X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/5a420beeb6c64efc3ca0ef13d4ab9ac6c654c3ab..5ffb79040668114c58bf35c3e18a8302b8d94445:/services/ws/session.go

diff --git a/services/ws/session.go b/services/ws/session.go
index 98164e3549..9111c6cc28 100644
--- a/services/ws/session.go
+++ b/services/ws/session.go
@@ -1,8 +1,27 @@
 package main
 
 type session interface {
-	Receive(map[string]interface{}, []byte)
-	EventMessage(*event) ([]byte, error)
+	// Receive processes a message received from the client. If
+	// the returned response is non-nil, it will be queued and
+	// sent the client.
+	Receive(map[string]interface{}, []byte) []byte
+
+	// Filter returns true if the event should be queued for
+	// sending to the client. It should return as fast as
+	// possible, and must not block.
 	Filter(*event) bool
+
+	// EventMessage encodes the given event (from the front of the
+	// queue) into a form suitable to send to the client. If a
+	// non-nil error is returned, the connection is terminated. If
+	// the returned buffer is empty, nothing is sent to the client
+	// and the event is not counted in statistics.
+	//
+	// Unlike Filter, EventMessage can block without affecting
+	// other connections. If EventMessage is slow, additional
+	// incoming events will be queued. If the event queue fills
+	// up, the connection will be dropped.
+	EventMessage(*event) ([]byte, error)
+
 	debugLogf(string, ...interface{})
 }