Handle conflict properly.

org.jdrupes.vmoperator.common/src/org/jdrupes/vmoperator/common/K8sGenericStub.java

@@ -193,42 +193,41 @@ public class K8sGenericStub<O extends KubernetesObject,
     }
 
     /**
-     * Updates the object's status, retrying for the given number of times
+     * Updates the object's status.
-     * if the update fails due to a conflict.
      *
      * @param object the current state of the object (passed to `status`)
      * @param status function that returns the new status
-     * @param retries the retries
+     * @return the updated model or empty if the object was not found
-     * @return the updated model or empty if not successful
      * @throws ApiException the api exception
      */
     @SuppressWarnings("PMD.AssignmentInOperand")
-    public Optional<O> updateStatus(O object,
+    public Optional<O> updateStatus(O object, Function<O, Object> status)
-            Function<O, Object> status, int retries) throws ApiException {
+            throws ApiException {
-        while (true) {
-            try {
         return K8s.optional(api.updateStatus(object, status));
+    }
+
+    /**
+     * Gets the object and updates the status. In case of conflict, retries
+     * up to `retries` times.
+     *
+     * @param status the status
+     * @param retries the retries in case of conflict
+     * @return the updated model or empty if the object was not found
+     * @throws ApiException the api exception
+     */
+    @SuppressWarnings({ "PMD.AssignmentInOperand", "PMD.UnusedAssignment" })
+    public Optional<O> updateStatus(Function<O, Object> status, int retries)
+            throws ApiException {
+        try {
+            return updateStatus(api.get(namespace, name).throwsApiException()
+                .getObject(), status);
         } catch (ApiException e) {
             if (HttpURLConnection.HTTP_CONFLICT != e.getCode()
                 || retries-- <= 0) {
                 throw e;
             }
         }
-        }
+        return Optional.empty();
-    }
-
-    /**
-     * Updates the object's status, retrying up to 16 times if there
-     * is a conflict.
-     *
-     * @param object the current state of the object (passed to `status`)
-     * @param status function that returns the new status
-     * @return the updated model or empty if not successful
-     * @throws ApiException the api exception
-     */
-    public Optional<O> updateStatus(O object,
-            Function<O, Object> status) throws ApiException {
-        return updateStatus(object, status, 16);
     }
 
     /**
@@ -241,8 +240,7 @@ public class K8sGenericStub<O extends KubernetesObject,
      */
     public Optional<O> updateStatus(Function<O, Object> status)
             throws ApiException {
-        return updateStatus(
+        return updateStatus(status, 16);
-            api.get(namespace, name).throwsApiException().getObject(), status);
     }
 
     /**

org.jdrupes.vmoperator.manager/src/org/jdrupes/vmoperator/manager/Controller.java

@@ -24,6 +24,7 @@ import io.kubernetes.client.custom.V1Patch;
 import io.kubernetes.client.openapi.ApiException;
 import io.kubernetes.client.openapi.Configuration;
 import java.io.IOException;
+import java.net.HttpURLConnection;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.time.Instant;
@@ -211,7 +212,10 @@ public class Controller extends Component {
     }
 
     /**
-     * Update the assignment information in the status of the VM CR.
+     * Attempt to Update the assignment information in the status of the
+     * VM CR. Returns true if successful. The handler does not attempt
+     * retries, because in case of failure it will be necessary to
+     * re-evaluate the chosen VM.
      *
      * @param event the event
      * @param channel the channel
@@ -220,18 +224,27 @@ public class Controller extends Component {
     @Handler
     public void onUpdatedAssignment(UpdateAssignment event, VmChannel channel)
             throws ApiException {
+        try {
             var vmDef = channel.vmDefinition();
             var vmStub = VmDefinitionStub.get(channel.client(),
                 new GroupVersionKind(VM_OP_GROUP, "", VM_OP_KIND_VM),
                 vmDef.namespace(), vmDef.name());
-        vmStub.updateStatus(from -> {
+            if (vmStub.updateStatus(vmDef, from -> {
                 JsonObject status = from.statusJson();
                 var assignment = GsonPtr.to(status).to("assignment");
                 assignment.set("pool", event.usedPool());
                 assignment.set("user", event.toUser());
                 assignment.set("lastUsed", Instant.now().toString());
                 return status;
-        });
+            }).isPresent()) {
                 event.setResult(true);
             }
+        } catch (ApiException e) {
+            // Log exceptions except for conflict, which can be expected
+            if (HttpURLConnection.HTTP_CONFLICT != e.getCode()) {
+                throw e;
+            }
+        }
+        event.setResult(false);
+    }
 }

