Used time.monotonic() instead of time.time() where applicable.

time.monotonic() available from Python 3.3:

- Nicely communicates a narrow intent of "get a local system monotonic
  clock time" instead of possible "get a not necessarily accurate Unix
  time stamp because it needs to be communicated to outside of this
  process/machine" when time.time() is used.
  
- Its result isn't affected by the system clock updates.

There are two classes of time.time() uses changed to time.monotonic()
by this change:

- measuring time taken to run some code.

- setting and checking a "close_at" threshold for for persistent db
  connections (django/db/backends/base/base.py).

django/db/backends/base/base.py

@@ -187,7 +187,7 @@ class BaseDatabaseWrapper:
         self.needs_rollback = False
         # Reset parameters defining when to close the connection
         max_age = self.settings_dict['CONN_MAX_AGE']
-        self.close_at = None if max_age is None else time.time() + max_age
+        self.close_at = None if max_age is None else time.monotonic() + max_age
         self.closed_in_transaction = False
         self.errors_occurred = False
         # Establish the connection
@@ -510,7 +510,7 @@ class BaseDatabaseWrapper:
                     self.close()
                     return
 
-            if self.close_at is not None and time.time() >= self.close_at:
+            if self.close_at is not None and time.monotonic() >= self.close_at:
                 self.close()
                 return
 

django/db/backends/utils.py

@@ -3,8 +3,8 @@ import decimal
 import functools
 import hashlib
 import logging
+import time
 from contextlib import contextmanager
-from time import time
 
 from django.conf import settings
 from django.db.utils import NotSupportedError
@@ -105,11 +105,11 @@ class CursorDebugWrapper(CursorWrapper):
 
     @contextmanager
     def debug_sql(self, sql=None, params=None, use_last_executed_query=False, many=False):
-        start = time()
+        start = time.monotonic()
         try:
             yield
         finally:
-            stop = time()
+            stop = time.monotonic()
             duration = stop - start
             if use_last_executed_query:
                 sql = self.db.ops.last_executed_query(self.cursor, sql, params)