From 182a979e717b2482d8194095c3232bf7eefe24d1 Mon Sep 17 00:00:00 2001
From: Julien Duponchelle <julien@duponchelle.info>
Date: Fri, 10 Jun 2016 17:51:19 +0200
Subject: [PATCH] Generic class for watch file change

---
 gns3server/config.py             | 25 ++++--------
 gns3server/utils/file_watcher.py | 68 ++++++++++++++++++++++++++++++++
 tests/utils/test_file_watcher.py | 46 +++++++++++++++++++++
 3 files changed, 122 insertions(+), 17 deletions(-)
 create mode 100644 gns3server/utils/file_watcher.py
 create mode 100644 tests/utils/test_file_watcher.py

diff --git a/gns3server/config.py b/gns3server/config.py
index bd47931d..63516d95 100644
--- a/gns3server/config.py
+++ b/gns3server/config.py
@@ -24,6 +24,8 @@ import os
 import configparser
 import asyncio
 
+from .utils.file_watcher import FileWatcher
+
 import logging
 log = logging.getLogger(__name__)
 
@@ -100,24 +102,13 @@ class Config(object):
         self.read_config()
 
     def _watch_config_file(self):
-        asyncio.get_event_loop().call_later(1, self._check_config_file_change)
+        for file in self._files:
+            self._watched_files[file] = FileWatcher(file, self._config_file_change)
 
-    def _check_config_file_change(self):
-        """
-        Check if configuration file has changed on the disk
-        """
-        changed = False
-        for file in self._watched_files:
-            try:
-                if os.stat(file).st_mtime != self._watched_files[file]:
-                    changed = True
-            except OSError:
-                continue
-        if changed:
-            self.read_config()
-            for section in self._override_config:
-                self.set_section_config(section, self._override_config[section])
-        self._watch_config_file()
+    def _config_file_change(self, path):
+        self.read_config()
+        for section in self._override_config:
+            self.set_section_config(section, self._override_config[section])
 
     def reload(self):
         """
diff --git a/gns3server/utils/file_watcher.py b/gns3server/utils/file_watcher.py
new file mode 100644
index 00000000..0ca7c101
--- /dev/null
+++ b/gns3server/utils/file_watcher.py
@@ -0,0 +1,68 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2016 GNS3 Technologies Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import asyncio
+import os
+
+
+class FileWatcher:
+    """
+    Watch for file change and call the callback when something happen
+    """
+    def __init__(self, path, callback, delay=1):
+        if not isinstance(path, str):
+            path = str(path)
+        self._path = path
+        self._callback = callback
+        self._delay = delay
+        self._closed = False
+
+        try:
+            self._mtime = os.stat(path).st_mtime
+        except OSError:
+            self._mtime = None
+        asyncio.get_event_loop().call_later(self._delay, self._check_config_file_change)
+
+    def __del__(self):
+        self._closed = True
+
+    def close(self):
+        self._closed = True
+
+    def _check_config_file_change(self):
+        if self._closed:
+            return
+        changed = False
+        try:
+            if os.stat(self._path).st_mtime != self._mtime:
+                changed = True
+                self._mtime = os.stat(self._path).st_mtime
+        except OSError:
+            self._mtime = None
+        if changed:
+            self._callback(self._path)
+        asyncio.get_event_loop().call_later(self._delay, self._check_config_file_change)
+
+    @property
+    def callback(self):
+        return self._callback
+
+    @callback.setter
+    def callback(self, val):
+        self._callback = val
+
+
diff --git a/tests/utils/test_file_watcher.py b/tests/utils/test_file_watcher.py
new file mode 100644
index 00000000..84e86bc6
--- /dev/null
+++ b/tests/utils/test_file_watcher.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2016 GNS3 Technologies Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import asyncio
+from unittest.mock import MagicMock
+
+
+from gns3server.utils.file_watcher import FileWatcher
+
+
+def test_file_watcher(async_run, tmpdir):
+    file = tmpdir / "test"
+    file.write("a")
+    callback = MagicMock()
+    fw = FileWatcher(file, callback, delay=0.5)
+    async_run(asyncio.sleep(1))
+    assert not callback.called
+    file.write("b")
+    async_run(asyncio.sleep(1.5))
+    callback.assert_called_with(str(file))
+
+
+def test_file_watcher_not_existing(async_run, tmpdir):
+    file = tmpdir / "test"
+    callback = MagicMock()
+    fw = FileWatcher(file, callback, delay=0.5)
+    async_run(asyncio.sleep(1))
+    assert not callback.called
+    file.write("b")
+    async_run(asyncio.sleep(1.5))
+    callback.assert_called_with(str(file))
+