go-pulse/p2p/nodestate/nodestate.go
Felföldi Zsolt 4eb9296910
p2p/nodestate: ensure correct callback order (#21436)
This PR adds an extra guarantee to NodeStateMachine: it ensures that all
immediate effects of a certain change are processed before any subsequent
effects of any of the immediate effects on the same node. In the original
version, if a cascaded change caused a subscription callback to be called
multiple times for the same node then these calls might have happened in a
wrong chronological order.

For example:

- a subscription to flag0 changes flag1 and flag2
- a subscription to flag1 changes flag3
- a subscription to flag1, flag2 and flag3 was called in the following order:

   [flag1] -> [flag1, flag3]
   [] -> [flag1]
   [flag1, flag3] -> [flag1, flag2, flag3]

This happened because the tree of changes was traversed in a "depth-first
order". Now it is traversed in a "breadth-first order"; each node has a
FIFO queue for pending callbacks and each triggered subscription callback
is added to the end of the list. The already existing guarantees are
retained; no SetState or SetField returns until the callback queue of the
node is empty again. Just like before, it is the responsibility of the
state machine design to ensure that infinite state loops are not possible.
Multiple changes affecting the same node can still happen simultaneously;
in this case the changes can be interleaved in the FIFO of the node but the
correct order is still guaranteed.

A new unit test is also added to verify callback order in the above scenario.
2020-09-14 14:01:18 +02:00

999 lines
29 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 nodestate
import (
"errors"
"reflect"
"sync"
"time"
"unsafe"
"github.com/ethereum/go-ethereum/common/mclock"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/p2p/enr"
"github.com/ethereum/go-ethereum/rlp"
)
var (
ErrInvalidField = errors.New("invalid field type")
ErrClosed = errors.New("already closed")
)
type (
// NodeStateMachine implements a network node-related event subscription system.
// It can assign binary state flags and fields of arbitrary type to each node and allows
// subscriptions to flag/field changes which can also modify further flags and fields,
// potentially triggering further subscriptions. An operation includes an initial change
// and all resulting subsequent changes and always ends in a consistent global state.
// It is initiated by a "top level" SetState/SetField call that blocks (also blocking other
// top-level functions) until the operation is finished. Callbacks making further changes
// should use the non-blocking SetStateSub/SetFieldSub functions. The tree of events
// resulting from the initial changes is traversed in a breadth-first order, ensuring for
// each subscription callback that all other callbacks caused by the same change triggering
// the current callback are processed before anything is triggered by the changes made in the
// current callback. In practice this logic ensures that all subscriptions "see" events in
// the logical order, callbacks are never called concurrently and "back and forth" effects
// are also possible. The state machine design should ensure that infinite event cycles
// cannot happen.
// The caller can also add timeouts assigned to a certain node and a subset of state flags.
// If the timeout elapses, the flags are reset. If all relevant flags are reset then the timer
// is dropped. State flags with no timeout are persisted in the database if the flag
// descriptor enables saving. If a node has no state flags set at any moment then it is discarded.
// Note: in order to avoid mutex deadlocks the callbacks should never lock a mutex that
// might be locked when the top level SetState/SetField functions are called. If a function
// potentially performs state/field changes then it is recommended to mention this fact in the
// function description, along with whether it should run inside an operation callback.
NodeStateMachine struct {
started, closed bool
lock sync.Mutex
clock mclock.Clock
db ethdb.KeyValueStore
dbNodeKey []byte
nodes map[enode.ID]*nodeInfo
offlineCallbackList []offlineCallback
opFlag bool // an operation has started
opWait *sync.Cond // signaled when the operation ends
opPending []func() // pending callback list of the current operation
// Registered state flags or fields. Modifications are allowed
// only when the node state machine has not been started.
setup *Setup
fields []*fieldInfo
saveFlags bitMask
// Installed callbacks. Modifications are allowed only when the
// node state machine has not been started.
stateSubs []stateSub
// Testing hooks, only for testing purposes.
saveNodeHook func(*nodeInfo)
}
// Flags represents a set of flags from a certain setup
Flags struct {
mask bitMask
setup *Setup
}
// Field represents a field from a certain setup
Field struct {
index int
setup *Setup
}
// flagDefinition describes a node state flag. Each registered instance is automatically
// mapped to a bit of the 64 bit node states.
