lotus/chain/events/events_called.go
2020-10-30 14:00:32 +01:00

610 lines
18 KiB
Go

package events
import (
"context"
"math"
"sync"
"github.com/filecoin-project/go-state-types/abi"
"github.com/ipfs/go-cid"
"golang.org/x/xerrors"
"github.com/filecoin-project/lotus/chain/types"
)
const NoTimeout = math.MaxInt64
const NoHeight = abi.ChainEpoch(-1)
type triggerID = uint64
// msgH is the block height at which a message was present / event has happened
type msgH = abi.ChainEpoch
// triggerH is the block height at which the listener will be notified about the
// message (msgH+confidence)
type triggerH = abi.ChainEpoch
type eventData interface{}
// EventHandler arguments:
// `prevTs` is the previous tipset, eg the "from" tipset for a state change.
// `ts` is the event tipset, eg the tipset in which the `msg` is included.
// `curH`-`ts.Height` = `confidence`
type EventHandler func(data eventData, prevTs, ts *types.TipSet, curH abi.ChainEpoch) (more bool, err error)
// CheckFunc is used for atomicity guarantees. If the condition the callbacks
// wait for has already happened in tipset `ts`
//
// If `done` is true, timeout won't be triggered
// If `more` is false, no messages will be sent to EventHandler (RevertHandler
// may still be called)
type CheckFunc func(ts *types.TipSet) (done bool, more bool, err error)
// Keep track of information for an event handler
type handlerInfo struct {
confidence int
timeout abi.ChainEpoch
disabled bool // TODO: GC after gcConfidence reached
handle EventHandler
revert RevertHandler
}
// When a change occurs, a queuedEvent is created and put into a queue
// until the required confidence is reached
type queuedEvent struct {
trigger triggerID
prevH abi.ChainEpoch
h abi.ChainEpoch
data eventData
called bool
}
// Manages chain head change events, which may be forward (new tipset added to
// chain) or backward (chain branch discarded in favour of heavier branch)
type hcEvents struct {
cs eventAPI
tsc *tipSetCache
ctx context.Context
gcConfidence uint64
lastTs *types.TipSet
lk sync.Mutex
ctr triggerID
triggers map[triggerID]*handlerInfo
// maps block heights to events
// [triggerH][msgH][event]
confQueue map[triggerH]map[msgH][]*queuedEvent
// [msgH][triggerH]
revertQueue map[msgH][]triggerH
// [timeoutH+confidence][triggerID]{calls}
timeouts map[abi.ChainEpoch]map[triggerID]int
messageEvents
watcherEvents
}
func newHCEvents(ctx context.Context, cs eventAPI, tsc *tipSetCache, gcConfidence uint64) *hcEvents {
e := hcEvents{
ctx: ctx,
cs: cs,
tsc: tsc,
gcConfidence: gcConfidence,
confQueue: map[triggerH]map[msgH][]*queuedEvent{},
revertQueue: map[msgH][]triggerH{},
triggers: map[triggerID]*handlerInfo{},
timeouts: map[abi.ChainEpoch]map[triggerID]int{},
}
e.messageEvents = newMessageEvents(ctx, &e, cs)
e.watcherEvents = newWatcherEvents(ctx, &e, cs)
return &e
}
// Called when there is a change to the head with tipsets to be
// reverted / applied
func (e *hcEvents) processHeadChangeEvent(rev, app []*types.TipSet) error {
e.lk.Lock()
defer e.lk.Unlock()
for _, ts := range rev {
e.handleReverts(ts)
e.lastTs = ts
}
for _, ts := range app {
// Check if the head change caused any state changes that we were
// waiting for
stateChanges := e.watcherEvents.checkStateChanges(e.lastTs, ts)
// Queue up calls until there have been enough blocks to reach
// confidence on the state changes
for tid, data := range stateChanges {
e.queueForConfidence(tid, data, e.lastTs, ts)
}
// Check if the head change included any new message calls
newCalls, err := e.messageEvents.checkNewCalls(ts)
if err != nil {
return err
}
// Queue up calls until there have been enough blocks to reach
// confidence on the message calls
for tid, data := range newCalls {
e.queueForConfidence(tid, data, nil, ts)
}
for at := e.lastTs.Height(); at <= ts.Height(); at++ {
// Apply any queued events and timeouts that were targeted at the
