Ignore NoSuchFileException with ifExists

2 files changed, 38 insertions, 8 deletions

diff --git a/yolean/src/main/java/com/yahoo/yolean/Exceptions.java b/yolean/src/main/java/com/yahoo/yolean/Exceptions.java
index 82677a14242..bbd03bbdc9e 100644
--- a/yolean/src/main/java/com/yahoo/yolean/Exceptions.java
+++ b/yolean/src/main/java/com/yahoo/yolean/Exceptions.java
@@ -3,6 +3,8 @@ package com.yahoo.yolean;
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
+import java.nio.file.NoSuchFileException;
+import java.util.Optional;
 
 /**
  * Helper methods for handling exceptions
@@ -70,6 +72,18 @@ public class Exceptions {
         }
     }
 
+
+    /** Similar to uncheck() except NoSuchFileException is silently ignored. */
+    public static void ifExists(RunnableThrowingIOException runnable) {
+        try {
+            runnable.run();
+        } catch (NoSuchFileException e) {
+            // Do nothing - OK
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
     @FunctionalInterface
     public interface RunnableThrowingIOException {
         void run() throws IOException;
@@ -98,6 +112,17 @@ public class Exceptions {
         }
     }
 
+    /** Similar to uncheck() except the return value is wrapped in an Optional, and empty is returned on NoSuchFileException. */
+    public static <T> Optional<T> ifExists(SupplierThrowingIOException<T> supplier) {
+        try {
+            return Optional.ofNullable(supplier.get());
+        } catch (NoSuchFileException e) {
+            return Optional.empty();
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
     @FunctionalInterface
     public interface SupplierThrowingIOException<T> {
         T get() throws IOException;
diff --git a/yolean/src/test/java/com/yahoo/yolean/ExceptionsTestCase.java b/yolean/src/test/java/com/yahoo/yolean/ExceptionsTestCase.java
index 31e27fa2675..e1786528b31 100644
--- a/yolean/src/test/java/com/yahoo/yolean/ExceptionsTestCase.java
+++ b/yolean/src/test/java/com/yahoo/yolean/ExceptionsTestCase.java
@@ -5,8 +5,10 @@ import org.junit.Test;
 
 import java.io.IOException;
 import java.io.UncheckedIOException;
+import java.nio.file.NoSuchFileException;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 
 /**
  * @author bratseth
@@ -27,35 +29,38 @@ public class ExceptionsTestCase {
     @Test
     public void testUnchecks() {
         try {
-            Exceptions.uncheck(this::throwIO);
+            Exceptions.uncheck(this::throwNoSuchFileException);
         } catch (UncheckedIOException e) {
             assertEquals("root cause", e.getCause().getMessage());
         }
 
         try {
-            Exceptions.uncheck(this::throwIO, "additional %s", "info");
+            Exceptions.uncheck(this::throwNoSuchFileException, "additional %s", "info");
         } catch (UncheckedIOException e) {
             assertEquals("additional info", e.getMessage());
         }
 
         try {
-            int i = Exceptions.uncheck(this::throwIOWithReturnValue);
+            int i = Exceptions.uncheck(this::throwNoSuchFileExceptionSupplier);
         } catch (UncheckedIOException e) {
             assertEquals("root cause", e.getCause().getMessage());
         }
 
         try {
-            int i = Exceptions.uncheck(this::throwIOWithReturnValue, "additional %s", "info");
+            int i = Exceptions.uncheck(this::throwNoSuchFileExceptionSupplier, "additional %s", "info");
         } catch (UncheckedIOException e) {
             assertEquals("additional info", e.getMessage());
         }
+
+        Exceptions.ifExists(this::throwNoSuchFileException);
+        assertFalse(Exceptions.ifExists(this::throwNoSuchFileExceptionSupplier).isPresent());
     }
 
-    private void throwIO() throws IOException {
-        throw new IOException("root cause");
+    private void throwNoSuchFileException() throws IOException {
+        throw new NoSuchFileException("root cause");
     }
 
-    private int throwIOWithReturnValue() throws IOException {
-        throw new IOException("root cause");
+    private int throwNoSuchFileExceptionSupplier() throws IOException {
+        throw new NoSuchFileException("root cause");
     }
 }