problem: treats a fresh Syncing node as a normal one

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

@@ -142,7 +142,15 @@ abstract class DefaultUpstream(
         if (forked.get()) {
             return UpstreamAvailability.IMMATURE
         }
-        return status.get().status
+        val value = status.get().status
+        if (value == UpstreamAvailability.UNAVAILABLE || value == UpstreamAvailability.SYNCING) {
+            return value
+        }
+        // if height is 0, then it's definitely on OK, probably just started with syncing
+        if (this.getHead().getCurrentHeight() == 0L) {
+            return UpstreamAvailability.SYNCING
+        }
+        return value
     }
 
     open fun setStatus(status: UpstreamAvailability) {
@@ -158,13 +166,21 @@ abstract class DefaultUpstream(
             // the status calculation and trust the proposed value as is
             return proposed
         }
-        return if (proposed == UpstreamAvailability.OK) {
-            when {
-                lag > 6 -> UpstreamAvailability.SYNCING
-                lag > 1 -> UpstreamAvailability.LAGGING
-                else -> proposed
+        return when {
+            proposed == UpstreamAvailability.OK -> {
+                // make sure it's actually usable
+                when {
+                    lag > 6 -> UpstreamAvailability.SYNCING
+                    lag > 1 -> UpstreamAvailability.LAGGING
+                    else -> proposed
+                }
             }
-        } else proposed
+            proposed == UpstreamAvailability.LAGGING && lag > 6 -> {
+                // to large lag, mark as syncing
+                UpstreamAvailability.SYNCING
+            }
+            else -> proposed
+        }
     }
 
     val availabilityByForks: Flux<UpstreamAvailability>

src/test/kotlin/io/emeraldpay/dshackle/upstream/DefaultUpstreamTest.kt

@@ -3,6 +3,7 @@ package io.emeraldpay.dshackle.upstream
 import io.emeraldpay.api.Chain
 import io.emeraldpay.dshackle.config.UpstreamsConfig
 import io.emeraldpay.dshackle.reader.StandardRpcReader
+import io.emeraldpay.dshackle.test.FixedHead
 import io.emeraldpay.dshackle.test.ForkWatchMock
 import io.emeraldpay.dshackle.upstream.calls.DefaultEthereumMethods
 import io.kotest.core.spec.style.ShouldSpec
@@ -15,6 +16,7 @@ class DefaultUpstreamTest : ShouldSpec({
 
     should("Produce current status availability") {
         val upstream = DefaultUpstreamTestImpl("test", ForkWatch.Never())
+        upstream.setLag(3)
         upstream.setStatus(UpstreamAvailability.LAGGING)
         val act = upstream.availabilityByStatus.take(1)
             .collectList().block(Duration.ofSeconds(1))
@@ -23,15 +25,17 @@ class DefaultUpstreamTest : ShouldSpec({
 
     should("Produce updated status availability") {
         val upstream = DefaultUpstreamTestImpl("test", ForkWatch.Never())
+        upstream.setLag(3)
         upstream.setStatus(UpstreamAvailability.LAGGING)
         val act = upstream.availabilityByStatus.take(2)
 
         StepVerifier.create(act)
             .expectNext(UpstreamAvailability.LAGGING)
             .then {
+                upstream.setLag(10)
                 upstream.setStatus(UpstreamAvailability.OK)
             }
-            // syncing because we didn't set the height lag
+            // syncing because lag is too big
             .expectNext(UpstreamAvailability.SYNCING)
             .expectComplete()
             .verify(Duration.ofSeconds(1))
@@ -115,17 +119,34 @@ class DefaultUpstreamTest : ShouldSpec({
         upstream.watchHttpCodes.accept(429)
         upstream.getStatus() shouldBe UpstreamAvailability.UNAVAILABLE
     }
+
+    should("Be Syncing when height is 0") {
+        val upstream = DefaultUpstreamTestImpl("test", ForkWatch.Never(), head = FixedHead(0))
+        upstream.setStatus(UpstreamAvailability.LAGGING)
+        val act = upstream.getStatus()
+        act shouldBe UpstreamAvailability.SYNCING
+    }
+
+    should("Switch to syncing when lag is too large") {
+        val upstream = DefaultUpstreamTestImpl("test", ForkWatch.Never())
+        upstream.setLag(100)
+        upstream.setStatus(UpstreamAvailability.LAGGING)
+        val act = upstream.availabilityByStatus.take(1)
+            .collectList().block(Duration.ofSeconds(1))
+        act shouldBe listOf(UpstreamAvailability.SYNCING)
+    }
 })
 
 class DefaultUpstreamTestImpl(
     id: String,
     forkWatch: ForkWatch,
-    options: UpstreamsConfig.Options = UpstreamsConfig.PartialOptions.getDefaults().build()
+    options: UpstreamsConfig.Options = UpstreamsConfig.PartialOptions.getDefaults().build(),
+    private val head: Head = FixedHead(100)
 ) : DefaultUpstream(
     id, Chain.ETHEREUM, forkWatch, options, UpstreamsConfig.UpstreamRole.PRIMARY, DefaultEthereumMethods(Chain.ETHEREUM)
 ) {
     override fun getHead(): Head {
-        throw NotImplementedError()
+        return head
     }
 
     override fun getIngressReader(): StandardRpcReader {