From 0d77334bff2ca1c70690cf70db6368ef73a25a0b Mon Sep 17 00:00:00 2001
From: Yuxin Wang <yuxinwang.dev@gmail.com>
Date: Wed, 26 Sep 2018 22:18:56 -0400
Subject: [PATCH] Check if same file is being downloaded.

---
 p2pfs/core/peer.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/p2pfs/core/peer.py b/p2pfs/core/peer.py
index ddb0096..c0d29a8 100644
--- a/p2pfs/core/peer.py
+++ b/p2pfs/core/peer.py
@@ -77,17 +77,22 @@ class Peer(MessageServer):
         with self._file_list_lock:
             if self._file_list is None or file not in self._file_list.keys():
                 return False, 'Requested file {} does not exist, try list_file?'.format(file)
+        with self._download_lock:
+            if file in self._download_results:
+                return False, 'Download {} already in progress.'.format(file)
+            self._download_results[file] = Queue()
 
         self._write_message(self._server_sock, {
             'type': MessageType.REQUEST_FILE_LOCATION,
             'filename': file
         })
-
-        self._download_results[file] = Queue()
         # wait until reply is ready
         fileinfo, chunkinfo = self._download_results[file].get()
         logger.debug('{}: {} ==> {}'.format(file, fileinfo, chunkinfo))
 
+        with self._download_lock:
+            del self._download_results[file]
+
         return True, 'File {} dowloaded to {}'.format(file, destination)
 
     def exit(self):