all: ensure subscription is not nil

core/chain_indexer.go

@@ -145,7 +145,9 @@ func (c *ChainIndexer) AddCheckpoint(section uint64, shead common.Hash) {
 func (c *ChainIndexer) Start(chain ChainIndexerChain) {
 	events := make(chan ChainHeadEvent, 10)
 	sub := chain.SubscribeChainHeadEvent(events)
-
+	if sub == nil {
+		log.Crit("Failed to create chain head subscription")
+	}
 	go c.eventLoop(chain.CurrentHeader(), events, sub)
 }
 

core/tx_pool.go

@@ -297,6 +297,9 @@ func NewTxPool(config TxPoolConfig, chainconfig *params.ChainConfig, chain block
 
 	// Subscribe events from blockchain and start the main event loop.
 	pool.chainHeadSub = pool.chain.SubscribeChainHeadEvent(pool.chainHeadCh)
+	if pool.chainHeadSub == nil {
+		log.Crit("Failed to create chain head subscription")
+	}
 	pool.wg.Add(1)
 	go pool.loop()
 

eth/enr_entry.go

@@ -19,6 +19,7 @@ package eth
 import (
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/forkid"
+	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -40,7 +41,9 @@ func (e ethEntry) ENRKey() string {
 func (eth *Ethereum) startEthEntryUpdate(ln *enode.LocalNode) {
 	var newHead = make(chan core.ChainHeadEvent, 10)
 	sub := eth.blockchain.SubscribeChainHeadEvent(newHead)
-
+	if sub == nil {
+		log.Crit("Failed to create chain head subscription")
+	}
 	go func() {
 		defer sub.Unsubscribe()
 		for {

ethstats/ethstats.go

@@ -145,15 +145,18 @@ func (s *Service) loop() {
 		blockchain = s.les.BlockChain()
 		txpool = s.les.TxPool()
 	}
-
 	chainHeadCh := make(chan core.ChainHeadEvent, chainHeadChanSize)
 	headSub := blockchain.SubscribeChainHeadEvent(chainHeadCh)
+	if headSub == nil {
+		log.Crit("Failed to create chain head subscription")
+	}
 	defer headSub.Unsubscribe()
-
 	txEventCh := make(chan core.NewTxsEvent, txChanSize)
 	txSub := txpool.SubscribeNewTxsEvent(txEventCh)
+	if txSub == nil {
+		log.Crit("Failed to create new tx subscription")
+	}
 	defer txSub.Unsubscribe()
-
 	// Start a goroutine that exhausts the subsciptions to avoid events piling up
 	var (
 		quitCh = make(chan struct{})

les/server.go

@@ -227,6 +227,9 @@ func (s *LesServer) capacityManagement() {
 
 	processCh := make(chan bool, 100)
 	sub := s.handler.blockchain.SubscribeBlockProcessingEvent(processCh)
+	if sub == nil {
+		log.Crit("Failed to create block processing subscription")
+	}
 	defer sub.Unsubscribe()
 
 	totalRechargeCh := make(chan uint64, 100)

les/server_handler.go

@@ -898,6 +898,9 @@ func (h *serverHandler) broadcastHeaders() {
 
 	headCh := make(chan core.ChainHeadEvent, 10)
 	headSub := h.blockchain.SubscribeChainHeadEvent(headCh)
+	if headSub == nil {
+		log.Crit("Failed to create chain head subscription")
+	}
 	defer headSub.Unsubscribe()
 
 	var (

light/txpool.go

@@ -105,6 +105,9 @@ func NewTxPool(config *params.ChainConfig, chain *LightChain, relay TxRelayBacke
 	}
 	// Subscribe events from blockchain
 	pool.chainHeadSub = pool.chain.SubscribeChainHeadEvent(pool.chainHeadCh)
+	if pool.chainHeadSub == nil {
+		log.Crit("Failed to create chain head subscription")
+	}
 	go pool.eventLoop()
 
 	return pool

miner/worker.go

@@ -205,7 +205,9 @@ func newWorker(config *Config, chainConfig *params.ChainConfig, engine consensus
 	// Subscribe events for blockchain
 	worker.chainHeadSub = eth.BlockChain().SubscribeChainHeadEvent(worker.chainHeadCh)
 	worker.chainSideSub = eth.BlockChain().SubscribeChainSideEvent(worker.chainSideCh)
-
+	if worker.txsSub == nil || worker.chainHeadSub == nil || worker.chainSideSub == nil {
+		log.Crit("Failed to create subscriptions")
+	}
 	// Sanitize recommit interval if the user-specified one is too short.
 	recommit := worker.config.Recommit
 	if recommit < minRecommitInterval {