Fix 'Resource leak: <variable> is never closed' warnings

photon-core/src/main/java/org/photonvision/common/configuration/LegacyConfigProvider.java

@@ -32,6 +32,7 @@
 import java.time.format.DateTimeFormatter;
 import java.time.temporal.TemporalAccessor;
 import java.util.*;
+import java.util.stream.Stream;
 import org.photonvision.common.logging.LogGroup;
 import org.photonvision.common.logging.Logger;
 import org.photonvision.common.util.file.FileUtils;
@@ -282,9 +283,8 @@ public boolean saveToDisk() {
 
     private HashMap<String, CameraConfiguration> loadCameraConfigs() {
         HashMap<String, CameraConfiguration> loadedConfigurations = new HashMap<>();
-        try {
-            var subdirectories =
-                    Files.list(camerasFolder.toPath()).filter(f -> f.toFile().isDirectory()).toList();
+        try (Stream<Path> files = Files.list(camerasFolder.toPath())) {
+            var subdirectories = files.filter(f -> f.toFile().isDirectory()).toList();
 
             for (var subdir : subdirectories) {
                 var cameraConfigPath = Path.of(subdir.toString(), "config.json");
@@ -325,9 +325,11 @@ private HashMap<String, CameraConfiguration> loadCameraConfigs() {
                 // Load pipelines by mapping the files within the pipelines subdir
                 // to their deserialized equivalents
                 var pipelineSubdirectory = Path.of(subdir.toString(), "pipelines");
-                List<CVPipelineSettings> settings =
-                        pipelineSubdirectory.toFile().exists()
-                                ? Files.list(pipelineSubdirectory)
+                List<CVPipelineSettings> settings = Collections.emptyList();
+                if (pipelineSubdirectory.toFile().exists()) {
+                    try (Stream<Path> subdirectoryFiles = Files.list(pipelineSubdirectory)) {
+                        settings =
+                                subdirectoryFiles
                                         .filter(p -> p.toFile().isFile())
                                         .map(
                                                 p -> {
@@ -350,8 +352,9 @@ private HashMap<String, CameraConfiguration> loadCameraConfigs() {
                                                     return null;
                                                 })
                                         .filter(Objects::nonNull)
-                                        .toList()
-                                : Collections.emptyList();
+                                        .toList();
+                    }
+                }
 
                 loadedConfig.driveModeSettings = driverMode;
                 loadedConfig.addPipelineSettings(settings);

photon-core/src/main/java/org/photonvision/common/configuration/NeuralNetworkModelManager.java

@@ -33,6 +33,7 @@
 import java.util.Optional;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
+import java.util.stream.Stream;
 import org.photonvision.common.configuration.NeuralNetworkPropertyManager.ModelProperties;
 import org.photonvision.common.hardware.Platform;
 import org.photonvision.common.logging.LogGroup;
@@ -365,8 +366,8 @@ public void discoverModels() {
 
         models = new HashMap<>();
 
-        try {
-            Files.walk(modelsDirectory.toPath())
+        try (Stream<Path> files = Files.walk(modelsDirectory.toPath())) {
+            files
                     .filter(Files::isRegularFile)
                     .filter(
                             path ->
@@ -469,8 +470,8 @@ public boolean clearModels() {
         File modelsDirectory = ConfigManager.getInstance().getModelsDirectory();
 
         if (modelsDirectory.exists()) {
-            try {
-                Files.walk(modelsDirectory.toPath())
+            try (Stream<Path> files = Files.walk(modelsDirectory.toPath())) {
+                files
                         .sorted((a, b) -> b.compareTo(a))
                         .forEach(
                                 path -> {

photon-core/src/test/java/org/photonvision/common/configuration/SQLConfigTest.java

@@ -21,16 +21,12 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import edu.wpi.first.cscore.UsbCameraInfo;
-import java.io.File;
-import java.io.IOException;
-import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Comparator;
 import java.util.List;
-import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Order;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.photonvision.common.util.TestUtils;
 import org.photonvision.vision.camera.CameraQuirk;
 import org.photonvision.vision.camera.PVCameraInfo;
@@ -39,22 +35,11 @@
 import org.photonvision.vision.pipeline.ReflectivePipelineSettings;
 
 public class SQLConfigTest {
-    private static Path tmpDir;
+    @TempDir private static Path tmpDir;
 
