b4a2681120
This PR reimplements the light client server pool. It is also a first step to move certain logic into a new lespay package. This package will contain the implementation of the lespay token sale functions, the token buying and selling logic and other components related to peer selection/prioritization and service quality evaluation. Over the long term this package will be reusable for incentivizing future protocols. Since the LES peer logic is now based on enode.Iterator, it can now use DNS-based fallback discovery to find servers. This document describes the function of the new components: https://gist.github.com/zsfelfoldi/3c7ace895234b7b345ab4f71dab102d4
129 lines
3.5 KiB
Go
129 lines
3.5 KiB
Go
// Copyright 2020 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package client
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import (
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"sync"
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"github.com/ethereum/go-ethereum/les/utils"
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"github.com/ethereum/go-ethereum/p2p/enode"
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"github.com/ethereum/go-ethereum/p2p/nodestate"
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)
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// WrsIterator returns nodes from the specified selectable set with a weighted random
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// selection. Selection weights are provided by a callback function.
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type WrsIterator struct {
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lock sync.Mutex
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cond *sync.Cond
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ns *nodestate.NodeStateMachine
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wrs *utils.WeightedRandomSelect
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nextNode *enode.Node
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closed bool
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}
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// NewWrsIterator creates a new WrsIterator. Nodes are selectable if they have all the required
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// and none of the disabled flags set. When a node is selected the selectedFlag is set which also
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// disables further selectability until it is removed or times out.
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func NewWrsIterator(ns *nodestate.NodeStateMachine, requireFlags, disableFlags nodestate.Flags, weightField nodestate.Field) *WrsIterator {
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wfn := func(i interface{}) uint64 {
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n := ns.GetNode(i.(enode.ID))
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if n == nil {
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return 0
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}
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wt, _ := ns.GetField(n, weightField).(uint64)
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return wt
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}
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w := &WrsIterator{
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ns: ns,
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wrs: utils.NewWeightedRandomSelect(wfn),
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}
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w.cond = sync.NewCond(&w.lock)
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ns.SubscribeField(weightField, func(n *enode.Node, state nodestate.Flags, oldValue, newValue interface{}) {
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if state.HasAll(requireFlags) && state.HasNone(disableFlags) {
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w.lock.Lock()
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w.wrs.Update(n.ID())
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w.lock.Unlock()
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w.cond.Signal()
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}
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})
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ns.SubscribeState(requireFlags.Or(disableFlags), func(n *enode.Node, oldState, newState nodestate.Flags) {
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oldMatch := oldState.HasAll(requireFlags) && oldState.HasNone(disableFlags)
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newMatch := newState.HasAll(requireFlags) && newState.HasNone(disableFlags)
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if newMatch == oldMatch {
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return
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}
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w.lock.Lock()
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if newMatch {
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w.wrs.Update(n.ID())
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} else {
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w.wrs.Remove(n.ID())
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}
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w.lock.Unlock()
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w.cond.Signal()
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})
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return w
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}
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// Next selects the next node.
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func (w *WrsIterator) Next() bool {
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w.nextNode = w.chooseNode()
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return w.nextNode != nil
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}
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func (w *WrsIterator) chooseNode() *enode.Node {
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w.lock.Lock()
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defer w.lock.Unlock()
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for {
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for !w.closed && w.wrs.IsEmpty() {
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w.cond.Wait()
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}
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if w.closed {
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return nil
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}
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// Choose the next node at random. Even though w.wrs is guaranteed
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// non-empty here, Choose might return nil if all items have weight
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// zero.
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if c := w.wrs.Choose(); c != nil {
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id := c.(enode.ID)
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w.wrs.Remove(id)
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return w.ns.GetNode(id)
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}
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}
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}
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// Close ends the iterator.
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func (w *WrsIterator) Close() {
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w.lock.Lock()
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w.closed = true
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w.lock.Unlock()
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w.cond.Signal()
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}
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// Node returns the current node.
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func (w *WrsIterator) Node() *enode.Node {
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w.lock.Lock()
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defer w.lock.Unlock()
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return w.nextNode
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}
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