feat: expose pending messages metric in async pipeline

rust/numaflow-core/src/mapper/map.rs

@@ -1,3 +1,13 @@
+use std::sync::Arc;
+use std::time::Duration;
+
+use numaflow_pb::clients::map::map_client::MapClient;
+use tokio::sync::{mpsc, oneshot, OwnedSemaphorePermit, Semaphore};
+use tokio::task::JoinHandle;
+use tokio_stream::wrappers::ReceiverStream;
+use tokio_stream::StreamExt;
+use tonic::transport::Channel;
+
 use crate::config::pipeline::map::MapMode;
 use crate::error;
 use crate::error::Error;
@@ -6,14 +16,6 @@ use crate::mapper::map::user_defined::{
 };
 use crate::message::Message;
 use crate::tracker::TrackerHandle;
-use numaflow_pb::clients::map::map_client::MapClient;
-use std::sync::Arc;
-use std::time::Duration;
-use tokio::sync::{mpsc, oneshot, OwnedSemaphorePermit, Semaphore};
-use tokio::task::JoinHandle;
-use tokio_stream::wrappers::ReceiverStream;
-use tokio_stream::StreamExt;
-use tonic::transport::Channel;
 pub(super) mod user_defined;
 
 /// UnaryActorMessage is a message that is sent to the UnaryMapperActor.
@@ -481,19 +483,20 @@ impl MapHandle {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-    use crate::Result;
     use std::time::Duration;
 
-    use crate::message::{MessageID, Offset, StringOffset};
-    use crate::shared::grpc::create_rpc_channel;
     use numaflow::mapstream;
     use numaflow::{batchmap, map};
     use numaflow_pb::clients::map::map_client::MapClient;
     use tempfile::TempDir;
     use tokio::sync::mpsc::Sender;
     use tokio::sync::oneshot;
 
+    use super::*;
+    use crate::message::{MessageID, Offset, StringOffset};
+    use crate::shared::grpc::create_rpc_channel;
+    use crate::Result;
+
     struct SimpleMapper;
 
     #[tonic::async_trait]

rust/numaflow-core/src/mapper/map/user_defined.rs

@@ -430,12 +430,12 @@ impl UserDefinedStreamMap {
 
 #[cfg(test)]
 mod tests {
-    use numaflow::mapstream;
     use std::error::Error;
     use std::sync::Arc;
     use std::time::Duration;
 
     use numaflow::batchmap::Server;
+    use numaflow::mapstream;
     use numaflow::{batchmap, map};
     use numaflow_pb::clients::map::map_client::MapClient;
     use tempfile::TempDir;

rust/numaflow-core/src/message.rs

@@ -218,14 +218,15 @@ impl TryFrom<Bytes> for Message {
 
 #[cfg(test)]
 mod tests {
-    use crate::error::Result;
+    use std::collections::HashMap;
+
     use chrono::TimeZone;
     use numaflow_pb::objects::isb::{
         Body, Header, Message as ProtoMessage, MessageId, MessageInfo,
     };
-    use std::collections::HashMap;
 
     use super::*;
+    use crate::error::Result;
 
     #[test]
     fn test_offset_display() {