// If persistent is true then the node is saved when state machine is shutdown.
flagDefinition struct {
name string
persistent bool
}
// fieldDefinition describes an optional node field of the given type. The contents
// of the field are only retained for each node as long as at least one of the
// state flags is set.
fieldDefinition struct {
name string
ftype reflect.Type
encode func(interface{}) ([]byte, error)
decode func([]byte) (interface{}, error)
}
// stateSetup contains the list of flags and fields used by the application
Setup struct {
Version uint
flags []flagDefinition
fields []fieldDefinition
}
// bitMask describes a node state or state mask. It represents a subset
// of node flags with each bit assigned to a flag index (LSB represents flag 0).
bitMask uint64
// StateCallback is a subscription callback which is called when one of the
// state flags that is included in the subscription state mask is changed.
// Note: oldState and newState are also masked with the subscription mask so only
// the relevant bits are included.
StateCallback func(n *enode.Node, oldState, newState Flags)
// FieldCallback is a subscription callback which is called when the value of
// a specific field is changed.
FieldCallback func(n *enode.Node, state Flags, oldValue, newValue interface{})
// nodeInfo contains node state, fields and state timeouts
nodeInfo struct {
node *enode.Node
state bitMask
timeouts []*nodeStateTimeout
fields []interface{}
fieldCount int
db, dirty bool
}
nodeInfoEnc struct {
Enr enr.Record
Version uint
State bitMask
Fields [][]byte
}
stateSub struct {
mask bitMask
callback StateCallback
}
nodeStateTimeout struct {
mask bitMask
timer mclock.Timer
}
fieldInfo struct {
fieldDefinition
subs []FieldCallback
}
offlineCallback struct {
node *nodeInfo
state bitMask
fields []interface{}
}
)
// offlineState is a special state that is assumed to be set before a node is loaded from
// the database and after it is shut down.
const offlineState = bitMask(1)
// NewFlag creates a new node state flag
func (s *Setup) NewFlag(name string) Flags {
if s.flags == nil {
s.flags = []flagDefinition{{name: "offline"}}
}
f := Flags{mask: bitMask(1) << uint(len(s.flags)), setup: s}
s.flags = append(s.flags, flagDefinition{name: name})
return f
}
// NewPersistentFlag creates a new persistent node state flag
func (s *Setup) NewPersistentFlag(name string) Flags {
if s.flags == nil {
s.flags = []flagDefinition{{name: "offline"}}
}
f := Flags{mask: bitMask(1) << uint(len(s.flags)), setup: s}
s.flags = append(s.flags, flagDefinition{name: name, persistent: true})
return f
}
// OfflineFlag returns the system-defined offline flag belonging to the given setup
func (s *Setup) OfflineFlag() Flags {
return Flags{mask: offlineState, setup: s}
}
// NewField creates a new node state field
func (s *Setup) NewField(name string, ftype reflect.Type) Field {
f := Field{index: len(s.fields), setup: s}
s.fields = append(s.fields, fieldDefinition{
name: name,
ftype: ftype,
})
return f
}
// NewPersistentField creates a new persistent node field
func (s *Setup) NewPersistentField(name string, ftype reflect.Type, encode func(interface{}) ([]byte, error), decode func([]byte) (interface{}, error)) Field {
f := Field{index: len(s.fields), setup: s}
s.fields = append(s.fields, fieldDefinition{
name: name,
ftype: ftype,
encode: encode,
decode: decode,
})
return f
}
// flagOp implements binary flag operations and also checks whether the operands belong to the same setup
func flagOp(a, b Flags, trueIfA, trueIfB, trueIfBoth bool) Flags {
if a.setup == nil {
if a.mask != 0 {
panic("Node state flags have no setup reference")
}
a.setup = b.setup
}
if b.setup == nil {
if b.mask != 0 {
panic("Node state flags have no setup reference")
}
b.setup = a.setup
}
if a.setup != b.setup {
panic("Node state flags belong to a different setup")
}
res := Flags{setup: a.setup}
if trueIfA {
