status-im/status-go

package rpcfilters

import (
    "context"
    "math/big"
    "time"

    ethereum "github.com/ethereum/go-ethereum"
    "github.com/ethereum/go-ethereum/common/hexutil"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/log"
    getRpc "github.com/ethereum/go-ethereum/rpc"
    gocommon "github.com/status-im/status-go/common"
)

// ContextCaller provides CallContext method as ethereums rpc.Client.
type ContextCaller interface {
    CallContext(ctx context.Context, result interface{}, chainID uint64, method string, args ...interface{}) error
}

func pollLogs(client ContextCaller, chainID uint64, f *logsFilter, timeout, period time.Duration) {
    defer gocommon.LogOnPanic()
    query := func() {
        ctx, cancel := context.WithTimeout(f.ctx, timeout)
        defer cancel()
        logs, err := getLogs(ctx, client, chainID, f.criteria())
        if err != nil {
            log.Error("Error fetch logs", "criteria", f.crit, "error", err)
            return
        }
        if err := f.add(logs); err != nil {
            log.Error("Error adding logs", "logs", logs, "error", err)
        }
    }
    query()
    latest := time.NewTicker(period)
    defer latest.Stop()
    for {
        select {
        case <-latest.C:
            query()
        case <-f.done:
            log.Debug("Filter was stopped", "ID", f.id, "crit", f.crit)
            return
        }
    }
}
func getLogs(ctx context.Context, client ContextCaller, chainID uint64, crit ethereum.FilterQuery) (rst []types.Log, err error) {
    return rst, client.CallContext(ctx, &rst, chainID, "eth_getLogs", toFilterArg(crit))
}

func toFilterArg(q ethereum.FilterQuery) interface{} {
    arg := map[string]interface{}{
        "fromBlock": toBlockNumArg(q.FromBlock),
        "toBlock":   toBlockNumArg(q.ToBlock),
        "address":   q.Addresses,
        "topics":    q.Topics,
    }
    if q.FromBlock == nil {
        arg["fromBlock"] = "0x0"
    }
    return arg
}

func toBlockNumArg(number *big.Int) string {
    if number == nil || number.Int64() == getRpc.LatestBlockNumber.Int64() {
        return "latest"
    } else if number.Int64() == getRpc.PendingBlockNumber.Int64() {
        return "pending"
    }
    return hexutil.EncodeBig(number)
}