Fix the bug related to buffer resize

Still cannot locate where is the problem. Failed to reproduce it with a unit test.
The guess of the cause of bug is related to reading a big chunk that cannot be fit in buffer after the first INIT message. It seems INIT might hold a reference to a memory view somewhere.

Author: Zhen

neo4j/bolt/_io.pyx

@@ -101,6 +101,9 @@ cdef class MessageFrame(object):
             value.extend(self.read(n - (end - start)))
         return value
 
+    cpdef close(self):
+        self._view = None
+
 
 cdef class ChunkedInputBuffer(object):
 
@@ -245,6 +248,7 @@ cdef class ChunkedInputBuffer(object):
 
     cpdef discard_message(self):
         if self._frame is not None:
+            self._frame.close()
             self._origin = self._limit
             self._limit = -1
             self._frame = None

neo4j/bolt/connection.py

@@ -170,7 +170,11 @@ def __init__(self, address, sock, error_handler, **config):
         self.socket = sock
         self.error_handler = error_handler
         self.server = ServerInfo(SocketAddress.from_socket(sock))
-        self.input_buffer = ChunkedInputBuffer()
+        input_buffer_size = config.get("default_read_buffer_size")
+        if input_buffer_size:
+            self.input_buffer = ChunkedInputBuffer(capacity=input_buffer_size)
+        else:
+            self.input_buffer = ChunkedInputBuffer()
         self.output_buffer = ChunkedOutputBuffer()
         self.packer = Packer(self.output_buffer)
         self.unpacker = Unpacker()

neo4j/bolt/io.py

@@ -83,6 +83,9 @@ def read(self, n):
             value.extend(self.read(n - (end - start)))
         return value
 
+    def close(self):
+        self._view = None
+
 
 class ChunkedInputBuffer(object):
 
@@ -200,6 +203,7 @@ def frame_message(self):
 
     def discard_message(self):
         if self._frame is not None:
+            self._frame.close()
             self._origin = self._limit
             self._limit = -1
             self._frame = None

test/integration/test_session.py

@@ -23,12 +23,11 @@
 from neo4j.v1 import \
     READ_ACCESS, WRITE_ACCESS, \
     CypherError, SessionError, TransactionError, \
-    Node, Relationship, Path
+    Node, Relationship, Path, GraphDatabase
 from neo4j.exceptions import CypherSyntaxError
 
 from test.integration.tools import DirectIntegrationTestCase
 
-
 class AutoCommitTransactionTestCase(DirectIntegrationTestCase):
 
     def test_can_run_simple_statement(self):
@@ -459,6 +458,12 @@ def test_errors_on_begin_transaction(self):
         with self.assertRaises(SessionError):
             session.begin_transaction()
 
+    def test_large_values(self):
+        driver = GraphDatabase.driver(self.bolt_uri, auth=self.auth_token, default_read_buffer_size=16)
+        session = driver.session()
+        session.run("RETURN '{}'".format("A" * 251172))
+        session.close()
+        driver.close()
 
 class TransactionCommittedTestCase(DirectIntegrationTestCase):