[psycopg2] add support for version 2.4

Author: Emanuele Palazzetti

.circleci/config.yml

@@ -579,7 +579,7 @@ jobs:
           keys:
               - tox-cache-pycopg-{{ checksum "tox.ini" }}
       - run: tox -e 'wait' postgres
-      - run: tox -e '{py27,py34,py35,py36}-psycopg2{25,26,27}' --result-json /tmp/psycopg.results
+      - run: tox -e '{py27,py34,py35,py36}-psycopg2{24,25,26,27}' --result-json /tmp/psycopg.results
       - persist_to_workspace:
           root: /tmp
           paths:

ddtrace/contrib/psycopg/patch.py

@@ -124,10 +124,15 @@ def prepare(self, *args, **kwargs):
     (psycopg2._psycopg.register_type,
      psycopg2._psycopg, 'register_type',
      _extensions_register_type),
-    (psycopg2._json.register_type,
-     psycopg2._json, 'register_type',
-     _extensions_register_type),
     (psycopg2.extensions.adapt,
      psycopg2.extensions, 'adapt',
      _extensions_adapt),
 ]
+
+# `_json` attribute is only available for psycopg >= 2.5
+if getattr(psycopg2, '_json', None):
+    _psycopg2_extensions += [
+        (psycopg2._json.register_type,
+         psycopg2._json, 'register_type',
+         _extensions_register_type),
+    ]

docs/index.rst

@@ -567,7 +567,7 @@ We officially support Python 2.7, 3.4 and above.
 +-----------------+--------------------+
 | mysqlclient     | >= 1.3             |
 +-----------------+--------------------+
-| psycopg2        | >= 2.5             |
+| psycopg2        | >= 2.4             |
 +-----------------+--------------------+
 | pylibmc         | >= 1.4             |
 +-----------------+--------------------+

tests/contrib/psycopg/test_psycopg.py

@@ -6,6 +6,8 @@
 from psycopg2 import _psycopg
 from psycopg2 import extensions
 from psycopg2 import extras
+
+from unittest import skipIf
 from nose.tools import eq_, ok_
 
 # project
@@ -18,6 +20,7 @@
 from tests.test_tracer import get_dummy_tracer
 
 
+PSYCOPG_VERSION = tuple(map(int, psycopg2.__version__.split()[0].split('.')))
 TEST_PORT = str(POSTGRES_CONFIG['port'])
 
 
@@ -84,10 +87,10 @@ def assert_conn_is_traced(self, tracer, db, service):
         eq_(span.meta["out.port"], TEST_PORT)
         eq_(span.span_type, "sql")
 
+    @skipIf(PSYCOPG_VERSION < (2, 5), 'context manager not available in psycopg2==2.4')
     def test_cursor_ctx_manager(self):
         # ensure cursors work with context managers
         # https://github.com/DataDog/dd-trace-py/issues/228
-
         conn, tracer = self._get_conn_and_tracer()
         t = type(conn.cursor())
         with conn.cursor() as cur:
@@ -110,6 +113,7 @@ def test_disabled_execute(self):
         conn.cursor().execute("select 'blah'")
         assert not tracer.writer.pop()
 
+    @skipIf(PSYCOPG_VERSION < (2, 5), '_json is not available in psycopg2==2.4')
     def test_manual_wrap_extension_types(self):
         conn, _ = self._get_conn_and_tracer()
         # NOTE: this will crash if it doesn't work.

tox.ini

@@ -64,7 +64,7 @@ envlist =
     {py27,py34,py35,py36}-pyramid-autopatch{17,18,19}-webtest
     {py27,py34,py35,py36}-requests{208,209,210,211,212,213}
     {py27,py34,py35,py36}-sqlalchemy{10,11}-psycopg2{27}-mysqlconnector{21}
-    {py27,py34,py35,py36}-psycopg2{25,26,27}
+    {py27,py34,py35,py36}-psycopg2{24,25,26,27}
     {py34,py35,py36}-aiobotocore{02,03,04}
     {py34,py35,py36}-aiopg{012,013}
     {py27,py34,py35,py36}-redis{26,27,28,29,210}
@@ -195,6 +195,7 @@ deps =
     pyramid-autopatch17: pyramid>=1.7,<1.8
     pyramid-autopatch18: pyramid>=1.8,<1.9
     pyramid-autopatch19: pyramid>=1.9,<1.10
+    psycopg224: psycopg2>=2.4,<2.5
     psycopg225: psycopg2>=2.5,<2.6
     psycopg226: psycopg2>=2.6,<2.7
     psycopg227: psycopg2>=2.7,<2.8
@@ -265,7 +266,7 @@ commands =
     pyramid{17,18,19}: nosetests {posargs} tests/contrib/pyramid/test_pyramid.py
     pyramid-autopatch{17,18,19}: ddtrace-run nosetests {posargs} tests/contrib/pyramid/test_pyramid_autopatch.py
     mongoengine: nosetests {posargs} tests/contrib/mongoengine
-    psycopg2{25,26,27}: nosetests {posargs} tests/contrib/psycopg
+    psycopg2{24,25,26,27}: nosetests {posargs} tests/contrib/psycopg
     py{34}-aiopg{012,013}: nosetests {posargs} --exclude=".*(test_aiopg_35).*" tests/contrib/aiopg
     py{35,36}-aiopg{012,013}: nosetests {posargs} tests/contrib/aiopg
     redis{26,27,28,29,210}: nosetests {posargs} tests/contrib/redis