From 6ee8e6567d1ecee705cf4fbc9e8d0e56f4a87892 Mon Sep 17 00:00:00 2001
From: Sonia Zorba <sonia.zorba@inaf.it>
Date: Thu, 21 Jan 2021 16:02:38 +0100
Subject: [PATCH] Fixed concurrency issue on multiple files upload

---
 .../ia2/transfer/controller/PutFileController.java   | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/main/java/it/inaf/ia2/transfer/controller/PutFileController.java b/src/main/java/it/inaf/ia2/transfer/controller/PutFileController.java
index 440f8a3..0314f7b 100644
--- a/src/main/java/it/inaf/ia2/transfer/controller/PutFileController.java
+++ b/src/main/java/it/inaf/ia2/transfer/controller/PutFileController.java
@@ -83,9 +83,15 @@ public class PutFileController {
 
         File file = path.toFile();
 
-        if (!file.getParentFile().exists()) {
-            if (!file.getParentFile().mkdirs()) {
-                throw new IllegalStateException("Unable to create parent folder: " + file.getParentFile().getAbsolutePath());
+        /**
+         * This block must be synchronized, to avoid concurrency issues when
+         * multiple files are uploaded to a new folder in parallel.
+         */
+        synchronized (this) {
+            if (!file.getParentFile().exists()) {
+                if (!file.getParentFile().mkdirs()) {
+                    throw new IllegalStateException("Unable to create parent folder: " + file.getParentFile().getAbsolutePath());
+                }
             }
         }
 
-- 
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