*: threading.Lock -> sync.Mutex

Similarly to 78d85cdc (sync: threading.Event -> chan) replace everywhere
threaing.Lock usage with sync.Mutex . This brings 2 goods:

- sync.Mutex becomes more well tested;
- we untie ourselves from threading python module (threading.Lock was
  the last user).

golang/context.py

@@ -28,8 +28,8 @@ See the following links about Go contexts:
 from __future__ import print_function, absolute_import
 
 from golang import go, chan, select, default, nilchan
+from golang import _sync # avoid cycle: context -> sync -> context
 from golang import time
-import threading
 
 # Context is the interface that every context must implement.
 #
@@ -154,7 +154,7 @@ class _BaseCtx(object):
         # does not change after setup.
         ctx._parentv    = parentv
 
-        ctx._mu         = threading.Lock()
+        ctx._mu         = _sync.PyMutex()
         ctx._children   = set() # children of this context - we propagate cancel there (all _BaseCtx)
         ctx._err        = None
 

golang/golang_test.py

@@ -21,9 +21,10 @@
 from __future__ import print_function, absolute_import
 
 from golang import go, chan, select, default, nilchan, _PanicError, func, panic, defer, recover
+from golang import sync
 from pytest import raises
 from os.path import dirname
-import os, sys, threading, inspect, importlib
+import os, sys, inspect, importlib
 from subprocess import Popen, PIPE
 from six.moves import range as xrange
 import gc, weakref
@@ -106,7 +107,7 @@ def test_chan():
     # sync: close vs multiple recv
     ch = chan()
     done = chan()
-    mu = threading.Lock()
+    mu = sync.Mutex()
     s  = set()
     def _():
         assert ch.recv_() == (None, False)

golang/sync.py

@@ -26,7 +26,7 @@ See the following link about Go sync package:
 
 from __future__ import print_function, absolute_import
 
-import threading, sys
+import sys
 from golang import go, chan, defer, func, panic
 from golang import context
 
@@ -46,7 +46,7 @@ from golang._sync import \
 #   once.do(doSomething)
 class Once(object):
     def __init__(once):
-        once._mu    = threading.Lock()
+        once._mu    = Mutex()
         once._done  = False
 
     def do(once, f):
@@ -59,7 +59,7 @@ class Once(object):
 # WaitGroup allows to wait for collection of tasks to finish.
 class WaitGroup(object):
     def __init__(wg):
-        wg._mu      = threading.Lock()
+        wg._mu      = Mutex()
         wg._count   = 0
         wg._done    = chan()    # closed & recreated every time ._count drops to 0
 
@@ -113,7 +113,7 @@ class WorkGroup(object):
     def __init__(g, ctx):
         g._ctx, g._cancel = context.with_cancel(ctx)
         g._wg   = WaitGroup()
-        g._mu   = threading.Lock()
+        g._mu   = Mutex()
         g._err  = None
 
     def go(g, f, *argv, **kw):

golang/sync_test.py

@@ -22,7 +22,6 @@ from __future__ import print_function, absolute_import
 
 from golang import go, chan
 from golang import sync, context, time
-import threading
 from pytest import raises
 from golang.golang_test import import_pyx_tests, panics
 from golang.time_test import dt
@@ -145,7 +144,7 @@ def test_waitgroup():
 
 def test_workgroup():
     ctx, cancel = context.with_cancel(context.background())
-    mu = threading.Lock()
+    mu = sync.Mutex()
 
     # t1=ok, t2=ok
     wg = sync.WorkGroup(ctx)

golang/time.py

@@ -27,7 +27,7 @@ See the following link about Go time package:
 from __future__ import print_function, absolute_import
 
 from golang import go, chan, select, default, nilchan, panic
-import threading
+from golang import _sync # avoid cycle: context -> time -> sync -> context
 
 from golang._time import \
     pysecond        as second,      \
@@ -77,7 +77,7 @@ class Ticker(object):
             panic("ticker: dt <= 0")
         self.c      = chan(1)   # 1-buffer -- same as in Go
         self._dt    = dt
-        self._mu    = threading.Lock()
+        self._mu    = _sync.PyMutex()
         self._stop  = False
         go(self._tick)
 
@@ -119,7 +119,7 @@ class Timer(object):
     def __init__(self, dt, f=None):
         self._f     = f
         self.c      = chan(1) if f is None else nilchan
-        self._mu    = threading.Lock()
+        self._mu    = _sync.PyMutex()
         self._dt    = None  # None - stopped, float - armed
         self._ver   = 0     # current timer was armed by n'th reset
         self.reset(dt)