problem: caching is not verified

src/main/kotlin/io/emeraldpay/dshackle/rpc/NativeCall.kt

@@ -108,6 +108,10 @@ class NativeCall(
 
     fun fetch(ctx: CallContext<ParsedCallDetails>): Mono<CallContext<ByteArray>> {
         return fetchFromCache(ctx)
+                .onErrorResume { t ->
+                    log.warn("Failed to read from cache", t);
+                    Mono.empty()
+                }
                 .switchIfEmpty(
                         Mono.just(ctx).flatMap(this::executeOnRemote)
                 )

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

@@ -27,6 +27,7 @@ import io.infinitape.etherjar.hex.HexQuantity
 import io.infinitape.etherjar.rpc.json.BlockJson
 import io.infinitape.etherjar.rpc.json.ResponseJson
 import io.infinitape.etherjar.rpc.json.TransactionRefJson
+import org.slf4j.LoggerFactory
 import reactor.core.publisher.Mono
 import java.util.function.Function
 
@@ -37,6 +38,8 @@ open class CachingEthereumApi(
 ): EthereumApi(objectMapper) {
 
     companion object {
+        private val log = LoggerFactory.getLogger(CachingEthereumApi::class.java)
+
         @JvmStatic
         fun empty(): CachingEthereumApi {
             return CachingEthereumApi(ObjectMapper(), EmptyReader(), EmptyEthereumHead())
@@ -55,6 +58,10 @@ open class CachingEthereumApi(
                         .map { BlockHash.from(it as String) }
                         .flatMap(cache::read)
                         .map(toJson(id))
+                        .onErrorResume { t ->
+                            log.warn("Error during read from cache", t)
+                            Mono.empty()
+                        }
                 else Mono.empty()
             else ->
                 Mono.empty()

src/test/groovy/io/emeraldpay/dshackle/upstream/CachingEthereumApiSpec.groovy

@@ -0,0 +1,77 @@
+package io.emeraldpay.dshackle.upstream
+
+import io.emeraldpay.dshackle.cache.BlocksMemCache
+import io.emeraldpay.dshackle.reader.BlockCacheReader
+import io.emeraldpay.dshackle.reader.EmptyReader
+import io.emeraldpay.dshackle.test.TestingCommons
+import io.emeraldpay.dshackle.upstream.ethereum.EthereumHead
+import io.infinitape.etherjar.domain.BlockHash
+import io.infinitape.etherjar.domain.TransactionId
+import io.infinitape.etherjar.rpc.json.BlockJson
+import io.infinitape.etherjar.rpc.json.TransactionRefJson
+import reactor.core.publisher.Flux
+import reactor.test.StepVerifier
+import spock.lang.Specification
+
+import java.time.Duration
+
+class CachingEthereumApiSpec extends Specification {
+
+    def "Get blockNumber from head"() {
+        setup:
+        def head = Mock(EthereumHead.class)
+        def api = new CachingEthereumApi(
+                TestingCommons.objectMapper(),
+                new EmptyReader<BlockHash, BlockJson<TransactionRefJson>>(),
+                head
+        )
+        1 * head.getFlux() >> Flux.just(new BlockJson<TransactionRefJson>(number: 100))
+        when:
+        def act = api.execute(1, "eth_blockNumber", []).map { new String(it)}
+
+        then:
+        StepVerifier.create(act)
+            .expectNext('{"jsonrpc":"2.0","id":1,"result":"0x64"}')
+            .expectComplete()
+            .verify(Duration.ofSeconds(3))
+    }
+
+    def "Return empty if block is not cached"() {
+        setup:
+        def head = Mock(EthereumHead.class)
+        def api = new CachingEthereumApi(
+                TestingCommons.objectMapper(),
+                new EmptyReader<BlockHash, BlockJson<TransactionRefJson>>(),
+                head
+        )
+        when:
+        def act = api.execute(1, "eth_getBlockByHash", ["0x5b4590a9905fa1c9cc273f32e6dc63b4c512f0ee14edc6fa41c26b416a7b5d58", false]).map { new String(it)}
+
+        then:
+        StepVerifier.create(act)
+                .expectComplete()
+                .verify(Duration.ofSeconds(3))
+    }
+
+    def "Return block when cached"() {
+        setup:
+        def cache = new BlocksMemCache();
+        def head = Mock(EthereumHead.class)
+        def api = new CachingEthereumApi(
+                TestingCommons.objectMapper(),
+                new BlockCacheReader(cache),
+                head
+        )
+        cache.add(new BlockJson<TransactionRefJson>(number: 100, hash: BlockHash.from("0x5b4590a9905fa1c9cc273f32e6dc63b4c512f0ee14edc6fa41c26b416a7b5d58")))
+
+        when:
+        def act = api.execute(1, "eth_getBlockByHash", ["0x5b4590a9905fa1c9cc273f32e6dc63b4c512f0ee14edc6fa41c26b416a7b5d58", false]).map { new String(it)}
+
+        then:
+        StepVerifier.create(act)
+                .expectNext('{"jsonrpc":"2.0","id":1,"result":{"number":"0x64","hash":"0x5b4590a9905fa1c9cc273f32e6dc63b4c512f0ee14edc6fa41c26b416a7b5d58","transactions":[],"uncles":[]}}')
+                .expectComplete()
+                .verify(Duration.ofSeconds(3))
+    }
+
+}