Move DD code into its own directory (#6)

reference/ddtrace/contrib/mysqldb/__init__.py

@@ -0,0 +1,38 @@
+"""Instrument mysqlclient / MySQL-python to report MySQL queries.
+
+``patch_all`` will automatically patch your mysql connection to make it work.
+
+::
+
+    # Make sure to import MySQLdb and not the 'connect' function,
+    # otherwise you won't have access to the patched version
+    from ddtrace import Pin, patch
+    import MySQLdb
+
+    # If not patched yet, you can patch mysqldb specifically
+    patch(mysqldb=True)
+
+    # This will report a span with the default settings
+    conn = MySQLdb.connect(user="alice", passwd="b0b", host="localhost", port=3306, db="test")
+    cursor = conn.cursor()
+    cursor.execute("SELECT 6*7 AS the_answer;")
+
+    # Use a pin to specify metadata related to this connection
+    Pin.override(conn, service='mysql-users')
+
+This package works for mysqlclient or MySQL-python. Only the default
+full-Python integration works. The binary C connector provided by
+_mysql is not yet supported.
+
+Help on mysqlclient can be found on:
+https://mysqlclient.readthedocs.io/
+"""
+from ...utils.importlib import require_modules
+
+required_modules = ['MySQLdb']
+
+with require_modules(required_modules) as missing_modules:
+    if not missing_modules:
+        from .patch import patch
+
+        __all__ = ['patch']

reference/ddtrace/contrib/mysqldb/patch.py

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+# 3p
+import MySQLdb
+
+from ddtrace.vendor.wrapt import wrap_function_wrapper as _w
+
+# project
+from ddtrace import Pin
+from ddtrace.contrib.dbapi import TracedConnection
+
+from ...ext import net, db
+from ...utils.wrappers import unwrap as _u
+
+KWPOS_BY_TAG = {
+    net.TARGET_HOST: ('host', 0),
+    db.USER: ('user', 1),
+    db.NAME: ('db', 3),
+}
+
+
+def patch():
+    # patch only once
+    if getattr(MySQLdb, '__datadog_patch', False):
+        return
+    setattr(MySQLdb, '__datadog_patch', True)
+
+    # `Connection` and `connect` are aliases for
+    # `Connect`; patch them too
+    _w('MySQLdb', 'Connect', _connect)
+    if hasattr(MySQLdb, 'Connection'):
+        _w('MySQLdb', 'Connection', _connect)
+    if hasattr(MySQLdb, 'connect'):
+        _w('MySQLdb', 'connect', _connect)
+
+
+def unpatch():
+    if not getattr(MySQLdb, '__datadog_patch', False):
+        return
+    setattr(MySQLdb, '__datadog_patch', False)
+
+    # unpatch MySQLdb
+    _u(MySQLdb, 'Connect')
+    if hasattr(MySQLdb, 'Connection'):
+        _u(MySQLdb, 'Connection')
+    if hasattr(MySQLdb, 'connect'):
+        _u(MySQLdb, 'connect')
+
+
+def _connect(func, instance, args, kwargs):
+    conn = func(*args, **kwargs)
+    return patch_conn(conn, *args, **kwargs)
+
+
+def patch_conn(conn, *args, **kwargs):
+    tags = {t: kwargs[k] if k in kwargs else args[p]
+            for t, (k, p) in KWPOS_BY_TAG.items()
+            if k in kwargs or len(args) > p}
+    tags[net.TARGET_PORT] = conn.port
+    pin = Pin(service='mysql', app='mysql', tags=tags)
+
+    # grab the metadata from the conn
+    wrapped = TracedConnection(conn, pin=pin)
+    pin.onto(wrapped)
+    return wrapped