9187: Add comments.

[arvados.git] / sdk / go / dispatch / dispatch.go

diff --git a/sdk/go/dispatch/dispatch.go b/sdk/go/dispatch/dispatch.go
index 33569953da8751a16651d9725c40691fc60e5703..54d596fee86ed400d595432fd7e75d72b0c086e7 100644 (file)
--- a/sdk/go/dispatch/dispatch.go
+++ b/sdk/go/dispatch/dispatch.go
@@ -102,9 +102,9 @@ func (dispatcher *Dispatcher) notMine(uuid string) {
        }
 }
 
-// Check if there is a channel for updates associated with this container.  If
-// so (and update is true) send the container record on the channel and return
-// true, if not return false.
+// checkMine returns true/false if there is a channel for updates associated
+// with container c.  If update is true, also send the container record on
+// the channel.
 func (dispatcher *Dispatcher) checkMine(c Container, update bool) bool {
        dispatcher.mineMutex.Lock()
        defer dispatcher.mineMutex.Unlock()
@@ -177,6 +177,10 @@ func (dispatcher *Dispatcher) pollContainers() {
 
 func (dispatcher *Dispatcher) handleUpdate(container Container) {
        if container.State == Queued && dispatcher.checkMine(container, false) {
+               // If we previously started the job, something failed, and it
+               // was re-queued, this dispatcher might still be monitoring it.
+               // Stop the existing monitor, then try to lock and run it
+               // again.
                dispatcher.notMine(container.UUID)
        }