org.jdrupes.vmoperator.manager/src/org/jdrupes/vmoperator/manager/VmMonitor.java

@@ -256,20 +256,21 @@ public class VmMonitor extends
     @SuppressWarnings("PMD.AvoidInstantiatingObjectsInLoops")
     public void onAssignVm(AssignVm event)
             throws ApiException, InterruptedException {
+        while (true) {
             // Search for existing assignment.
-        var assignedVm = channelManager.channels().stream()
+            var vmQuery = channelManager.channels().stream()
                 .filter(c -> c.vmDefinition().assignedFrom()
                     .map(p -> p.equals(event.fromPool())).orElse(false))
                 .filter(c -> c.vmDefinition().assignedTo()
                     .map(u -> u.equals(event.toUser())).orElse(false))
                 .findFirst();
-        if (assignedVm.isPresent()) {
+            if (vmQuery.isPresent()) {
-            var vmDef = assignedVm.get().vmDefinition();
+                var vmDef = vmQuery.get().vmDefinition();
-            event.setResult(new VmData(vmDef, assignedVm.get()));
+                event.setResult(new VmData(vmDef, vmQuery.get()));
                 return;
             }
 
-        // Get the pool definition assignability check
+            // Get the pool definition for checking possible assignment
             VmPool vmPool = newEventPipeline().fire(new GetPools()
                 .withName(event.fromPool())).get().stream().findFirst()
                 .orElse(null);
@@ -278,7 +279,7 @@ public class VmMonitor extends
             }
 
             // Find available VM.
-        assignedVm = channelManager.channels().stream()
+            vmQuery = channelManager.channels().stream()
                 .filter(c -> vmPool.isAssignable(c.vmDefinition()))
                 .sorted(Comparator.comparing((VmChannel c) -> c.vmDefinition()
                     .assignmentLastUsed().orElse(Instant.ofEpochSecond(0)))
@@ -286,19 +287,25 @@ public class VmMonitor extends
                 .findFirst();
 
             // None found
-        if (assignedVm.isEmpty()) {
+            if (vmQuery.isEmpty()) {
                 return;
             }
 
             // Assign to user
-        assignedVm.get().pipeline().fire(new UpdateAssignment(vmPool.name(),
+            var chosenVm = vmQuery.get();
-            event.toUser()), assignedVm.get()).get();
+            var vmPipeline = chosenVm.pipeline();
-        var vmDef = assignedVm.get().vmDefinition();
+            if (Optional.ofNullable(vmPipeline.fire(new UpdateAssignment(
-        event.setResult(new VmData(vmDef, assignedVm.get()));
+                vmPool.name(), event.toUser()), chosenVm).get())
+                .orElse(false)) {
+                var vmDef = chosenVm.vmDefinition();
+                event.setResult(new VmData(vmDef, chosenVm));
 
                 // Make sure that a newly assigned VM is running.
-        assignedVm.get().pipeline().fire(new ModifyVm(vmDef.name(),
+                chosenVm.pipeline().fire(new ModifyVm(vmDef.name(),
-            "state", "Running", assignedVm.get()));
+                    "state", "Running", chosenVm));
+                return;
+            }
+        }
     }
 
     private static Comparator<VmChannel> preferRunning