Merge branch '8784-dir-listings'

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

diff --git a/sdk/go/dispatch/dispatch.go b/sdk/go/dispatch/dispatch.go
index e489ac79f3c3cbe59aab8b031eeb74d257081f0e..356d087a46f31c7f97ce92ad975300f0a0959990 100644 (file)
--- a/sdk/go/dispatch/dispatch.go
+++ b/sdk/go/dispatch/dispatch.go
@@ -1,3 +1,7 @@
+// Copyright (C) The Arvados Authors. All rights reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+
 // Package dispatch is a helper library for building Arvados container
 // dispatchers.
 package dispatch
@@ -21,6 +25,7 @@ const (
        Cancelled = arvados.ContainerStateCancelled
 )
 
+// Dispatcher struct
 type Dispatcher struct {
        Arv *arvadosclient.ArvadosClient
 
@@ -130,7 +135,7 @@ func (d *Dispatcher) checkForUpdates(filters [][]interface{}) {
                        log.Printf("Error getting list of containers: %q", err)
                        return
                }
-               more = list.ItemsAvailable > len(list.Items)
+               more = len(list.Items) > 0 && list.ItemsAvailable > len(list.Items)+offset
                d.checkListForUpdates(list.Items)
        }
 }
@@ -174,7 +179,7 @@ func (d *Dispatcher) checkListForUpdates(containers []arvados.Container) {
                                }
                                d.trackers[c.UUID] = d.start(c)
                        case Cancelled, Complete:
-                               tracker.close()
+                               // no-op (we already stopped monitoring)
                        }
                }
        }
@@ -202,6 +207,43 @@ func (d *Dispatcher) Unlock(uuid string) error {
        return d.Arv.Call("POST", "containers", uuid, "unlock", nil, nil)
 }
 
+// TrackContainer ensures a tracker is running for the given UUID,
+// regardless of the current state of the container (except: if the
+// container is locked by a different dispatcher, a tracker will not
+// be started). If the container is not in Locked or Running state,
+// the new tracker will close down immediately.
+//
+// This allows the dispatcher to put its own RunContainer func into a
+// cleanup phase (for example, to kill local processes created by a
+// prevous dispatch process that are still running even though the
+// container state is final) without the risk of having multiple
+// goroutines monitoring the same UUID.
+func (d *Dispatcher) TrackContainer(uuid string) error {
+       var cntr arvados.Container
+       err := d.Arv.Call("GET", "containers", uuid, "", nil, &cntr)
+       if err != nil {
+               return err
+       }
+       if cntr.LockedByUUID != "" && cntr.LockedByUUID != d.auth.UUID {
+               return nil
+       }
+
+       d.mtx.Lock()
+       defer d.mtx.Unlock()
+       if _, alreadyTracking := d.trackers[uuid]; alreadyTracking {
+               return nil
+       }
+       if d.trackers == nil {
+               d.trackers = make(map[string]*runTracker)
+       }
+       d.trackers[uuid] = d.start(cntr)
+       switch cntr.State {
+       case Queued, Cancelled, Complete:
+               d.trackers[uuid].close()
+       }
+       return nil
+}
+
 type runTracker struct {
        closing bool
        updates chan arvados.Container
@@ -225,8 +267,3 @@ func (tracker *runTracker) update(c arvados.Container) {
        }
        tracker.updates <- c
 }
-
-// Start a tracker for the given uuid if one is not already existing, despite its state.
-// its vs. it's -- episode 5 from Series 1 of Netflix' "A Series of Unfortunate Events"
-func (dispatcher *Dispatcher) TrackContainer(uuid string) {
-}