CompletionStages returned by CloudProviders no longer fail with IO and NIO exceptions but define their own exceptions with CloudProviderException being their common base.

Also, CloudProviderException no longer extends CompletionException due to strange behaviour of CompletableFuture which ditches intermediate causes when thrown ExecutionException: "In case of exceptional completion with a CompletionException, methods get() and get(long, TimeUnit) throw an ExecutionException with the same cause as held in the corresponding CompletionException."

Author: overheadhunter

src/main/java/org/cryptomator/cloudaccess/api/CloudProvider.java

@@ -1,5 +1,7 @@
 package org.cryptomator.cloudaccess.api;
 
+import org.cryptomator.cloudaccess.api.exceptions.CloudProviderException;
+
 import java.io.InputStream;
 import java.nio.file.Path;
 import java.util.Optional;
@@ -21,8 +23,8 @@ public interface CloudProvider {
      * <p>
      * The returned CompletionStage might complete exceptionally with one of the following exceptions:
      * <ul>
-     *     <li>{@link java.nio.file.NoSuchFileException} If no item exists for the given path</li>
-     *     <li>{@link java.io.IOException} in case of generic I/O errors</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.NotFoundException} If no item exists for the given path</li>
+     *     <li>{@link CloudProviderException} in case of generic I/O errors</li>
      * </ul>
      *
      * @param node The remote path of the file or folder, whose metadata to fetch.
@@ -37,10 +39,10 @@ public interface CloudProvider {
      * <p>
      * The returned CompletionStage might complete exceptionally with one of the following exceptions:
      * <ul>
-     *     <li>{@link java.nio.file.NoSuchFileException} If no item exists for the given path</li>
-     *     <li>{@link java.nio.file.NotDirectoryException} If the path doesn't represent a folder</li>
-     *     <li>{@link java.io.IOException} in case of generic I/O errors</li>
-     *     <li>{@link InvalidPageTokenException} if <code>pageToekn</code> is invalid</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.NotFoundException} If no item exists for the given path</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.TypeMismatchException} If the path doesn't represent a folder</li>
+     *     <li>{@link CloudProviderException} in case of generic I/O errors</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.InvalidPageTokenException} if <code>pageToken</code> is invalid</li>
      * </ul>
      *
      * @param folder    The remote path of the folder to list.
@@ -90,8 +92,8 @@ default CompletionStage<InputStream> read(Path file, ProgressListener progressLi
      * <p>
      * The returned CompletionStage might complete exceptionally with one of the following exceptions:
      * <ul>
-     *     <li>{@link java.nio.file.NoSuchFileException} If no item exists for the given path</li>
-     *     <li>{@link java.io.IOException} in case of generic I/O errors</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.NotFoundException} If no item exists for the given path</li>
+     *     <li>{@link CloudProviderException} in case of generic I/O errors</li>
      * </ul>
      *
      * @param file             A remote path referencing a file
@@ -107,9 +109,10 @@ default CompletionStage<InputStream> read(Path file, ProgressListener progressLi
      * <p>
      * The returned CompletionStage might complete exceptionally with one of the following exceptions:
      * <ul>
-     *     <li>{@link java.nio.file.NoSuchFileException} If the parent directory of this file doesn't exist</li>
-     *     <li>{@link java.nio.file.FileAlreadyExistsException} If a node with the given path already exists and <code>replace</code> is false</li>
-     *     <li>{@link java.io.IOException} in case of generic I/O errors</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.NotFoundException} If the parent directory of this file doesn't exist</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.TypeMismatchException} If the path points to a node that isn't a file</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.AlreadyExistsException} If a node with the given path already exists and <code>replace</code> is false</li>
+     *     <li>{@link CloudProviderException} in case of generic I/O errors</li>
      * </ul>
      *
      * @param file             A remote path referencing a file
@@ -126,7 +129,7 @@ default CompletionStage<InputStream> read(Path file, ProgressListener progressLi
      * The returned CompletionStage might complete exceptionally with one of the following exceptions:
      * <ul>
      *     <li>{@link java.nio.file.FileAlreadyExistsException} If a node with the given path already exists</li>
-     *     <li>{@link java.io.IOException} in case of generic I/O errors</li>
+     *     <li>{@link CloudProviderException} in case of generic I/O errors</li>
      * </ul>
      *
      * @param folder The remote path of the folder to create.
@@ -139,8 +142,8 @@ default CompletionStage<InputStream> read(Path file, ProgressListener progressLi
      * <p>
      * The returned CompletionStage might complete exceptionally with one of the following exceptions:
      * <ul>
-     *     <li>{@link java.nio.file.NoSuchFileException} If no item exists for the given path</li>
-     *     <li>{@link java.io.IOException} in case of generic I/O errors</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.NotFoundException} If no item exists for the given path</li>
+     *     <li>{@link CloudProviderException} in case of generic I/O errors</li>
      * </ul>
      *
      * @param node The remote path of the file or folder to delete.
@@ -153,9 +156,9 @@ default CompletionStage<InputStream> read(Path file, ProgressListener progressLi
      * <p>
      * The returned CompletionStage might complete exceptionally with one of the following exceptions:
      * <ul>
-     *     <li>{@link java.nio.file.NoSuchFileException} If no item exists for the given source path</li>
-     *     <li>{@link java.nio.file.FileAlreadyExistsException} If a node with the given target path already exists and <code>replace</code> is false</li>
-     *     <li>{@link java.io.IOException} in case of generic I/O errors</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.NotFoundException} If no item exists for the given source path</li>
+     *     <li>{@link org.cryptomator.cloudaccess.api.exceptions.AlreadyExistsException} If a node with the given target path already exists and <code>replace</code> is false</li>
+     *     <li>{@link CloudProviderException} in case of generic I/O errors</li>
      * </ul>
      *
      * @param source  The remote path of the file or folder to be moved.

