Create FileLogger JNI (#1517)

photon-targeting/src/main/java/org/photonvision/jni/QueuedFileLogger.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) Photon Vision.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.photonvision.jni;
+
+public class QueuedFileLogger {
+    long m_handle = 0;
+
+    public QueuedFileLogger(String path) {
+        m_handle = QueuedFileLogger.create(path);
+    }
+
+    public String[] getNewlines() {
+        String newBuffer = null;
+
+        synchronized (this) {
+            if (m_handle == 0) {
+                System.err.println("QueuedFileLogger use after free");
+                return new String[0];
+            }
+
+            newBuffer = QueuedFileLogger.getNewLines(m_handle);
+        }
+
+        if (newBuffer == null) {
+            return new String[0];
+        }
+
+        return newBuffer.split("\n");
+    }
+
+    public void stop() {
+        synchronized (this) {
+            if (m_handle != 0) {
+                QueuedFileLogger.destroy(m_handle);
+                m_handle = 0;
+            }
+        }
+    }
+
+    private static native long create(String path);
+
+    private static native void destroy(long handle);
+
+    private static native String getNewLines(long handle);
+}