8460: Support created_at filters.

[arvados.git] / services / ws / session.go

diff --git a/services/ws/session.go b/services/ws/session.go
index 98164e354995970e05e8298c4dfb03defebef621..9111c6cc2858eb9b94b47b765d54cb5f56977aa5 100644 (file)
--- 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{})
 }