solution: access logging for Describe method

src/main/kotlin/io/emeraldpay/dshackle/monitoring/accesslog/AccessHandler.kt

@@ -42,6 +42,7 @@ class AccessHandler(
             "SubscribeTxStatus" -> processSubscribeTxStatus(call, headers, next)
             "GetBalance" -> processSubscribeBalance(call, headers, next, false)
             "NativeCall" -> processNativeCall(call, headers, next)
+            "Describe" -> processDescribe(call, headers, next)
             else -> {
                 log.trace("unsupported method `{}`", method)
                 next.startCall(call, headers)
@@ -117,6 +118,25 @@ class AccessHandler(
         } as ServerCall.Listener<ReqT>
     }
 
+    @Suppress("UNCHECKED_CAST")
+    private fun <ReqT : Any, RespT : Any> processDescribe(
+            call: ServerCall<ReqT, RespT>,
+            headers: Metadata,
+            next: ServerCallHandler<ReqT, RespT>
+    ): ServerCall.Listener<ReqT> {
+        val builder = EventsBuilder.Describe()
+                .start(headers, call.attributes)
+
+        val callWrapper: ServerCall<ReqT, RespT> = OnDescribeResponse(
+                call as ServerCall<BlockchainOuterClass.DescribeRequest, BlockchainOuterClass.DescribeResponse>,
+                builder,
+                accessLogWriter
+        ) as ServerCall<ReqT, RespT>
+        return OnDescribeRequest(
+                next.startCall(callWrapper, headers) as ServerCall.Listener<BlockchainOuterClass.DescribeRequest>,
+                builder) as ServerCall.Listener<ReqT>
+    }
+
     class OnSubscribeHead(
             val next: ServerCall.Listener<Common.Chain>,
             val builder: EventsBuilder.SubscribeHead
@@ -193,6 +213,20 @@ class AccessHandler(
         }
     }
 
+    class OnDescribeRequest(
+            val next: ServerCall.Listener<BlockchainOuterClass.DescribeRequest>,
+            val builder: EventsBuilder.Describe
+    ) : ForwardingServerCallListener<BlockchainOuterClass.DescribeRequest>() {
+
+        override fun onMessage(message: BlockchainOuterClass.DescribeRequest) {
+            super.onMessage(message)
+        }
+
+        override fun delegate(): ServerCall.Listener<BlockchainOuterClass.DescribeRequest> {
+            return next
+        }
+    }
+
     abstract class BaseCallResponse<ReqT : Any, RespT : Any>(
             val next: ServerCall<ReqT, RespT>
     ) : ForwardingServerCall<ReqT, RespT>() {
@@ -258,4 +292,17 @@ class AccessHandler(
             super.sendMessage(message)
         }
     }
+
+    class OnDescribeResponse(
+            next: ServerCall<BlockchainOuterClass.DescribeRequest, BlockchainOuterClass.DescribeResponse>,
+            val builder: EventsBuilder.Describe,
+            val accessLogWriter: AccessLogWriter
+    ) : BaseCallResponse<BlockchainOuterClass.DescribeRequest, BlockchainOuterClass.DescribeResponse>(next) {
+
+        override fun sendMessage(message: BlockchainOuterClass.DescribeResponse) {
+            val event = builder.onReply()
+            accessLogWriter.submit(event)
+            super.sendMessage(message)
+        }
+    }
 }

src/main/kotlin/io/emeraldpay/dshackle/monitoring/accesslog/Events.kt

@@ -28,14 +28,15 @@ class Events {
     }
 
     abstract class Base(
-            val id: UUID
+            val id: UUID,
+            val method: String
     ) {
         val ts = Instant.now()
     }
 
     abstract class ChainBase(
-            val blockchain: Chain, val method: String, id: UUID
+            val blockchain: Chain, method: String, id: UUID
-    ) : Base(id)
+    ) : Base(id, method)
 
     @JsonInclude(JsonInclude.Include.NON_NULL)
     class SubscribeHead(
@@ -95,6 +96,12 @@ class Events {
             val nativeCall: NativeCallItemDetails
     ) : ChainBase(blockchain, "NativeCall", id)
 
+    @JsonInclude(JsonInclude.Include.NON_NULL)
+    class Describe(
+            id: UUID,
+            val request: StreamRequestDetails
+    ) : Base(id, "Describe")
+
     data class StreamRequestDetails(
             val id: UUID,
             val start: Instant,

src/main/kotlin/io/emeraldpay/dshackle/monitoring/accesslog/EventsBuilder.kt

@@ -227,4 +227,19 @@ class EventsBuilder {
             }
         }
     }
+
+    class Describe : Base<Describe>() {
+
+        override fun getT(): Describe {
+            return this
+        }
+
+        fun onReply(): Events.Describe {
+            return Events.Describe(
+                    id = UUID.randomUUID(),
+                    request = requestDetails
+            )
+        }
+    }
+
 }