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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