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eth/filters: fix potential deadlock in filter timeout loop (#22178)

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This fixes #22131 and adds a test reproducing the issue.
This commit is contained in:
Sina Mahmoodi
2021-01-21 12:17:10 +01:00
committed by GitHub
parent ddadc3d273
commit c4307a9339
4 changed files with 101 additions and 22 deletions
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33
eth/filters/api.go
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@ -34,10 +34,6 @@ import (
"github.com/ethereum/go-ethereum/rpc"
)
var (
deadline = 5 * time.Minute // consider a filter inactive if it has not been polled for within deadline
)
// filter is a helper struct that holds meta information over the filter type
// and associated subscription in the event system.
type filter struct {
@ -59,25 +55,28 @@ type PublicFilterAPI struct {
events *EventSystem
filtersMu sync.Mutex
filters map[rpc.ID]*filter
timeout time.Duration
}
// NewPublicFilterAPI returns a new PublicFilterAPI instance.
func NewPublicFilterAPI(backend Backend, lightMode bool) *PublicFilterAPI {
func NewPublicFilterAPI(backend Backend, lightMode bool, timeout time.Duration) *PublicFilterAPI {
api := &PublicFilterAPI{
backend: backend,
chainDb: backend.ChainDb(),
events: NewEventSystem(backend, lightMode),
filters: make(map[rpc.ID]*filter),
timeout: timeout,
}
go api.timeoutLoop()
go api.timeoutLoop(timeout)
return api
}
// timeoutLoop runs every 5 minutes and deletes filters that have not been recently used.
// Tt is started when the api is created.
func (api *PublicFilterAPI) timeoutLoop() {
ticker := time.NewTicker(5 * time.Minute)
func (api *PublicFilterAPI) timeoutLoop(timeout time.Duration) {
var toUninstall []*Subscription
ticker := time.NewTicker(timeout)
defer ticker.Stop()
for {
<-ticker.C
@ -85,13 +84,21 @@ func (api *PublicFilterAPI) timeoutLoop() {
for id, f := range api.filters {
select {
case <-f.deadline.C:
f.s.Unsubscribe()
toUninstall = append(toUninstall, f.s)
delete(api.filters, id)
default:
continue
}
}
api.filtersMu.Unlock()
// Unsubscribes are processed outside the lock to avoid the following scenario:
// event loop attempts broadcasting events to still active filters while
// Unsubscribe is waiting for it to process the uninstall request.
for _, s := range toUninstall {
s.Unsubscribe()
}
toUninstall = nil
}
}
@ -109,7 +116,7 @@ func (api *PublicFilterAPI) NewPendingTransactionFilter() rpc.ID {
)
api.filtersMu.Lock()
api.filters[pendingTxSub.ID] = &filter{typ: PendingTransactionsSubscription, deadline: time.NewTimer(deadline), hashes: make([]common.Hash, 0), s: pendingTxSub}
api.filters[pendingTxSub.ID] = &filter{typ: PendingTransactionsSubscription, deadline: time.NewTimer(api.timeout), hashes: make([]common.Hash, 0), s: pendingTxSub}
api.filtersMu.Unlock()
go func() {
@ -179,7 +186,7 @@ func (api *PublicFilterAPI) NewBlockFilter() rpc.ID {
)
api.filtersMu.Lock()
api.filters[headerSub.ID] = &filter{typ: BlocksSubscription, deadline: time.NewTimer(deadline), hashes: make([]common.Hash, 0), s: headerSub}
api.filters[headerSub.ID] = &filter{typ: BlocksSubscription, deadline: time.NewTimer(api.timeout), hashes: make([]common.Hash, 0), s: headerSub}
api.filtersMu.Unlock()
go func() {
@ -296,7 +303,7 @@ func (api *PublicFilterAPI) NewFilter(crit FilterCriteria) (rpc.ID, error) {
}
api.filtersMu.Lock()
api.filters[logsSub.ID] = &filter{typ: LogsSubscription, crit: crit, deadline: time.NewTimer(deadline), logs: make([]*types.Log, 0), s: logsSub}
api.filters[logsSub.ID] = &filter{typ: LogsSubscription, crit: crit, deadline: time.NewTimer(api.timeout), logs: make([]*types.Log, 0), s: logsSub}
api.filtersMu.Unlock()
go func() {
@ -421,7 +428,7 @@ func (api *PublicFilterAPI) GetFilterChanges(id rpc.ID) (interface{}, error) {
// receive timer value and reset timer
<-f.deadline.C
}
f.deadline.Reset(deadline)
f.deadline.Reset(api.timeout)
switch f.typ {
case PendingTransactionsSubscription, BlocksSubscription: