Refactor eventloop to enable async comms

Author: halleysfifthinc

src/eventloop.jl

@@ -1,51 +1,95 @@
-function eventloop(socket)
-    task_local_storage(:IJulia_task, "write task")
-    try
-        while true
-            msg = recv_ipython(socket)
-            try
-                send_status("busy", msg)
-                invokelatest(get(handlers, msg.header["msg_type"], unknown_request), socket, msg)
-            catch e
-                # Try to keep going if we get an exception, but
-                # send the exception traceback to the front-ends.
-                # (Ignore SIGINT since this may just be a user-requested
-                #  kernel interruption to interrupt long calculations.)
-                if !isa(e, InterruptException)
-                    content = error_content(e, msg="KERNEL EXCEPTION")
-                    map(s -> println(orig_stderr[], s), content["traceback"])
-                    send_ipython(publish[], msg_pub(execute_msg, "error", content))
+function eventloop(socket::Socket, msgs::Channel, handlers)
+    while true
+        try
+            while true
+                msg = take!(msgs)
+                try
+                    send_status("busy", msg)
+                    invokelatest(get(handlers, msg.header["msg_type"], unknown_request), socket, msg)
+                catch e
+                    # Try to keep going if we get an exception, but
+                    # send the exception traceback to the front-ends.
+                    # (Ignore SIGINT since this may just be a user-requested
+                    #  kernel interruption to interrupt long calculations.)
+                    if !isa(e, InterruptException)
+                        content = error_content(e, msg="KERNEL EXCEPTION")
+                        map(s -> println(orig_stderr[], s), content["traceback"])
+                        send_ipython(publish[], msg_pub(execute_msg, "error", content))
+                    else
+                        rethrow()
+                    end
+                finally
+                    flush_all()
+                    send_status("idle", msg)
                 end
-            finally
-                flush_all()
-                send_status("idle", msg)
+                yield()
+            end
+        catch e
+            # the Jupyter manager may send us a SIGINT if the user
+            # chooses to interrupt the kernel; don't crash on this
+            if !isa(e, InterruptException)
+                rethrow()
             end
         end
-    catch e
-        # the Jupyter manager may send us a SIGINT if the user
-        # chooses to interrupt the kernel; don't crash on this
-        if isa(e, InterruptException)
-            eventloop(socket)
-        else
-            rethrow()
-        end
+        yield()
     end
 end
 
+const iopub_task = Ref{Task}()
 const requests_task = Ref{Task}()
 function waitloop()
-    @async eventloop(control[])
-    requests_task[] = @async eventloop(requests[])
+    control_msgs = Channel{Msg}(32) do ch
+        task_local_storage(:IJulia_task, "control_msgs task")
+        while isopen(control[])
+            msg::Msg = recv_ipython(control[])
+            put!(ch, msg)
+            yield()
+        end
+    end
+
+    iopub_msgs = Channel{Msg}(32)
+    request_msgs = Channel{Msg}(32) do ch
+        task_local_storage(:IJulia_task, "request_msgs task")
+        while isopen(requests[])
+            msg::Msg = recv_ipython(requests[])
+            if haskey(iopub_handlers,  msg.header["msg_type"])
+                put!(iopub_msgs, msg)
+            else
+                put!(ch, msg)
+            end
+            yield()
+        end
+    end
+
+    control_task = @async begin
+        task_local_storage(:IJulia_task, "control handle/write task")
+        eventloop(control[], control_msgs, handlers)
+    end
+    requests_task[] = @async begin
+        task_local_storage(:IJulia_task, "requests handle/write task")
+        eventloop(requests[], request_msgs, handlers)
+    end
+    iopub_task[] = @async begin
+        task_local_storage(:IJulia_task, "iopub handle/write task")
+        eventloop(requests[], iopub_msgs, iopub_handlers)
+    end
+
+    bind(control_msgs, control_task)
+    bind(request_msgs, requests_task[])
+    bind(iopub_msgs, iopub_task[])
+
     while true
         try
             wait()
         catch e
             # send interrupts (user SIGINT) to the code-execution task
             if isa(e, InterruptException)
+                @async Base.throwto(iopub_task[], e)
                 @async Base.throwto(requests_task[], e)
             else
                 rethrow()
             end
         end
     end
 end
+

src/handlers.jl

@@ -271,6 +271,7 @@ end
 
 function interrupt_request(socket, msg)
     @async Base.throwto(requests_task[], InterruptException())
+    @async Base.throwto(iopub_task[], InterruptException())
     send_ipython(requests[], msg_reply(msg, "interrupt_reply", Dict()))
 end
 
@@ -291,5 +292,11 @@ const handlers = Dict{String,Function}(
     "comm_open" => comm_open,
     "comm_info_request" => comm_info_request,
     "comm_msg" => comm_msg,
-    "comm_close" => comm_close
+    "comm_close" => comm_close,
+)
+
+const iopub_handlers = Dict{String,Function}(
+    "comm_open" => comm_open,
+    "comm_msg" => comm_msg,
+    "comm_close" => comm_close,
 )