Improvements to path watching: set the path earlier, make the test more comprehensive.

gevent/corecffi.py

@@ -1067,19 +1067,29 @@ class stat(watcher):
     _watcher_ffi_cb = "void(*)(struct ev_loop *, struct %s *, int)" % _watcher_type
 
     def __init__(self, _loop, path, interval=0.0, ref=True, priority=None):
-        self.path = path
-        watcher.__init__(self, _loop, ref=ref, priority=priority, args=(path, interval))
-        # XXX: self._watcher.path is not getting properly set at the C level
-        # (Possibly because ev_stat_init is actually a macro? I don't know)
-        # Something overwrites it or fails to set it. We reset it in start() method
+        if not isinstance(path, bytes):
+            # XXX: Filesystem encoding? Python itself has issues here, were they fixed?
+            path = path.encode('utf-8')
+
+        watcher.__init__(self, _loop, ref=ref, priority=priority,
+                         # cffi doesn't automatically marshal byte strings to
+                         # char* in the function call; instead it passes an
+                         # empty string or garbage pointer. If the watcher's
+                         # path is incorrect, watching silently fails
+                         # (the underlying call to lstat() keeps erroring out)
+                         args=(ffi.new('char[]', path),
+                               interval))
 
     def start(self, callback, *args):
-        self._watcher.path = ffi.new("char[]", self.path)
         watcher.start(self, callback, *args)
 
     def stop(self):
         watcher.stop(self)
 
+    @property
+    def path(self):
+        return ffi.string(self._watcher.path)
+
     @property
     def attr(self):
         if not self._watcher.attr.st_nlink:

greentest/test__core_stat.py

@@ -23,7 +23,14 @@ try:
         f.close()
 
     greenlet = gevent.spawn_later(DELAY, write)
-    watcher = hub.loop.stat(filename)
+    # If we don't specify an interval, we default to zero.
+    # libev interprets that as meaning to use its default interval,
+    # which is about 5 seconds. If we go below it's minimum check
+    # threshold, it bumps it up to the minimum.
+    watcher = hub.loop.stat(filename, interval=-1)
+    if hasattr(watcher, 'path'):
+        assert watcher.path == filename
+    assert watcher.interval == -1
 
     start = time.time()
 
@@ -37,6 +44,8 @@ try:
     assert reaction >= 0.0, 'Watcher %s reacted too early (write): %.3fs' % (watcher, reaction)
     assert watcher.attr is not None, watcher.attr
     assert watcher.prev is not None, watcher.prev
+    # The watcher interval changed after it started; -1 is illegal
+    assert watcher.interval != -1
 
     greenlet.join()
     gevent.spawn_later(DELAY, os.unlink, filename)