res.mask |= a.mask & ^b.mask
}
if trueIfB {
res.mask |= b.mask & ^a.mask
}
if trueIfBoth {
res.mask |= a.mask & b.mask
}
return res
}
// And returns the set of flags present in both a and b
func (a Flags) And(b Flags) Flags { return flagOp(a, b, false, false, true) }
// AndNot returns the set of flags present in a but not in b
func (a Flags) AndNot(b Flags) Flags { return flagOp(a, b, true, false, false) }
// Or returns the set of flags present in either a or b
func (a Flags) Or(b Flags) Flags { return flagOp(a, b, true, true, true) }
// Xor returns the set of flags present in either a or b but not both
func (a Flags) Xor(b Flags) Flags { return flagOp(a, b, true, true, false) }
// HasAll returns true if b is a subset of a
func (a Flags) HasAll(b Flags) bool { return flagOp(a, b, false, true, false).mask == 0 }
// HasNone returns true if a and b have no shared flags
func (a Flags) HasNone(b Flags) bool { return flagOp(a, b, false, false, true).mask == 0 }
// Equals returns true if a and b have the same flags set
func (a Flags) Equals(b Flags) bool { return flagOp(a, b, true, true, false).mask == 0 }
// IsEmpty returns true if a has no flags set
func (a Flags) IsEmpty() bool { return a.mask == 0 }
// MergeFlags merges multiple sets of state flags
func MergeFlags(list ...Flags) Flags {
if len(list) == 0 {
return Flags{}
}
res := list[0]
for i := 1; i < len(list); i++ {
res = res.Or(list[i])
}
return res
}
// String returns a list of the names of the flags specified in the bit mask
func (f Flags) String() string {
if f.mask == 0 {
return "[]"
}
s := "["
comma := false
for index, flag := range f.setup.flags {
if f.mask&(bitMask(1)<<uint(index)) != 0 {
if comma {
s = s + ", "
}
s = s + flag.name
comma = true
}
}
s = s + "]"
return s
}
// NewNodeStateMachine creates a new node state machine.
// If db is not nil then the node states, fields and active timeouts are persisted.
// Persistence can be enabled or disabled for each state flag and field.
func NewNodeStateMachine(db ethdb.KeyValueStore, dbKey []byte, clock mclock.Clock, setup *Setup) *NodeStateMachine {
if setup.flags == nil {
panic("No state flags defined")
}
if len(setup.flags) > 8*int(unsafe.Sizeof(bitMask(0))) {
panic("Too many node state flags")
}
ns := &NodeStateMachine{
db: db,
dbNodeKey: dbKey,
clock: clock,
setup: setup,
nodes: make(map[enode.ID]*nodeInfo),
fields: make([]*fieldInfo, len(setup.fields)),
}
ns.opWait = sync.NewCond(&ns.lock)
stateNameMap := make(map[string]int)
for index, flag := range setup.flags {
if _, ok := stateNameMap[flag.name]; ok {
panic("Node state flag name collision: " + flag.name)
}
stateNameMap[flag.name] = index
if flag.persistent {
ns.saveFlags |= bitMask(1) << uint(index)
}
}
fieldNameMap := make(map[string]int)
for index, field := range setup.fields {
if _, ok := fieldNameMap[field.name]; ok {
panic("Node field name collision: " + field.name)
}
ns.fields[index] = &fieldInfo{fieldDefinition: field}
fieldNameMap[field.name] = index
}
return ns
}
// stateMask checks whether the set of flags belongs to the same setup and returns its internal bit mask
func (ns *NodeStateMachine) stateMask(flags Flags) bitMask {
if flags.setup != ns.setup && flags.mask != 0 {
panic("Node state flags belong to a different setup")
}
return flags.mask
}
// fieldIndex checks whether the field belongs to the same setup and returns its internal index
func (ns *NodeStateMachine) fieldIndex(field Field) int {
if field.setup != ns.setup {
panic("Node field belongs to a different setup")
}
return field.index
}
// SubscribeState adds a node state subscription. The callback is called while the state
// machine mutex is not held and it is allowed to make further state updates using the
// non-blocking SetStateSub/SetFieldSub functions. All callbacks of an operation are running
// from the thread/goroutine of the initial caller and parallel operations are not permitted.
