Add count method to TaskStore

Author: FlorentinD

core/src/main/java/org/neo4j/gds/core/utils/progress/EmptyTaskStore.java

@@ -55,4 +55,9 @@ public boolean isEmpty() {
         return true;
     }
 
+    @Override
+    public long tasksCount() {
+        return 0;
+    }
+
 }

core/src/main/java/org/neo4j/gds/core/utils/progress/GlobalTaskStore.java

@@ -87,4 +87,9 @@ public boolean isEmpty() {
             .stream()
             .allMatch(Map::isEmpty);
     }
+
+    @Override
+    public long tasksCount() {
+        return registeredTasks.values().stream().mapToLong(Map::size).sum();
+    }
 }

core/src/main/java/org/neo4j/gds/core/utils/progress/TaskStore.java

@@ -40,4 +40,6 @@ public interface TaskStore {
     Stream<Task> taskStream();
 
     boolean isEmpty();
+
+    long tasksCount();
 }

core/src/test/java/org/neo4j/gds/core/utils/progress/GlobalTaskStoreTest.java

@@ -42,4 +42,20 @@ void shouldReturnEmptyResultWhenStoreIsEmpty() {
             .isNotNull()
             .isEmpty();
     }
+
+    @Test
+    void shouldCountAcrossUsers() {
+        var taskStore = new GlobalTaskStore();
+        taskStore.store("a", new JobId(), Tasks.leaf("v"));
+
+        assertThat(taskStore.tasksCount()).isEqualTo(1);
+
+        taskStore.store("b", new JobId(), Tasks.leaf("x"));
+
+        assertThat(taskStore.tasksCount()).isEqualTo(2);
+
+        taskStore.store("b", new JobId(), Tasks.leaf("y"));
+
+        assertThat(taskStore.tasksCount()).isEqualTo(3);
+    }
 }