Merge branch 'develop'

Author: Gerald Unterrainer

pom.xml

@@ -10,7 +10,7 @@
 
 	<modelVersion>4.0.0</modelVersion>
 	<artifactId>jre-utils</artifactId>
-	<version>0.2.3</version>
+	<version>0.2.4</version>
 	<name>JreUtils</name>
 	<packaging>jar</packaging>
 

src/main/java/info/unterrainer/commons/jreutils/Exceptions.java

@@ -8,44 +8,109 @@
 public class Exceptions {
 
 	/**
-	 * Swallows any given Exception (checked or unchecked alike) silently.
+	 * Swallows any given Exception (checked or unchecked alike) silently that is
+	 * thrown when running the given supplier.
 	 *
 	 * @param runnable   the {@link Runnable} that could throw the exception to
 	 *                   swallow
-	 * @param throwables a List of Exception-types
+	 * @param exceptions a List of Exception-types
 	 */
 	@SafeVarargs
-	public static void swallow(final Runnable runnable, final Class<?>... throwables) {
+	public static void swallow(final Runnable runnable, final Class<?>... exceptions) {
 		Supplier<Void> supplier = () -> {
 			runnable.run();
 			return null;
 		};
-		swallowReturning(supplier, throwables);
+		swallowReturning(supplier, exceptions);
 	}
 
 	/**
-	 * Swallows any given Exception (checked or unchecked alike) silently.
+	 * Swallows any given Exception (checked or unchecked alike) silently that is
+	 * thrown when running the given supplier and returns the return-value
+	 * otherwise.
 	 *
 	 * @param <T>        the return-value of the {@link Supplier}
 	 * @param supplier   the {@link Supplier} that could throw the exception to
 	 *                   swallow
-	 * @param throwables a List of Exception-types
+	 * @param exceptions a List of Exception-types
 	 * @return the return-value of the {@link Supplier}
 	 */
 	@SafeVarargs
-	public static <T> T swallowReturning(final Supplier<T> supplier, final Class<?>... throwables) {
+	public static <T> T swallowReturning(final Supplier<T> supplier, final Class<?>... exceptions) {
 		try {
 			return supplier.get();
-		} catch (Exception throwable) {
-			boolean swallow = false;
-			for (Class<?> omit : throwables)
-				if (omit.isAssignableFrom(throwable.getClass())) {
-					swallow = true;
-					break;
-				}
-			if (!swallow)
-				throw throwable;
+		} catch (Exception e) {
+			if (!containsException(e, exceptions))
+				throw e;
 			return null;
 		}
 	}
+
+	/**
+	 * If one of the specified exceptions occur while running the given supplier, it
+	 * retries running the supplier [times] times with [backOffInMillis]ms in
+	 * between tries.
+	 * <p>
+	 * If the number of retries are used up and the supplier still throws an
+	 * exception, that exception is re-thrown.
+	 *
+	 * @param runnable        the {@link Runnable} that could throw the exception to
+	 *                        swallow
+	 * @param times           the number of times to retry before throwing the
+	 *                        exception for real
+	 * @param backOffInMillis the time to wait in between retries
+	 * @param exceptions      a List of Exception-types to retry upon
+	 */
+	@SafeVarargs
+	public static void retry(final int times, final long backOffInMillis, final Runnable runnable,
+			final Class<?>... exceptions) {
+		Supplier<Void> supplier = () -> {
+			runnable.run();
+			return null;
+		};
+		retryReturning(times, backOffInMillis, supplier, exceptions);
+	}
+
+	/**
+	 * If one of the specified exceptions occur while running the given supplier, it
+	 * retries running the supplier [times] times with [backOffInMillis]ms in
+	 * between tries. It returns the return-value of the given supplier.
+	 * <p>
+	 * If the number of retries are used up and the supplier still throws an
+	 * exception, that exception is re-thrown.
+	 *
+	 * @param <T>             the return-value of the {@link Supplier}
+	 * @param supplier        the {@link Supplier} that could throw the exception to
+	 *                        retry upon
+	 * @param times           the number of times to retry before throwing the
+	 *                        exception for real
+	 * @param backOffInMillis the time to wait in between retries
+	 * @param exceptions      a List of Exception-types to retry upon
+	 * @return the return-value of the {@link Supplier}
+	 */
+	@SafeVarargs
+	public static <T> T retryReturning(final int times, final long backOffInMillis, final Supplier<T> supplier,
+			final Class<?>... exceptions) {
+		T result = null;
+		for (int i = 0; i < times; i++)
+			try {
+				result = supplier.get();
+			} catch (Exception e) {
+				if (!containsException(e, exceptions) || i == times - 1)
+					throw e;
+				try {
+					Thread.sleep(backOffInMillis);
+				} catch (InterruptedException e1) {
+					Thread.currentThread().interrupt();
+				}
+			}
+		return result;
+	}
+
+	public static boolean containsException(final Exception e, final Class<?>... exceptions) {
+		for (Class<?> omit : exceptions)
+			if (omit.isAssignableFrom(e.getClass()))
+				return true;
+		return false;
+	}
 }