// Therefore the callback is never called concurrently. It is the responsibility of the
// implemented state logic to avoid deadlocks and to reach a stable state in a finite amount
// of steps.
// State subscriptions should be installed before loading the node database or making the
// first state update.
func (ns *NodeStateMachine) SubscribeState(flags Flags, callback StateCallback) {
ns.lock.Lock()
defer ns.lock.Unlock()
if ns.started {
panic("state machine already started")
}
ns.stateSubs = append(ns.stateSubs, stateSub{ns.stateMask(flags), callback})
}
// SubscribeField adds a node field subscription. Same rules apply as for SubscribeState.
func (ns *NodeStateMachine) SubscribeField(field Field, callback FieldCallback) {
ns.lock.Lock()
defer ns.lock.Unlock()
if ns.started {
panic("state machine already started")
}
f := ns.fields[ns.fieldIndex(field)]
f.subs = append(f.subs, callback)
}
// newNode creates a new nodeInfo
func (ns *NodeStateMachine) newNode(n *enode.Node) *nodeInfo {
return &nodeInfo{node: n, fields: make([]interface{}, len(ns.fields))}
}
// checkStarted checks whether the state machine has already been started and panics otherwise.
func (ns *NodeStateMachine) checkStarted() {
if !ns.started {
panic("state machine not started yet")
}
}
// Start starts the state machine, enabling state and field operations and disabling
// further subscriptions.
func (ns *NodeStateMachine) Start() {
ns.lock.Lock()
if ns.started {
panic("state machine already started")
}
ns.started = true
if ns.db != nil {
ns.loadFromDb()
}
ns.opStart()
ns.offlineCallbacks(true)
ns.opFinish()
ns.lock.Unlock()
}
// Stop stops the state machine and saves its state if a database was supplied
func (ns *NodeStateMachine) Stop() {
ns.lock.Lock()
defer ns.lock.Unlock()
ns.checkStarted()
if !ns.opStart() {
panic("already closed")
}
for _, node := range ns.nodes {
fields := make([]interface{}, len(node.fields))
copy(fields, node.fields)
ns.offlineCallbackList = append(ns.offlineCallbackList, offlineCallback{node, node.state, fields})
}
if ns.db != nil {
ns.saveToDb()
}
ns.offlineCallbacks(false)
ns.closed = true
ns.opFinish()
}
// loadFromDb loads persisted node states from the database
func (ns *NodeStateMachine) loadFromDb() {
it := ns.db.NewIterator(ns.dbNodeKey, nil)
for it.Next() {
var id enode.ID
if len(it.Key()) != len(ns.dbNodeKey)+len(id) {
log.Error("Node state db entry with invalid length", "found", len(it.Key()), "expected", len(ns.dbNodeKey)+len(id))
continue
}
copy(id[:], it.Key()[len(ns.dbNodeKey):])
ns.decodeNode(id, it.Value())
}
}
type dummyIdentity enode.ID
func (id dummyIdentity) Verify(r *enr.Record, sig []byte) error { return nil }
func (id dummyIdentity) NodeAddr(r *enr.Record) []byte { return id[:] }
// decodeNode decodes a node database entry and adds it to the node set if successful
func (ns *NodeStateMachine) decodeNode(id enode.ID, data []byte) {
var enc nodeInfoEnc
if err := rlp.DecodeBytes(data, &enc); err != nil {
log.Error("Failed to decode node info", "id", id, "error", err)
return
}
n, _ := enode.New(dummyIdentity(id), &enc.Enr)
node := ns.newNode(n)
node.db = true
if enc.Version != ns.setup.Version {
log.Debug("Removing stored node with unknown version", "current", ns.setup.Version, "stored", enc.Version)
