status-go/services/wallet/history/transfers_watcher.go

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package history
import (
"context"
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/log"
"github.com/status-im/status-go/services/wallet/async"
"github.com/status-im/status-go/services/wallet/transfer"
"github.com/status-im/status-go/services/wallet/walletevent"
)
type TransfersLoadedCb func(chainID uint64, addresses []common.Address, block *big.Int)
// Watcher executes a given callback whenever an account gets added/removed
type Watcher struct {
feed *event.Feed
group *async.Group
callback TransfersLoadedCb
}
func NewWatcher(feed *event.Feed, callback TransfersLoadedCb) *Watcher {
return &Watcher{
feed: feed,
callback: callback,
}
}
func (w *Watcher) Start() {
if w.group != nil {
return
}
w.group = async.NewGroup(context.Background())
w.group.Add(func(ctx context.Context) error {
return watch(ctx, w.feed, w.callback)
})
}
func (w *Watcher) Stop() {
if w.group != nil {
w.group.Stop()
w.group.Wait()
w.group = nil
}
}
func onTransfersLoaded(callback TransfersLoadedCb, chainID uint64, addresses []common.Address, blockNum *big.Int) {
if callback != nil {
callback(chainID, addresses, blockNum)
}
}
func watch(ctx context.Context, feed *event.Feed, callback TransfersLoadedCb) error {
ch := make(chan walletevent.Event, 100)
sub := feed.Subscribe(ch)
defer sub.Unsubscribe()
for {
select {
case <-ctx.Done():
return nil
case err := <-sub.Err():
if err != nil {
log.Error("history: transfers watcher subscription failed", "error", err)
}
case ev := <-ch:
if ev.Type == transfer.EventNewTransfers {
onTransfersLoaded(callback, ev.ChainID, ev.Accounts, ev.BlockNumber)
}
}
}
}