Add exponential backoff if starting download fails

1 files changed, 12 insertions, 2 deletions

diff --git a/filedistribution/src/main/java/com/yahoo/vespa/filedistribution/FileReferenceDownloader.java b/filedistribution/src/main/java/com/yahoo/vespa/filedistribution/FileReferenceDownloader.java
index e3edee2956f..1f7649b4dbc 100644
--- a/filedistribution/src/main/java/com/yahoo/vespa/filedistribution/FileReferenceDownloader.java
+++ b/filedistribution/src/main/java/com/yahoo/vespa/filedistribution/FileReferenceDownloader.java
@@ -57,14 +57,14 @@ public class FileReferenceDownloader {
         int retryCount = 0;
         Connection connection = connectionPool.getCurrent();
         do {
+            backoff(retryCount);
+
             if (FileDownloader.fileReferenceExists(fileReference, downloadDirectory))
                 return;
             if (startDownloadRpc(fileReferenceDownload, retryCount, connection))
                 return;
 
-            try { Thread.sleep(sleepBetweenRetries.toMillis()); } catch (InterruptedException e) { /* ignored */}
             retryCount++;
-
             // There is no one connection that will always work for each file reference (each file reference might
             // exist on just one config server, and which one could be different for each file reference), so we
             // should get a new connection for every retry
@@ -75,6 +75,16 @@ public class FileReferenceDownloader {
         downloads.remove(fileReference);
     }
 
+    private void backoff(int retryCount) {
+        if (retryCount > 0) {
+            try {
+                Thread.sleep((long) (Math.pow(2, retryCount)) * sleepBetweenRetries.toMillis());
+            } catch (InterruptedException e) {
+                /* ignored */
+            }
+        }
+    }
+
     Future<Optional<File>> startDownload(FileReferenceDownload fileReferenceDownload) {
         FileReference fileReference = fileReferenceDownload.fileReference();
         Optional<FileReferenceDownload> inProgress = downloads.get(fileReference);