package syncer import ( "context" "time" "github.com/alitto/pond" "github.com/celo-org/celo-blockchain/core/types" "github.com/celo-org/celo-blockchain/ethclient" "github.com/grassrootseconomics/cic-chain-events/internal/pipeline" "github.com/zerodha/logf" ) const ( jobTimeout = 5 * time.Second ) type ( HeadSyncerOpts struct { Logg logf.Logger Pipeline *pipeline.Pipeline Pool *pond.WorkerPool Stats *Stats WsEndpoint string } HeadSyncer struct { ethClient *ethclient.Client logg logf.Logger pipeline *pipeline.Pipeline pool *pond.WorkerPool stats *Stats } ) func NewHeadSyncer(o HeadSyncerOpts) (*HeadSyncer, error) { ethClient, err := ethclient.Dial(o.WsEndpoint) if err != nil { return nil, err } return &HeadSyncer{ ethClient: ethClient, logg: o.Logg, pipeline: o.Pipeline, pool: o.Pool, stats: o.Stats, }, nil } // Start creates a websocket subscription and actively receives new blocks until stopped // or a critical error occurs. func (hs *HeadSyncer) Start(ctx context.Context) error { headerReceiver := make(chan *types.Header, 1) sub, err := hs.ethClient.SubscribeNewHead(context.Background(), headerReceiver) if err != nil { return err } defer sub.Unsubscribe() for { select { case <-ctx.Done(): hs.logg.Info("head syncer: shutdown signal received") return nil case err := <-sub.Err(): return err case header := <-headerReceiver: blockNumber := header.Number.Uint64() hs.logg.Debug("head syncer: received new block", "block", blockNumber) hs.stats.UpdateHeadCursor(blockNumber) hs.pool.Submit(func() { ctx, cancel := context.WithTimeout(context.Background(), jobTimeout) defer cancel() if err := hs.pipeline.Run(ctx, blockNumber); err != nil { hs.logg.Error("head syncer: piepline run error", "error", err) } }) } } }