[4.4] Fix bufferviews + rewrite timeouts on send (#843)

* Fixes `BufferError: Existing exports of data: object cannot be re-sized`
exceptions masking erroneous flows in the driver's code.
* Correctly rewrites socket timeouts on sending

Author: robsdedude

neo4j/io/__init__.py

@@ -43,6 +43,7 @@
 import logging
 from logging import getLogger
 from random import choice
+import socket
 from threading import (
     Condition,
     RLock,
@@ -52,6 +53,7 @@
 from neo4j._exceptions import (
     BoltError,
     BoltHandshakeError,
+    SocketDeadlineExceeded,
 )
 from neo4j._deadline import (
     connection_deadline,
@@ -509,11 +511,12 @@ def _append(self, signature, fields=(), response=None):
         self.responses.append(response)
 
     def _send_all(self):
-        data = self.outbox.view()
-        if data:
+        with self.outbox.view() as data:
+            if not data:
+                return
             try:
                 self.socket.sendall(data)
-            except OSError as error:
+            except (OSError, socket.timeout, SocketDeadlineExceeded) as error:
                 self._set_defunct_write(error)
             self.outbox.clear()
 

neo4j/io/_common.py

@@ -114,22 +114,21 @@ def _chunk_data(self):
         )
         num_chunks = num_full_chunks + bool(chunk_rest)
 
-        data_view = memoryview(self._raw_data)
-        header_start = len(self._chunked_data)
-        data_start = header_start + 2
-        raw_data_start = 0
-        for i in range(num_chunks):
-            chunk_size = min(data_len - raw_data_start,
-                             self._max_chunk_size)
-            self._chunked_data[header_start:data_start] = struct_pack(
-                ">H", chunk_size
-            )
-            self._chunked_data[data_start:(data_start + chunk_size)] = \
-                data_view[raw_data_start:(raw_data_start + chunk_size)]
-            header_start += chunk_size + 2
+        with memoryview(self._raw_data) as data_view:
+            header_start = len(self._chunked_data)
             data_start = header_start + 2
-            raw_data_start += chunk_size
-        del data_view
+            raw_data_start = 0
+            for i in range(num_chunks):
+                chunk_size = min(data_len - raw_data_start,
+                                 self._max_chunk_size)
+                self._chunked_data[header_start:data_start] = struct_pack(
+                    ">H", chunk_size
+                )
+                self._chunked_data[data_start:(data_start + chunk_size)] = \
+                    data_view[raw_data_start:(raw_data_start + chunk_size)]
+                header_start += chunk_size + 2
+                data_start = header_start + 2
+                raw_data_start += chunk_size
         self._raw_data.clear()
 
     def wrap_message(self):

neo4j/packstream.py

@@ -477,9 +477,9 @@ def receive(self, sock, n_bytes):
         end = self.used + n_bytes
         if end > len(self.data):
             self.data += bytearray(end - len(self.data))
-        view = memoryview(self.data)
-        while self.used < end:
-            n = sock.recv_into(view[self.used:end], end - self.used)
-            if n == 0:
-                raise OSError("No data")
-            self.used += n
+        with memoryview(self.data) as view:
+            while self.used < end:
+                n = sock.recv_into(view[self.used:end], end - self.used)
+                if n == 0:
+                    raise OSError("No data")
+                self.used += n