// current chain height
e.applyWithConfidence(ts, at)
e.applyTimeouts(ts)
}
// Update the latest known tipset
e.lastTs = ts
}
return nil
}
func (e *hcEvents) handleReverts(ts *types.TipSet) {
reverts, ok := e.revertQueue[ts.Height()]
if !ok {
return // nothing to do
}
for _, triggerH := range reverts {
toRevert := e.confQueue[triggerH][ts.Height()]
for _, event := range toRevert {
if !event.called {
continue // event wasn't apply()-ied yet
}
trigger := e.triggers[event.trigger]
if err := trigger.revert(e.ctx, ts); err != nil {
log.Errorf("reverting chain trigger (@H %d, triggered @ %d) failed: %s", ts.Height(), triggerH, err)
}
}
delete(e.confQueue[triggerH], ts.Height())
}
delete(e.revertQueue, ts.Height())
}
// Queue up events until the chain has reached a height that reflects the
// desired confidence
func (e *hcEvents) queueForConfidence(trigID uint64, data eventData, prevTs, ts *types.TipSet) {
trigger := e.triggers[trigID]
prevH := NoHeight
if prevTs != nil {
prevH = prevTs.Height()
}
appliedH := ts.Height()
triggerH := appliedH + abi.ChainEpoch(trigger.confidence)
byOrigH, ok := e.confQueue[triggerH]
if !ok {
byOrigH = map[abi.ChainEpoch][]*queuedEvent{}
e.confQueue[triggerH] = byOrigH
}
byOrigH[appliedH] = append(byOrigH[appliedH], &queuedEvent{
trigger: trigID,
prevH: prevH,
h: appliedH,
data: data,
})
e.revertQueue[appliedH] = append(e.revertQueue[appliedH], triggerH)
}
// Apply any events that were waiting for this chain height for confidence
func (e *hcEvents) applyWithConfidence(ts *types.TipSet, height abi.ChainEpoch) {
byOrigH, ok := e.confQueue[height]
if !ok {
return // no triggers at this height
}
for origH, events := range byOrigH {
triggerTs, err := e.tsc.get(origH)
if err != nil {
log.Errorf("events: applyWithConfidence didn't find tipset for event; wanted %d; current %d", origH, height)
}
for _, event := range events {
if event.called {
continue
}
trigger := e.triggers[event.trigger]
if trigger.disabled {
continue
}
// Previous tipset - this is relevant for example in a state change
// from one tipset to another
var prevTs *types.TipSet
if event.prevH != NoHeight {
prevTs, err = e.tsc.get(event.prevH)
if err != nil {
log.Errorf("events: applyWithConfidence didn't find tipset for previous event; wanted %d; current %d", event.prevH, height)
continue
}
}
more, err := trigger.handle(event.data, prevTs, triggerTs, height)
if err != nil {
log.Errorf("chain trigger (@H %d, triggered @ %d) failed: %s", origH, height, err)
continue // don't revert failed calls
}
event.called = true
touts, ok := e.timeouts[trigger.timeout]
if ok {
touts[event.trigger]++
}
trigger.disabled = !more
}
}
}
// Apply any timeouts that expire at this height
func (e *hcEvents) applyTimeouts(ts *types.TipSet) {
triggers, ok := e.timeouts[ts.Height()]
if !ok {
return // nothing to do
}
for triggerID, calls := range triggers {
if calls > 0 {
continue // don't timeout if the method was called
}
trigger := e.triggers[triggerID]
if trigger.disabled {
continue
}
timeoutTs, err := e.tsc.get(ts.Height() - abi.ChainEpoch(trigger.confidence))
if err != nil {
log.Errorf("events: applyTimeouts didn't find tipset for event; wanted %d; current %d", ts.Height()-abi.ChainEpoch(trigger.confidence), ts.Height())
}
more, err := trigger.handle(nil, nil, timeoutTs, ts.Height())
if err != nil {
log.Errorf("chain trigger (call @H %d, called @ %d) failed: %s", timeoutTs.Height(), ts.Height(), err)
continue // don't revert failed calls
}
trigger.disabled = !more // allows messages after timeout
}
}
// Listen for an event
// - CheckFunc: immediately checks if the event already occurred
// - EventHandler: called when the event has occurred, after confidence tipsets
// - RevertHandler: called if the chain head changes causing the event to revert
// - confidence: wait this many tipsets before calling EventHandler
// - timeout: at this chain height, timeout on waiting for this event
