Merge branch '1428-android-debug-logging' into 'master'

Enable debug logging for debug and beta builds

Closes #1428

See merge request briar/briar!1154

briar-android/src/main/java/org/briarproject/briar/android/BriarApplicationImpl.java

@@ -37,6 +37,7 @@ import static android.app.ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREG
 import static android.os.Build.VERSION.SDK_INT;
 import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
 import static org.acra.ReportField.ANDROID_VERSION;
 import static org.acra.ReportField.APP_VERSION_CODE;
 import static org.acra.ReportField.APP_VERSION_NAME;
@@ -82,7 +83,7 @@ public class BriarApplicationImpl extends Application
 		implements BriarApplication {
 
 	private static final Logger LOG =
-			Logger.getLogger(BriarApplicationImpl.class.getName());
+			getLogger(BriarApplicationImpl.class.getName());
 
 	private final CachingLogHandler logHandler = new CachingLogHandler();
 	private final BackgroundMonitor backgroundMonitor = new BackgroundMonitor();
@@ -108,12 +109,16 @@ public class BriarApplicationImpl extends Application
 
 		if (IS_DEBUG_BUILD) enableStrictMode();
 
-		Logger rootLogger = Logger.getLogger("");
-		if (!IS_DEBUG_BUILD && !IS_BETA_BUILD) {
-			// Remove default log handlers so system log is not used
-			for (Handler handler : rootLogger.getHandlers()) {
-				rootLogger.removeHandler(handler);
-			}
+		Logger rootLogger = getLogger("");
+		Handler[] handlers = rootLogger.getHandlers();
+		// Disable the Android logger for release builds
+		for (Handler handler : handlers) rootLogger.removeHandler(handler);
+		if (IS_DEBUG_BUILD || IS_BETA_BUILD) {
+			// We can't set the level of the Android logger at runtime, so
+			// raise records to the logger's default level
+			rootLogger.addHandler(new LevelRaisingHandler(FINE, INFO));
+			// Restore the default handlers after the level raising handler
+			for (Handler handler : handlers) rootLogger.addHandler(handler);
 		}
 		rootLogger.addHandler(logHandler);
 		rootLogger.setLevel(IS_DEBUG_BUILD || IS_BETA_BUILD ? FINE : INFO);

briar-android/src/main/java/org/briarproject/briar/android/LevelRaisingHandler.java

+package org.briarproject.briar.android;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.LogRecord;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * Log handler that raises all records at or above a given source level to a
+ * given destination level. This affects the level seen by subsequent handlers.
+ */
+@Immutable
+@NotNullByDefault
+class LevelRaisingHandler extends Handler {
+
+	private final Level dest;
+	private final int srcInt, destInt;
+
+	LevelRaisingHandler(Level src, Level dest) {
+		this.dest = dest;
+		srcInt = src.intValue();
+		destInt = dest.intValue();
+		if (srcInt > destInt) throw new IllegalArgumentException();
+	}
+
+	@Override
+	public void publish(LogRecord record) {
+		int recordInt = record.getLevel().intValue();
+		if (recordInt >= srcInt && recordInt < destInt) record.setLevel(dest);
+	}
+
+	@Override
+	public void flush() {
+	}
+
+	@Override
+	public void close() {
+	}
+}