go-pulse/les/vflux/client/fillset.go
2021-02-19 14:44:16 +01:00

108 lines
3.1 KiB
Go

// 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"
)
// FillSet tries to read nodes from an input iterator and add them to a node set by
// setting the specified node state flag(s) until the size of the set reaches the target.
// Note that other mechanisms (like other FillSet instances reading from different inputs)
// can also set the same flag(s) and FillSet will always care about the total number of
// nodes having those flags.
type FillSet struct {
lock sync.Mutex
cond *sync.Cond
ns *nodestate.NodeStateMachine
input enode.Iterator
closed bool
flags nodestate.Flags
count, target int
}
// NewFillSet creates a new FillSet
func NewFillSet(ns *nodestate.NodeStateMachine, input enode.Iterator, flags nodestate.Flags) *FillSet {
fs := &FillSet{
ns: ns,
input: input,
flags: flags,
}
fs.cond = sync.NewCond(&fs.lock)
ns.SubscribeState(flags, func(n *enode.Node, oldState, newState nodestate.Flags) {
fs.lock.Lock()
if oldState.Equals(flags) {
fs.count--
}
if newState.Equals(flags) {
fs.count++
}
if fs.target > fs.count {
fs.cond.Signal()
}
fs.lock.Unlock()
})
go fs.readLoop()
return fs
}
// readLoop keeps reading nodes from the input and setting the specified flags for them
// whenever the node set size is under the current target
func (fs *FillSet) readLoop() {
for {
fs.lock.Lock()
for fs.target <= fs.count && !fs.closed {
fs.cond.Wait()
}
fs.lock.Unlock()
if !fs.input.Next() {
return
}
fs.ns.SetState(fs.input.Node(), fs.flags, nodestate.Flags{}, 0)
}
}
// SetTarget sets the current target for node set size. If the previous target was not
// reached and FillSet was still waiting for the next node from the input then the next
// incoming node will be added to the set regardless of the target. This ensures that
// all nodes coming from the input are eventually added to the set.
func (fs *FillSet) SetTarget(target int) {
fs.lock.Lock()
defer fs.lock.Unlock()
fs.target = target
if fs.target > fs.count {
fs.cond.Signal()
}
}
// Close shuts FillSet down and closes the input iterator
func (fs *FillSet) Close() {
fs.lock.Lock()
defer fs.lock.Unlock()
fs.closed = true
fs.input.Close()
fs.cond.Signal()
}