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events.go
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events.go
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package events
import (
"context"
"sync"
"time"
"github.com/filecoin-project/go-state-types/abi"
"github.com/ipfs/go-cid"
logging "github.com/ipfs/go-log/v2"
"golang.org/x/xerrors"
"github.com/filecoin-project/go-address"
"github.com/filecoin-project/lotus/api"
"github.com/filecoin-project/lotus/build"
"github.com/filecoin-project/lotus/chain/store"
"github.com/filecoin-project/lotus/chain/types"
)
var log = logging.Logger("events")
// HeightHandler `curH`-`ts.Height` = `confidence`
type (
HeightHandler func(ctx context.Context, ts *types.TipSet, curH abi.ChainEpoch) error
RevertHandler func(ctx context.Context, ts *types.TipSet) error
)
type heightHandler struct {
confidence int
called bool
handle HeightHandler
revert RevertHandler
}
type EventAPI interface {
ChainNotify(context.Context) (<-chan []*api.HeadChange, error)
ChainGetBlockMessages(context.Context, cid.Cid) (*api.BlockMessages, error)
ChainGetTipSetByHeight(context.Context, abi.ChainEpoch, types.TipSetKey) (*types.TipSet, error)
ChainHead(context.Context) (*types.TipSet, error)
StateSearchMsg(ctx context.Context, from types.TipSetKey, msg cid.Cid, limit abi.ChainEpoch, allowReplaced bool) (*api.MsgLookup, error)
ChainGetTipSet(context.Context, types.TipSetKey) (*types.TipSet, error)
StateGetActor(ctx context.Context, actor address.Address, tsk types.TipSetKey) (*types.Actor, error) // optional / for CalledMsg
}
type Events struct {
api EventAPI
tsc *tipSetCache
lk sync.Mutex
ready chan struct{}
readyOnce sync.Once
heightEvents
*hcEvents
observers []TipSetObserver
}
func NewEventsWithConfidence(ctx context.Context, api EventAPI, gcConfidence abi.ChainEpoch) *Events {
tsc := newTSCache(gcConfidence, api)
e := &Events{
api: api,
tsc: tsc,
heightEvents: heightEvents{
tsc: tsc,
ctx: ctx,
gcConfidence: gcConfidence,
heightTriggers: map[uint64]*heightHandler{},
htTriggerHeights: map[abi.ChainEpoch][]uint64{},
htHeights: map[abi.ChainEpoch][]uint64{},
},
hcEvents: newHCEvents(ctx, api, tsc, uint64(gcConfidence)),
ready: make(chan struct{}),
observers: []TipSetObserver{},
}
go e.listenHeadChanges(ctx)
// Wait for the first tipset to be seen or bail if shutting down
select {
case <-e.ready:
case <-ctx.Done():
}
return e
}
func NewEvents(ctx context.Context, api EventAPI) *Events {
gcConfidence := 2 * build.ForkLengthThreshold
return NewEventsWithConfidence(ctx, api, gcConfidence)
}
func (e *Events) listenHeadChanges(ctx context.Context) {
for {
if err := e.listenHeadChangesOnce(ctx); err != nil {
log.Errorf("listen head changes errored: %s", err)
} else {
log.Warn("listenHeadChanges quit")
}
select {
case <-build.Clock.After(time.Second):
case <-ctx.Done():
log.Warnf("not restarting listenHeadChanges: context error: %s", ctx.Err())
return
}
log.Info("restarting listenHeadChanges")
}
}
func (e *Events) listenHeadChangesOnce(ctx context.Context) error {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
notifs, err := e.api.ChainNotify(ctx)
if err != nil {
// Retry is handled by caller
return xerrors.Errorf("listenHeadChanges ChainNotify call failed: %w", err)
}
var cur []*api.HeadChange
var ok bool
// Wait for first tipset or bail
select {
case cur, ok = <-notifs:
if !ok {
return xerrors.Errorf("notification channel closed")
}
case <-ctx.Done():
return ctx.Err()
}
if len(cur) != 1 {
return xerrors.Errorf("unexpected initial head notification length: %d", len(cur))
}
if cur[0].Type != store.HCCurrent {
return xerrors.Errorf("expected first head notification type to be 'current', was '%s'", cur[0].Type)
}
if err := e.tsc.add(cur[0].Val); err != nil {
log.Warnf("tsc.add: adding current tipset failed: %v", err)
}
e.readyOnce.Do(func() {
e.lastTs = cur[0].Val
// Signal that we have seen first tipset
close(e.ready)
})
for notif := range notifs {
var rev, app []*types.TipSet
for _, notif := range notif {
switch notif.Type {
case store.HCRevert:
rev = append(rev, notif.Val)
case store.HCApply:
app = append(app, notif.Val)
default:
log.Warnf("unexpected head change notification type: '%s'", notif.Type)
}
}
if err := e.headChange(ctx, rev, app); err != nil {
log.Warnf("headChange failed: %s", err)
}
// sync with fake chainstore (for tests)
if fcs, ok := e.api.(interface{ notifDone() }); ok {
fcs.notifDone()
}
}
return nil
}
func (e *Events) headChange(ctx context.Context, rev, app []*types.TipSet) error {
if len(app) == 0 {
return xerrors.New("events.headChange expected at least one applied tipset")
}
e.lk.Lock()
defer e.lk.Unlock()
if err := e.headChangeAt(rev, app); err != nil {
return err
}
if err := e.observeChanges(ctx, rev, app); err != nil {
return err
}
return e.processHeadChangeEvent(rev, app)
}
// A TipSetObserver receives notifications of tipsets
type TipSetObserver interface {
Apply(ctx context.Context, ts *types.TipSet) error
Revert(ctx context.Context, ts *types.TipSet) error
}
// TODO: add a confidence level so we can have observers with difference levels of confidence
func (e *Events) Observe(obs TipSetObserver) error {
e.lk.Lock()
defer e.lk.Unlock()
e.observers = append(e.observers, obs)
return nil
}
// observeChanges expects caller to hold e.lk
func (e *Events) observeChanges(ctx context.Context, rev, app []*types.TipSet) error {
for _, ts := range rev {
for _, o := range e.observers {
_ = o.Revert(ctx, ts)
}
}
for _, ts := range app {
for _, o := range e.observers {
_ = o.Apply(ctx, ts)
}
}
return nil
}