX_STEPS);
-
- if (destination_found) {
- if (count_in_stats)
- find_node_success++;
- if (queries > 4)
- XBT_VERB("FIND_NODE on %08x success in %u steps", id_to_find, steps);
- routingTableUpdate(id_to_find);
- } else {
- if (count_in_stats) {
- find_node_failed++;
- XBT_VERB("%08x not found in %u steps", id_to_find, steps);
- }
- }
- delete node_list;
- return destination_found;
-}
-
-/** @brief Does a pseudo-random lookup for someone in the system
- * @param node caller node data
- */
-void Node::randomLookup()
-{
- unsigned int id_to_look = RANDOM_LOOKUP_NODE; // Totally random.
- /* TODO: Use some pseudo-random generator. */
- XBT_DEBUG("I'm doing a random lookup");
- findNode(id_to_look, true);
-}
-
-/** @brief Handles the answer to an incoming "find_node" task */
-void Node::handleFindNode(const Message* msg)
-{
- routingTableUpdate(msg->sender_id_);
- XBT_VERB("Received a FIND_NODE from %s (%s), he's trying to find %08x", msg->answer_to_->get_cname(),
- msg->issuer_host_name_.c_str(), msg->destination_id_);
- // Building the answer to the request
- Message* answer =
- new Message(id_, msg->destination_id_, findClosest(msg->destination_id_),
- simgrid::s4u::Mailbox::by_name(std::to_string(id_)), simgrid::s4u::Host::current()->get_cname());
- // Sending the answer
- msg->answer_to_->put_init(answer, 1)->detach(kademlia::destroy);
-}
-}
-/**@brief Returns an identifier which is in a specific bucket of a routing table
- * @param id id of the routing table owner
- * @param prefix id of the bucket where we want that identifier to be
- */
-unsigned int get_id_in_prefix(unsigned int id, unsigned int prefix)
-{
- if (prefix == 0) {
- return 0;
- } else {
- return (1U << ((unsigned int)(prefix - 1))) ^ id;
- }
-}
-
-/** @brief Returns the prefix of an identifier.
- * The prefix is the id of the bucket in which the remote identifier xor our identifier should be stored.
- * @param id : big unsigned int id to test
- * @param nb_bits : key size
- */
-unsigned int get_node_prefix(unsigned int id, unsigned int nb_bits)
-{
- unsigned int size = sizeof(unsigned int) * 8;
- for (unsigned int j = 0; j < size; j++) {
- if (((id >> (size - 1 - j)) & 0x1) != 0) {
- return nb_bits - (j);
- }
- }
- return 0;
-}
