master: support optional args

src/runtime/src/comms.rs

@@ -448,22 +448,23 @@ async fn handle_run_kernel(
             #[cfg(has_drtio)]
             kernel::Message::SubkernelMsgRecvRequest { id, timeout } => {
                 let message_received = subkernel::message_await(id, timeout, timer).await;
-                let status = match message_received {
+                let (status, count) = match message_received {
-                    Ok(_) => kernel::SubkernelStatus::NoError,
+                    Ok(ref message) => (kernel::SubkernelStatus::NoError, message.count),
-                    Err(SubkernelError::Timeout) => kernel::SubkernelStatus::Timeout,
+                    Err(SubkernelError::Timeout) => (kernel::SubkernelStatus::Timeout, 0),
-                    Err(SubkernelError::IncorrectState) => kernel::SubkernelStatus::IncorrectState,
+                    Err(SubkernelError::IncorrectState) => (kernel::SubkernelStatus::IncorrectState, 0),
-                    Err(SubkernelError::CommLost) => kernel::SubkernelStatus::CommLost,
+                    Err(SubkernelError::CommLost) => (kernel::SubkernelStatus::CommLost, 0),
-                    Err(_) => kernel::SubkernelStatus::OtherError,
+                    Err(_) => (kernel::SubkernelStatus::OtherError, 0),
                 };
                 control
                     .borrow_mut()
                     .tx
-                    .async_send(kernel::Message::SubkernelMsgRecvReply { status: status })
+                    .async_send(kernel::Message::SubkernelMsgRecvReply { status: status, count: count })
                     .await;
-                if let Ok((tag, data)) = message_received {
+                if let Ok(message) = message_received {
                     // receive code almost identical to RPC recv, except we are not reading from a stream
-                    let mut reader = Cursor::new(data);
+                    let mut reader = Cursor::new(message.data);
-                    let mut tag: [u8; 1] = [tag];
+                    let mut tag: [u8; 1] = [message.tag];
+                    let mut i = 0;
                     loop {
                         // kernel has to consume all arguments in the whole message
                         let slot = match fast_recv(&mut control.borrow_mut().rx).await {
@@ -493,10 +494,12 @@ async fn handle_run_kernel(
                             .tx
                             .async_send(kernel::Message::RpcRecvReply(Ok(0)))
                             .await;
-                        match reader.read_u8() {
+                        i += 1;
-                            Ok(0) | Err(_) => break, // reached the end of data, we're done
+                        if i < count {
-                            Ok(t) => tag[0] = t,     // update the tag for next read
+                            tag[0] = reader.read_u8()?;
-                        };
+                        } else {
+                            break;
+                        }
                     }
                 }
             }

src/runtime/src/kernel/mod.rs

@@ -116,6 +116,7 @@ pub enum Message {
     #[cfg(has_drtio)]
     SubkernelMsgRecvReply {
         status: SubkernelStatus,
+        count: u8,
     },
 }
 

src/runtime/src/kernel/subkernel.rs

@@ -51,18 +51,20 @@ pub extern "C" fn await_finish(id: u32, timeout: u64) {
     }
 }
 
-pub extern "C" fn send_message(id: u32, tag: &CSlice<u8>, data: *const *const ()) {
+pub extern "C" fn send_message(id: u32, count: u8, tag: &CSlice<u8>, data: *const *const ()) {
     let mut buffer = Vec::<u8>::new();
     send_args(&mut buffer, 0, tag.as_ref(), data).expect("RPC encoding failed");
+    // overwrite service tag, include how many tags are in the message
+    buffer[3] = count;
     unsafe {
         KERNEL_CHANNEL_1TO0.as_mut().unwrap().send(Message::SubkernelMsgSend {
             id: id,
-            data: buffer[4..].to_vec(),
+            data: buffer[3..].to_vec(),
         });
     }
 }
 
-pub extern "C" fn await_message(id: u32, timeout: u64) {
+pub extern "C" fn await_message(id: u32, timeout: u64, min: u8, max: u8) {
     unsafe {
         KERNEL_CHANNEL_1TO0
             .as_mut()
@@ -75,18 +77,27 @@ pub extern "C" fn await_message(id: u32, timeout: u64) {
     match unsafe { KERNEL_CHANNEL_0TO1.as_mut().unwrap() }.recv() {
         Message::SubkernelMsgRecvReply {
             status: SubkernelStatus::NoError,
-        } => (),
+            count
+        } => {
+            if min > count || count > max {
+                artiq_raise!("SubkernelError", "Received more or less arguments than required")
+            }
+        },
         Message::SubkernelMsgRecvReply {
             status: SubkernelStatus::IncorrectState,
+            ..
         } => artiq_raise!("SubkernelError", "Subkernel not running"),
         Message::SubkernelMsgRecvReply {
             status: SubkernelStatus::Timeout,
+            ..
         } => artiq_raise!("SubkernelError", "Subkernel timed out"),
         Message::SubkernelMsgRecvReply {
             status: SubkernelStatus::CommLost,
+            ..
         } => artiq_raise!("SubkernelError", "Lost communication with satellite"),
         Message::SubkernelMsgRecvReply {
             status: SubkernelStatus::OtherError,
+            ..
         } => artiq_raise!("SubkernelError", "An error occurred during subkernel operation"),
         _ => panic!("expected SubkernelMsgRecvReply after SubkernelMsgRecvRequest"),
     }

src/runtime/src/subkernel.rs

@@ -209,8 +209,9 @@ pub async fn await_finish(
     }
 }
 
-struct Message {
+pub struct Message {
     from_id: u32,
+    pub count: u8,
     pub tag: u8,
     pub data: Vec<u8>,
 }
@@ -234,8 +235,9 @@ pub async fn message_handle_incoming(id: u32, last: bool, length: usize, data: &
                 id,
                 Message {
                     from_id: id,
-                    tag: data[0],
+                    count: data[0],
-                    data: data[1..length].to_vec(),
+                    tag: data[1],
+                    data: data[2..length].to_vec(),
                 },
             );
         }
@@ -249,7 +251,7 @@ pub async fn message_handle_incoming(id: u32, last: bool, length: usize, data: &
     }
 }
 
-pub async fn message_await(id: u32, timeout: u64, timer: GlobalTimer) -> Result<(u8, Vec<u8>), Error> {
+pub async fn message_await(id: u32, timeout: u64, timer: GlobalTimer) -> Result<Message, Error> {
     match SUBKERNELS.async_lock().await.get(&id).unwrap().state {
         SubkernelState::Finished {
             status: FinishStatus::CommLost,
@@ -265,7 +267,7 @@ pub async fn message_await(id: u32, timeout: u64, timer: GlobalTimer) -> Result<
                 let msg = &message_queue[i];
                 if msg.from_id == id {
                     let message = message_queue.remove(i);
-                    return Ok((message.tag, message.data));
+                    return Ok(message);
                 }
             }
         }