solution: refer to current height when requesting balance

fix: #31

src/main/kotlin/io/emeraldpay/dshackle/rpc/TrackERC20Address.kt

@@ -5,6 +5,7 @@ import io.emeraldpay.api.proto.Common
 import io.emeraldpay.dshackle.BlockchainType
 import io.emeraldpay.dshackle.SilentException
 import io.emeraldpay.dshackle.config.TokensConfig
+import io.emeraldpay.dshackle.upstream.Head
 import io.emeraldpay.dshackle.upstream.MultistreamHolder
 import io.emeraldpay.dshackle.upstream.Selector
 import io.emeraldpay.dshackle.upstream.ethereum.EthereumMultistream
@@ -14,6 +15,7 @@ import io.emeraldpay.grpc.Chain
 import io.infinitape.etherjar.domain.Address
 import io.infinitape.etherjar.erc20.ERC20Token
 import io.infinitape.etherjar.hex.Hex32
+import io.infinitape.etherjar.hex.HexQuantity
 import org.slf4j.LoggerFactory
 import org.springframework.beans.factory.annotation.Autowired
 import org.springframework.stereotype.Service
@@ -84,10 +86,11 @@ class TrackERC20Address(
     }
 
     fun getBalance(addr: TrackedAddress): Mono<BigInteger> {
-        return getUpstream(addr.chain)
+        val upstream = getUpstream(addr.chain)
+        return upstream
                 .getDirectApi(Selector.empty)
                 .flatMap { api ->
-                    api.read(prepareEthCall(addr.token, addr.address))
+                    api.read(prepareEthCall(addr.token, addr.address, upstream.getHead()))
                             .flatMap(JsonRpcResponse::requireStringResult)
                             .map {
                                 Hex32.from(it).asQuantity().value
@@ -95,11 +98,12 @@ class TrackERC20Address(
                 }
     }
 
-    fun prepareEthCall(token: ERC20Token, target: Address): JsonRpcRequest {
+    fun prepareEthCall(token: ERC20Token, target: Address, head: Head): JsonRpcRequest {
         val call = token
                 .readBalanceOf(target)
                 .toJson()
-        return JsonRpcRequest("eth_call", listOf(call, "latest"))
+        val height = head.getCurrentHeight()?.let { HexQuantity.from(it).toHex() } ?: "latest"
+        return JsonRpcRequest("eth_call", listOf(call, height))
     }
 
     fun getUpstream(chain: Chain): EthereumMultistream {

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

@@ -89,7 +89,8 @@ class EthereumDirectReader(
         }
         balanceReader = object : Reader<Address, Wei> {
             override fun read(key: Address): Mono<Wei> {
-                val request = JsonRpcRequest("eth_getBalance", listOf(key.toHex(), "latest"))
+                val height = up.getHead().getCurrentHeight()?.let { HexQuantity.from(it).toHex() } ?: "latest"
+                val request = JsonRpcRequest("eth_getBalance", listOf(key.toHex(), height))
                 return readWithQuorum(request)
                         .timeout(Defaults.timeoutInternal, Mono.error(TimeoutException("Balance not read $key")))
                         .map {

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

@@ -130,6 +130,7 @@ open class EthereumReader(
     }
 
     fun balance(): Reader<Address, Wei> {
+        //TODO include height as part of cache?
         return CompoundReader(
                 balanceCache, directReader.balanceReader
         )

src/test/groovy/io/emeraldpay/dshackle/rpc/TrackEthereumAddressSpec.groovy

@@ -101,7 +101,7 @@ class TrackEthereumAddressSpec extends Specification {
         TrackEthereumAddress trackAddress = new TrackEthereumAddress(upstreams)
 
         apiMock.answerOnce("eth_getBalance", ["0xe2c8fa8120d813cd0b5e6add120295bf20cfa09f", "latest"], "0x499602D2")
-        apiMock.answerOnce("eth_getBalance", ["0xe2c8fa8120d813cd0b5e6add120295bf20cfa09f", "latest"], "0xff98")
+        apiMock.answerOnce("eth_getBalance", ["0xe2c8fa8120d813cd0b5e6add120295bf20cfa09f", "0x1"], "0xff98")
         when:
         def flux = trackAddress.subscribe(req)
         then:

src/test/groovy/io/emeraldpay/dshackle/upstream/ethereum/EthereumDirectReaderSpec.groovy