src/main/java/org/cryptomator/cloudaccess/api/exceptions/AlreadyExistsException.java

@@ -0,0 +1,12 @@
+package org.cryptomator.cloudaccess.api.exceptions;
+
+public class AlreadyExistsException extends CloudProviderException {
+
+    public AlreadyExistsException(Throwable cause) {
+        super(cause);
+    }
+
+    public AlreadyExistsException(String name) {
+        super(name);
+    }
+}

src/main/java/org/cryptomator/cloudaccess/api/exceptions/BackendException.java

@@ -0,0 +1,21 @@
+package org.cryptomator.cloudaccess.api.exceptions;
+
+public class CloudProviderException extends RuntimeException {
+
+    public CloudProviderException() {
+        super();
+    }
+
+    public CloudProviderException(Throwable e) {
+        super(e);
+    }
+
+    public CloudProviderException(String message) {
+        super(message);
+    }
+
+    public CloudProviderException(String message, Throwable e) {
+        super(message, e);
+    }
+
+}

src/main/java/org/cryptomator/cloudaccess/api/exceptions/CloudNodeAlreadyExistsException.java

@@ -1,4 +1,4 @@
 package org.cryptomator.cloudaccess.api.exceptions;
 
-public class InsufficientStorageException extends BackendException {
+public class InsufficientStorageException extends CloudProviderException {
 }

src/main/java/org/cryptomator/cloudaccess/api/exceptions/CloudProviderException.java

@@ -1,6 +1,6 @@
-package org.cryptomator.cloudaccess.api;
+package org.cryptomator.cloudaccess.api.exceptions;
 
-public class InvalidPageTokenException extends IllegalArgumentException {
+public class InvalidPageTokenException extends CloudProviderException {
     public InvalidPageTokenException(String message) {
         super(message);
     }

src/main/java/org/cryptomator/cloudaccess/api/exceptions/ForbiddenException.java

@@ -1,10 +1,14 @@
 package org.cryptomator.cloudaccess.api.exceptions;
 
-public class NotFoundException extends BackendException {
+public class NotFoundException extends CloudProviderException {
 
     public NotFoundException() {
     }
 
+    public NotFoundException(Throwable cause) {
+        super(cause);
+    }
+
     public NotFoundException(String name) {
         super(name);
     }

src/main/java/org/cryptomator/cloudaccess/api/exceptions/InsufficientStorageException.java

@@ -0,0 +1,18 @@
+package org.cryptomator.cloudaccess.api.exceptions;
+
+/**
+ * Indicates that an operation expected a different {@link org.cryptomator.cloudaccess.api.CloudItemType}.
+ */
+public class TypeMismatchException extends CloudProviderException {
+
+    public TypeMismatchException() {
+    }
+
+    public TypeMismatchException(Throwable cause) {
+        super(cause);
+    }
+
+    public TypeMismatchException(String name) {
+        super(name);
+    }
+}