124 lines
3.3 KiB
Go
124 lines
3.3 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/p2p/enode"
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"github.com/ethereum/go-ethereum/p2p/nodestate"
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)
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// QueueIterator returns nodes from the specified selectable set in the same order as
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// they entered the set.
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type QueueIterator 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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queue []*enode.Node
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nextNode *enode.Node
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waitCallback func(bool)
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fifo, closed bool
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}
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// NewQueueIterator creates a new QueueIterator. 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 NewQueueIterator(ns *nodestate.NodeStateMachine, requireFlags, disableFlags nodestate.Flags, fifo bool, waitCallback func(bool)) *QueueIterator {
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qi := &QueueIterator{
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ns: ns,
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fifo: fifo,
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waitCallback: waitCallback,
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}
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qi.cond = sync.NewCond(&qi.lock)
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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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qi.lock.Lock()
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defer qi.lock.Unlock()
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if newMatch {
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qi.queue = append(qi.queue, n)
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} else {
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id := n.ID()
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for i, qn := range qi.queue {
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if qn.ID() == id {
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copy(qi.queue[i:len(qi.queue)-1], qi.queue[i+1:])
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qi.queue = qi.queue[:len(qi.queue)-1]
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break
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}
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}
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}
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qi.cond.Signal()
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})
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return qi
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}
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// Next moves to the next selectable node.
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func (qi *QueueIterator) Next() bool {
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qi.lock.Lock()
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if !qi.closed && len(qi.queue) == 0 {
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if qi.waitCallback != nil {
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qi.waitCallback(true)
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}
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for !qi.closed && len(qi.queue) == 0 {
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qi.cond.Wait()
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}
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if qi.waitCallback != nil {
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qi.waitCallback(false)
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}
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}
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if qi.closed {
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qi.nextNode = nil
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qi.lock.Unlock()
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return false
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}
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// Move to the next node in queue.
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if qi.fifo {
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qi.nextNode = qi.queue[0]
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copy(qi.queue[:len(qi.queue)-1], qi.queue[1:])
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qi.queue = qi.queue[:len(qi.queue)-1]
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} else {
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qi.nextNode = qi.queue[len(qi.queue)-1]
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qi.queue = qi.queue[:len(qi.queue)-1]
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}
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qi.lock.Unlock()
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return true
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}
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// Close ends the iterator.
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func (qi *QueueIterator) Close() {
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qi.lock.Lock()
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qi.closed = true
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qi.lock.Unlock()
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qi.cond.Signal()
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}
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// Node returns the current node.
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func (qi *QueueIterator) Node() *enode.Node {
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qi.lock.Lock()
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defer qi.lock.Unlock()
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return qi.nextNode
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}
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