func (e *hcEvents) onHeadChanged(check CheckFunc, hnd EventHandler, rev RevertHandler, confidence int, timeout abi.ChainEpoch) (triggerID, error) {
e.lk.Lock()
defer e.lk.Unlock()
// Check if the event has already occurred
ts, err := e.tsc.best()
if err != nil {
return 0, xerrors.Errorf("error getting best tipset: %w", err)
}
done, more, err := check(ts)
if err != nil {
return 0, xerrors.Errorf("called check error (h: %d): %w", ts.Height(), err)
}
if done {
timeout = NoTimeout
}
// Create a trigger for the event
id := e.ctr
e.ctr++
e.triggers[id] = &handlerInfo{
confidence: confidence,
timeout: timeout + abi.ChainEpoch(confidence),
disabled: !more,
handle: hnd,
revert: rev,
}
// If there's a timeout, set up a timeout check at that height
if timeout != NoTimeout {
if e.timeouts[timeout+abi.ChainEpoch(confidence)] == nil {
e.timeouts[timeout+abi.ChainEpoch(confidence)] = map[uint64]int{}
}
e.timeouts[timeout+abi.ChainEpoch(confidence)][id] = 0
}
return id, nil
}
// headChangeAPI is used to allow the composed event APIs to call back to hcEvents
// to listen for changes
type headChangeAPI interface {
onHeadChanged(check CheckFunc, hnd EventHandler, rev RevertHandler, confidence int, timeout abi.ChainEpoch) (triggerID, error)
}
// watcherEvents watches for a state change
type watcherEvents struct {
ctx context.Context
cs eventAPI
hcAPI headChangeAPI
lk sync.RWMutex
matchers map[triggerID]StateMatchFunc
}
func newWatcherEvents(ctx context.Context, hcAPI headChangeAPI, cs eventAPI) watcherEvents {
return watcherEvents{
ctx: ctx,
cs: cs,
hcAPI: hcAPI,
matchers: make(map[triggerID]StateMatchFunc),
}
}
// Run each of the matchers against the previous and current state to see if
// there's a change
func (we *watcherEvents) checkStateChanges(oldState, newState *types.TipSet) map[triggerID]eventData {
we.lk.RLock()
defer we.lk.RUnlock()
res := make(map[triggerID]eventData)
for tid, matchFn := range we.matchers {
ok, data, err := matchFn(oldState, newState)
if err != nil {
log.Errorf("event diff fn failed: %s", err)
continue
}
if ok {
res[tid] = data
}
}
return res
}
// StateChange represents a change in state
type StateChange interface{}
// StateChangeHandler arguments:
// `oldTs` is the state "from" tipset
// `newTs` is the state "to" tipset
// `states` is the change in state
// `curH`-`ts.Height` = `confidence`
type StateChangeHandler func(oldTs, newTs *types.TipSet, states StateChange, curH abi.ChainEpoch) (more bool, err error)
type StateMatchFunc func(oldTs, newTs *types.TipSet) (bool, StateChange, error)
// StateChanged registers a callback which is triggered when a specified state
// change occurs or a timeout is reached.
//
// * `CheckFunc` callback is invoked immediately with a recent tipset, it
// returns two booleans - `done`, and `more`.
//
// * `done` should be true when some on-chain state change we are waiting
// for has happened. When `done` is set to true, timeout trigger is disabled.
//
// * `more` should be false when we don't want to receive new notifications
// through StateChangeHandler. Note that notifications may still be delivered to
// RevertHandler
//
// * `StateChangeHandler` is called when the specified state change was observed
// on-chain, and a confidence threshold was reached, or the specified `timeout`
// height was reached with no state change observed. When this callback is
// invoked on a timeout, `oldState` and `newState` are set to nil.
// This callback returns a boolean specifying whether further notifications
// should be sent, like `more` return param from `CheckFunc` above.
//
// * `RevertHandler` is called after apply handler, when we drop the tipset
// containing the message. The tipset passed as the argument is the tipset
// that is being dropped. Note that the event dropped may be re-applied
// in a different tipset in small amount of time.
