plugeth/les/vflux/client/queueiterator.go

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// Copyright 2020 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package client
import (
"sync"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/p2p/nodestate"
)
// QueueIterator returns nodes from the specified selectable set in the same order as
// they entered the set.
type QueueIterator struct {
lock sync.Mutex
cond *sync.Cond
ns *nodestate.NodeStateMachine
queue []*enode.Node
nextNode *enode.Node
waitCallback func(bool)
fifo, closed bool
}
// NewQueueIterator creates a new QueueIterator. Nodes are selectable if they have all the required
// and none of the disabled flags set. When a node is selected the selectedFlag is set which also
// disables further selectability until it is removed or times out.
func NewQueueIterator(ns *nodestate.NodeStateMachine, requireFlags, disableFlags nodestate.Flags, fifo bool, waitCallback func(bool)) *QueueIterator {
qi := &QueueIterator{
ns: ns,
fifo: fifo,
waitCallback: waitCallback,
}
qi.cond = sync.NewCond(&qi.lock)
ns.SubscribeState(requireFlags.Or(disableFlags), func(n *enode.Node, oldState, newState nodestate.Flags) {
oldMatch := oldState.HasAll(requireFlags) && oldState.HasNone(disableFlags)
newMatch := newState.HasAll(requireFlags) && newState.HasNone(disableFlags)
if newMatch == oldMatch {
return
}
qi.lock.Lock()
defer qi.lock.Unlock()
if newMatch {
qi.queue = append(qi.queue, n)
} else {
id := n.ID()
for i, qn := range qi.queue {
if qn.ID() == id {
copy(qi.queue[i:len(qi.queue)-1], qi.queue[i+1:])
qi.queue = qi.queue[:len(qi.queue)-1]
break
}
}
}
qi.cond.Signal()
})
return qi
}
// Next moves to the next selectable node.
func (qi *QueueIterator) Next() bool {
qi.lock.Lock()
if !qi.closed && len(qi.queue) == 0 {
if qi.waitCallback != nil {
qi.waitCallback(true)
}
for !qi.closed && len(qi.queue) == 0 {
qi.cond.Wait()
}
if qi.waitCallback != nil {
qi.waitCallback(false)
}
}
if qi.closed {
qi.nextNode = nil
qi.lock.Unlock()
return false
}
// Move to the next node in queue.
if qi.fifo {
qi.nextNode = qi.queue[0]
copy(qi.queue[:len(qi.queue)-1], qi.queue[1:])
qi.queue = qi.queue[:len(qi.queue)-1]
} else {
qi.nextNode = qi.queue[len(qi.queue)-1]
qi.queue = qi.queue[:len(qi.queue)-1]
}
qi.lock.Unlock()
return true
}
// Close ends the iterator.
func (qi *QueueIterator) Close() {
qi.lock.Lock()
qi.closed = true
qi.lock.Unlock()
qi.cond.Signal()
}
// Node returns the current node.
func (qi *QueueIterator) Node() *enode.Node {
qi.lock.Lock()
defer qi.lock.Unlock()
return qi.nextNode
}