Problem: unused cancel function in filter is not cleanup (#386) (#387)

* Problem: f.cancel nil is not checked

* Update CHANGELOG.md



* cleanup

---------

Signed-off-by: mmsqe <mavis@crypto.com>

CHANGELOG.md

@@ -68,6 +68,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (rpc) [#364](https://github.com/crypto-org-chain/ethermint/pull/364) Only use NextBaseFee as last item to avoid concurrent write in `eth_feeHistory`.
 * (config) [#365](https://github.com/crypto-org-chain/ethermint/pull/365) Avoid redundant parse chainID from gensis when start server.
 * (rpc) [#382](https://github.com/crypto-org-chain/ethermint/pull/382) Align tracer config with go-ethereum.
+* (rpc) [#386](https://github.com/crypto-org-chain/ethermint/pull/386) Cleanup unused cancel function in filter.
 
 ### Improvements
 

rpc/namespaces/ethereum/eth/filters/api.go

@@ -74,7 +74,6 @@ type filter struct {
  typ filters.Type
  deadline *time.Timer // filter is inactive when deadline triggers
  crit filters.FilterCriteria
- cancel context.CancelFunc
  offset int // offset for stream subscription
 }
 
@@ -118,7 +117,6 @@ func (api *PublicFilterAPI) timeoutLoop() {
  for id, f := range api.filters {
  select {
  case <-f.deadline.C:
- f.cancel()
  delete(api.filters, id)
  default:
  continue