github.com/DxChainNetwork/dxc@v0.8.1-0.20220824085222-1162e304b6e7/les/vflux/client/fillset.go (about)

     1  // Copyright 2020 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package client
    18  
    19  import (
    20  	"sync"
    21  
    22  	"github.com/DxChainNetwork/dxc/p2p/enode"
    23  	"github.com/DxChainNetwork/dxc/p2p/nodestate"
    24  )
    25  
    26  // FillSet tries to read nodes from an input iterator and add them to a node set by
    27  // setting the specified node state flag(s) until the size of the set reaches the target.
    28  // Note that other mechanisms (like other FillSet instances reading from different inputs)
    29  // can also set the same flag(s) and FillSet will always care about the total number of
    30  // nodes having those flags.
    31  type FillSet struct {
    32  	lock          sync.Mutex
    33  	cond          *sync.Cond
    34  	ns            *nodestate.NodeStateMachine
    35  	input         enode.Iterator
    36  	closed        bool
    37  	flags         nodestate.Flags
    38  	count, target int
    39  }
    40  
    41  // NewFillSet creates a new FillSet
    42  func NewFillSet(ns *nodestate.NodeStateMachine, input enode.Iterator, flags nodestate.Flags) *FillSet {
    43  	fs := &FillSet{
    44  		ns:    ns,
    45  		input: input,
    46  		flags: flags,
    47  	}
    48  	fs.cond = sync.NewCond(&fs.lock)
    49  
    50  	ns.SubscribeState(flags, func(n *enode.Node, oldState, newState nodestate.Flags) {
    51  		fs.lock.Lock()
    52  		if oldState.Equals(flags) {
    53  			fs.count--
    54  		}
    55  		if newState.Equals(flags) {
    56  			fs.count++
    57  		}
    58  		if fs.target > fs.count {
    59  			fs.cond.Signal()
    60  		}
    61  		fs.lock.Unlock()
    62  	})
    63  
    64  	go fs.readLoop()
    65  	return fs
    66  }
    67  
    68  // readLoop keeps reading nodes from the input and setting the specified flags for them
    69  // whenever the node set size is under the current target
    70  func (fs *FillSet) readLoop() {
    71  	for {
    72  		fs.lock.Lock()
    73  		for fs.target <= fs.count && !fs.closed {
    74  			fs.cond.Wait()
    75  		}
    76  
    77  		fs.lock.Unlock()
    78  		if !fs.input.Next() {
    79  			return
    80  		}
    81  		fs.ns.SetState(fs.input.Node(), fs.flags, nodestate.Flags{}, 0)
    82  	}
    83  }
    84  
    85  // SetTarget sets the current target for node set size. If the previous target was not
    86  // reached and FillSet was still waiting for the next node from the input then the next
    87  // incoming node will be added to the set regardless of the target. This ensures that
    88  // all nodes coming from the input are eventually added to the set.
    89  func (fs *FillSet) SetTarget(target int) {
    90  	fs.lock.Lock()
    91  	defer fs.lock.Unlock()
    92  
    93  	fs.target = target
    94  	if fs.target > fs.count {
    95  		fs.cond.Signal()
    96  	}
    97  }
    98  
    99  // Close shuts FillSet down and closes the input iterator
   100  func (fs *FillSet) Close() {
   101  	fs.lock.Lock()
   102  	defer fs.lock.Unlock()
   103  
   104  	fs.closed = true
   105  	fs.input.Close()
   106  	fs.cond.Signal()
   107  }