     @BeforeAll
     public static void init() {
         TestUtils.loadLibraries();
-        try {
-            tmpDir = Files.createTempDirectory("SQLConfigTest");
-        } catch (IOException e) {
-            System.out.println("Couldn't create temporary directory, using current directory");
-            tmpDir = Path.of("jdbc_test", "temp");
-        }
-    }
-
-    @AfterAll
-    public static void cleanUp() throws IOException {
-        Files.walk(tmpDir).sorted(Comparator.reverseOrder()).map(Path::toFile).forEach(File::delete);
     }
 
     @Test

photon-lib/src/main/java/org/photonvision/simulation/VideoSimUtil.java

@@ -100,6 +100,14 @@ public static Point[] getImageCorners(Size size) {
     /**
      * Gets the 10x10 (grayscale) image of a specific 36h11 AprilTag.
      *
+     * <p>WARNING: This creates a {@link RawFrame} instance but does not close it, which would result
+     * in a resource leak if the {@link Mat} is garbage-collected. Unfortunately, closing the {@code
+     * RawFrame} inside this function would delete the underlying data that backs the {@code
+     * ByteBuffer} that is passed to the {@code Mat} constructor (see comments on <a
+     * href="https://github.com/PhotonVision/photonvision/pull/2023">PR 2023</a> for details).
+     * Luckily, this method is private and is (as of Aug 2025) only used to populate the {@link
+     * #kTag36h11Images} static map at static-initialization time.
+     *
      * @param id The fiducial id of the desired tag
      */
     private static Mat get36h11TagImage(int id) {

photon-lib/src/main/java/org/photonvision/simulation/VisionSystemSim.java

@@ -122,6 +122,7 @@ public void clearCameras() {
      * @return If the camera was present and removed
      */
     public boolean removeCamera(PhotonCameraSim cameraSim) {
+        @SuppressWarnings("resource")
         boolean success = camSimMap.remove(cameraSim.getCamera().getName()) != null;
         camTrfMap.remove(cameraSim);
         return success;

photon-lib/src/test/java/org/photonvision/PhotonCameraTest.java

@@ -117,31 +117,31 @@ public void testTimeSyncServerWithPhotonCamera() throws InterruptedException, IO
         inst.stopClient();
         inst.startServer();
 
-        var camera = new PhotonCamera(inst, "Arducam_OV2311_USB_Camera");
-        PhotonCamera.setVersionCheckEnabled(false);
-
-        for (int i = 0; i < 5; i++) {
-            Thread.sleep(500);
-
-            var res = camera.getLatestResult();
-            var captureTime = res.getTimestampSeconds();
-            var now = Timer.getFPGATimestamp();
-
-            // expectTrue(captureTime < now);
-
-            System.out.println(
-                    "sequence "
-                            + res.metadata.sequenceID
-                            + " image capture "
-                            + captureTime
-                            + " received at "
-                            + res.getTimestampSeconds()
-                            + " now: "
-                            + NetworkTablesJNI.now() / 1e6
-                            + " time since last pong: "
-                            + res.metadata.timeSinceLastPong / 1e6);
+        try (PhotonCamera camera = new PhotonCamera(inst, "Arducam_OV2311_USB_Camera")) {
+            PhotonCamera.setVersionCheckEnabled(false);
+
+            for (int i = 0; i < 5; i++) {
+                Thread.sleep(500);
+
+                var res = camera.getLatestResult();
+                var captureTime = res.getTimestampSeconds();
+                var now = Timer.getFPGATimestamp();
+
+                // expectTrue(captureTime < now);
+
+                System.out.println(
+                        "sequence "
+                                + res.metadata.sequenceID
+                                + " image capture "
+                                + captureTime
+                                + " received at "
+                                + res.getTimestampSeconds()
+                                + " now: "
+                                + NetworkTablesJNI.now() / 1e6
+                                + " time since last pong: "
+                                + res.metadata.timeSinceLastPong / 1e6);
+            }
         }
-
         HAL.shutdown();
     }
 
@@ -335,62 +335,62 @@ public void testAlerts() throws InterruptedException {
             Thread.sleep(20);
         }
 
