Fix reconnect to newHeads (#178)

* Fix reconnect to newHeads

src/main/kotlin/io/emeraldpay/dshackle/upstream/AbstractHead.kt

@@ -67,11 +67,6 @@ abstract class AbstractHead @JvmOverloads constructor(
     }
 
     fun follow(source: Flux<BlockContainer>): Disposable {
-        if (completed) {
-            // if stream was already completed it cannot accept messages (with FAIL_TERMINATED), so needs to be recreated
-            stream = Sinks.many().multicast().directBestEffort<BlockContainer>()
-            completed = false
-        }
         return source
             .filter {
                 log.trace("Filtering block $upstreamId block $it")
@@ -85,9 +80,7 @@ abstract class AbstractHead @JvmOverloads constructor(
                     log.warn("Received signal $upstreamId $it unexpectedly - restart head")
                     lastHeadUpdated = 0L
                 } else {
-                    log.warn("Received signal $upstreamId $it - stop emit new head")
-                    completed = true
-                    stream.tryEmitComplete()
+                    log.warn("Received signal $upstreamId $it, continue emit heads")
                 }
             }
             .subscribeOn(Schedulers.boundedElastic())
@@ -155,6 +148,9 @@ abstract class AbstractHead @JvmOverloads constructor(
         future = null
     }
 
+    override fun onNoHeadUpdates() {
+    }
+
     override fun start() {
         stopping = false
         log.debug("Start ${this.javaClass.simpleName} $upstreamId")
@@ -165,6 +161,7 @@ abstract class AbstractHead @JvmOverloads constructor(
                     delayed.set(delay > awaitHeadTimeoutMs)
                     if (delayed.get()) {
                         log.warn("No head updates $upstreamId for $delay ms @ ${this.javaClass.simpleName}")
+                        onNoHeadUpdates()
                     }
                 }, 180, 30, TimeUnit.SECONDS
             )

src/main/kotlin/io/emeraldpay/dshackle/upstream/EmptyHead.kt

@@ -36,4 +36,7 @@ class EmptyHead : Head {
 
     override fun stop() {
     }
+
+    override fun onNoHeadUpdates() {
+    }
 }

src/main/kotlin/io/emeraldpay/dshackle/upstream/Head.kt

@@ -41,4 +41,6 @@ interface Head {
     fun start()
 
     fun stop()
+
+    fun onNoHeadUpdates()
 }

src/main/kotlin/io/emeraldpay/dshackle/upstream/ethereum/EthereumWsHead.kt

@@ -28,6 +28,7 @@ import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcRequest
 import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcResponse
 import io.emeraldpay.etherjar.rpc.json.BlockJson
 import io.emeraldpay.etherjar.rpc.json.TransactionRefJson
+import org.slf4j.LoggerFactory
 import reactor.core.Disposable
 import reactor.core.publisher.Flux
 import reactor.core.publisher.Mono
@@ -44,6 +45,10 @@ class EthereumWsHead(
     private val skipEnhance: Boolean
 ) : DefaultEthereumHead(upstreamId, forkChoice, blockValidator), Lifecycle {
 
+    companion object {
+        private val log = LoggerFactory.getLogger(EthereumWsHead::class.java)
+    }
+
     private var subscription: Disposable? = null
 
     override fun isRunning(): Boolean {
@@ -61,6 +66,11 @@ class EthereumWsHead(
         this.subscription = super.follow(heads)
     }
 
+    override fun onNoHeadUpdates() {
+        log.warn("Restart ws head, upstreamId: $upstreamId")
+        start()
+    }
+
     fun listenNewHeads(): Flux<BlockContainer> {
         return wsSubscriptions.subscribe("newHeads")
             .map {