update logs oracle (#379)

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

@@ -33,12 +33,24 @@ class LogsOracle(
     }
 
     fun estimate(
+        limit: Long?,
         fromBlock: Long,
         toBlock: Long,
         address: List<String>,
         topics: List<List<String>>,
-    ): Mono<Long> {
+    ): Mono<String> {
-        return Mono.fromCallable { db.Query(fromBlock, toBlock, address, topics) }
+        return Mono.fromCallable {
+            try {
+                val estimate = db.Query(limit, fromBlock, toBlock, address, topics)
+                "{\"total\":$estimate,\"overflow\":false}"
+            } catch (e: org.drpc.logsoracle.LogsOracle.LogsOracleException) {
+                if (e.isQueryOverflow()) {
+                    "{\"total\":\"-1\",\"overflow\":true}"
+                } else {
+                    throw e
+                }
+            }
+        }
             .subscribeOn(scheduler)
     }
 }

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

@@ -183,6 +183,10 @@ class EthereumLocalReader(
 
         val req = params[0] as LinkedHashMap<String, Any?>
 
+        val limit = try { req.get("limit") as Integer? } catch (_: IllegalArgumentException) {
+            throw RpcException(RpcResponseError.CODE_INVALID_METHOD_PARAMS, "Invalid 'limit' parameter")
+        }
+
         val fromBlock = try { parseBlockRef(req.get("fromBlock") as String?) } catch (_: IllegalArgumentException) {
             throw RpcException(RpcResponseError.CODE_INVALID_METHOD_PARAMS, "Invalid 'fromBlock' parameter")
         }
@@ -217,8 +221,8 @@ class EthereumLocalReader(
             throw RpcException(RpcResponseError.CODE_INVALID_METHOD_PARAMS, "Invalid 'topics' parameter")
         }
 
-        return logsOracle.estimate(fromBlock, toBlock, address, topics)
+        return logsOracle.estimate(limit?.toLong() ?: null, fromBlock, toBlock, address, topics)
-            .map { "{\"result\":$it}".toByteArray() to null }
+            .map { it.toByteArray() to null }
     }
 
     private fun parseBlockRef(blockRef: String?): Long {