ns.deleteNode(id)
return
}
if len(enc.Fields) > len(ns.setup.fields) {
log.Error("Invalid node field count", "id", id, "stored", len(enc.Fields))
return
}
// Resolve persisted node fields
for i, encField := range enc.Fields {
if len(encField) == 0 {
continue
}
if decode := ns.fields[i].decode; decode != nil {
if field, err := decode(encField); err == nil {
node.fields[i] = field
node.fieldCount++
} else {
log.Error("Failed to decode node field", "id", id, "field name", ns.fields[i].name, "error", err)
return
}
} else {
log.Error("Cannot decode node field", "id", id, "field name", ns.fields[i].name)
return
}
}
// It's a compatible node record, add it to set.
ns.nodes[id] = node
node.state = enc.State
fields := make([]interface{}, len(node.fields))
copy(fields, node.fields)
ns.offlineCallbackList = append(ns.offlineCallbackList, offlineCallback{node, node.state, fields})
log.Debug("Loaded node state", "id", id, "state", Flags{mask: enc.State, setup: ns.setup})
}
// saveNode saves the given node info to the database
func (ns *NodeStateMachine) saveNode(id enode.ID, node *nodeInfo) error {
if ns.db == nil {
return nil
}
storedState := node.state & ns.saveFlags
for _, t := range node.timeouts {
storedState &= ^t.mask
}
enc := nodeInfoEnc{
Enr: *node.node.Record(),
Version: ns.setup.Version,
State: storedState,
Fields: make([][]byte, len(ns.fields)),
}
log.Debug("Saved node state", "id", id, "state", Flags{mask: enc.State, setup: ns.setup})
lastIndex := -1
for i, f := range node.fields {
if f == nil {
continue
}
encode := ns.fields[i].encode
if encode == nil {
continue
}
blob, err := encode(f)
if err != nil {
return err
}
enc.Fields[i] = blob
lastIndex = i
}
if storedState == 0 && lastIndex == -1 {
if node.db {
node.db = false
ns.deleteNode(id)
}
node.dirty = false
return nil
}
enc.Fields = enc.Fields[:lastIndex+1]
data, err := rlp.EncodeToBytes(&enc)
if err != nil {
return err
}
if err := ns.db.Put(append(ns.dbNodeKey, id[:]...), data); err != nil {
return err
}
node.dirty, node.db = false, true
if ns.saveNodeHook != nil {
ns.saveNodeHook(node)
}
return nil
}
// deleteNode removes a node info from the database
func (ns *NodeStateMachine) deleteNode(id enode.ID) {
ns.db.Delete(append(ns.dbNodeKey, id[:]...))
}
// saveToDb saves the persistent flags and fields of all nodes that have been changed
func (ns *NodeStateMachine) saveToDb() {
for id, node := range ns.nodes {
if node.dirty {
err := ns.saveNode(id, node)
if err != nil {
log.Error("Failed to save node", "id", id, "error", err)
}
}
}
}
// updateEnode updates the enode entry belonging to the given node if it already exists
func (ns *NodeStateMachine) updateEnode(n *enode.Node) (enode.ID, *nodeInfo) {
id := n.ID()
node := ns.nodes[id]
if node != nil && n.Seq() > node.node.Seq() {
node.node = n
}
return id, node
}
// Persist saves the persistent state and fields of the given node immediately
func (ns *NodeStateMachine) Persist(n *enode.Node) error {
ns.lock.Lock()
defer ns.lock.Unlock()
ns.checkStarted()
if id, node := ns.updateEnode(n); node != nil && node.dirty {
err := ns.saveNode(id, node)
if err != nil {
log.Error("Failed to save node", "id", id, "error", err)
}
return err
}
return nil
}
// SetState updates the given node state flags and blocks until the operation is finished.
