fix: keep project version data in telemetry after a clear (#24827)

The dev-mode usage statistics file is shared by all dev servers running
on a machine. After a successful upload StatisticsSender clears the
whole
projects array, which also wipes the data of other still-running dev
servers that did not trigger the upload. Until now the version and
source
identity (flowVersion, vaadinVersion, hillaVersion, sourceId) was only
written by trackGlobalData() at dev-mode startup, so any event from a
continued session (live reload, browser data, ...) recreated the project
entry with just that event's field and no versions. The next report then
contained rows with an empty flowVersion and devModeStarts == 0.

Re-assert the project identity data whenever the running session writes
project data and the entry is missing it, so a continued session repairs
its own entry before the next report is sent. devModeStarts stays a true
per-interval counter (0 for a continued session) but now always comes
with complete version information.

---------

Co-authored-by: totally-not-ai[bot] <290682512+totally-not-ai[bot]@users.noreply.github.com>

Author: totally-not-ai[bot]

vaadin-dev-server/src/main/java/com/vaadin/base/devserver/stats/DevModeUsageStatistics.java

@@ -151,20 +151,55 @@ private void trackGlobalData() {
             }
 
             // Update basic project statistics and save
-            projectData.setValue(StatisticsConstants.FIELD_FLOW_VERSION,
-                    Version.getFullVersion());
-            projectData.setValue(StatisticsConstants.FIELD_VAADIN_VERSION,
-                    ServerInfo.fetchVaadinVersion());
-            projectData.setValue(StatisticsConstants.FIELD_HILLA_VERSION,
-                    ServerInfo.fetchHillaVersion());
-            projectData.setValue(StatisticsConstants.FIELD_SOURCE_ID,
-                    ProjectHelpers.getProjectSource(projectFolder));
+            populateProjectData(projectData);
             projectData.increment(
                     StatisticsConstants.FIELD_PROJECT_DEVMODE_STARTS);
         });
 
     }
 
+    /**
+     * Populates the static identity data (versions and source id) of the
+     * current project.
+     *
+     * @param projectData
+     *            the project specific data to populate
+     */
+    private void populateProjectData(StatisticsContainer projectData) {
+        projectData.setValue(StatisticsConstants.FIELD_FLOW_VERSION,
+                Version.getFullVersion());
+        projectData.setValue(StatisticsConstants.FIELD_VAADIN_VERSION,
+                ServerInfo.fetchVaadinVersion());
+        projectData.setValue(StatisticsConstants.FIELD_HILLA_VERSION,
+                ServerInfo.fetchHillaVersion());
+        projectData.setValue(StatisticsConstants.FIELD_SOURCE_ID,
+                ProjectHelpers.getProjectSource(projectFolder));
+    }
+
+    /**
+     * Makes sure the current project entry carries its identity data.
+     * <p>
+     * The statistics file is shared by all dev servers running on the machine,
+     * and after a successful upload the whole projects array is cleared (see
+     * {@link StatisticsSender}). That clear also wipes the data of other dev
+     * servers that did not trigger the upload. Any subsequent event from a
+     * still-running session (live reload, browser data, ...) would otherwise
+     * recreate the project entry with only that event's field and no version
+     * information, leading to reports with empty {@code flowVersion} and
+     * {@code devModeStarts == 0}. Re-asserting the identity data when it is
+     * missing lets a continued session repair its own entry before the next
+     * report is sent.
+     *
+     * @param projectData
+     *            the project specific data to verify and repair
+     */
+    private void ensureProjectData(StatisticsContainer projectData) {
+        if (!projectData
+                .containsField(StatisticsConstants.FIELD_FLOW_VERSION)) {
+            populateProjectData(projectData);
+        }
+    }
+
     /**
      * Stores telemetry data received from the browser.
      *
@@ -179,6 +214,7 @@ public static void handleBrowserData(JsonNode data) {
         }
 
         get().storage.update((global, project) -> {
+            get().ensureProjectData(project);
             try {
                 String json = data.get("browserData").toString();
                 JsonNode clientData = JsonHelpers.getJsonMapper()
@@ -218,7 +254,10 @@ public static void collectEvent(String name) {
         }
 