//
// * `StateMatchFunc` is called against each tipset state. If there is a match,
// the state change is queued up until the confidence interval has elapsed (and
// `StateChangeHandler` is called)
func (we *watcherEvents) StateChanged(check CheckFunc, scHnd StateChangeHandler, rev RevertHandler, confidence int, timeout abi.ChainEpoch, mf StateMatchFunc) error {
hnd := func(data eventData, prevTs, ts *types.TipSet, height abi.ChainEpoch) (bool, error) {
states, ok := data.(StateChange)
if data != nil && !ok {
panic("expected StateChange")
}
return scHnd(prevTs, ts, states, height)
}
id, err := we.hcAPI.onHeadChanged(check, hnd, rev, confidence, timeout)
if err != nil {
return err
}
we.lk.Lock()
defer we.lk.Unlock()
we.matchers[id] = mf
return nil
}
// messageEvents watches for message calls to actors
type messageEvents struct {
ctx context.Context
cs eventAPI
hcAPI headChangeAPI
lk sync.RWMutex
matchers map[triggerID]MsgMatchFunc
}
func newMessageEvents(ctx context.Context, hcAPI headChangeAPI, cs eventAPI) messageEvents {
return messageEvents{
ctx: ctx,
cs: cs,
hcAPI: hcAPI,
matchers: make(map[triggerID]MsgMatchFunc),
}
}
// Check if there are any new actor calls
func (me *messageEvents) checkNewCalls(ts *types.TipSet) (map[triggerID]eventData, error) {
pts, err := me.cs.ChainGetTipSet(me.ctx, ts.Parents()) // we actually care about messages in the parent tipset here
if err != nil {
log.Errorf("getting parent tipset in checkNewCalls: %s", err)
return nil, err
}
me.lk.RLock()
defer me.lk.RUnlock()
// For each message in the tipset
res := make(map[triggerID]eventData)
me.messagesForTs(pts, func(msg *types.Message) {
// TODO: provide receipts
// Run each trigger's matcher against the message
for tid, matchFn := range me.matchers {
matched, err := matchFn(msg)
if err != nil {
log.Errorf("event matcher failed: %s", err)
continue
}
// If there was a match, include the message in the results for the
// trigger
if matched {
res[tid] = msg
}
}
})
return res, nil
}
// Get the messages in a tipset
func (me *messageEvents) messagesForTs(ts *types.TipSet, consume func(*types.Message)) {
seen := map[cid.Cid]struct{}{}
for _, tsb := range ts.Blocks() {
msgs, err := me.cs.ChainGetBlockMessages(context.TODO(), tsb.Cid())
if err != nil {
log.Errorf("messagesForTs MessagesForBlock failed (ts.H=%d, Bcid:%s, B.Mcid:%s): %s", ts.Height(), tsb.Cid(), tsb.Messages, err)
// this is quite bad, but probably better than missing all the other updates
continue
}
for _, m := range msgs.BlsMessages {
_, ok := seen[m.Cid()]
if ok {
continue
}
seen[m.Cid()] = struct{}{}
consume(m)
}
for _, m := range msgs.SecpkMessages {
_, ok := seen[m.Message.Cid()]
if ok {
continue
}
seen[m.Message.Cid()] = struct{}{}
consume(&m.Message)
}
}
}
// MsgHandler arguments:
// `ts` is the tipset, in which the `msg` is included.
// `curH`-`ts.Height` = `confidence`
type MsgHandler func(msg *types.Message, rec *types.MessageReceipt, ts *types.TipSet, curH abi.ChainEpoch) (more bool, err error)
type MsgMatchFunc func(msg *types.Message) (matched bool, err error)
// Called registers a callback which is triggered when a specified method is
// called on an actor, or a timeout is reached.
//
// * `CheckFunc` callback is invoked immediately with a recent tipset, it
// returns two booleans - `done`, and `more`.
//
// * `done` should be true when some on-chain action we are waiting for has
// happened. When `done` is set to true, timeout trigger is disabled.
//
// * `more` should be false when we don't want to receive new notifications
// through MsgHandler. Note that notifications may still be delivered to
// RevertHandler
//
// * `MsgHandler` is called when the specified event was observed on-chain,
// and a confidence threshold was reached, or the specified `timeout` height
// was reached with no events observed. When this callback is invoked on a
// timeout, `msg` is set to nil. This callback returns a boolean specifying
// whether further notifications should be sent, like `more` return param
// from `CheckFunc` above.
//
// * `RevertHandler` is called after apply handler, when we drop the tipset
// containing the message. The tipset passed as the argument is the tipset
// that is being dropped. Note that the message dropped may be re-applied
// in a different tipset in small amount of time.
//
// * `MsgMatchFunc` is called against each message. If there is a match, the
// message is queued up until the confidence interval has elapsed (and
// `MsgHandler` is called)
func (me *messageEvents) Called(check CheckFunc, msgHnd MsgHandler, rev RevertHandler, confidence int, timeout abi.ChainEpoch, mf MsgMatchFunc) error {
hnd := func(data eventData, prevTs, ts *types.TipSet, height abi.ChainEpoch) (bool, error) {
msg, ok := data.(*types.Message)
if data != nil && !ok {
panic("expected msg")
}
rec, err := me.cs.StateGetReceipt(me.ctx, msg.Cid(), ts.Key())
if err != nil {
return false, err
}
return msgHnd(msg, rec, ts, height)
}
id, err := me.hcAPI.onHeadChanged(check, hnd, rev, confidence, timeout)
if err != nil {
return err
}
me.lk.Lock()
defer me.lk.Unlock()
me.matchers[id] = mf
return nil
}
// Convenience function for checking and matching messages
func (me *messageEvents) CalledMsg(ctx context.Context, hnd MsgHandler, rev RevertHandler, confidence int, timeout abi.ChainEpoch, msg types.ChainMsg) error {
return me.Called(me.CheckMsg(ctx, msg, hnd), hnd, rev, confidence, timeout, me.MatchMsg(msg.VMMessage()))
}