// If a flag with a timeout is set again, the operation removes or replaces the existing timeout.
func (ns *NodeStateMachine) SetState(n *enode.Node, setFlags, resetFlags Flags, timeout time.Duration) error {
ns.lock.Lock()
defer ns.lock.Unlock()
if !ns.opStart() {
return ErrClosed
}
ns.setState(n, setFlags, resetFlags, timeout)
ns.opFinish()
return nil
}
// SetStateSub updates the given node state flags without blocking (should be called
// from a subscription/operation callback).
func (ns *NodeStateMachine) SetStateSub(n *enode.Node, setFlags, resetFlags Flags, timeout time.Duration) {
ns.lock.Lock()
defer ns.lock.Unlock()
ns.opCheck()
ns.setState(n, setFlags, resetFlags, timeout)
}
func (ns *NodeStateMachine) setState(n *enode.Node, setFlags, resetFlags Flags, timeout time.Duration) {
ns.checkStarted()
set, reset := ns.stateMask(setFlags), ns.stateMask(resetFlags)
id, node := ns.updateEnode(n)
if node == nil {
if set == 0 {
return
}
node = ns.newNode(n)
ns.nodes[id] = node
}
oldState := node.state
newState := (node.state & (^reset)) | set
changed := oldState ^ newState
node.state = newState
// Remove the timeout callbacks for all reset and set flags,
// even they are not existent(it's noop).
ns.removeTimeouts(node, set|reset)
// Register the timeout callback if required
if timeout != 0 && set != 0 {
ns.addTimeout(n, set, timeout)
}
if newState == oldState {
return
}
if newState == 0 && node.fieldCount == 0 {
delete(ns.nodes, id)
if node.db {
ns.deleteNode(id)
}
} else {
if changed&ns.saveFlags != 0 {
node.dirty = true
}
}
callback := func() {
for _, sub := range ns.stateSubs {
if changed&sub.mask != 0 {
sub.callback(n, Flags{mask: oldState & sub.mask, setup: ns.setup}, Flags{mask: newState & sub.mask, setup: ns.setup})
}
}
}
ns.opPending = append(ns.opPending, callback)
}
// opCheck checks whether an operation is active
func (ns *NodeStateMachine) opCheck() {
if !ns.opFlag {
panic("Operation has not started")
}
}
// opStart waits until other operations are finished and starts a new one
func (ns *NodeStateMachine) opStart() bool {
for ns.opFlag {
ns.opWait.Wait()
}
if ns.closed {
return false
}
ns.opFlag = true
return true
}
// opFinish finishes the current operation by running all pending callbacks.
// Callbacks resulting from a state/field change performed in a previous callback are always
// put at the end of the pending list and therefore processed after all callbacks resulting
// from the previous state/field change.
func (ns *NodeStateMachine) opFinish() {
for len(ns.opPending) != 0 {
list := ns.opPending
ns.lock.Unlock()
for _, cb := range list {
cb()
}
ns.lock.Lock()
ns.opPending = ns.opPending[len(list):]
}
ns.opPending = nil
ns.opFlag = false
ns.opWait.Signal()
}
// Operation calls the given function as an operation callback. This allows the caller
// to start an operation with multiple initial changes. The same rules apply as for
// subscription callbacks.
