fix setting blob verified event and canceling blob writers

-raise OSError if multiple writers for one peer are opened for a blob

lbrynet/blob/blob_file.py

@@ -194,15 +194,14 @@ class AbstractBlob:
             return
         if self.is_writeable():
             self._write_blob(verified_bytes)
+            self.verified.set()
             if self.blob_completed_callback:
-                self.blob_completed_callback(self).add_done_callback(lambda _: self.verified.set())
-            else:
-                self.verified.set()
+                self.blob_completed_callback(self)
 
     def get_blob_writer(self, peer_address: typing.Optional[str] = None,
                         peer_port: typing.Optional[int] = None) -> HashBlobWriter:
         if (peer_address, peer_port) in self.writers:
-            log.exception("attempted to download blob twice from %s:%s", peer_address, peer_port)
+            raise OSError(f"attempted to download blob twice from {peer_address}:{peer_port}")
         fut = asyncio.Future(loop=self.loop)
         writer = HashBlobWriter(self.blob_hash, self.get_length, fut)
         self.writers[(peer_address, peer_port)] = writer

lbrynet/blob/writer.py

@@ -62,6 +62,8 @@ class HashBlobWriter:
             self.close_handle()
 
     def close_handle(self):
+        if not self.finished.done():
+            self.finished.cancel()
         if self.buffer is not None:
             self.buffer.close()
             self.buffer = None

lbrynet/blob_exchange/client.py

@@ -145,18 +145,17 @@ class BlobExchangeClientProtocol(asyncio.Protocol):
         self.buf = b''
 
     async def download_blob(self, blob: 'AbstractBlob') -> typing.Tuple[int, typing.Optional[asyncio.Transport]]:
+        blob_hash = blob.blob_hash
         if blob.get_is_verified() or not blob.is_writeable():
             return 0, self.transport
         try:
-
-            self.blob, self.writer, self._blob_bytes_received = blob, blob.get_blob_writer(self.peer_address,
-                                                                                           self.peer_port), 0
+            self._blob_bytes_received = 0
+            self.blob, self.writer = blob, blob.get_blob_writer(self.peer_address, self.peer_port)
             self._response_fut = asyncio.Future(loop=self.loop)
             return await self._download_blob()
         except OSError as e:
-            log.error("race happened downloading from %s:%i", self.peer_address, self.peer_port)
             # i'm not sure how to fix this race condition - jack
-            log.exception(e)
+            log.exception("race happened downloading %s from %s:%i", blob_hash, self.peer_address, self.peer_port)
             return self._blob_bytes_received, self.transport
         except asyncio.TimeoutError:
             if self._response_fut and not self._response_fut.done():