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https://github.com/oxen-io/lokinet.git
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f3deabdb96
* add remove_node_from_failing to remove a node by pubkey from the failing set * if a router is deregistered we remove it from the failing set so we don't retest it * remove a router from the failing set if we get a test success
149 lines
6.1 KiB
C++
149 lines
6.1 KiB
C++
#pragma once
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#include <chrono>
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#include <queue>
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#include <random>
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#include <unordered_map>
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#include <unordered_set>
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#include <vector>
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#include <llarp/util/time.hpp>
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#include <llarp/router_id.hpp>
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namespace llarp
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{
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struct AbstractRouter;
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}
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namespace llarp::consensus
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{
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namespace detail
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{
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using clock_t = std::chrono::steady_clock;
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using time_point_t = std::chrono::time_point<clock_t>;
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// Returns std::greater on the std::get<N>(v)th element value.
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template <typename T, size_t N>
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struct nth_greater
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{
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constexpr bool
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operator()(const T& lhs, const T& rhs) const
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{
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return std::greater<std::tuple_element_t<N, T>>{}(std::get<N>(lhs), std::get<N>(rhs));
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}
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};
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struct incoming_test_state
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{
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time_point_t last_test{};
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time_point_t last_whine{};
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bool was_failing = false;
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};
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} // namespace detail
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using time_point_t = detail::time_point_t;
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using clock_t = detail::clock_t;
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// How often we tick the timer to check whether we need to do any tests.
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constexpr auto REACHABILITY_TESTING_TIMER_INTERVAL = 50ms;
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class reachability_testing
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{
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public:
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// Distribution for the seconds between node tests: we throw in some randomness to avoid
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// potential clustering of tests. (Note that there is some granularity here as the test timer
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// only runs every REACHABILITY_TESTING_TIMER_INTERVAL).
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std::normal_distribution<float> TESTING_INTERVAL{10.0, 3.0};
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// The linear backoff after each consecutive test failure before we re-test. Specifically we
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// schedule the next re-test for (TESTING_BACKOFF*previous_failures) + TESTING_INTERVAL(rng).
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inline static constexpr auto TESTING_BACKOFF = 10s;
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// The upper bound for the re-test interval.
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inline static constexpr auto TESTING_BACKOFF_MAX = 2min;
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// The maximum number of nodes that we will re-test at once (i.e. per TESTING_TIMING_INTERVAL);
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// mainly intended to throttle ourselves if, for instance, our own connectivity loss makes us
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// accumulate tons of nodes to test all at once. (Despite the random intervals, this can happen
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// if we also get decommissioned during which we can't test at all but still have lots of
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// failing nodes we want to test right away when we get recommissioned).
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inline static constexpr int MAX_RETESTS_PER_TICK = 4;
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// Maximum time without a ping before we start whining about it.
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//
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// We have a probability of about 0.368* of *not* getting pinged within a ping interval (10s),
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// and so the probability of not getting a ping for 2 minutes (i.e. 12 test spans) just because
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// we haven't been selected is extremely small (0.0000061). It also coincides nicely with
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// blockchain time (i.e. two minutes) and our max testing backoff.
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//
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// * = approx value of ((n-1)/n)^n for non-tiny values of n
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inline static constexpr auto MAX_TIME_WITHOUT_PING = 2min;
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// How often we whine in the logs about being unreachable
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inline static constexpr auto WHINING_INTERVAL = 2min;
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private:
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// Queue of pubkeys of service nodes to test; we pop off the back of this until the queue
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// empties then we refill it with a shuffled list of all pubkeys then pull off of it until it is
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// empty again, etc.
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std::vector<RouterID> testing_queue;
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// The next time for a general test
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time_point_t next_general_test = time_point_t::min();
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// When we started, so that we know not to hold off on whining about no pings for a while.
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const time_point_t startup = clock_t::now();
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// Pubkeys, next test times, and sequential failure counts of service nodes that are currently
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// in "failed" status along with the last time they failed; we retest them first after 10s then
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// back off linearly by an additional 10s up to a max testing interval of 2m30s, until we get a
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// successful response.
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using FailingPK = std::tuple<RouterID, time_point_t, int>;
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std::priority_queue<FailingPK, std::vector<FailingPK>, detail::nth_greater<FailingPK, 1>>
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failing_queue;
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std::unordered_set<RouterID> failing;
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// Track the last time *this node* was tested by other network nodes; used to detect and warn
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// about possible network issues.
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detail::incoming_test_state last;
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public:
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// If it is time to perform another random test, this returns the next node to test from the
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// testing queue and returns it, also updating the timer for the next test. If it is not yet
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// time, or if the queue is empty and cannot current be replenished, returns std::nullopt. If
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// the queue empties then this builds a new one by shuffling current public keys in the swarm's
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// "all nodes" then starts using the new queue for this an subsequent calls.
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//
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// `requeue` is mainly for internal use: if false it avoids rebuilding the queue if we run
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// out (and instead just return nullopt).
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std::optional<RouterID>
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next_random(
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AbstractRouter* router, const time_point_t& now = clock_t::now(), bool requeue = true);
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// Removes and returns up to MAX_RETESTS_PER_TICK nodes that are due to be tested (i.e.
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// next-testing-time <= now). Returns [snrecord, #previous-failures] for each.
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std::vector<std::pair<RouterID, int>>
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get_failing(const time_point_t& now = clock_t::now());
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// Adds a bad node pubkey to the failing list, to be re-tested soon (with a backoff depending on
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// `failures`; see TESTING_BACKOFF). `previous_failures` should be the number of previous
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// failures *before* this one, i.e. 0 for a random general test; or the failure count returned
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// by `get_failing` for repeated failures.
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void
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add_failing_node(const RouterID& pk, int previous_failures = 0);
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/// removes the public key from the failing set
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void
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remove_node_from_failing(const RouterID& pk);
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// Called when this router receives an incomming session
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void
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incoming_ping(const time_point_t& now = clock_t::now());
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// Check whether we received incoming pings recently
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void
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check_incoming_tests(const time_point_t& now = clock_t::now());
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};
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} // namespace llarp::consensus
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