func (ns *NodeStateMachine) Operation(fn func()) error {
ns.lock.Lock()
started := ns.opStart()
ns.lock.Unlock()
if !started {
return ErrClosed
}
fn()
ns.lock.Lock()
ns.opFinish()
ns.lock.Unlock()
return nil
}
// offlineCallbacks calls state update callbacks at startup or shutdown
func (ns *NodeStateMachine) offlineCallbacks(start bool) {
for _, cb := range ns.offlineCallbackList {
cb := cb
callback := func() {
for _, sub := range ns.stateSubs {
offState := offlineState & sub.mask
onState := cb.state & sub.mask
if offState == onState {
continue
}
if start {
sub.callback(cb.node.node, Flags{mask: offState, setup: ns.setup}, Flags{mask: onState, setup: ns.setup})
} else {
sub.callback(cb.node.node, Flags{mask: onState, setup: ns.setup}, Flags{mask: offState, setup: ns.setup})
}
}
for i, f := range cb.fields {
if f == nil || ns.fields[i].subs == nil {
continue
}
for _, fsub := range ns.fields[i].subs {
if start {
fsub(cb.node.node, Flags{mask: offlineState, setup: ns.setup}, nil, f)
} else {
fsub(cb.node.node, Flags{mask: offlineState, setup: ns.setup}, f, nil)
}
}
}
}
ns.opPending = append(ns.opPending, callback)
}
ns.offlineCallbackList = nil
}
// AddTimeout adds a node state timeout associated to the given state flag(s).
// After the specified time interval, the relevant states will be reset.
func (ns *NodeStateMachine) AddTimeout(n *enode.Node, flags Flags, timeout time.Duration) error {
ns.lock.Lock()
defer ns.lock.Unlock()
ns.checkStarted()
if ns.closed {
return ErrClosed
}
ns.addTimeout(n, ns.stateMask(flags), timeout)
return nil
}
// addTimeout adds a node state timeout associated to the given state flag(s).
func (ns *NodeStateMachine) addTimeout(n *enode.Node, mask bitMask, timeout time.Duration) {
_, node := ns.updateEnode(n)
if node == nil {
return
}
mask &= node.state
if mask == 0 {
return
}
ns.removeTimeouts(node, mask)
t := &nodeStateTimeout{mask: mask}
t.timer = ns.clock.AfterFunc(timeout, func() {
ns.SetState(n, Flags{}, Flags{mask: t.mask, setup: ns.setup}, 0)
})
node.timeouts = append(node.timeouts, t)
if mask&ns.saveFlags != 0 {
node.dirty = true
}
}
// removeTimeout removes node state timeouts associated to the given state flag(s).
// If a timeout was associated to multiple flags which are not all included in the
// specified remove mask then only the included flags are de-associated and the timer
// stays active.
func (ns *NodeStateMachine) removeTimeouts(node *nodeInfo, mask bitMask) {
for i := 0; i < len(node.timeouts); i++ {
t := node.timeouts[i]
match := t.mask & mask
if match == 0 {
continue
}
t.mask -= match
if t.mask != 0 {
continue
}
t.timer.Stop()
node.timeouts[i] = node.timeouts[len(node.timeouts)-1]
node.timeouts = node.timeouts[:len(node.timeouts)-1]
i--
if match&ns.saveFlags != 0 {
node.dirty = true
}
}
}
// GetField retrieves the given field of the given node. Note that when used in a
// subscription callback the result can be out of sync with the state change represented
// by the callback parameters so extra safety checks might be necessary.
func (ns *NodeStateMachine) GetField(n *enode.Node, field Field) interface{} {
ns.lock.Lock()
defer ns.lock.Unlock()
ns.checkStarted()
if ns.closed {
return nil
}
if _, node := ns.updateEnode(n); node != nil {
return node.fields[ns.fieldIndex(field)]
}
return nil
}
// SetField sets the given field of the given node and blocks until the operation is finished
func (ns *NodeStateMachine) SetField(n *enode.Node, field Field, value interface{}) error {
ns.lock.Lock()
defer ns.lock.Unlock()
if !ns.opStart() {
return ErrClosed
}
err := ns.setField(n, field, value)
ns.opFinish()
return err
}
// SetFieldSub sets the given field of the given node without blocking (should be called
// from a subscription/operation callback).