@@ -7,6 +7,7 @@ import io.emeraldpay.dshackle.quorum.QuorumReaderFactory
 import io.emeraldpay.dshackle.quorum.QuorumRpcReader
 import io.emeraldpay.dshackle.reader.Reader
 import io.emeraldpay.dshackle.upstream.ApiSource
+import io.emeraldpay.dshackle.upstream.Head
 import io.emeraldpay.dshackle.upstream.Multistream
 import io.emeraldpay.dshackle.upstream.calls.DefaultEthereumMethods
 import io.emeraldpay.dshackle.upstream.rpcclient.JsonRpcRequest
@@ -142,10 +143,13 @@ class EthereumDirectReaderSpec extends Specification {
                 .verify(Duration.ofSeconds(1))
     }
 
-    def "Reads balance"() {
+    def "Reads balance - height is unknown"() {
         setup:
         def up = Mock(Multistream) {
             1 * getApiSource(_) >> Stub(ApiSource)
+            1 * getHead() >> Mock(Head) {
+                1 * getCurrentHeight() >> null
+            }
         }
         def calls = Mock(Factory) {
             1 * create() >> new DefaultEthereumMethods(Chain.ETHEREUM)
@@ -171,4 +175,36 @@ class EthereumDirectReaderSpec extends Specification {
                 .verify(Duration.ofSeconds(1))
     }
 
+    def "Reads balance - height is known"() {
+        setup:
+        def up = Mock(Multistream) {
+            1 * getApiSource(_) >> Stub(ApiSource)
+            1 * getHead() >> Mock(Head) {
+                1 * getCurrentHeight() >> 11_061_691
+            }
+        }
+        def calls = Mock(Factory) {
+            1 * create() >> new DefaultEthereumMethods(Chain.ETHEREUM)
+        }
+        EthereumDirectReader reader = new EthereumDirectReader(
+                up, Caches.default(), new CurrentBlockCache(), calls
+        )
+        reader.quorumReaderFactory = Mock(QuorumReaderFactory) {
+            1 * create(_, _) >> Mock(Reader) {
+                1 * read(new JsonRpcRequest("eth_getBalance", [address1, "0xa8c9bb"])) >> Mono.just(
+                        new QuorumRpcReader.Result(
+                                Global.objectMapper.writeValueAsBytes("0x100"), 1
+                        )
+                )
+            }
+        }
+        when:
+        def act = reader.balanceReader.read(Address.from(address1))
+        then:
+        StepVerifier.create(act)
+                .expectNext(Wei.from("0x100"))
+                .expectComplete()
+                .verify(Duration.ofSeconds(1))
+    }
+
 }

src/test/groovy/io/emeraldpay/dshackle/upstream/ethereum/EthereumReaderSpec.groovy

@@ -197,8 +197,10 @@ class EthereumReaderSpec extends Specification {
     def "Caches balance until block mined"() {
         setup:
         def api = TestingCommons.api()
+        // no height
         api.answerOnce("eth_getBalance", ["0x70b91ff87a902b53dc6e2f6bda8bb9b330ccd30c", "latest"], "0x10")
-        api.answerOnce("eth_getBalance", ["0x70b91ff87a902b53dc6e2f6bda8bb9b330ccd30c", "latest"], "0xff")
+        // height 101 + 1 => 102 => 0x66
+        api.answerOnce("eth_getBalance", ["0x70b91ff87a902b53dc6e2f6bda8bb9b330ccd30c", "0x66"], "0xff")
         EthereumUpstreamMock upstream = new EthereumUpstreamMock(Chain.ETHEREUM, api)
         def upstreams = TestingCommons.multistream(upstream)
         def reader = new EthereumReader(upstreams, Caches.default(), calls)