go-ethereum/p2p/simulations/events.go
Ferenc Szabo 50b872bf05 p2p, swarm: fix node up races by granular locking (#18976)
* swarm/network: DRY out repeated giga comment

I not necessarily agree with the way we wait for event propagation.
But I truly disagree with having duplicated giga comments.

* p2p/simulations: encapsulate Node.Up field so we avoid data races

The Node.Up field was accessed concurrently without "proper" locking.
There was a lock on Network and that was used sometimes to access
the  field. Other times the locking was missed and we had
a data race.

For example: https://github.com/ethereum/go-ethereum/pull/18464
The case above was solved, but there were still intermittent/hard to
reproduce races. So let's solve the issue permanently.

resolves: ethersphere/go-ethereum#1146

* p2p/simulations: fix unmarshal of simulations.Node

Making Node.Up field private in 13292ee897e345045fbfab3bda23a77589a271c1
broke TestHTTPNetwork and TestHTTPSnapshot. Because the default
UnmarshalJSON does not handle unexported fields.

Important: The fix is partial and not proper to my taste. But I cut
scope as I think the fix may require a change to the current
serialization format. New ticket:
https://github.com/ethersphere/go-ethereum/issues/1177

* p2p/simulations: Add a sanity test case for Node.Config UnmarshalJSON

* p2p/simulations: revert back to defer Unlock() pattern for Network

It's a good patten to call `defer Unlock()` right after `Lock()` so
(new) error cases won't miss to unlock. Let's get back to that pattern.

The patten was abandoned in 85a79b3ad3c5863f8612d25c246bcfad339f36b7,
while fixing a data race. That data race does not exist anymore,
since the Node.Up field got hidden behind its own lock.

* p2p/simulations: consistent naming for test providers Node.UnmarshalJSON

* p2p/simulations: remove JSON annotation from private fields of Node

As unexported fields are not serialized.

* p2p/simulations: fix deadlock in Network.GetRandomDownNode()

Problem: GetRandomDownNode() locks -> getDownNodeIDs() ->
GetNodes() tries to lock -> deadlock

On Network type, unexported functions must assume that `net.lock`
is already acquired and should not call exported functions which
might try to lock again.

* p2p/simulations: ensure method conformity for Network

Connect* methods were moved to p2p/simulations.Network from
swarm/network/simulation. However these new methods did not follow
the pattern of Network methods, i.e., all exported method locks
the whole Network either for read or write.

* p2p/simulations: fix deadlock during network shutdown

`TestDiscoveryPersistenceSimulationSimAdapter` often got into deadlock.
The execution was stuck on two locks, i.e, `Kademlia.lock` and
`p2p/simulations.Network.lock`. Usually the test got stuck once in each
20 executions with high confidence.

`Kademlia` was stuck in `Kademlia.EachAddr()` and `Network` in
`Network.Stop()`.

Solution: in `Network.Stop()` `net.lock` must be released before
calling `node.Stop()` as stopping a node (somehow - I did not find
the exact code path) causes `Network.InitConn()` to be called from
`Kademlia.SuggestPeer()` and that blocks on `net.lock`.

Related ticket: https://github.com/ethersphere/go-ethereum/issues/1223

* swarm/state: simplify if statement in DBStore.Put()

* p2p/simulations: remove faulty godoc from private function

The comment started with the wrong method name.

The method is simple and self explanatory. Also, it's private.
=> Let's just remove the comment.
2019-02-18 07:38:14 +01:00

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Go

// Copyright 2017 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 simulations
import (
"fmt"
"time"
)
// EventType is the type of event emitted by a simulation network
type EventType string
const (
// EventTypeNode is the type of event emitted when a node is either
// created, started or stopped
EventTypeNode EventType = "node"
// EventTypeConn is the type of event emitted when a connection is
// is either established or dropped between two nodes
EventTypeConn EventType = "conn"
// EventTypeMsg is the type of event emitted when a p2p message it
// sent between two nodes
EventTypeMsg EventType = "msg"
)
// Event is an event emitted by a simulation network
type Event struct {
// Type is the type of the event
Type EventType `json:"type"`
// Time is the time the event happened
Time time.Time `json:"time"`
// Control indicates whether the event is the result of a controlled
// action in the network
Control bool `json:"control"`
// Node is set if the type is EventTypeNode
Node *Node `json:"node,omitempty"`
// Conn is set if the type is EventTypeConn
Conn *Conn `json:"conn,omitempty"`
// Msg is set if the type is EventTypeMsg
Msg *Msg `json:"msg,omitempty"`
//Optionally provide data (currently for simulation frontends only)
Data interface{} `json:"data"`
}
// NewEvent creates a new event for the given object which should be either a
// Node, Conn or Msg.
//
// The object is copied so that the event represents the state of the object
// when NewEvent is called.
func NewEvent(v interface{}) *Event {
event := &Event{Time: time.Now()}
switch v := v.(type) {
case *Node:
event.Type = EventTypeNode
node := *v
event.Node = &node
case *Conn:
event.Type = EventTypeConn
conn := *v
event.Conn = &conn
case *Msg:
event.Type = EventTypeMsg
msg := *v
event.Msg = &msg
default:
panic(fmt.Sprintf("invalid event type: %T", v))
}
return event
}
// ControlEvent creates a new control event
func ControlEvent(v interface{}) *Event {
event := NewEvent(v)
event.Control = true
return event
}
// String returns the string representation of the event
func (e *Event) String() string {
switch e.Type {
case EventTypeNode:
return fmt.Sprintf("<node-event> id: %s up: %t", e.Node.ID().TerminalString(), e.Node.Up())
case EventTypeConn:
return fmt.Sprintf("<conn-event> nodes: %s->%s up: %t", e.Conn.One.TerminalString(), e.Conn.Other.TerminalString(), e.Conn.Up)
case EventTypeMsg:
return fmt.Sprintf("<msg-event> nodes: %s->%s proto: %s, code: %d, received: %t", e.Msg.One.TerminalString(), e.Msg.Other.TerminalString(), e.Msg.Protocol, e.Msg.Code, e.Msg.Received)
default:
return ""
}
}