When multipart uploads fail, cancel remaining part transfers

Suppose we have 10 parts, if we fail on part aws#2 we fire a "TRANFER_FAILED_EVENT" back to the client. We should assume that
clients will react to this failure, possibly with custom logic to retry. Supposing that part aws#3 succeeds, the client will then get
other transfer events past the "TRANSFER_FAILED_EVENT". I assume here that "TRANSFER_FAILED_EVENT" is a terminal event and that
a client should not expect to receive further events for that transfer, successful or not. However, the meaning of TRANSFER_FAILED_EVENT
is not clearly defined in the javadocs.

relates to: aws#2263

Author: jamesceddy

aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/transfer/internal/CompleteMultipartUpload.java

@@ -115,17 +115,23 @@ public UploadResult call() throws Exception {
      */
     private List<PartETag> collectPartETags() {
 
-        final List<PartETag> partETags = new ArrayList<PartETag>();
+        final List<PartETag> partETags = new ArrayList<PartETag>(eTagsBeforeResume.size());
         partETags.addAll(eTagsBeforeResume);
-        for (Future<PartETag> future : futures) {
-            try {
-                partETags.add(future.get());
-            } catch (Exception e) {
-                throw new SdkClientException(
-                        "Unable to complete multi-part upload. Individual part upload failed : "
-                                + e.getCause().getMessage(), e.getCause());
+
+        int index = 0;
+        try {
+            for (; index < futures.size(); index++) {
+                partETags.add(futures.get(index).get());
             }
+        } catch (Exception e) {
+            for (; index < futures.size(); index++) {
+                futures.get(index).cancel(true);
+            }
+            throw new SdkClientException(
+                    "Unable to complete multi-part upload. Individual part upload failed : "
+                            + e.getCause().getMessage(), e.getCause());
         }
+
         return partETags;
     }
 }