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logs_filter.go
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logs_filter.go
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package rpcfilters
import (
"context"
"fmt"
"math/big"
"sync"
"time"
ethereum "github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/rpc"
)
type logsFilter struct {
mu sync.RWMutex
logs []types.Log
crit ethereum.FilterQuery // will be modified and different from original
originalCrit ethereum.FilterQuery // not modified version of the criteria
logsCache *cache
id rpc.ID
timer *time.Timer
ctx context.Context
cancel context.CancelFunc
done chan struct{}
}
func (f *logsFilter) criteria() ethereum.FilterQuery {
f.mu.RLock()
defer f.mu.RUnlock()
return f.crit
}
func (f *logsFilter) add(data interface{}) error {
logs, ok := data.([]types.Log)
if !ok {
return fmt.Errorf("can't cast %v to types.Log", data)
}
filtered := filterLogs(logs, f.crit)
if len(filtered) > 0 {
f.mu.Lock()
defer f.mu.Unlock()
added, replaced, err := f.logsCache.add(filtered)
if err != nil {
return err
}
for _, log := range replaced {
log.Removed = true
f.logs = append(f.logs, log)
}
if len(added) > 0 {
f.logs = append(f.logs, added...)
}
// if there was no replaced logs - keep polling only latest logs
if len(replaced) == 0 {
adjustFromBlock(&f.crit)
} else {
// otherwise poll earliest known block in cache
earliest := f.logsCache.earliestBlockNum()
if earliest != 0 {
f.crit.FromBlock = new(big.Int).SetUint64(earliest)
}
}
}
return nil
}
func (f *logsFilter) pop() interface{} {
f.mu.Lock()
defer f.mu.Unlock()
rst := f.logs
f.logs = nil
return rst
}
func (f *logsFilter) stop() {
select {
case <-f.done:
return
default:
close(f.done)
if f.cancel != nil {
f.cancel()
}
}
}
func (f *logsFilter) deadline() *time.Timer {
return f.timer
}
// adjustFromBlock adjusts crit.FromBlock to latest to avoid querying same logs.
func adjustFromBlock(crit *ethereum.FilterQuery) {
latest := big.NewInt(rpc.LatestBlockNumber.Int64())
// don't adjust if filter is not interested in newer blocks
if crit.ToBlock != nil && crit.ToBlock.Cmp(latest) == 1 {
return
}
// don't adjust if from block is already pending
if crit.FromBlock != nil && crit.FromBlock.Cmp(latest) == -1 {
return
}
crit.FromBlock = latest
}
func includes(addresses []common.Address, a common.Address) bool {
for _, addr := range addresses {
if addr == a {
return true
}
}
return false
}
// filterLogs creates a slice of logs matching the given criteria.
func filterLogs(logs []types.Log, crit ethereum.FilterQuery) (
ret []types.Log) {
for _, log := range logs {
if matchLog(log, crit) {
ret = append(ret, log)
}
}
return
}
func matchLog(log types.Log, crit ethereum.FilterQuery) bool {
if crit.FromBlock != nil && crit.FromBlock.Int64() >= 0 && crit.FromBlock.Uint64() > log.BlockNumber {
return false
}
if crit.ToBlock != nil && crit.ToBlock.Int64() >= 0 && crit.ToBlock.Uint64() < log.BlockNumber {
return false
}
if len(crit.Addresses) > 0 && !includes(crit.Addresses, log.Address) {
return false
}
if len(crit.Topics) > len(log.Topics) {
return false
}
return matchTopics(log, crit.Topics)
}
func matchTopics(log types.Log, topics [][]common.Hash) bool {
for i, sub := range topics {
match := len(sub) == 0 // empty rule set == wildcard
for _, topic := range sub {
if log.Topics[i] == topic {
match = true
break
}
}
if !match {
return false
}
}
return true
}