historiclogs.go

ETHER_PAYMENT_EVENT_ID     = "0xb66556f6cabf16c4a3460f3164c6fe631dc20e73625d505042244a586761c346"
VENDING_MACHINE_ADDR       = "0xa9d00e3a19a4ddebde3cb96d883658a721f4df38"
VENDING_MACHINE_CHECKPOINT = 9927996

fromBlock = big.NewInt(VENDING_MACHINE_CHECKPOINT)

query := ethereum.FilterQuery{
    FromBlock: fromBlock,
    ToBlock:   nil,
    Addresses: []common.Address{common.HexToAddress(VENDING_MACHINE_ADDR)},
    Topics: [][]common.Hash{
        []common.Hash{
            // Only listening for EtherPurchase Events
            common.HexToHash(ETHER_PAYMENT_EVENT_ID),
        },
    },
}

// Then later, called by an hourly loop:

func checkHistory(client *ethclient.Client,
	query ethereum.FilterQuery, processorInput chan types.Log) {

	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	logs, err := client.FilterLogs(ctx, query)
	if err != nil {
		log.Println("Error Querying Historic Logs:", err)
	}

	for _, log := range logs {
		processorInput <- log
	}
}