Prevent false version mismatches when saving annotations

CHANGELOG.unreleased.md

@@ -20,7 +20,7 @@ For upgrade instructions, please check the [migration guide](MIGRATIONS.released
 
 ### Fixed
 
-- 
+- Fixed retrying of failed save requests sent during tracingstore restart. [#4591](https://github.com/scalableminds/webknossos/pull/4591)
 
 ### Removed
 

webknossos-tracingstore/app/com/scalableminds/webknossos/tracingstore/tracings/FossilDBClient.scala

@@ -80,11 +80,20 @@ class FossilDBClient(collection: String, config: TracingStoreConfig) extends Fox
       case e: Exception => Fox.failure("Could not get from FossilDB: " + e.getMessage)
     }
 
-  def getVersion(key: String, version: Option[Long] = None, mayBeEmpty: Option[Boolean] = None): Fox[Long] =
+  def getVersion(key: String,
+                 version: Option[Long] = None,
+                 mayBeEmpty: Option[Boolean],
+                 emptyFallback: Option[Long] = None): Fox[Long] =
     try {
       val reply = blockingStub.get(GetRequest(collection, key, version, mayBeEmpty))
-      if (!reply.success) throw new Exception(reply.errorMessage.getOrElse(""))
-      Fox.successful(reply.actualVersion)
+      if (reply.success) Fox.successful(reply.actualVersion)
+      else {
+        if (mayBeEmpty.contains(true) && emptyFallback.isDefined && reply.errorMessage.contains("No such element")) {
+          emptyFallback.toFox
+        } else {
+          throw new Exception(reply.errorMessage.getOrElse(""))
+        }
+      }
     } catch {
       case e: Exception => Fox.failure("Could not get from FossilDB: " + e.getMessage)
     }

webknossos-tracingstore/app/com/scalableminds/webknossos/tracingstore/tracings/skeleton/SkeletonTracingService.scala

@@ -33,7 +33,7 @@ class SkeletonTracingService @Inject()(tracingDataStore: TracingDataStore,
   implicit val updateActionJsonFormat = SkeletonUpdateAction.skeletonUpdateActionFormat
 
   def currentVersion(tracingId: String): Fox[Long] =
-    tracingDataStore.skeletonUpdates.getVersion(tracingId, mayBeEmpty = Some(true)).getOrElse(0L)
+    tracingDataStore.skeletonUpdates.getVersion(tracingId, mayBeEmpty = Some(true), emptyFallback = Some(0L))
 
   def handleUpdateGroup(tracingId: String,
                         updateActionGroup: UpdateActionGroup[SkeletonTracing],
@@ -70,14 +70,21 @@ class SkeletonTracingService @Inject()(tracingDataStore: TracingDataStore,
   private def findDesiredOrNewestPossibleVersion(tracing: SkeletonTracing,
                                                  tracingId: String,
                                                  desiredVersion: Option[Long]): Fox[Long] =
-    (for {
-      newestUpdateVersion <- tracingDataStore.skeletonUpdates.getVersion(tracingId, mayBeEmpty = Some(true))
+    /*
+     * Determines the newest saved version from the updates column.
+     * if there are no updates at all, assume tracing is brand new (possibly created from NML,
+     * hence the emptyFallbck tracing.version)
+     */
+    for {
+      newestUpdateVersion <- tracingDataStore.skeletonUpdates.getVersion(tracingId,
+                                                                         mayBeEmpty = Some(true),
+                                                                         emptyFallback = Some(tracing.version))
     } yield {
       desiredVersion match {
         case None              => newestUpdateVersion
         case Some(desiredSome) => math.min(desiredSome, newestUpdateVersion)
       }
-    }).getOrElse(tracing.version) //if there are no updates at all, assume tracing is brand new (possibly created from NML)
+    }
 
   private def findPendingUpdates(tracingId: String,
                                  existingVersion: Long,

webknossos-tracingstore/app/com/scalableminds/webknossos/tracingstore/tracings/volume/VolumeTracingService.scala

@@ -63,7 +63,7 @@ class VolumeTracingService @Inject()(
   val binaryDataService = new BinaryDataService(Paths.get(""), 10 seconds, 100, null)
 
   override def currentVersion(tracingId: String): Fox[Long] =
-    tracingDataStore.volumes.getVersion(tracingId).getOrElse(0L)
+    tracingDataStore.volumes.getVersion(tracingId, mayBeEmpty = Some(true), emptyFallback = Some(0L))
 
   def handleUpdateGroup(tracingId: String,
                         updateGroup: UpdateActionGroup[VolumeTracing],