func (ns *NodeStateMachine) SetFieldSub(n *enode.Node, field Field, value interface{}) error {
ns.lock.Lock()
defer ns.lock.Unlock()
ns.opCheck()
return ns.setField(n, field, value)
}
func (ns *NodeStateMachine) setField(n *enode.Node, field Field, value interface{}) error {
ns.checkStarted()
id, node := ns.updateEnode(n)
if node == nil {
if value == nil {
return nil
}
node = ns.newNode(n)
ns.nodes[id] = node
}
fieldIndex := ns.fieldIndex(field)
f := ns.fields[fieldIndex]
if value != nil && reflect.TypeOf(value) != f.ftype {
log.Error("Invalid field type", "type", reflect.TypeOf(value), "required", f.ftype)
return ErrInvalidField
}
oldValue := node.fields[fieldIndex]
if value == oldValue {
return nil
}
if oldValue != nil {
node.fieldCount--
}
if value != nil {
node.fieldCount++
}
node.fields[fieldIndex] = value
if node.state == 0 && node.fieldCount == 0 {
delete(ns.nodes, id)
if node.db {
ns.deleteNode(id)
}
} else {
if f.encode != nil {
node.dirty = true
}
}
state := node.state
callback := func() {
for _, cb := range f.subs {
cb(n, Flags{mask: state, setup: ns.setup}, oldValue, value)
}
}
ns.opPending = append(ns.opPending, callback)
return nil
}
// ForEach calls the callback for each node having all of the required and none of the
// disabled flags set.
// Note that this callback is not an operation callback but ForEach can be called from an
// Operation callback or Operation can also be called from a ForEach callback if necessary.
func (ns *NodeStateMachine) ForEach(requireFlags, disableFlags Flags, cb func(n *enode.Node, state Flags)) {
ns.lock.Lock()
ns.checkStarted()
type callback struct {
node *enode.Node
state bitMask
}
require, disable := ns.stateMask(requireFlags), ns.stateMask(disableFlags)
var callbacks []callback
for _, node := range ns.nodes {
if node.state&require == require && node.state&disable == 0 {
callbacks = append(callbacks, callback{node.node, node.state & (require | disable)})
}
}
ns.lock.Unlock()
for _, c := range callbacks {
cb(c.node, Flags{mask: c.state, setup: ns.setup})
}
}
// GetNode returns the enode currently associated with the given ID
func (ns *NodeStateMachine) GetNode(id enode.ID) *enode.Node {
ns.lock.Lock()
defer ns.lock.Unlock()
ns.checkStarted()
if node := ns.nodes[id]; node != nil {
return node.node
}
return nil
}
// AddLogMetrics adds logging and/or metrics for nodes entering, exiting and currently
// being in a given set specified by required and disabled state flags
func (ns *NodeStateMachine) AddLogMetrics(requireFlags, disableFlags Flags, name string, inMeter, outMeter metrics.Meter, gauge metrics.Gauge) {
var count int64
ns.SubscribeState(requireFlags.Or(disableFlags), func(n *enode.Node, oldState, newState Flags) {
oldMatch := oldState.HasAll(requireFlags) && oldState.HasNone(disableFlags)
newMatch := newState.HasAll(requireFlags) && newState.HasNone(disableFlags)
if newMatch == oldMatch {
return
}
if newMatch {
count++
if name != "" {
log.Debug("Node entered", "set", name, "id", n.ID(), "count", count)
}
if inMeter != nil {
inMeter.Mark(1)
}
} else {
count--
if name != "" {
log.Debug("Node left", "set", name, "id", n.ID(), "count", count)
}
if outMeter != nil {
outMeter.Mark(1)
}
}
if gauge != nil {
gauge.Update(count)
}
})
}