         try {
-            get().storage.update((global, project) -> project.increment(name));
+            get().storage.update((global, project) -> {
+                get().ensureProjectData(project);
+                project.increment(name);
+            });
         } catch (Exception e) {
             getLogger().debug("Failed to log '" + name + "'", e);
         }
@@ -240,8 +279,10 @@ public static void collectEvent(String name, double value) {
             return;
 
         try {
-            get().storage.update(
-                    (global, project) -> project.aggregate(name, value));
+            get().storage.update((global, project) -> {
+                get().ensureProjectData(project);
+                project.aggregate(name, value);
+            });
         } catch (Exception e) {
             getLogger().debug("Failed to collect event '" + name + "'", e);
         }
@@ -260,7 +301,10 @@ public void set(String name, String value) {
             return;
 
         try {
-            storage.update((global, project) -> project.setValue(name, value));
+            storage.update((global, project) -> {
+                ensureProjectData(project);
+                project.setValue(name, value);
+            });
         } catch (Exception e) {
             getLogger().debug("Failed to set  '" + name + "'", e);
         }

vaadin-dev-server/src/main/java/com/vaadin/base/devserver/stats/StatisticsContainer.java

@@ -126,6 +126,17 @@ public void aggregate(String name, double newValue) {
         json.put(name, newValue);
     }
 
+    /**
+     * Checks whether the given field is present.
+     *
+     * @param name
+     *            name of the field to check
+     * @return {@code true} if the field is present, {@code false} otherwise
+     */
+    public boolean containsField(String name) {
+        return json.has(name);
+    }
+
     /**
      * Returns the given field value as a string.
      *

vaadin-dev-server/src/test/java/com/vaadin/base/devserver/stats/DevModeUsageStatisticsTest.java

@@ -25,6 +25,7 @@
 
 import com.vaadin.flow.internal.JacksonUtils;
 import com.vaadin.flow.internal.StringUtil;
+import com.vaadin.flow.server.Version;
 import com.vaadin.flow.testutil.TestUtils;
 import com.vaadin.pro.licensechecker.MachineId;
 
@@ -211,6 +212,44 @@ void multipleProjects() throws Exception {
 
     }
 
+    @Test
+    void eventAfterClearRestoresProjectVersionData() {
+        // A running dev session for this project
+        File mavenProjectFolder = TestUtils
+                .getTestFolder("stats-data/maven-project-folder1");
+        DevModeUsageStatistics.init(mavenProjectFolder, storage, sender);
+
+        // A successful upload (possibly triggered by another project sharing
+        // the machine-wide statistics file) clears all project data
+        storage.clearAllProjectData();
+        assertEquals(0, getNumberOfProjects(storage.read()),
+                "Expected the projects array to be cleared");
+
+        // The still-running session keeps reporting events without a restart
+        DevModeUsageStatistics
+                .collectEvent(StatisticsConstants.EVENT_LIVE_RELOAD);
+
+        // The recreated entry must still carry the project identity data so
+        // that the next report does not contain an empty-version row
+        StatisticsContainer projectData = new StatisticsContainer(
+                storage.readProject());
+        assertEquals(Version.getFullVersion(),
+                projectData.getValue(StatisticsConstants.FIELD_FLOW_VERSION),
+                "flowVersion must be restored after a clear");
+        assertEquals("https://start.vaadin.com/test/1",
+                projectData.getValue(StatisticsConstants.FIELD_SOURCE_ID),
+                "sourceId must be restored after a clear");
+        // No restart happened, so devModeStarts stays 0 for this interval
+        assertEquals(0,
+                projectData.getValueAsInt(
+                        StatisticsConstants.FIELD_PROJECT_DEVMODE_STARTS),
+                "devModeStarts must not be incremented by a plain event");
+        assertEquals(1,
+                projectData
+                        .getValueAsInt(StatisticsConstants.EVENT_LIVE_RELOAD),
+                "The live reload event must be recorded");
+    }
+
     @Test
     void mavenProjectProjectId() {
         File mavenProjectFolder1 = TestUtils