-        // GIVEN a simulated camera
-        var sim = new PhotonCameraSim(camera);
-        // AND a result with a timeSinceLastPong in the past
-        PhotonPipelineResult noPongResult =
-                new PhotonPipelineResult(
-                        new PhotonPipelineMetadata(
-                                1, 2, 3, 10 * 1000000 // 10 seconds -> us since last pong
-                                ),
-                        List.of(),
-                        Optional.empty());
+        // GIVEN a simulated camera AND a result with a timeSinceLastPong in the past
+        try (PhotonCameraSim sim = new PhotonCameraSim(camera)) {
+            PhotonPipelineResult noPongResult =
+                    new PhotonPipelineResult(
+                            new PhotonPipelineMetadata(
+                                    1, 2, 3, 10 * 1000000 // 10 seconds -> us since last pong
+                                    ),
+                            List.of(),
+                            Optional.empty());
+
+            // Loop to hit cases past first iteration
+            for (int i = 0; i < 10; i++) {
+                // AND a PhotonCamera with a "new" result
+                sim.submitProcessedFrame(noPongResult);
+
+                // WHEN we update the camera
+                camera.getAllUnreadResults();
+
+                // AND we tick SmartDashboard
+                SmartDashboard.updateValues();
+
+                // THEN the camera isn't disconnected
+                assertTrue(
+                        Arrays.stream(SmartDashboard.getStringArray("PhotonAlerts/warnings", new String[0]))
+                                .noneMatch(it -> it.equals(disconnectedCameraString)));
+                // AND the alert string looks like a timesync warning
+                assertTrue(
+                        Arrays.stream(SmartDashboard.getStringArray("PhotonAlerts/warnings", new String[0]))
+                                        .filter(it -> it.contains("is not connected to the TimeSyncServer"))
+                                        .count()
+                                == 1);
+
+                Thread.sleep(20);
+            }
 
-        // Loop to hit cases past first iteration
-        for (int i = 0; i < 10; i++) {
-            // AND a PhotonCamera with a "new" result
-            sim.submitProcessedFrame(noPongResult);
+            final double HEARTBEAT_TIMEOUT = 0.5;
 
-            // WHEN we update the camera
+            // GIVEN a PhotonCamera provided new results
+            SimHooks.pauseTiming();
+            sim.submitProcessedFrame(noPongResult);
             camera.getAllUnreadResults();
+            // AND in a connected state
+            assertTrue(camera.isConnected());
 
-            // AND we tick SmartDashboard
-            SmartDashboard.updateValues();
+            // WHEN we wait the timeout
+            SimHooks.stepTiming(HEARTBEAT_TIMEOUT * 1.5);
 
-            // THEN the camera isn't disconnected
-            assertTrue(
-                    Arrays.stream(SmartDashboard.getStringArray("PhotonAlerts/warnings", new String[0]))
-                            .noneMatch(it -> it.equals(disconnectedCameraString)));
-            // AND the alert string looks like a timesync warning
-            assertTrue(
-                    Arrays.stream(SmartDashboard.getStringArray("PhotonAlerts/warnings", new String[0]))
-                                    .filter(it -> it.contains("is not connected to the TimeSyncServer"))
-                                    .count()
-                            == 1);
+            // THEN the camera will not be connected
+            assertFalse(camera.isConnected());
 
-            Thread.sleep(20);
+            // WHEN we then provide new results
+            SimHooks.stepTiming(0.02);
+            sim.submitProcessedFrame(noPongResult);
+            camera.getAllUnreadResults();
+            // THEN the camera will not be connected
+            assertTrue(camera.isConnected());
         }
-
-        final double HEARTBEAT_TIMEOUT = 0.5;
-
-        // GIVEN a PhotonCamera provided new results
-        SimHooks.pauseTiming();
-        sim.submitProcessedFrame(noPongResult);
-        camera.getAllUnreadResults();
-        // AND in a connected state
-        assertTrue(camera.isConnected());
-
-        // WHEN we wait the timeout
-        SimHooks.stepTiming(HEARTBEAT_TIMEOUT * 1.5);
-
-        // THEN the camera will not be connected
-        assertFalse(camera.isConnected());
-
-        // WHEN we then provide new results
-        SimHooks.stepTiming(0.02);
-        sim.submitProcessedFrame(noPongResult);
-        camera.getAllUnreadResults();
-        // THEN the camera will not be connected
-        assertTrue(camera.isConnected());
     }
 }