rpc: filter set filter value (#19491)

Set Default filter to 10000 (as Geth) the Algo to evict oldest data is
already present

Author: lupin012

rpc/rpchelper/config.go

@@ -18,21 +18,23 @@ package rpchelper
 
 // FiltersConfig defines the configuration settings for RPC subscription filters.
 // Each field represents a limit on the number of respective items that can be stored per subscription.
+// A value of 0 disables the limit (no cap). Oldest items are evicted first (FIFO) when the limit is reached.
 type FiltersConfig struct {
-	RpcSubscriptionFiltersMaxLogs      int // Maximum number of logs to store per subscription. Default: 0 (no limit)
-	RpcSubscriptionFiltersMaxHeaders   int // Maximum number of block headers to store per subscription. Default: 0 (no limit)
-	RpcSubscriptionFiltersMaxTxs       int // Maximum number of transactions to store per subscription. Default: 0 (no limit)
+	RpcSubscriptionFiltersMaxLogs      int // Maximum number of logs to store per subscription. Default: 10000
+	RpcSubscriptionFiltersMaxHeaders   int // Maximum number of block headers to store per subscription. Default: 10000
+	RpcSubscriptionFiltersMaxTxs       int // Maximum number of transactions to store per subscription. Default: 10000
 	RpcSubscriptionFiltersMaxAddresses int // Maximum number of addresses per subscription to filter logs by. Default: 0 (no limit)
 	RpcSubscriptionFiltersMaxTopics    int // Maximum number of topics per subscription to filter logs by. Default: 0 (no limit)
 }
 
 // DefaultFiltersConfig defines the default settings for filter configurations.
-// These default values set no limits on the number of logs, block headers, transactions,
-// addresses, or topics that can be stored per subscription.
+// Logs, headers and transactions are capped at 10000 items per subscription to prevent
+// unbounded memory growth when polling clients stop calling eth_getFilterChanges.
+// Oldest items are evicted first (FIFO) when the cap is reached.
 var DefaultFiltersConfig = FiltersConfig{
-	RpcSubscriptionFiltersMaxLogs:      0, // No limit on the number of logs per subscription
-	RpcSubscriptionFiltersMaxHeaders:   0, // No limit on the number of block headers per subscription
-	RpcSubscriptionFiltersMaxTxs:       0, // No limit on the number of transactions per subscription
-	RpcSubscriptionFiltersMaxAddresses: 0, // No limit on the number of addresses per subscription to filter logs by
-	RpcSubscriptionFiltersMaxTopics:    0, // No limit on the number of topics per subscription to filter logs by
+	RpcSubscriptionFiltersMaxLogs:      10000,
+	RpcSubscriptionFiltersMaxHeaders:   10000,
+	RpcSubscriptionFiltersMaxTxs:       10000,
+	RpcSubscriptionFiltersMaxAddresses: 0, // no limit
+	RpcSubscriptionFiltersMaxTopics:    0, // no limit
 }